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BeagleBone Black Cookbook

1. How to do it See also How to do it There s more How to do it There s more See also Programmable real time units an introduction How to do it See also How to do it How to do it How to do it 8 The Internet of Things Introduction Location based recipes hooking up GPS cipes Bluetooth LE and Beacons There s more How to do it There s more sing GPredict and RTL SDR There s more BeagleBone Black Cookbook BeagleBone Black Cookbook Copyright O 2015 Packt Publishing All rights reserved No part of this book may be reproduced stored in a retrieval system or transmitted in any form or by any means without the prior written permission of the publisher except in the case of brief quotations embedded in critical articles or reviews Every effort has been made in the preparation of this book to ensure the accuracy of the information presented However the information contained in this book is sold without warranty either express or implied Neither the author nor Packt Publishing and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals However Packt Publ
2. e RT PREEMPT o used for modifying kernel Modifying the kernel using Xenomai How to do it There s more e RTL SDR O O O O used for tracking Tracking using RTL SDR See also URL See also used for airplane tracking Airplane tracking with RTL SDR How to do it used for satellite tracking Satellite tracking using GPredict and RTL SDR How to do it S e satellite tracker o about Satellite tracking using GPredict and RTL SDR e satellite tracking o GPredict used Satellite tracking using GPredict and RTL SDR Getting ready How to do it o RTL SDR used Satellite tracking using GPredict and RTL SDR Getting ready How to do it Satellite tracking using the SatNogs Network client ground station and RTL SDR Getting ready How to do it o SatNogs Network client used Satellite tracking dicing the SatNogs Network client ground station and RTL SDR How to do it o ground station used Satellite tracking using the SatNogs Network client ground station and RTL SDR Getting ready How to do it e SatNogs Network client o used for satellite tracking Satellite tracking using the SatNogs Network client ground station and RTL SDR How to do it e script o running to check DT usage on GPIO pins Running a script to check DT usage on GPIO pins How to do it e sensors o using with ThingSpeak Using sensors and data with ThingSpeak How to do ore e Serial Peri
3. 4 ff P O L Bone LT eMMC 2G 00A0 Texas Instrument BB BONE EMMC 2G 5 ff P 0 Bone Black HDMI 00A0 Texas Instrument BB BONELT HDMI 6 ff P O L Bone Black HDMIN 00A0 Texas Instrument BB BONELT HDMIN 7 ff P O L Override Board Name 00A0 Override Manuf BB BONE AUDI 02 13 14 15 You should see in the last line our AUDI 02 device now enabled So let s test the default audio output first For this use the following command speaker test You should hear white noise playing To quit press Ctrl c Note Avoid using Ctrl z as the process will likely not end gracefully and prevent you from running additional tests on the cape Finally we can optionally test the input and the output This assumes that you have a microphone plugged into the input jack on the cape or a USB mic via the USB port First capture an audio sample using the following command arecord D default CARD devicename r 44100 c 1 f S16_LE t wav vv d 10 example wav Then play it back by simply using aplay example wav There s more Once you get the cape working you will probably find that audio levels are too low So we need to adjust this with the following commands using an installed audio application called amixer which is part of Advanced Linux Sound Architecture ALSA s utilities toolset ALSA is the multifaceted layer that connects to the kernel and provides audio functionality to user space amixer set PCM 5
4. cat sys devices bone_capemgr 9 slots 0 54 PF 55 PF 56 PF 57 PF ff P O L Bone LT eMMC 2G 00A0 Texas Instrument BB BONE EMMC 2G Ff P O L Bone Black HDMI 00A0 Texas Instrument BB BONELT HDMI ff P O L Override Board Name 00A0 Override Manuf BB UART4 ff P O L Override Board Name 00A0 Override Manuf BB BONE PRU 01 ONO RWN EE A new overlay should appear in the last slot namely BB BONE PRU 01 Your slot number for the PRU may differ according to other drivers and daughterboards you already have loaded Note If you ran the universal I O device tree recipe in our prior chapter you may get the following error bash echo write error File exists If so don t despair All this means is that universal I O properly loaded your PRU device tree already So you re good to go Run an additional command 1smod which shows all modules loaded into the kernel We want to confirm that the uio_pruss driver connected properly since it is the module that opens a gate between user space applications and the PRU allowing them to speak to one another lsmod Module Size Used by uio_pruss 4066 0 g_multi 50407 2 libcomposite 15028 1 g_multi 8192cu 449033 0 omap_rng 4062 0 mt7601Usta 601404 0 To be safe we should also run dmesg in order to peek at the kernel messages and see if any other errors occurred Add the options pipe and less so you don t get one big output dump on the screen
5. explore network Ifconfig How to do it Device Tree O O 0 0 about Device Tree and its roots benefits Device Tree and its roots basic build Device Tree basic build How to do it overlay adding to run custom cape Device Tree advanced adding DT overlay to run a custom cape Getting ready How to do it See also Device Tree Blob DTB Device Tree and its roots Diamond Antenna o URL Getting ready Digital Musical Instruments DMIs See also Digital to Analog Converter DAC o URL Wiring up a mini amp and speakers Docker o URL See also dongles o URL See also Dropbox o URL Getting ready Dweet io Freeboard o URL See also E Speak o URL There s more Eclipse o application debugging remotely Debug an application remotely from Eclipse and GDB server How to do it electronics o about The essentials of electronics Eric Steven Raymond ESR See also Estimote teardown o URL There s more Evothings Studio o URL How to do it external LEDs o controlling Controlling external LEDs How to do it GDB o used for debugging C code application from command line Debug a simple C code application from the command line using GDB How to do it See also General Purpose In Out GPIO o about Introduction to BoneScript Git o compile and install from source How to do it GNU Linux commands o command shell Essential GNU Linux c
6. python c import bbio as GPIO print GPIO If all went as hoped with the installation your output should look similar to this PyBBIO initialized lt module bbio from usr local lib python2 7 dist packages PyBBIO 0 9 4 py2 7 linux armv71 egg bbio _ init_ pyc gt Finished PyBBIO cleanup Running a Python script to control the LEDs In the next chapter we ll look at more robust ways to begin using the GPIO pin library In the meantime let s wrap up by doing an on board LED blink similar to the recipe we did earlier in the chapter However instead of BoneScript we ll do a variation of the recipe in Python and specifically pull on the PyBBIO library s functionality This recipe will work on both Debian Wheezy and Jessie How to do it Perform the following steps to run Python scripts to control LEDs 1 Open up LX Terminal 2 Create a python project directory within the bbb_recipe_book directory and navigate to it as follows mkdir python cd bbb_recipe book projects python 3 Create a new Python file using the following code note the py file format sudo nano major_tom_blinks py 4 Copy and paste the following code into the window usr bin python Blinks one of the Beaglebone Black s on board LEDs until CTRL C is pressed These LEDs include USRO USR1 USR2 USR3 Import PyBBIO library from bbio import import the time module which allows us to set the timing for a loop event import time
7. Create variable called ledPin which refers to one of the designated onboard USR LEDs You can change the number to any of the USR LEDs listed above ledPin USR3 Create a setup function def setup Set one of the USR LEDs as output pinMode ledPin OUTPUT Set up a loop and the blink timing to two second intervals while True Start the pin state at LOW off digitalWrite ledPin LOW Hold this state for 2 seconds time sleep 2 Change the pin state to HIGH on digitalWrite ledPin HIGH time sleep 2 Note If you run into problems copying and pasting the code you can download the code from https github com HudsonWerks Python examples blob master major_tom_blinks py 5 Run this script sudo python major_tom_blinks py 6 The on board USR3 LED should now be blinking at regular 2 second intervals 7 To quit the script press Ctrl z on your keyboard There s more Python is a big subject and the web is jammed with great resources to learn it more deeply Here is a small select sample of starting points to teach yourself Python e MIT s online course is on demand free and taught by one of their computer science department s favorite teachers Prof John Guttag You can find it at https www edx org course introduction computer science mitx 6 00 1x 5 e Coursera has several strong online courses Most of their courses are not available on demand but for specific schedules throughou
8. If you have any problems logging in and you are on your own local LAN you can also do the following ssh root volumio local Check that you have a solid internet connection from either your SSH remote session or directly on the BBB by typing in ping www google com Your screen output should show stable ping responses If it does not you may need to reboot and repeat steps 7 through 10 To quit the ping command remember to press Ctrl C on your keyboard We are not quite ready to play your fabulous music library but we can do a test to get a quick feel good hit So open up a browser on your desktop client and type in the address http volumio local Voila A fancy GUI with all kinds of knobs buttons and sliders appears Tip One of the appealing things about Volumio is that its main controller is a web based open source UI and not a bloated proprietary piece of software This means that with a touch of HTML and a dash of jQuery you can mod your own controller UI In the GUI click on Browse WEBRADIO You will see a list of streaming radio stations that came preloaded with the install Let s choose one that has a reliably consistent streaming URL the Beeb which is also known as BBC World Radio After clicking twice on the link the mellifluous sounds of a British newscaster will pour from your speakers 11 12 13 14 15 16 17 18 19 Note You may find that many
9. In the following illustration the image on the left hand side shows the voltage flowing across s1 and s4 for one motor direction and on the right hand side across s2 and s3 for the reverse direction In our recipe s code we will only turn the motor in one direction so the voltage will only flow across one bridge circuit as shown in the following image Y Q Note The preceding image has been taken from Wikipedia The H bridge controller has 16 pins for interfacing although only a few of them are used in our recipe 1 2EN 1 161 Vcc 1A 2 151 4A 1Y 3 141 4Y HEAT SINK AND J 131 L HEAT SINK AND GROUND 121 J GROUND 2Y 6 11 3Y 2A 7 10 3A Voce U 8 91 3 4EN Pin outs on H bridge 2 DC power Instead of powering from the BBB directly we offload the power for the motor to a separate 9V battery source This both ensures a reliable and consistent voltage to the motor and removes any possibility of damaging the board Servo motors For those new to servomechanisms commonly referred to as servos it may be useful to understand the basics of the device because the ingredients in the recipe reveal the unique nature of this type of motor Servos are typically used as actuators in embedded electronics scenarios such as CNC machinery robotics and automated manufacturing and even for radio controlled toys For their size these motors are incredibly powerful deliver a considerable torque a
10. This is sold by Adafruit as the same product as 1 however there seems to be some difference since a powered USB is not required The board may freeze up without using a powered USB May also need to reboot and run Use the reset S1 button to get a connection Pe Be PR poa USB Logic UWN200 Supply Ralink MediaTekMT7601 powered USB This uses antennae Note UWN200 is not tested by the author but cited by the BBB Google forum posters as a compatible dongle with possibly superior performance given the antenna addition How to do it Method one Graphical desktop application In lieu of the command line the current distribution of Debian 7 3 8 13 bone71 Wheezy includes a handy graphical tool Wicd Network Manager to set up Wi Fi This recipe is quite simple 1 2 2 Power up your BBB via 5V DC Log in to a desktop session In the lower left hand corner of your screen click on the bird like icon and then navigate to Internet Wicd Network Manager In the newly opened window of the application click on the Switch On Wi Fi button The dongle will now begin scanning for accessible networks Wicd Network Manager 54 Network Switch Off Wi Fi E Disconnect All Refresh 716 Preferences wW Choose from the networks below TWCWiFi Passpoint 100 WPA2 Channel 8 Automatically connect to this network u Never connect to this network 115 1 Connect P Properties
11. cd NowPix 1s 4 Assuming that your script executed properly and the images were downloaded to the right directory we now need to set up a process in order for the script to run transparently so that you don t have to run it each time you want to download images To perform this we will set up a cron job that automatically runs the script at specified intervals We will begin this part by opening crontab in our default editor with the following command crontab e The e option tells the shell to open our default editor which in our case is nano Note You should take note of these comments from the original script developer Running as cron job Dropbox Uploader relies on a different configuration file for each system user The default configuration file location is HOME_DIRECTORY dropbox_uploader This means that if you do the setup with your user and then try to run a cron job as root it will not work So when you run this script using cron keep the following things in mind Remember to set up the script that the user used to run the cron job Always use the f option to specify the full configuration file path because sometimes in the cron environment the home folder path is not detected correctly For security reasons I recommend you to not share the same configuration file with different users Add the following code to the end of the file that opens on your screen 3 home debian Dropbox Uploader
12. print gpsd fix latitude gpsd fix longitude Time gpsd utc If you find the output overwhelming you can always modify the print commands to simplify the display as follows print print GPS reading print print latitude gpsd fix latitude print longitude gpsd fix longitude print time utc gpsd utc gpsd fix time print altitude m gpsd fix altitude print eps gpsd fix eps print epx gpsd fix epx print epv gpsd fix epv print ept f gpsd fix ept print speed m s gpsd fix speed print climb gpsd fix climb print track gpsd fix track print mode gpsd fix mode print print sats gpsd satellites time sleep 5 4 Now close the script and run the following command python GPStest1 py In a few seconds the nicely formatted GPS data will be displayed in your terminal window There s more e Sparkfun s tutorial on GPS is definitely worth the read at https learn sparkfun com tutorials gps basics all e For further GPSD troubleshooting refer to http www catb org gpsd troubleshooting html Location based recipes Bluetooth LE and Beacons In the past you may have had the opportunity to use Bluetooth devices in your projects However in all probability that would have been an earlier version of BT now commonly referred to as classic Bluetooth Before we jump into an
13. BeagleBone Black Cookbook E VAF en rr Alm S F Al tji mm FA E ALS tare rial ro mn j nfa 2 El Ju ERAS a A A A a a JL IMEI il are A 0 EL A engineers to create projects using the BeagleBone Black BeagleBone Black Cookbook Table of Contents BeagleBone Black Cookbook Credits About the Author About the Reviewers www PacktPub com Support files eBooks discount offers and more Why Subscribe Free Access for Packt account holders Preface What this book covers What you need for this book Who this book is for Sections Getting ready How to do it How it works There s more See also Conventions Reader feedback Customer support Downloading the example code Downloading the color images of this book Errata Piracy Questions 1 Setting Up for the First Time Introduction First boot up System navig How to do it There s more System navigational command show your current director How to do it System navigational command find a file find How to do it Device and system insight shows what s inside a directory Is How to do it Device and system insight find out what USB devices are connected lsusb How to do it Device and system insight get information about connected devices cat proc bus input devices How to do it There s more How to do it Device and system insight
14. Install drivers I won t belabor this step It suffices to say that your desktop whether it s a Windows Mac or Linux machine requires certain drivers to recognize and run the BBB via USB properly If your desktop OS doesn t come with the drivers already installed as some do install them via the link http beagleboard org Getting Started Once your drivers are installed browse to the BASIC_START htm file on the BEAGLE_BONE device and open it If the planets are aligned and the drivers are installed properly you will see the following at the top of the browser window Your board is connected BeagleBone Black rev 0A5C S N xxxxxxxxxxxx running BoneScript 1 2 3 at 192 168 7 2 At this point you re ready to fly at least at low altitude With a co pilot on an emulator Power requirements basic guidelines Giving your BBB the proper amount of love and power is crucial to having a happy board Following these basic guidelines will ensure that your BBB operates reliably and predictably The board s user manual recommends that you supply current to at least 1 2A or 6W However if you connect up anything over the USB at least 2A or 10W is recommended Here are some additional rules of thumb e You can power the BBB via the USB tether However if you attach additional USB devices such as webcams Wi Fi or Bluetooth dongles keyboards and mice and then power them through the USB tether it may lead to un
15. On your smartphone shoot a photograph with a camera app Save the photo to a custom album on your phone that you need to create Name it NowPix Set up the IFTTT trigger on your phone to send the saved album file to Dropbox Setting up and testing the Dropbox script on the BBB Perform the following steps 1 If you do not already have a Dropbox account sign up for a free account at https www dropbox com home Download and install a custom bash script called Dropbox Uploader This is a wonderfully useful open source tool created by developer Andrea Fabrizi The script provides an easy method to interact directly with the Dropbox s API authentication process so providing your username and password is not necessary Now make sure that you are in your home directory cd Then clone the Dropbox Uploader code using the following command git clone https github com andreafabrizi Dropbox Uploader Make sure that the directory was created as shown in the following command cd Dropbox Uploader Set permissions with the following command chmod x dropbox_uploader sh dropbox_uploader sh Then run the script as follows Dropbox Uploader dropbox_uploader sh You should see the screen output with a set of instructions This is the first time you run this script Back to your desktop client Before responding to the terminal prompts you will now need to set up a Dropbox App via your
16. Source Charles Steinkuehler and his MachineKit LinuxCNC milling machine use cases Typical latency with a Xenomai patched kernel for the BBB is about 25 uS with worst case around 70 80 uS Note For more information refer to http www embedded com design operating svstems 4204740 Getting real time about embedded GNU Linux Installing a test tool Before we can convert our BeagleBone Black to a blazing real time wonder we need a way to measure latency in the Linux kernel A popular tool for this purpose is cyclictest Cylictest measures the amount of time that passes between when a timer expires and when the thread that set the timer actually runs It uses time snapshots one just before a specific time interval t1 then another one just after the timer finishes t2 We can then compare these two snapshot values to pinpoint excessive latency sources within the kernel Getting ready The usual minimal setup is all you need a BBB powered over mini USB with Internet connectivity enabled How to do it Cyclictest isn t available as a prebuilt binary So we will have to compile it from source 1 Log in as root sudo i 2 Go get the source files for cyclictest git clone git git kernel org pub scm linux kernel git cirkwllms rt tests git 3 Navigate to the new directory that git creates cd rt tests 4 Compile that baby make all 5 Make a copy of the binary in the usr bin directory so you can
17. The sample code runs and you get an error Symbol EXIT_SUCCESS could not be resolved Aaargh The error says that some C code symbols cannot be resolved by the compiler Not to worry though This error can be ignored because according to the Eclipse documentation it is inaccurate and does not affect the successful operation of the application Now we will build the project On the Eclipse main menu select Project Build All Then open the Console window to see the build output messages You should see the compiler prefix being used for the gcc compiler as follows 00 24 52 Build of configuration Debug for project bbb_ground_control make all Building file src bbb_ground_control cInvoking Cross GCC Compilerarm linux gnueabihf gcc 00 g3 Wall c fmessage length 0 MMD MP MF src bbb_ground_control d MT src bbb_ground_control d o src bbb_ground_control o src bbb_ground_control c Finished building src bbb_ground_control c Building target bbb_ground_control Invoking Cross GCC Linkerarm linux gnueabihf gcc o bbb_ground_control src bbb_ground_control o Finished building target bbb_ground_control 00 24 52 Build Finished took 172ms For the Eclipse remote connection setup on the main menu click on Run Run Configurations Select C C Remote Application Click twice on this to open another dialog window A drop down option should show bbb_Hello_World Debug Click on the New button in the mi
18. dmesg less Scroll through the output by tapping the spacebar at the bottom of the terminal screen until you start seeing output for bone capemgr bone_capemgr 9 Keep advancing to the next screen until you begin to see the following 2268 218496 bone capemgr bone_capemgr 9 part_number BB BONE PRU 01 version N A 2268 218670 bone capemgr bone_capemgr 9 slot 8 generic override 2268 218713 bone capemgr bone_capemgr 9 bone Using override eeprom data at slot 8 2268 218761 bone capemgr bone_capemgr 9 slot 8 Override Board Name 00A0 Override Manuf BB BONE PRU 01 2268 219031 bone capemgr bone_capemgr 9 slot 8 Requesting part number version based BB BONE PRU 01 00A0 dtbo 2268 219079 bone capemgr bone_capemgr 9 slot 8 Requesting firmware BB BONE PRU 01 00A0 dtbo for board name Override Board 10 Name version 00A0 2268 219140 bone capemgr bone_capemgr 9 slot 8 dtbo BB BONE PRU 01 00A0 dtbo loaded converting to live tree 2268 219821 bone capemgr bone_capemgr 9 slot 8 2 overlays 2268 241573 omap_hwmod pruss failed to hardreset 2268 248299 bone capemgr bone_capemgr 9 slot 8 Applied 2 overlays Before moving on to an actual test application we should add an additional ingredient to make our preceding echo command stick Although this step is optional you should still go through the process of doing it so that when we reboot we will not lose the loaded DT f
19. similar to the ones in the following screenshot Poccnn India um TH Indonesia Featured Ground Station Hackerspace gr 1 Owner John Giannelos 23 73 38 02 Antennas UHF yagi Canada United States M xico Latest Observations Satellite mis B FUNCUBE 1 AO 73 ISS ZARYA ISS ZARYA ISS ZARYA FUNCUBE 1 AO 73 Scheduled Observations Frequency 145 815 Mhz 145 800 Mhz 145 825 Mhz 145 800 Mhz 145 815 Mhz Encoding cw FM FM FM cw Ground stations swarm control at your fingertips NA Timeframe 2015 08 12 08 00 00 2015 08 12 10 32 00 2015 08 11 17 18 00 2015 08 11 18 18 00 2015 08 09 21 34 00 2015 08 09 23 53 00 2015 08 08 15 00 00 2015 08 08 20 00 00 2015 08 08 07 05 00 2015 08 08 08 05 00 Now the next time you reboot or shut down the server and the virtualenv environment and want to run SatNogs again just jump right to the following three main steps and you will be off to the races cd satnogs network workon satnogs network sudo manage py runserver your_ip_address 8000 Poccua MN India Observer Robert OE6RKE Robert OEGRKE Robert OE6RKE Robert OE6RKE Robert OE6RKE Adding other interfaces ISS tracking and text to speech It s time to make the dog talk Or at least make BeagleBone Black a little more verbal Here we will show you the ingredients to have the board
20. 12 We will first install Eclipse on our VM with the following code root debian sudo apt get install eclipse eclipse cdt Then open Eclipse and set up a workspace by closing the welcome screen and navigating to Window Show view C C Projects Create anew C project by navigating to File New C Project Give the project aname bbb_ground_control Select Project type Hello World ANSI C Project Then select Toolchain Cross GCC and click on Next Enter the basic settings such as the author name in the next window Click on Next to bring up the Select Configurations window Now click on the Advanced settings to bring up a Properties window From the left hand side navigate to C C Build Settings to bring up Tool Settings for the Debug configuration Choose the Tool Settings tab then fill the Prefix and Path fields in the following manner Prefix arm 1inux gnueabihf Note Be sure to include the hyphen at the end of the preceding prefix Path home user bbb tools gec linaro arm linux gnueabihf 4 8 2013 10_linux bin Then click on OK This brings up another C Project window which annoyingly asks you to repeat what you just did in the prior step This may be a bug but do it anyway Prefix arm 1inux gnueabihf 13 14 15 16 17 18 19 20 21 22 23 24 25 Path home cah bbb tools gcc linaro arm linux gnueabihf 4 8 2013 10_linux bin Then click on Finish
21. GPIO_68 GPIO_44 GPIO_26 GPIO_46 GPIO_65 26 GPIO_61 28 Bae BWW WwW W BRNO OD BNO Header pin array with their various functions designated by pin number Although we will have a dash of Python code here and there the recipes in this chapter will primarily consist of BoneScript JavaScript ingredients and its powerful potions for physical computing For an extensive documentation of the BoneScript Library and its up to date reference refer to http beagleboard org Support BoneScript Before we head off to the recipe land and since this chapter is actually about how to make some basic electrical circuits we need to take a quick look at some of the foundational principles of electricity and current Knowing a few things about them will prevent you from accidentally frying your board The essentials of electronics How much power does an LED need What would happen if I ran a 5V circuit with a 3V power supply Will my 12V battery pack keep the robot going long enough to get the data I need Also most importantly can I attach the Spottiswoode Great Induction Coil Cape to pins 9_11 and 37 on the BeagleBone Black Tip The earlier versions of BeagleBones were larger than the Black version However you should never connect an old or new BeagleBone Black to a Spottiswoode Great Induction Coil Source William Spottiswoode and induction coil from Wikimedia Commons The London Edinburgh and Dublin Philosophical
22. How to do it How to do it How to do it There s more How to do it There s more Modify content data commands clean up files autoclean How to do it How to do it Modify content data commands shutdown the system How to do it How to do it See also SSH Remote access How to do it Using VNC to control your BBB How to do it There s more How to do it There s more How to do it See also How to do it There s more See also How to do it There s more There s more How to do it How to do it There s more See also photocell How to do it How it works Servo motors How to do it How to do it See also How to do it There s n ore systemd services There s more See also Basic commands for systemd services How to do it There s more Optimize boot time How to do it How to do it How it works How to do it Installing and building a custom kernel How to do it Interactions with the kernel sysfs entries and controlling 1 How to do it There s more Device Tree and its roots There s more Device Tree basic build How to do it How to do it There s more See also Universal cape overlay
23. can understand within a compiled program o o This specifies the name of the compiled file The compiler will output a file called majortom_gdb no file type Note The current Debian distribution comes preloaded with the C C compiler If for some reason you get errors that indicate that the compile will not run or is not present install the compiler with sudo apt get install g Run the compiled file in gdb using the following code gdb majortom_gdb This is how the output should look GNU gdb GDB 7 4 1 debian Copyright C 2012 Free Software Foundation Inc License GPLv3 GNU GPL version 3 or later lt http gnu org licenses gpl html gt This is free software you are free to change and redistribute it There is NO WARRANTY to the extent permitted by law Type show copying and show warranty for details This GDB was configured as arm linux gnueabihf For bug reporting instructions please see lt http www gnu org software gdb bugs gt Reading symbols from home debian bbb_recipe_book projects debug majortom_gdb done gdb Note gdb at the end of the output This indicates that you have started a debug session and can now use GDB commands to control the tool So now enter the following code gdb run Boom Your output should show a bug the dreaded segfault the segmentation fault The error also tells us that we attempted to access an invalid memory address as shown in the follow
24. interrupt can take priority or get in the way of a real time event no excuses You may ask why is this a problem anyway After all aren t Linux and our super duper BBB supposed to be super fast Yes But all systems experience delays in processing events We have all seen evidence of this even in mundane circumstances where not much was happening For example from time to time your cursor doesn t quite move from point A to point B on the screen as quickly as you expect Alternatively when you clicked on a taskbar item and the pop up window didn t appear as lightning fast as it did when you clicked on it five minutes ago This kind of latency is typical for all systems and Linux is not immune to it In our case we will refer to this phenomenon as kernel jitter Also certain scenarios absolutely cannot abide by any kind of jitters For example a milling machine can t have late commands in its I O otherwise the project could be ruined Therefore there has to be a solution that delivers real time performance For the BeagleBone Black there are in fact three actually four choices to make your system real time sometimes referred to as an RTOS or real time operating system The recipes follow in order of least to most real timely 1 PREEMPT_RT 2 XENOMAI 3 PRUs 4 PRU Xenomai Now we will take a look at how to define real time categories There are shades of real time not all scenarios require nanosecond manag
25. learn adafruit com adafruit tpa2016 2 8w agc stereo audio amplifier Perform the following steps 1 Your tasks begin with soldering an 8 pin header strip to the 8 holed side of the PCB amp and then soldering the speaker terminal blocks into the marked slots along the opposite side of the board This is shown for you in the following image Note This recipe is not a general how to on soldering If you have never soldered a wire or joint on a PCB consult the following excellent tutorials How to Solder Through hole Soldering https learn sparkfun com tutorials how to solder through hole soldering NYU s ITP soldering lesson https itp nyu edu physcomp Labs Solderin Adafruit s excellent guide to soldering https learn adafruit com adafruit guide excellent solderin Instructable secrets of good soldering http www instructables com id How to solder the secrets of good soldering After this you can begin by inserting the long pins of a header strip with 8 pins into the breadboard short pins sticking up as shown in the following picture As it is important to get your PCB amp mounted on an even plane the easiest way to do this is by using the leftover pins to support the board on the opposite edge To clarify these pins will not be soldered they are only there for temporary support TPA2 1602 Aa t T t2 f a aa glass D Stereo c Audio Amp Cc ey You then need to solder u
26. locations extremely accurate Client martphone or tablet Central Device App looks for pings from peripheral device Peripheral Device Advertises presence Makes data available as services and characteristics Transmits UUID Major ID Minor ID Location determined from distance to beacon Content triggered based on location TX Power Getting ready The BBB is powered up via USB and connected online either via Wi Fi or Ethernet with two additional items e USB Bluetooth LE BLE also known as Bluetooth 4 0 adapter we will use a Targus dongle product ID ACB10US1 This uses the Broadcom BCM20702 chipset There are far cheaper ones that should work fine on the BBB that cost around USD 10 00 15 00 Here is a list of compatible Bluetooth dongles for the Raspberry Pi http elinux org RPi USB Bluetooth adapters Many of those listed will likely work with the BBB although they have not all been tested for compatibility e Smartphone with Bluetooth LE iPhones starting from 4S to any of the current models are BLE compliant On the Android side there are exceptions By default the current models of an Android phone runs on 4 3 or higher BLE However any Android phones that cannot run on version 4 3 or higher will not work with this set of recipes How to do it Part 1 Setting up your smartphone As mentioned earlier in the chapter we need to install some apps on our smartphone in
27. software dl ti com codegen non esd downloads download htm Running an ultrasonic range sensor with the PRUs The fast twitch eye muscle on a robot is only as good as its processor And with many robotic projects where mobility and motion is part of the design the speed and reliability of the twitch can be the difference between a successful foray or a smash and crash Which is where nanosecond response time and reliability a PRU specialty is crucial To that end let us look at a more ambitious recipe that cooks up a way to use the PRUs with one of those cheap and ubiquitous ultrasonic range sensors the kind that are commonly found on basic robotic devices The sensor uses sound to send a ping similar to what a submarine does to measure the time between sending and receiving a signal for determining distance from an object Getting ready The requirements are as follows e BBB powered over 5V power supply If you only power the board via the USB tether you will deliver very unreliable power to the sensor so be sure you maintain a 5V supply Internet connectivity HC SRO4 sensor Breadboard Jumper pins Resistors 1x 1k and 1x 2k How to do it Perform the following steps to run an ultrasonic range center 1 Hook up your breadboard and BBB according to the diagram below Make note of two crucial items o Resistors As you should recall the BBB can only accept a maximum of 3 3V on its pins Therefore the wiri
28. we only need it temporarily and can disconnect it later e An LCD Monitor You need one of these plugged into the HDMI port As with the keyboard the monitor is only necessary for first boot and system tweaking e Connectivity We will first use an Ethernet cable plugged into the BBB for setup After we ve got a confirmed ping and stable setup we will remove the cable and use a USB Wi Fi dongle in our powered hub to establish a wireless environment e Audio out For output audio in this recipe you can use three different methods easy intermediate or advanced which are as follows o Easy method the USB audio dongle There are numerous flavors of these devices in the wild Unless you feel compelled to use an expensive one they can be purchased cheaply the kind pictured at the beginning of this chapter came for roughly USD 10 00 You should use a powered hub to supply power to the dongle instead of through the BBB s USB port o Intermediate method the RevB audio cape Although slightly more complex using the audio cape that we already used in Chapter 4 Exploring GNU Linux Recipes Using Bash Autotools Debugger and systemd is a more robust and elegant setup than using the USB audio dongle Refer to the same chapter for cape setup and audio testing o Advanced method the PCB audio amplifier daughterboard If you were with us in the previous section we just did a recipe with this and now we can use it for real Ref
29. 0 00 00 00 bash 2035 pts 0 00 00 00 ps So it is often better to modify the output in order to get more insight into the running processes and display this information in a more orderly fashion as in the following command ps aux The following is the output debian beaglebone ps aux USER PID CPU MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0 0 0 5 4468 2652 Ss 14 41 0 01 lib systemd systemd root 2 0 0 0 0 0 0 S 14 41 0 00 kthreadd root 3 0 0 0 0 0 0 S 14 41 0 02 ksoftirgd 0 root 5 0 0 0 0 0 0 S lt 14 41 0 00 kworker 0 0H root 7 0 0 0 0 0 o S lt 14 41 0 00 kworker u 0H root 8 0 0 0 0 0 0 S 14 41 0 00 watchdog 0 root 9 0 0 0 0 0 0 S lt 14 41 0 08 khelper root 10 0 0 0 0 0 0 S 14 41 0 00 kdevtmpfs root 11 0 0 0 0 0 0 S lt 14 41 0 00 netns root 12 0 0 0 0 0 0 S 14 41 0 00 bdi default root 14 0 0 0 0 0 0 S lt 14 41 0 00 kintegrityd root 15 0 0 0 0 0 0 S lt 14 41 0 00 kblockd root 16 0 0 0 0 0 0 S 14 41 0 00 khubd root 17 0 0 0 0 0 0 S 14 41 0 00 irq 70 44e0b000 root 18 0 0 0 0 0 0 S 14 41 0 00 kworker u 1 root 21 0 0 0 0 0 0 S 14 41 0 00 irq 7 tps65217 root 24 0 0 0 0 0 0 5 14 41 0 00 irq 30 4819c000 root 33 0 0 0 0 0 0 S lt 14 41 0 00 rpciod root 35 0 0 0 0 0 0 S 14 41 0 00 khungtaskd root 36 0 0 0 0 0 0 S 14 41 0 00 gatekeeper 0 The aux series of options complement the basic command by doing the following e The a option shows the processes
30. 20 21 GMT Fahrenheit 64 4 Celsius 18 Temperature at Ground Control for Tue 11 Aug 2015 19 20 31 GMT Fahrenheit 63 86 Celsius 17 7 If you are not getting readings from the sensor go back and check your wiring 12 Next we will hook up our code to the ThingSpeak channel that we set up in the first part of this recipe using the generated API Back on the ThingSpeak Channels tab drill down to the new channel you created and search for the API Keys tab option Select this tab and then copy Ctrl C the Write API Key generated as shown in the following screenshot LJ ThingSpeak Channels Apps Plugins Account Channels Channel 51138 Public View Channel Settings E Write API Key 4 Data Import Export Generate New Write API Key Read API Keys Generate New Read API Key 13 Back in the Cloud9 window on line 30 of the tmp36 code window paste your ThingSpeak Write API key to the designated part of the code as follows Post temperature data to ThingSpeak request post http api thingspeak com 80 update form f api_key THINGSPEAK_WRITE_API_KEY_HERE field1 temp_f field2 temp_c 14 Now it s time to see your temperature readings that is displayed on the ThingSpeak cloud service So as you again click on RUN in the IDE your Cloud9 console should be outputting temperature readings as before Within a few moments back on the ThingSpeak channel data points should be appearing at 10 se
31. 4298 debian 20 15152 10m 2436 S 0 3 2 2 6 02 92 Xtightvnc 5202 debian 20 2668 1148 792 R 0 3 0 2 0 00 48 top 1 root 20 4468 2652 1416S 0 0 0 5 0 01 11 systemd 2 root 20 0 0 0 OS 0 0 0 0 0 00 00 kthreadd 3 root 20 0 0 0 OS 0 0 0 0 0 02 34 ksoftirad 0 5 root 0 20 0 0 OS 0 0 0 0 0 00 00 kworker 0 0H 7 root 0 20 0 0 OS 0 0 0 0 0 00 00 kworker u 0H 8 root rt 0 0 0 OS 0 0 0 0 0 00 09 watchdog 9 root 0 20 0 0 OS 0 0 0 0 0 00 00 khelper 10 root 20 0 0 0 OS 0 0 0 0 0 00 00 kdevtmpfs 11 root 0 20 0 0 OS 0 0 0 0 0 00 00 netns 12 root 20 0 0 0 OS 0 0 0 0 0 00 00 bdi default The top command is adequate and one that you will hear most Linux users call upon but there is now a much lovelier easier way to read a package htop Let s install it and compare it to top with the following command sudo apt get install htop Now the output will be as follows CPU Mem Swp 205 226 539 549 552 555 679 1234 1235 1236 1237 1238 1239 1240 1243 556 689 root root root root avahi messagebu root root root root root root root root root root root root root root root TEEPE 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Tasks 68 152 thr 1 running Load average 0 31 0 20 0 11 usr sbin acpid 500000 00000000005000000 un e um Y Y Y Y 1 1 Y Y Y YN LN YN YN Y un un 500000 00000005000000005 5955995959999 95 ee ee eo0 000 amp vuvus gt 5 gt S gt S2SS
32. 4gb armhf YEAR MONTH DAY 4gb img xz The preceding link references a Rev C board the currently shipping version If you have another version of the BBB you can find software for prior releases at http elinux org Beagleboard BeagleBoneBlack Debian Debian Build Instructions Note Debian testing version You can also alternatively install Debian 8 Jessie using the same steps as the following substituting the URL and appending the month day and year accordingly https rcn ee com rootfs bb org testing Y EAR MONTHDAY xat 4gb BBB eMMC flasher debian 8 0 Ixqt 4gbarmhf YEAR MONTH DAY 4gb img xz 2 Next unpack unzip or unarchive the downloaded file using your favorite archive tool On my Mac I use Unarchive since it s easy to use and flexible After unarchiving there will be an img file available in your chosen folder 3 Now we will flash the img file to the microSD card The easiest method is to use a GUI type tool such as Pi Filler originally designed for Raspberry Pi but works equally well on the BBB for the Mac or Win32 Diskimager on your Windows box Wait for a prompt from the imaging software before actually inserting the SD card into the desktop s slot Depending upon the speed of your desktop box s environment the flashing writing process will take anywhere from 15 to 30 minutes 4 Remove the SD card from your desktop after the flashing finishes and then remove the microSD card Ensure that you
33. 916 35 916 RTD 0 958 2 041 15 749 ol ol 0 916 35 916 RTD 1 124 2 083 28 791 ol ol 0 916 35 916 RTD 1 583 2 083 31 541 ol ol 0 916 35 916 RTD 0 084 2 916 35 791 ol ol 0 084 35 916 RTD 0 916 2 083 28 041 ol ol 0 084 35 916 Finally run a test to see how the board performs under load This particular command xeno test requires several options to be included in order for it to run a useful test xeno test 1 dohell s 192 168 0 5 m mnt 1 ltp p 100 g histo Let s take a closer look at the various parts of this script so we can understand what it does dohell b lt path gt s lt server gt p lt port gt m lt path gt 1 lt path gt lt duration gt There s more If the preceding easy recipe for getting the Xenomai kernel installed does not exactly suit your specific needs you have a couple of other ways to attack it Use a prebuilt downloadable software image called MachineKit or you can install it from source MachineKit Developer and engineer Charles Steinkuehler has created an essentially turnkey real time Debian image that requires not much more than downloading and flashing a pre built kernel to a microSD card or the eMMC As its name suggests MachineKit targets machine users CNCs 3 D printers and comes with LinuxCNC Xenomai and other real time ingredients already loaded The image can save end users an enormous amount of time in installing and
34. Although there are other methods apt get is the easiest and most common way to handle packages for a beginner Getting ready Use the following steps to install packages 1 Updating packages Before actually installing new software in Linux it s best practice to ensure that you have downloaded the most current versions of your local package lists along with information about their dependencies You execute one of the most common commands in the Linux repertoire sudo apt get update As a result of this command we get a resynchronized package index file that is targeted not only at your specific Linux distributions but your hardware environment as well For the BBB this means that your package manager knows to only grab packages that are Debian savvy and compatible with the Arm board architecture 2 Upgrading packages Next you want to grab and upgrade to new versions of the packages already installed on your BBB which the apt get update will presumably have chronicled through the following command sudo apt get upgrade 3 Finally you get to install your new whizzy tool or app Use this command sudo apt get install pkg_name How to do it Let s do a real package though one that we will be using in a later chapter For our recipes focused on debugging in Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python we will use a tool called gdb also known as GNU Debugger which is a s
35. BeagleBone Black is pokey The challenge is that nowadays innovators developers product designers and engineers always demand faster more predictable results especially in scenarios where small latencies can make the difference between success or crash Crash in this case meaning bang crash goes the device not just a software crash So in this chapter we will examine recipes that help boost the responsiveness of your BBB under certain conditions To perform this we will explore the following topics e Kernel modifications for the purpose of creating real time environments using o RT PREEMPT o Xenomai e Programmable real time units And now for something completely contradictory Linux is not real time It is fast and efficient but it is not a real time system Harummph But isn t Linux supposed to be the sexy better alternative to all those bloated expensively closed systems out there It depends To begin with it s important to understand what Linux Mavens particularly the embedded folks mean when they refer to real time on their systems First it s not just about speedier performance Although squeezing out faster response times is always a goal and this can be one of the benefits of enabling a real time environment that s not an end in itself Real time is also about ensuring rock solid predictability on the system for example event x must occur within a very strict time frame No other event thread or
36. Create a superuser using this command manage py createsuperuser Follow the prompts to input a username e mail address and password Next we will add some demo data into the database so that there is something to look at the end of the road as follows manage py initialize Whew Time to run the server Use the following command sudo manage py runserver your_ip address _here 8000 If you experience problems getting the browser to resolve an address shut down the server by pressing Ctrl C and rerun the command with the following network address sudo manage py runserver 0 0 0 0 8000 The address 0 0 0 0 allows you to reach the server from any machine in your 18 19 network And now the last stop open up a browser on your desktop machine to the IP address and the port you used in the previous step The SatNogs Network web based GUI should open with a variety of functions for starting a satellite tracking project You can sign up as a Ground Station operator by first confirming your user credentials Look in the terminal window for the following output which contains a verification link User lt NAME gt at example com has given this as an email address To confirm this is correct go to http your_ip_address_here 8000 accounts confirm email generated_string_here Once you ve validated your email address you can add a Ground station on the SatNog Network https network dev satnogs org
37. Inc Pass 2 0 Error s Warning s Writing Code Image of 6 word s cc Wall Werror c o major tom pru o major tom pru c cc major tom pru o lpthread lprussdrv o major tom pru 4 The compiled binary created by assembler is what we now use to run a test program on the PRU be sure you include the sudo sudo major tom pru Your output should look like the following waiting for interrupt from PRUO PRU test program completed Major Tom s blast off event number 1 It should take approximately 3 seconds between the first line and the second The blast off event number will increase each time you run it In the major tom pru p file try changing the DELAYCOUNT default number currently set to 3 seconds to another number Then run make again and run the new major tom pru binary again You should be able to see differences in the duration according to any new values that you set Hooray You have now finished tackling one of the more arcane and advanced features of the BeagleBone Black Now let s do it again in the next section See also At the beginning of this recipe we also installed a command line version of Texas Instrument s PRU Code Generation Tools ti pru cgt installer The install comes not only with the assembler package but C code compile tools as well This toolset makes it possible to more easily develop PRU programs in C instead of assembly code You can download the extensive manual at http
38. LCD cape Resolution 128 x 128 purchased from http boardzoo com index php for around USD 30 00 e Let s go headless again and wireless which means we will need the following o A USB cable We will just power up via a mini USB cable o A Wi Fi dongle Insert this directly into the Ethernet port on your BBB Remote SSH calling sans an annoying Ethernet cable is the goal Although many users would suggest you to not use a dongle without a powered USB my tests have delivered stable connectivity without any external hub making the whole recipe and setup much cleaner Tip Note that this code is a variation of Professor Mark Yoder s code https github com MarkA Yoder BeagleBoard exercises tree master miniDisplay which is in turn a modification of the CircuitCo example code http elinux org images e e4 Minidisplay example tar gz How to do it With everything prepared what are you waiting for 1 First carefully insert the cape into the header pin slots on the BBB As the cape board has a recessed side to accommodate the BBB s Ethernet port it is difficult to get the orientation wrong The cape fully inserted into the pins Tip You may be a little tentative getting the pins footed properly as the pins are a very tight fit Once inserted removing the cape is a bit tricky due to the snugness so it s best to ease it out slowly from the board headers 2 With the cape fully inserted power up your BBB via
39. LT eMMC 2G 00A0 Texas Instrument BB BONE EMMC 2G Ff P O L Bone Black HDMI 00A0 Texas Instrument BB BONELT HDMI ff P O L Override Board Name 00A0 Override Manuf BB SPIDEVO NoB ONE 8 Now run the test application minidisplay test If all goes as planned the display will begin with a color bar test screen and then end with an image showing Major Tom s view of Earth from the International Space Station ISS Making a video chat client prototype using Linphone In this recipe we will first compile and install Linphone a well known open source chat client with the assumption that we ll use both audio and video After compiling and running we will test and optimize the package Getting ready Since we will run a more power intensive graphics and GUI centric environment for the next several recipes you will need to set up your BeagleBone Black board accordingly e LCD Attach an HDMI LCD to the micro HDMI port or an LCD cape if you have one As we will be running an x session headless is not possible e Apowered USB hub We will use a bushel of peripherals so plug the powered hub into the USB port and make the BBB happy e Keyboard and mouse The packages we will install do not like VNC sessions so you will need to include a USB keyboard and mouse in your powered USB hub e USB webcam As we are doing video chat sessions we have to have a camera and microphone a USB webcam is the fastest option How t
40. Packt e Copy and paste print and bookmark content e On demand and accessible via a web browser Free Access for Packt account holders If you have an account with Packt at www PacktPub com you can use this to access PacktLib today and view 9 entirely free books Simply use your login credentials for immediate access Preface It s maker madness out there SBCs MCUs FPGAs PCBs GPIOs BeagleBone Black and Whites Raspberry and Banana Pis Odroids Udoos Arduinos MCUduinos TinyDuinos What does this impossible stew of acronyms and techno arcana mean How do we make sense of it all especially if all you want to do is make invent and design great whizzy things that go beep and bump and flash brightly or just grab hot data from temperature sensors Most importantly what to do if you are not a specialist an engineer or a hard core software programmer This is a book precisely for those of you who want to know about BeagleBone Black but are afraid to ask overwhelmed by its complexity or underwhelmed by the dearth of understandable timely information about this tiny but powerful microcomputer Why BeagleBone Black Although many of the competing small board computers or SBCs have their strengths the virtues of BeagleBone Black are significant e Physical computing options With its huge array of pins you can wire up far more be it sensors motors displays or other hardware than almost any other board on the mar
41. Perform the following steps 1 2 10 Attach the antenna to the RTL SDR dongle via the USML adapter Power your BBB via a 5V power supply plug the SDR dongle directly into the USB port and connect via Ethernet Always ensure that your packages are up to date let s upgrade them here using the following command sudo apt get update amp amp sudo apt get upgrade Check that the dongle is recognized with this command lsusb The output should look similar to this with the Realtek SDR dongle appearing Bus 001 Device 002 ID Obda 2838 Realtek Semiconductor Corp RTL2838 DVB T Bus 001 Device 001 ID 1d6b 0002 Linux Foundation 2 0 root hub Bus 002 Device 001 ID 1d6b 0002 Linux Foundation 2 0 root hub Log in as root with this command sudo i As we will create a stripped down firmware toolset for RTL SDR here we need to compile software from source files We first need to install cmake a tool that we came across in an earlier chapter As a reminder cmake is an alternative method to build packages and can be installed as follows apt get install cmake Then install the USB library for RTL SDR as follows apt get install libusb 1 0 0 dev Next we will grab the RTL SDR library and configure and compile it with make The last command here will take a few minutes to complete git clone git git osmocom org rtl sdr git cd rtl sdr cmake DINSTALL_UDEV_RULES ON make Now insta
42. Pin function 10 setInterval blink 500 function blink state state b digitalWrite LED state Before running the code let s take a closer look at the parts First as noted in the prior chapter you need to invoke the BoneScript library so you have access to all its functions Setup var b require bonescript Please keep in mind that anything after the are comments and isn t functional code Now select the pin number where your LED is wired You can change this option easily just be sure to choose from an available pin Then make the change on your board as well Refer to the pin layout reference diagram at the beginning of this section for more background on the pin outs as shown in the following code var LED P8 15 This line defines the variable state of our pin which in this case has a LED connected to it Naturally the state will vary as either on or off where 0 is equal to off and 1 is equal to on var state 0 Following this as the pin has no preassigned value here we have to use pinMode to tell the pin P8_15 what type of pin it s supposed to be either an INPUT this would be used with a button or an OUTPUT In this case as we will control a LED our GPIO will be an output as follows b pinMode LED b OUTPUT You can also write it this way b pinMode LED out From the setup code we then shift to instructing the LED to evoke the blink function whi
43. This will prevent a vast majority of typing mistakes o Press Tab twice quickly and it will show all the commands that are currently in your path Conventions Early in the book we will frequently use the entire line from the command line including the user name address symbols connoting user type directory and so on So for example you will see a line that looks similar to the following debian beagle_bone mkdir However as we become more familiar with the shell we will mostly shorten the command instruction to only include the command itself mkdir Alternatively you will see a slight variation on the preceding command when we refer to a root user Note the sign in place of the sign in the following command mkdir Now let s move on to the commands A super duper subset of commands anyway We ve organized them into System navigational commands Device and system insight and Modify content data commands System navigational command change your directory cd To move from one directory to another there are numerous variations on how to do it How to do it Perform the following steps 1 To change from your current default directory to the Desktop directory type in these commands debian beaglebone cd Desktop debian beaglebone Desktop 2 To go back one directory level use the following command lines debian beaglebone Desktop cd debian beaglebone 3 Go to
44. USB You then need to log in via SSH and then as root with the following code debian beaglebone sudo i root beaglebone 3 Now that you re logged in and ready you need to download and compile some sample code for the display This code is a slight modification of an open source archived version wget https github com HudsonWerks minidisplay cape git 4 Finally navigate to the new directory created and compile the test application cd minidisplay cape make 5 The cape will need a Device Tree Overlay however before we take action on this let s take a look at what cape manager shows us about what is currently loaded using the following command cat sys devices bone_capemgr slots 0 54 PF 1 55 PF 2 56 PF 3 57 PF 4 ff P O L Bone LT eMMC 2G 00A0 Texas Instrument BB BONE EMMC 2G 5 ff P O L Bone Black HDMI 00A0 Texas Instrument BB BONELT HDMI 6 Next we will run the following command to load Device Tree so that the cape is recognized This is made considerably easier with the inclusion of universal Device Tree Overlay with the latest versions of the BBB firmware config pin overlay BB SPIDEVO 7 Check that the overlay loaded as expected by executing the following command cat sys devices bone_capemgr slots Your output should look similar to this with the last item in the slot list your loaded overlay 54 PF 55 PF 56 PF 57 PF ff P O L Bone
45. USRO gpmc_a5 the LED is set to pulldown or off fragment 0 target lt amp am33xx_pinmux gt _ overlay__ bs _pinmode_USRO_0x0 pinmux_bs pinmode_USRO_0x0 pinctrl single pins lt 0x054 0x0 gt 3 3 3 fragment 1 target lt amp ocp gt __overlay__ bs _pinmode_USRO_0x0_pinmux compatible bone pinmux helper status okay pinctrl names default pinctrl 0 lt amp bs_pinmode_USRO_0x0 gt Now close the window by pressing CTRL x then type N for no and run the following to move the file to its correct directory mv bspm_USRO_10 00A0 dts 1ib firmware Compile the file using this command which should finish within seconds dtc O dtb o lib firmware bspm_USRO_10 00A0 dtbo b 0 1ib firmware bspm_USRO_10 00A0 dts The command can basically be broken down in the following fashion dtc options lt input file gt 0 This capital O not zero is the output flag that is followed by the type of output desired which is a dtb file or Device Tree Blob also known as binary in this case b This means that you want the file blob to be loaded at boot time o This zero shows the physical boot ID which is 0 This ampersand means that the compiler will generate a symbol node which makes it possible to dynamically load the Device Tree lt file name source file gt The command ends with the source file target Assuming you received
46. a great tool set to scratch the itch that many JS developers have for hardware now One of its principal advantages is that it greatly simplifies the process of managing pins and allows a programmer to use more obvious naming conventions in their code such as LEDs buttons sensors and servos rather than high pins low pins and so on Although it does not yet have out of the box ease that BoneScript has for BBB you should consider it a viable and in some ways more robust alternative It is also a more modular library than BoneScript as the code can be easily ported to a variety of platforms Finally if you are an Arduino aficionado you will appreciate its familiarity as it is based on the Arduino Firmata protocol How to do it Perform the following steps to use Node js with Johnny Five 1 As usual good practice before installing a new package is to update your repositories You can use the following command line for this sudo apt get update 2 Next we will install Johnny Five as root user using npm node package manager and not apt get as follows sudo i npm install johnny five 3 Then we will add a BeagleBone specific plugin with the following command This will make our board s I O pins easily accessible npm install beaglebone io 4 Ina terminal window open up the nano editor with a new filename using this command sudo nano johnny5_led1 js 5 Copy and paste this code in the nano window var f
47. a toolset that makes manipulating GPIO pins and Device Tree infinitely simpler Chapter 6 Run Faster Run Real Time enables you to get more advanced in your skills you will learn how to modify the Linux kernel yikes and then dive into the realm of real time computing looking at recipes to use the RT PREEMPT patch Xenomai and the unique subsystem features of BeagleBone Black the programmable real time units PRUs Chapter 7 Applied Recipes Sound Picture and Video looks at some ways to use sound display and video in your projects We will begin by wiring up a mini sound amplifier and speakers and then take this lesson to creating a high quality audio platform using the open source music platform Volumio Then we will cook up a variety of recipes to utilize video and different types of displays in projects including an OLED and a mini LCD This chapter ends by building a video chat client from source Chapter 8 The Internet of Things plunges into a sampling of things for the Internet of Things things such as looking at ways to use sensors with middleware systems setting up location based devices to interact with BeagleBone Black and mix a recipe for making a smarter object specifically a cloud driven digital picture frame Chapter 9 The Black in Outer Space concludes the book by heading into more distant regions outer space or near space to be more exact delving into recipes to track satellites and craft such as
48. actual recipe on how to use these small radio devices we should take a look at some of the significant differences between the classic version of Bluetooth and the Bluetooth Low Energy BLE spec because they are very different animals Although they are both available as part of the 4 0 spec we will work only with the BLE piece for our recipe Classic Bluetooth With the classic version of the stack one device basically connects to another device data is exchanged serially and the data does not persist For example when you set up a BT headset the audio comes piping into your ears and the data goes on after the throughput Furthermore the connection does not reveal or show anything about what s happening in the middle of that pipe with the data itself Bluetooth Low Energy Although more challenging to work with and still nascent with its documentation BLE sometimes referred to as Bluetooth Smart is a far more robust environment for managing data particularly in the world of IoT Several key elements distinguish it from its earlier kin e Central device versus peripheral device rubric In a BLE ecosystem there will be a broadcast peripheral device that sends out data and a central device or devices that reads from this broadcast The device relationship is analogous to a community bulletin board with a bunch of readers or a client server relationship However in BLE land the normal assumptions are flipped the server is a very
49. ahead let s continue with the recipe s steps and take a look at how these lines actually affect the LED Now perform the following steps 1 Create a new directory called projects and save the file in it naming the file major_tom_blinks js Save As Filename major_tom_blinks js v G cloud9 Create folder Show files in tree Cancel Save 2 Now run the file in the terminal window at the bottom of the IDE First ensure that you navigate to the proper directory using the following lines of code cd projects node major_tom_blinks js The USRO LED which is the on board LED closest to the reset button should now have changed its constant heartbeat patterned blink to slower steadier 1 second blink intervals Now press Ctrl z or click on the Stop button in the terminal pane window at the bottom of the IDE Don t forget to do this otherwise you re likely to run into some errors or confusion in the upcoming recipes Finally it s a good idea to reset the LEDs so that you end up where you started For now the easiest way to do this is by running the restore script at http beagleboard org Support BoneScript demo_blinkled See also You can find more information at http beagleboard org Support BoneScript Node js basic recipes JavaScript on the server let that sink in for a moment What is Node js The quick and dirty answer is that it s a unique and very fast server environment to
50. appear skip to step 4 otherwise proceed to the next step Now install BlueZ with the following command sudo apt get install bluez Note You may want to install BlueZ from its source Here is the code for it sudo mkdir bluez cd bluez sudo wget www kernel org pub linux bluetooth bluez x xx tar xz Check for the current version of BlueZ before running wget Then connect the dongle to the USB port and verify that it is recognized with the following command lsusb Now we want to set up Bluetooth communications between the BBB and any other BLE devices that require using a series of BlueZ commands To do this we will use the hciconfig tool and begin by taking a look at the address of the USB adapter as follows hcitool dev Devices hcio 00 19 0E 15 DE 87 The preceding output shows one device present with the ID o that is prepended with hci this is part of the protocol s naming convention We will take this ID and append it to the command include the a option to output information about all the devices present and check the dongle s ready state as shown in the following code hciconfig a hcio da 10 Your screen should show the following code hci0 Type BR EDR Bus USB BD Address 00 19 0E 15 DE 87 ACL MTU 1021 8 SCO MTU 64 1 DOWN RX bytes 1267 acl 0 sco 0 events 47 errors 0 TX bytes 747 acl 0 sco 0 commands 47 errors 0 Features Oxbf Oxfe Oxcf Oxfe Oxdb Oxff Ox7b 0x87 Packet
51. archived file is common in Linux The various options that come with the tar command will considerably ease your management of the files that are not archived How to do it Use the following command to open a tar file tar zxvf file name tar gz Before actually running the command let s understand a bit about the options e z This is used to uncompress the resulting archive with the gzip command e x This is used to extract to disk from the archive e v This produces a verbose output which means that it shows progress and file names while extracting files e f document tar gz This reads the archive from the file called document tar gz Other file types include xz which is the actual file type we downloaded previously using wget wget 1 15 tar xz So here are the essential recipe steps 1 By default files are extracted into your current directory However you can simultaneously extract your files and put them in a different directory with the c option Using the following command we will extract files and put them in the test directory wget 1 15 tar xz C test 2 Check your work by navigating to the new directory created and running the following command cd test wget 1 15 You should see all the unarchived wget source files with their accompanying directories The flip side of unarchiving is archiving Here s how you can create a tar file tar cvf file tar inputfile1 inputfile2 Replace in
52. cd blinkled Next compile an assembly binary file make Run the Python file python blinkled py Oops You may have gotten an error If you didn t just skip the next step But if you did then it probably looked like this ERROR could not insert uio_pruss Numerical result out of range modprobe failed No such file or directory Traceback most recent call last File blinkled py line 7 in lt module gt pypruss modprobe This only has to be called once pr boot SystemError error return without exception set Errors always shows us something important that uio_pruss has to be loaded before the PRUs can be pinged just like we saw in our previous recipe Thus we will load that fragment echo BB BONE PRU 01 gt sys devices bone_capemgr 9 slots 12 Now try running the python script again python blinkled py Assuming all goes well now you should then see three of the user LEDs blink 10 times in rapid seizure inducing succession See also There are various resources for learning more about PRUs There is quite a bit to learn about how to use the PRUs on the BBB most of it well beyond the scope of this book However we have compiled a list of useful background information tutorials and projects to further your exploration of these unique real time subsystems e PRU wiki with the most up to date information http elinux org Ti AM33XX PRUSSv2 e Beagleboard s official overview of PRUs Mor
53. client machine 2 In a text editor on your client machine open up a file with the name BB BONE AUDI 02 00A0 dts 3 On your BBB log in as root and navigate to the firmware directory cd lib firmware As an optional step you can check the contents of the directory You should see dozens of Device Tree overlay files dtbo Otherwise you can skip this 4 Open a nano window on the BBB with the following filename nano BB BONE AUDI 02 00A0 dts 5 Copy the Device Tree overlay file contents from the text editor window on your client machine into the nano window on your BBB by executing the following code Copyright C 2012 Texas Instruments Incorporated http www ti com This program is free software you can redistribute it and or modify it under the terms of the GNU General Public License version 2 as published by the Free Software Foundation dts v1 plugin i compatible ti beaglebone ti beaglebone black identification part number BB BONE AUDI 02 version 00A0 AO 6 Then compile the Device Tree overlay as follows dtc O dtb o BB BONE AUDI 02 00A0 dtbo b 0 BB BONE AUDI 02 00A0 dts 7 Now we ll open up nano to edit the boot file You can optionally open the same file by browsing your client Mac or PC desktop and drilling down into the BEAGLE_BONE volume with the following code nano boot uEnv txt 10 11 12 Audio Cape need
54. comes to installing and supervising your software In some ways it is akin to what your smart phone universe is like you go to a centralized place Google Play App Store and so on and download a vetted application Of course there are huge differences in Land o Linux Firstly everything is free Secondly everything is mostly open source Thirdly pieces of your package dependencies libraries and so on that evolve and improve are treated as separate entities that only need to be conjoined when you are ready to actually install a piece of software This means that you re always getting the freshest most stable build Whereas in Closed Source Land executables are built to be self contained Any new module or better library that is built after the binary was compiled well too bad You will have to wait for the next release whenever that might be And then you have to pay for the upgrade Software applications for Linux are referred to as packages Henceforth we will mainly use the term package in lieu of application In this section we will learn the basics of package management through the following topics e Updating packages e Upgrading packages e Installing packages Note These recipes assume that you have internet connectivity working via any of the methods explained in the earlier Connectivity section For our recipes throughout this book we will principally use the apt get command for package management
55. custom kernel e Cape development Developers of cape expansion boards enjoy a standardized logic in the kernel This greatly simplifies life for the cape maker and end user as recompiling the kernel to make the cape function is rarely a requirement To reiterate Device Tree is a binary that describes the system hardware and loads at boot time Its tree nomenclature refers to the fact that it is written in a hierarchical node or tree data structure The nodes describe the physical device in the system The Device Tree overlay Device Tree is what is used by the kernel during bootup and is common to all modern ARM devices On BeagleBone Black and its earlier cousins Device Tree also comes accompanied with a kind of patch or overlay Applied at runtime Device Tree overlay helps reconfigure hardware resources on the board such as capes GPIO pins LCDs and so on and is handled by bone capemgr the cape manager Although we will do a recipe on the Device Tree overlay dtbo in a later section it might be helpful to browse the following directory to take a look at many of the dtbo files that come with the firmware cd lib firmware 1s 1 The sample output looks like this FW r r FW r r rw r r rw r r rw r r rw r r rw r r rw r r BPRERRB RBBB RB root root root root root root root root root root root root root root root root 1056 2885 2288 2583 4273 3259 45
56. dropbox_uploader sh s download IFTTT i0S_Photos NowPix home debian The number 3 is the frequency in which the cron job will run which in our case is every 3 minutes We have it set for such a high frequency only for testing purposes When we are finished with our testing you should change this number to a higher one perhaps every few hours or longer depending on how often you plan to add photos to your NowPix digital picture frame The rest of the line with all the asterisks corresponds to the following layout for a cron job minute 0 59 hour 0 23 0 midnight day 1 31 month 1 12 weekday 0 6 O Sunday command With cron it is a good idea to verify that the job has run as expected You can perform this easily with the following command that checks an e mail file that crontab automatically runs once a cron job has been set up tail f var mail debian You should see a log of the system e mails that crontab will send including the output from the downloader sh script This output should mirror the kind of output you saw when you were running the earlier bash script in the terminal window Next we need to install and set up a package that will open and cycle the images that we will download on the BBB For this we will use feh a lightweight and powerful image viewer as shown in the following code sudo apt get update sudo apt get install feh feh requires x so that you can run the app remotely v
57. favored approach and recommendation because it obviates the need for a keyboard monitor and mouse A USB hub We frequently recommend a powered hub otherwise the board s power draw will cause some peripherals such as Bluetooth dongles to underperform or not perform at all Note that this must be a powered USB hub A client machine Interacting and controlling BeagleBone Black is often greatly simplified by connecting it to a client desktop machine running Windows Mac OS or even Linux We are biased toward the Mac OS so most of the recipes assume that you are using a Macintosh box However if you are not on Mac the recipes are essentially the same and the principal steps and code are not affected A board enclosure This is not actually a requirement but a highly recommended nice to have tool Besides protecting the board from damage enclosing it in some kind of small box makes it much more manageable especially when you have multiple wires snaking all over the place You can find a variety of enclosures at http bit ly 1K TNPbE and on our site at http bit ly 1 WrBarv The software requirements are as follows Debian Linux If you purchased your board directly from a well established distributor it should have come preloaded with Debian 7 Wheezy kernel 3 8 x bone kernel which will be our principal assumption for the OS We will also be referencing Debian 8 Jessie kernel 3 14 x You will learn to load other versio
58. from web servers via HTTP HTTPS and FTP Unlike the experience of downloading a file in a web browser wget is noninteractive This means that you don t have to be logged on for the command to complete its task which is potentially a great time saver with large file downloads How to do it In order to download files you can use a command such as the following wget http This will download the Major Tom page at www hudsonwerks com into your current directory and create a file named index html Next perform the following steps 1 Check your work using the following command ls Desktop test index html 2 Now perform another wget this time download via ftp Here we will grab wget source code from the GNU site as follows wget ftp ftp gnu org pub gnu wget wget 1 15 tar xz 3 Check your work again using the following command this time ls Desktop test index html wget 1 15 tar xz There s more Where do we put the new tarballs packages and so on It is good practice to create a directory called home username Packages This is where you can put tarballs their extracted files compiled code backups of replaced files and installation scripts For this you can use the following command mkdir home username Packages wget P home debian packages lt download url gt Modify content data commands open a tar file tar options Working with files in the tar tarball format a type of
59. gdb This enlightens us to the fact that our string Ground Control to Major Tom contains 27 characters 13 Finally exit GDB normally by entering the following code quit See Nothing to it C code Crash Debug Fix C code All on a very little Linux box See also In Chapter 7 Applied Recipes Sound Picture and Video we will run a more advanced recipe where we will compile a SIP VOIP package for the purpose of exploring sound and video The compilation will include debugging examples with further use of GDB Debug an application remotely from Eclipse and GDB server You are about to dive into the arcane but necessary world of remote debugging cross compiling In this chapter we will specifically take a look at a recipe for setting up remote debugging using the GDB server We will set up a specific kind of environment on your client desktop another kind of environment on your BBB and use an IDE as a way to ease the potential collision between these two worlds Wait a minute Didn t we just do a debug recipe directly on BeagleBone Black using GDB And can t we just develop and compile right on BeagleBone Black Yes and yes But your BeagleBone Black is not quite powerful enough to serve as a serious development box Ideally what we want to do is hand off that work to a fancier faster desktop box Otherwise you will spend many unnecessary hours testing compiling debugging and watching reruns of Doctor Who
60. in the previous script s output here we used P8_13 The output reveals a great deal of information about this pin as follows node findGPIO js P8_13 name EHRPWM2B gpio 23 mux gpmc_ad9 eeprom 15 pwm module ehrpwm2 index 1 muxmode 4 path ehrpwm 2 1 name EHRPWM2B key P8_13 muxRegOffset 0x024 options gpmc_ad9 lcd_data22 mmc1_dat1 mmc2_dat5 ehrpwm2B pr1_mii0_col NA gpio0_23 P8_13 gpio 23 mode 7 gpio0_23 0x024 pulldown Receiver Active pin 9 44e10824 MUX UNCLAIMED GPIO UNCLAIMED Among other items of interest what we learn from the preceding example is that the P8_13 pin is one of the PWM cadre more specifically EHRPWM2B the type of pin we learned about in Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python that controls devices like motors Chapter 6 Run Faster Run Real Time In this chapter we will cover the following recipes Installing a test tool Modifying the kernel using RI PREEMPT Modifying the kernel using Xenomai Programmable real time units an introduction A simple PRU test with an assembler Running an ultrasonic range sensor with the PRUs Using Python with the PRUs Introduction Things are getting interesting no more blinky LEDs from sysfs It s real time time to learn about how to make your BeagleBone Black perform real time tricks This is not to say that the
61. inputi Uniq Handlers kbd event1 PROP 0 EV 13 KEY 78 0 e0000 0 0 O MSC 10 There s more The stem of this command is cat which is one of the most popular commands to quickly read files without writing or modifying them cat file4 You can try it with any file to see how the screen output looks Device and system insight get your version of Linux You can find out which version and distribution of Linux you are running through several methods How to do it To find out your version of Linux use the following command debian beaglebone lsb_release a The screen output will look similar to this No LSB modules are available Distributor ID Debian Description Debian GNU Linux 7 6 wheezy Release 7 6 Codename wheezy The preceding command is a good complement to the more typical way we determine the actual kernel version which is as follows uname r 3 8 13 bonexx Device and system insight find out running processes ps In Linux applications are referred to as processes and each is given a unique ID number or PID The ps that is process status command provides information about the currently running tasks or processes The output includes the PIDs How to do it This command takes a snapshot of your board You can run the command unadulterated and with no options as follows ps But the output is a thin gruel debian beaglebone ps PID TTY TIME CMD 1623 pts
62. install We also want to install the binary on your desktop client so that we can test a two way call connection with the BBB Downloadable binaries for other platforms Mac or Windows versions are available at http www linphone org technical corner linphone downloads Follow the on screen wizard to set up an account as you just did in the previous step 4 Making a video call Once you ve authenticated your new SIP telephone number and configured your account on Linphone you can make a video call You probably ran into problems while running the application Did it run slowly Did it take up most of your CPU s resources Could you make a connection to the desktop client and run a video chat session When it comes to CPU hogs such as video and audio the BBB does not shine However we have a plan for this thus take a look at the next part of this recipe Part II compiling and installing Linphone from source Now we will compile and install Linphone from source to note how the two versions compare Getting ready If you completed the first part of this recipe uninstall the prebuilt binary of Linphone before creating a new one and installing it from source So remove it completely by running sudo dpkg purge linphone How to do it Let s get to it 1 Begin by updating and upgrading your packages and then set up a directory to keep the source files with the following commands sudo apt get update amp amp
63. into data which in turn means the sensor functions as an effective measurement tool for ambient light In this recipe we show you how to read analog values captured from a light sensor using BoneScript along with an alternative Python script Note CdS stands for Cadmium Sulfide a compound that is non ROHs compliant due to the cadmium a chemical severely restricted in Europe as hazardous waste Getting ready Rustle up the items in the list below for this recipe e Photoresistor photocell Nothing fancy for our purposes here We re using one that costs less than USD 1 50 in many electronics stores such as SparkFun http bit ly 1kwejlt e Resistor 10 000 10k02 brown black orange gold bands e 3x jumper wires Easy to connect to breadboard e Breadboard How to do it 1 First make sure your BBB is powered down then wire up your breadboard Here s what your wiring should look like o BeagleBone We wire this sensor up differently from the temperature sensor so take care with the diagram If you are reading this recipe and want to see color versions of the fritzing diagrams for better clarity on the wiring you can find them online at http bit ly IMP2UNo Light sensor Plug the light sensor s wires into the breadboard positioning the wires four or five slots apart from one another for easier wiring management Resistor Plug the 10k resistor into the breadboard a couple of col
64. it is accurate within a range of 100 meters down to inches Thus far most of the interest around the Beacon technology is focused on how marketers and advertisers want to use it in order to send you targeted offers Yuck This is largely due to the fact that Apple s marketing centric version of the protocol called iBeacons has been the most commonly referenced and easiest type to get running quickly However the intrinsic BLE Beacon stack iBeacon or otherwise is very exciting for several reasons It delivers low cost radio signaling It provides fairly rapid and simple development requirements It requires very low power with its use of BLE It broadcasts far more precise location data than GPS For IoT like scenarios both indoor and outdoor Beacons provide much promise far beyond annoying marketing messages Also you can actually buy premade beacons for very little money sometimes for only a few dollars USD It may seem like overkill to be using a full blown microcomputer such as the BBB to serve as a Beacon However our intention is to create our own BBB version so that we have more flexibility in understanding and building the constituent parts of a Beacon network Doing this as an open source recipe allows you to pull the levers yourself A further point to clarify here is that BLE Beacons do not actually send content that a user receives on their smartphone app The beacon simply provides the rudimentary data to a mobile app
65. kernel uses a virtual file system interface or sysfs to read and write to the pins Sysfs easily and effectively exposes drivers for the hardware buttons LEDs sensors add ons and so on So you can control them Manipulating this system gives us insight into how the kernel and hardware can interoperate In this section we 1l look at how to activate the sysfs interface To reiterate instead of programming with a userland library this time we want a more direct understanding of what s happening with the platform So we will control some pins using a code that transparently accesses the Linux kernel To do this it means blinky LED time except that this time we will map a pin directly into the filesystem Note We ve referenced it before but you can never be reminded too many times of the value of a good GPIO reference diagram Here it is again http elinux org Beagleboard Cape Expansion Headers Getting ready Access to the various pins in the headers on the left and right hand sides of the BBB is done through the Linux kernel using its GPIO interfaces To demonstrate how to give this a spin we will attach an LED to designated GPIO and GND pins directly on the board s header The following are needed A BBB powered via USB LED a cheap LED of the ilk we used in the prior chapters Resistor anywhere from 700 7002 to 1k is fine We will use a 700Q here the violet black brown gold bands Two jumper wires
66. let s bring him back to earth for a moment with a very simple shell script How to do it Perform the following steps 1 10 Create a new directory as follows mkdir bin Then let s move to the new directory using the cd command cd bin Now create a new file that will become our shell script as shown in the following code bin sudo nano major_tom_bash_script At the beginning of the file it s a requirement to tell the shell the kind of script that we ll run so that it can interpret the code accordingly It could have been another recipe using Python but in this case we ve got a bash script bin bash Next it s a good practice to add a comment as follows Major Tom bash script On the next line of the file enter the echo string command which outputs whatever you input to the screen echo Commencing countdown engines on This is how the code looks bin bash Major Tom bash script echo Commencing countdown engines on Now save and close the file Then from the terminal you want to run a command that will give the shell the ability and permission to actually execute the script as shown in the following code bin sudo chmod 755 major_tom_bash_script Adding the 755 option instructs the script to allow read and execute access to everyone and write access to the file owner you as well Refer to Chapter 1 Setting Up for the First Time for our re
67. lightweight Qt variant of LXDE the Lightweight Desktop Environment Qt is a toolset to build cross platform applications that you can use on Mac OS X Windows and Linux It uses the C programming language and has a nice GUI builder so it is a popular choice for many open source centric developers Getting ready You will need the following BeagleBone Black powered down A 5V DC power supply You can also use a 5V wall wart power adapter with a USB port on it as long as it can deliver 1A A microSD card 4GB or greater An SD card reader You will insert the microSD card into the card reader and the card reader into an SD port on your desktop machine A board connected to either an HDMI monitor or an LCD cape as explained earlier in this chapter Note If you had it connected ensure that you remove the Ethernet cable before proceeding with this recipe as an Ethernet connection requires more current and will likely cause the software flashing to fail How to do it The following steps are used to flash the OS to your internal drive 1 Using the wget command get the software and put it on your desktop computer The latest version of the shipping OS Debian 7 Wheezy is available at http beagleboard org latest images So you need to get the exact URL and append it accordingly in the following command wget https rcn ee com rootfs bb org release YEAR MONTH DAY 1xde 4gb BBB eMMC flasher debian 7 8 1xde
68. look at the old chestnut manipulating LEDs an experience you re likely to have some familiarity with if you have read the last chapter or if you re an Arduino or Raspberry Pi user Next we ll play a bit with buttons because who doesn t like to push a button Then it gets more interesting as we add sensors to the mix After this we ll give you some basic recipes for locomotion that use some motors Finally we ll wind it up with the ingredients and steps for setting up a connection between your BBB and an Arduino board We ll march across the BBB draft the large army of pins that the board has at our disposal the GPIOs ADCs PWMs and UARTs a phalanx that makes the Raspberry Pi look feeble All of these acronyms may seem impenetrable however throughout the course of this book we will steadily learn something about all of them UART4_RXD 11 UART4_TXD GPIO_48 SPIO_CSO 21 GPIO_49 23 GPIO_117 25 GPIO_11S 27 29 U WW WwW N nu W GPIO_20 41 43 45 1513BBBK 0001 GPIO_66 GPIO_69 GPIO_45 10 12 14 GPIO_60 16 GPIO_47 18 SPIO_D1 GPIO_27 o PESAN CEMRPWMZA 22 SRIQISCLKRS MMC1_CLK 24 UART1_TXD MMC1_DAT4 26 UART1_RXD MMC1_DATO_ 22 cee _ LCD VSYNC 30 GPIO_112 _ LCD_HSYNC ll ai LED_DATA12 a RED_DATAS AS BECOK gt ey _ LCD_DATA4 2 LEDIDATAZ O 17 19 SSB 0OWWWWNHNHNN Pp Awa ON UWO ON TW GPIO_67
69. may want to optimize your system to squeeze out more CPU resources for higher resolution video display With systemd it s easier to control that load environment e Job scheduling You may have created a beautiful prototype for a weather measurement device However you had in mind a wireless battery driven design so power consumption is a concern In this case you can use systemd to schedule runtimes systemd Calendar Timers for the sensors to capture and transmit data and then revert to sleep mode when not needed thereby prolonging the battery life There s more Before we move on to the recipes you ll find a great deal of deeper insight into systemd by taking a look at some of the following referenced material e The definitive freedesktop org resource for systemd is available at http www freedesktop org wiki Software systemd e The quick reference cheat sheet for systemd commands is available at http dynacont net documentation linux Useful SystemD_commands e man systemd This is the command for the very extensive manual for the daemon It yields more information than you would probably ever want to know about systemd However it is there if you want it e If you want the full background on how systemd came to be one of the creators of the tool provides the full story and context at http Opointer de blog projects systemd html See also systemd is far from perfect Many Linux heads gripe about it being too pow
70. need to agree to the licensing terms to get the file which is why we cannot use wget or git to grab the file http www oracle com technetwork java javase downloads jdk8 arm downloads 2187472 html Tip When trying to download via your browser you may encounter the error Failed Insufficient permissions This tells us that when using the GUI s file browser window we do not have write privileges to the home directory by default Change permissions this way sudo chown lt user gt home After running this command you should no longer have read write problems and you will be able to download the Java archive without error With the permissions to access the file go to your home user directory as follows cd home user You should see the gz file there For a sanity check we will confirm that we are in the right directory with the output as follows pwd home user Tip As a reminder user will likely be debian unless you change it to another name We can then confirm that our downloaded file is in the right place ls Desktop bin jdk 0a0 linux arm vfp hflt tar gz packages You then need to unpack the Java TAR file in your home directory with TAR Note that you should be sure to replace the proper file name of the current version available with the following xx file names home tar zxvf jdk 8uXX linux arm vfp hf1t tar gz We can verify that our untar command did its job and created the new Java directo
71. no error message confirm that the compile did what you expected and built the bspm_USRO_10 00A0 dtbo file using the following command 1s Next we want to enable the overlay file that we just created with the following command echo bspm_USRO_10 gt sys devices bone_capemgr slots You will now see the heartbeat flashing USRO LED turn on immediately Hallelujah That darned blink is annoying isn t it Note Although at the time of writing this book the cape manager is at version 9 we use the wildcard option to ensure that later versions of bone_capemgr will still respond to this command We should now look at what just happened by doing the following dmesg tail 10 Your screen output should look similar to this 33 848704 IPv6 ADDRCONF NETDEV_CHANGE eth0 link becomes ready 153 829529 bone capemgr bone_capemgr 9 part_number bspm_USRO_10 version N A 153 829601 bone capemgr bone_capemgr 9 slot 7 generic override 153 829617 bone capemgr bone_capemgr 9 bone Using override eeprom data at slot 7 153 829633 bone capemgr bone_capemgr 9 slot 7 Override Board Name 00A0 Override Manuf bspm_USRO_10 153 829723 bone capemgr bone_capemgr 9 slot 7 Requesting part number version based bspm_USRO_10 00A0 dtbo 153 829738 bone capemgr bone_capemgr 9 slot 7 Requesting firmware bspm_USRO_10 00A0 dtbo for board name Override Board Name version 00A0 153 834371 bon
72. not being better at Rich Media However the difference is intentional RPi s engineers intended to make an educational hobbyist board with a desktop like experience to encompass Rich Media use cases On the other hand the BBB s engineers designed their platform to create advanced prototypes for embedded applications where high end graphics and sound are not commonly required With these caveats BeagleBone Black still remains more than up to the challenge of delivering sound and picture in many very useful scenarios including streaming music and videos Bringing audio onto BeagleBone Black The absence of onboard audio output or input is a real pain when it comes to the BBB Yet there are several methods of attacking this challenge Firstly you can go cheap and easy with a simple USB sound dongle two varieties are shown in the following picture attached to a powered USB port Secondly you can add a dedicated audio cape as we did in Chapter 5 Basic Programming Recipes with the Linux Kernel Thirdly you can do it the hard ish way using a dedicated PCB and by piggybacking on the GPIO pins Why bother with the latter This is because using USB is often inadequate for certain applications When you require faster more RT style performance running audio packets across USB can be disappointing We also want to stretch our limbs and add some complexity so that you have more types of technologies to draw upon in future projects and prot
73. open up the Cloud9 IDE in the manner described in the previous section How to do it Create a directory for your projects using the following command mkdir projects Perform the following steps after creating a directory for your project 1 Browse to this new directory and make another emailer directory using the following command cd projects mkdir emailer Now go to the new directory with the following command cd emailer Although it s not mandatory the following command is the proper first step to setting up your node environment npm init You will see a series of prompts that you can fill out you can skip them by hitting the return Enter key on your keyboard What you will do with these prompts and inputs is create the metadata to populate a file called package json This file s purpose is to give information to npm which allows it to identify the project as well as handle the project s dependencies Next we will use the following command to install the star of the current show a node package called nodemailer sudo npm install nodemailer save Navigate to the new directory created by the installation and open up a nano window with a new filename as described here cd node_modules nodemailer sudo nano nodemailer test js Copy and paste this code in the nano window This code has been modified from the nodemailer github example var nodemailer require node
74. or at least equipped with a basic working environment with happy flashing blue LEDs on your BeagleBone Black and some command line controls In later chapters you will learn how to use other physical pieces of the system including controlling the physical pins on the board Before we get there however you will need to take a quick dip into a handful of recipes using programming languages that are typical and essential for building robust compelling projects on BeagleBone Black So give a big round of applause to your soon to be faithful friends BoneScript Node js and Python Introduction to BoneScript BoneScript is BBB s handy Node js library What is Node js you ask Also why bother with another library We will talk more about Node js in the next section However as far as another library goes we re bothering with it because it s designed to work seamlessly with the hardware of your board making physical computing development under embedded Linux faster and simpler Using Arduino like functions BoneScript exploits the vast developer base of JavaScript Typically your intention in using Node js and BoneScript on BBB just as it is with Python in the next section is to gain access to the header pins the General Purpose In Out GPIO pins Although we will discuss more about GPIOs in a later chapter for now our plan is to briefly explore some fundamental methods to control the hardware Toggle LED In this section let
75. order to make this recipe meaningful and demonstrate the BBB s beacon ness For the iPhone we installed and tested two different free apps from the App Store one is called Locate by Radius Networks and the other is called Beacon Tool The developers must gotten up very early in the morning to come up with those names Locate has a few more functionalities than Beacon Tool because it lets us set the major and minor values for the Beacon Part 2 Setting up a simple IoT test environment You can test and track the iBeacon using a web service There are several businesses in this space We used a platform called EvoThings which is a free open source platform Evothings allows you to use a simple IDE on your desktop and then demonstrate an iBeacon app on a smartphone with a Beacon enabled BBB in the middle of the mix Perform the following steps 1 Download and install Evothings Studio http evothings com The installation requires a Workbench desktop and a mobile app all of which is explained on their website 2 After downloading Evothings Studio you will find a Mac OS X and a Windows version on the desktop Install your preferred client 3 For the mobile app install and start the Evothings client app on your mobile device Android and iOS are available at their respective online stores There are numerous demos and examples that come with Evothings Although they tend to be focused on how to use an Arduino as a beacon
76. other TTS options available such as E Speak Festival and Google Voice referenced at the end of this recipe Pico s quality is better than most and does not require a cloud connection 1 As it is not available in the Debian repos for ARM devices we need to install SVOX Pico from source First however we need to ensure that we have all dependencies with these commands sudo apt get update sudo apt get install automake libtool libpopt dev 2 Now we can install the source files using these commands It is not too lengthy an install it takes perhaps around five minutes to complete git clone b upstream patches git git debian org collab maint svox git svox pico cd svox pico cd pico automake sudo automake autogen sh configure sudo make all sudo make install sudo ldconfig PRDDNDNDNDNN 3 Run a sample text to speech test using two different audio playback tools mplayer which we just installed or aplay which is already on our system pico2wave w test wav This is Ground Control mplayer ao alsa device hw 0 test wav Take note of the various settings and options needed to run the package properly Pico2wave uses wav files so we will first use the w option and then the filename that we will create This will be followed by the actual text that will be recorded and spoken The last options are those to choose a playback tool in this case mplayer set the right device and then call the filename
77. out of space quickly on your card even after a modicum of packages are installed So save yourself a whole lot of hurt and expand your partition size now The following steps will be useful 1 Change to the root user with this command sudo i Check the disk space usage using the following command root beaglebone df h Go to this directory as follows cd dir opt scripts tools Check the available files using this command 1s You will see the grow_partition sh script This is a bash script included in the BBB distribution that will run a routine to expand your SD card space Now run the following bash grow_partition sh Alternatively you can also run the following command sh grow_partition sh Finally running 1s again on your drive will show a higher percentage of available space 1s Backing up a code image to a file 1 2 Insert a microSD card into your desktop machine s card reader and confirm that it s recognized On your desktop box Mac in our case open Terminal and type the following diskutil list From the list shown write down the ID for your SD card In my case it looks similar to this dev disk1 4 Now we will run a routine that backs up the content of the card to your desktop and simultaneously archives it to save space sudo dd if dev rdisk1 bs 1m gzip 9 gt Desktop backupimage img gz 5 Input your password at the prompt W
78. part of this recipe gt linphone call lt sip address of client box gt Well done It s not an easy install but it s a good intermediate recipe that yields a robust sophisticated tool running on your BBB Chapter 8 The Internet of Things In this chapter we will cover the following recipes e Location based recipes hooking up GPS e Location based recipes Bluetooth LE and Beacons e Using sensors and data with ThingSpeak e Making things smarter building a wireless digital picture frame Introduction The Internet of Things is a large basketful of things It is in fact so large that no one can see its edges yet It is an evolving and quickly expanding repo of products concepts fledgling business ventures prototypes middleware ersatz systems and hardware Some define loT as connecting things that are not normally connected thus making them a bit more useful than they were as unconnected devices We will not show you how to turn off the lights in your house using the BBB or how to autoraise the garage door when you drive onto your street There are a bunch of tutorials that do that already Instead we will take a look at some of the recipes that provide some fundamental elements for building IoT centric prototypes or demos Location based recipes hooking up GPS A common question in the IoT realm where is that darn thing That Internet of Things thing Being able to track and pinpoint the location o
79. pulse on a specific pin Perusing our complement of I O pins we can count two rows of 46 pin slots on the two expansion headers If you look closely you will see that one block is labeled P8 and the other one P9 All the references to a specific pin begin with this block number first followed by a number between 1 and 46 Therefore the example pins look similar to P8_2 P8_15 P8_24 P9_2 P9_15 and so on But what do you do with all these pins Not all of them are actually available Some have been drafted for other purposes According to the BBB reference manual the board has the following breakdown for pin purposes and availability pp pooo epo Note The BBB also includes another six male pins to accommodate a serial debug cable on the main board not the headers To understand the nitty gritty of the pins that may be available you can refer to the BeagleBone Black System Reference Manual at http elinux org Beagleboard BeagleBoneBlack Page 84 describes the pins on the P8 header and page 86 describes the pins on the P9 header There are also numerous reference guides online that help you understand the BBB s pin layouts Skip to the There s more section for additional sources In the meantime the following image a snapshot view of the board s entire pinmux You can also refer back to the pin mapping diagram at the beginning of this chapter PO P8 DGND IC DGND VDD_3V3 3v3 cta VIMCA_D s MMC
80. satellite watchers have been around nearly since the dawn of Sputnik an activity that fell under the rubric of ham radio or HamSat Nowadays there is a host of interesting tools available that play nicely on Linux as well as microcomputers such as BeagleBone Black For your smartphone alone you can find dozens of free downloadable tracking apps Given their basic purpose telling you when a satellite might pass nearby or passively receiving basic monitoring data they deliver quick hits of excitement However these apps are limited in functionality flexibility and purpose What we want to do is stretch what s possible to track a satellite bringing this information and data down to Earth in a more pliable form so that you can explore other useful and creative purposes for it So to begin our satellite tracking adventures we will begin with easy recipes Then we will continue with more advanced scenarios and robust tools that will give you greater control over the variety of data that you capture and simultaneously amp up user experience Grabbing the International Space Station flyover data and visualizing it The easiest scenario of all begins by piggybacking on preexisting web services and then making the interaction a little more interesting by combining it with some tasks executed by BeagleBone Black IFTTT for the ISS We used the IFTTT web service in our previous chapter to provide part of the machinery to send photos captur
81. setting up their machines e Download the software at http elinux org Beagleboard BeagleBoneBlack DebianfBBW 2FBBB_ 28All Revs e Instructions are at http blog machinekit io p machinekit_16 html At his site you will also find an extensive list of capes designed specifically for controlling 3 D printers and CNCs http blog machinekit io p hardware capes html Install from source There are several excellent tutorials for doing a custom build e Professor Mark Yoder s top notch lesson http elinux org EBC Xenomai e Installing Xenomai on Beaglebone using Debian distribution https randomlinuxhacks wordpress com 2015 02 22 installing xenomai on beaglebone using debian distribution e Xenomai on the Beaglebone Black in 14 easy steps http brunosmartins info xenomai on the beaglebone black in 14 easy steps See also To further explore the latency command and its numerous options check out the guide written by the Xenomai org team http www xenomai org documentation xenomai head html latency Another useful tool for testing the Xenomai kernel is klatency a test that requires either compiling Xenomai from source as outlined here or making kernel configuration changes that are beyond the scope of this recipe However in the following There s more section are several methods for installing Xenomai from source Programmable real time units an introduction Now it s time for hardware magic for serious real
82. should see the following lines in the file s open window HH WiFi Example auto wlan0 iface wlan0 inet dhcp wpa ssid mynetworkname wpa psk mypassphrase With the exception of the first explanatory line uncomment which means remove the sign at the beginning of each line To clarify it should look similar to this WiFi Example auto wlan0 iface wlan0 inet dhcp wpa ssid mynetworkname wpa psk mypassphrase Change mynetworkname to your Wi Fi network s name and mypassphrase to your Wi Fi password Note If your network name uses spaces or other odd characters some dongles may not recognize the name and establish a connection Close the file by pressing Ctrl x when prompted type y for yes and then press the return Enter key Power down the BBB in the terminal window with the following command sudo poweroff Power up the board again and log in to your BBB desktop You will now get a solid Wi Fi connection Test it via the command shell with this command ping www google com If all went well you should see a steady screen output from the ping Method Three command line option 2 Consult the table for the tested models that use the following steps The main difference between these steps and the previous recipe is that the drivers in these dongles require a different interface a wireless supplicant with the BBB to function properly Before starting the steps be sure
83. sources including David Scheltema s tutorial on Make Magazine http makezine com projects tracking planes with rtl sdr which is a Debian variation on an RPi version It also comes via the posts of David Taylor of Edinburgh Scotland satsignal eu raspberry pi dump1090 html and Drew Fustini of Chicago Illinois element14 com community community designcenter single board computers blog 2014 04 07 sdr and sbc cheap thrills with radio waves for Angstrom on the BBB Additionally Adafruit has a lesson for the RPi which either borrows from or is inspired by the references mentioned before All of these miss some steps however to make it fly on the current BeagleBone Black Debian distros be it Wheezy or Jessie Getting ready Here are the materials needed e The RTL SDR dongle e An antenna You could spend hundreds of dollars on this part of your kit However there are numerous low cost and plenty powerful antennas that will get you a good signal for all of our recipes Here we use a Diamond antenna http www aesham com glass magnet diamond antenna mr 75s and it only costs USD 38 00 e An antenna adapter If you use an antenna other than the small one that often comes with the dongle such as the one mentioned before you will need to buy a separate adapter Don t worry They re cheap too and ours was only about USD 6 00 http amzn to 1WoB7Lg e Powered USB e Ethernet or Wi Fi connectivity How to do it
84. stdout mux parseInt stdout split 3 16 Get the mux field out gpio key gpio gpio gpio mode mux amp 0x7 gpio options mux 0x7 gpio muxRegOffset if mux 0x8 Pullup or down is enabled if mux amp 0x10 dir up out pull dir if mux 0x20 out Receiver Active if mux 0x40 out Slew Control Slow console log out if flag exec grep addr PINMUX function error stdout stderr if error console log error error if stderr console log stderr stderr stdout stdout substring 0 stdout length 1 Get rid of extra n console log stdout var gpio flag process argv length lt 4 i for i 2 i lt process argv length i gpio process argv i toUpperCase if gpio 0 P gpio 0 u if flag console log b bone pins gpio pinMux b bone pins gpio flag else console log Looking for gpio gpio for var i in b bone pins if b bone pins i gpio parseInt gpio 10 if flag console log b bone pins i pinMux b bone pins i flag 5 To run this script we do not just click the RUN button in the IDE Instead we type the following command into the IDE s bash terminal window Note that we append the command with one of the pins specifically any of the pins that we saw output as available
85. steps to debug a C code application from the command line using GBD 1 Log in as a root user with the following command sudo su i 2 Now navigate to our projects directory as follows cd bbb_recipe book projects 3 Then create a new subdirectory called debug and navigate to it with the following code mkdir debug cd debug Now open the nano text editor create the C file and call it major_tom_gdb c as shown in the following code nano majortom_gdb c Copy and paste the following code to the nano editor window as follows majortom_gdb c include lt stdio h gt include lt stdlib h gt include lt string h gt size_t majortom_len const char s return strlen s int main int argc char argv const char a NULL printf The number of characters in Major Tom string a d n majortom_len a exit 0 Note If you run into problems copying and pasting the code you can download the code from https github com HudsonWerks debug samples blob master majortom_gdb c 4 Save and close the file and press Ctrl x when prompted type y for yes and then press return Enter key 5 Now we will compile the file using a C compiler command with options gcc majortom_gdb c g o majortom_gdb Here is a breakdown of the options in the command o gcc This is the basic compile command for a C program o g This generates the symbolic debugging information or symbols that GDB
86. sudo apt get upgrade mkdir packages cd packages To be sure we have certain basic packages install the following sudo apt get install automake autoconf gnu standards gettext build essential pkg config git libtool antlr3 libantlr3c dev intltool Next we will get the essential packages by executing the following commands git clone git git linphone org polarssl git clone git git linphone org belle sip git clone git git linphone org linphone recursive Then we will install the latest Oracle JDK This is a tricky but necessary set of steps because another package that we need to compile antlr is dependent on the correct installation of the JDK To start we should first look at the version of the JDK that comes preloaded on the current Debian BBB distribution note that your version may vary The following command will be useful for this java version java version 1 6 0 32 The output should look something similar to this OpenJDK Runtime Environment IcedTea6 1 13 4 6b32 1 13 4 1 deb7u1 OpenJDK Zero VM build 23 25 b01 mixed mode Let s move along to installing the new SDK To do this we will switch from pure command line interaction over to the BBB s desktop GUI Open up the Chrome web browser in your applications menu in the lower left corner Browse the following Oracle site and download the current JDK for ARM devices the hardfloat version into your home directory You will
87. switch from ground to positive or supply voltage VCC Floating means the circuit is neither tied to ground or a particular voltage This can create a situation where a pin may accumulate some kind of charge on it thus throwing off incorrect values You can create a more reliable circuit by writing code to correct for these potential false readings The purpose of this recipe is to read the state of a button press and have it turn an LED on and off When the button is not pressed the state of the input pin will be a 1 or high due to the resistor pulling the pin up When the button is pressed the input pin will be grounded low and have the value as 0 Getting ready You 1l need the following items for this recipe e 1x LED This is the same one you used in the previous section e 1 x pushbutton This is a simple one button four pronged tactile switch By default the button pins are open disconnected and momentarily closed connected when the button is pressed e Resistors 2x 700 7002 to 1k will be fine We will use the 700 here violet black brown gold bands e 5x jumper wires This is easy to connect to the breadboard e Breadboard How to do it 1 Wire your board and breadboard in the following manner 1 Connect the GND wire to GND at P9_2 on the BBB and the other end to GND in the first slot at the top of the second row on the breadboard Insert a red wire into the 3V slot at P9_3 and the other end into
88. tell us instead of showing us when the International Space Station is getting close Getting ready The materials needed are e A USB Audio dongle We will use an inexpensive low profile version http bit ly 1KxQatr though any USB version is fine An audio speaker with a mini jack that plugs into the audio dongle A USB powered hub A 5V power supply An Internet connection Ethernet or Wi Fi Power up your BBB via the 5V supply open a terminal window on your client box then SSH into the board How to do it There are five parts to this recipe Audio setup and testing Installing Text to Speech TTS and testing Python coding to calculate the ISS s current distance from you Bash scripting Doing a cron job to automatically run all of these Part I Audio Setup and testing Perform the following steps 1 Although you may have some of these tools on board your BBB already we should check to make sure The following commands will be useful sudo apt get update sudo apt get install alsa base alsa utils sudo apt get install mplayer Check that the system sees your audio dongle with this command lsusb Bus 001 Device 002 ID 1a40 0201 Terminus Technology Inc FE 2 1 7 port Hub Bus 001 Device 001 ID 1d6b 0002 Linux Foundation 2 0 root hub Bus 002 Device 001 ID 1d6b 0002 Linux Foundation 2 0 root hub Bus 001 Device 003 ID 0d8c 013c C Media Electronics Inc CM108 Audio Controller Take
89. that are easy to connect to the breadboard A breadboard How to do it Now that you re ready let s begin as follows 1 Ensure that your BBB is powered down 2 Now wire up your LED according to the diagram following these instructions o Two jumper wires run from P8_2 GND and P8_14 on the P8 header of the BBB onto the breadboard o Insert one end of the resistor direction does not matter into the slot corresponding to the P8_14 jumper wire and the other end a few slots above o Line up the LED s anode positive longer end into the breadboard slot at the upper end of the resistor while the cathode shorter ground end goes into the slot lined up with the ground wire BeagleBone re eee eee eee eee eee om Shim ee eee eee LO 0 o 041 000000s 060000 oe soe neneneeneteneeneeneneeneeneeeee enmreaeeneee eeeeseee eeeeeee eee ee e oe ewweneeeneenre eenee snseen ee eneee e ee e 3 You then need to power the BBB back up logging in as the root user with this command sudo i 4 Navigate to the gpio directory using the following command cd sys class gpio 5 While doing this take stock of the directory with 1s 1 so that you can compare what you see now with what will occur after the next step We will add the 1 option to view the output in a list format as follows ls 1 W 1 root root 4096 Oct 21 10 26 export Irwxrwxrwx 1 root root O Dec 31 199
90. the code is very flexible and open source so everything is customizable for other platforms For our first quick example in your desktop Evothings Workbench open the following file in a text editor Evothings Studio examples ibeacon scan index js Then scan about halfway down the page to find the following code Add your own manufacturer UUIDs to this list fuuid B9407F30 F5F8 466E AFF9 25556B57FE6D uuid F7826DA6 4FA2 4E98 8024 BC5B71E0893E uuid 8DEEFBB9 F738 4297 8040 96668BB44281 uuid A0B13730 3A9A 11E3 AA6GE 0800200C9YA66 Now add your generated UUID from the earlier step to line up with the following syntax uuid 3784B5B0 2DA7 11E4 8C21 0800200C9A66 Note Other than their own identity iBeacons do not push notifications to the central receiving devices However a mobile app on your phone can use signals received from iBeacons to trigger their own push notifications Part 3 Setting up the BBB Let s start with the essential package on how to control and interact with Bluetooth devices LE or otherwise and the Linux Bluetooth stack BlueZ On the current Debian distro that comes with any newly purchased BBB BlueZ should be already installed Perform the following steps 1 First update and upgrade the BBB with the following command sudo apt get update Then we will verify that BlueZ is installed using the following command bluetoothd v If you see a version number
91. the other principal tool that you just installed with the following command sudo cgps s e600 GS charleshamilton debian beaglebone ssh 80x24 Time 2014 12 02T17 03 53 000Z gt im SNR Used Latitude 40 729791 N Longitude 74 004598 W Altitude 190 9 ft Speed 1 4 mph Heading 132 8 deg true Climb 59 1 ft min Status 3D FIX 19 secs Longitude Err Latitude Err Altitude Err Course Err n a Speed Err 145 mph Time offset 2 618 Grid Square FN20xr Y Y Y Y N N N N N N N N N The output includes the current date and time in UTC the latitude and longitude and the approximate altitude Troubleshooting Part 1 You may run into problems here Commonly on a first time set up and running cgps may time out close by itself and lead you to believe that there is a problem with your setup If so the next steps can lead you back on the path to GPS nirvana 1 We will begin by stopping all the running instances of GPS as shown in the following code sudo killall gpsd 2 Now let s get rid of any sockets that the gpsd commands may have left behind with the following command sudo rm var run gpsd sock There is a systemd bug that we will typically need to address 3 Open the systemd GPSD service using the following command sudo nano lib systemd system gpsd service 4 Paste this command to the window with the following script Unit Description GPS Gl
92. the power rail on the breadboard The button will use the next wire Connect a wire to the pin on the P9_15 BBB and to the first slot in the same row in the upper left corner of the button on the breadboard Take another wire and connect one end to P8_11 on BBB and the other end to row 2 and column 1 on the breadboard The last wire serves as Ground for the button Connect one end of this wire to the GND rail and the other end next to the button s GND leg On the breadboard connect the LED s cathode pin the shorter end to the GND rail and the anode or the positive lead the longer end into the sixth row of the breadboard Insert one resistor to regulate the current to the LED and the other to regulate the flow through the button as shown in the following image ey RRRARARAARRRSE poe 9 0 oii e BeagleBone 2 Now open your Cloud9 IDE at http 192 168 7 2 3000 and create a new file called button 1led js 3 Then use the following code to turn the LED on and off with a push button Copy and paste it into the open IDE window Setup var b require bonescript Read library var LED P8_11 Pin where LED is connected var BUTTON P9_15 b pinMode LED b OUTPUT b pinMode BUTTON b INPUT setInterval readBUTTON 10 function readBUTTON b digitalRead BUTTON writeLED function writeLED x b digitalWrite LED x value o Before running
93. the soldering iron and make some nice shiny joints Many great add ons such as PCBs sensors headers and peripheral devices arrive at your doorstep unsoldered full of fiddly bits or just downright unsuitable out of the box So soldering is a must on the microcomputing landscape However this is only one part of the picture for this chapter on picture sound and video We will also explore different advanced methods to add a range of capes PCB add ons and some USB devices for more complex recipes using digital sound pictures and video and look at the following e Wiring up a mini sound amplifier and speakers e Creating a high quality audio platform with Volumio e Using videos and displays in projects that include these devices o OLED PCB o Mini LCD cape e Making a video chat client Here s the truth about BeagleBone Black when it comes to audio and video the BBB is not for the faint hearted Other than a single USB port which is obligatory for all kinds of reasons beyond just audio or video add ons the BBB is a tough system to learn for hardware and Linux newcomers There is no onboard camera port you have to piggyback on USB or buy a dedicated cape There is no onboard audio I O pin USB device or dedicated cape required either So if you are looking for a quick and easy media rich development box then dare I say it Raspberry Pi might be a better choice As a result of this difference the BBB is often criticized for
94. time and a shift away from mere software mods on the kernel It s time for Programmable Real Time Units And Industrial Controller Subsystem also known as PRU ICSS or PRUs How s that for a mouthful More techno acronyms are always so helpful and delicious OK Let s deconstruct it PRUs are specialized chips on the BeagleBone Black that give you real time task control over your system These two 32 bit microcontrollers are actually separate CPUs from the main CPU and the operating system That s right PRUs are separate hardware This means they are not reliant on the core kernel and are more efficient at accessing I O pins and driving real time events Having onboard PRUs is one of the BBB s big differentiators in the microcomputer market Real time hardware control typically requires adding on daughterboards such as FPGAs another big scary acronym that boost your system s mojo Using PRUs requires no overhead on the BBB s main processor and the hardware can be managed without worrying about interrupts from the OS This is a huge distinction and advantage from our prior examples of RI PREEMPT and Xenomai patches both of them software solutions for real time challenges ARM Subsystem Real Time Coprocessor Subsystem PRUO PRU1 lt gt PRUO VO 200 MHz 200 MHz lt gt PRU1 vo 1 L 1 instructior Cache L2 Data Cache GP VO PRUs exist as parallel but distinct processors on the board
95. type DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 Link policy RSWITCH SNIFF Link mode SLAVE ACCEPT Ensure that it says DOWN which is not what we want So up up and away we go sudo hciconfig hciO up Then verify that the command worked by repeating our earlier step Your stdout should look similar to the following command hciconfig a hci hci0 Type BR EDR Bus USB BD Address 00 19 0E 15 DE 87 ACL MTU 1021 8 SCO MTU 64 1 UP RUNNING RX bytes 990 acl 0 sco 0 events 44 errors 0 TX bytes 738 acl 0 sco 0 commands 44 errors 0 Features Oxbf Oxfe Oxcf Oxfe Oxdb Oxff Ox7b 0x87 Packet type DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 Link policy RSWITCH SNIFF Link mode SLAVE ACCEPT Name BCM20702A Class 0x000000 Service Classes Unspecified Device Class Miscellaneous HCI Version 4 0 0x6 Revision 0x1000 LMP Version 4 0 0x6 Subversion 0x220e Manufacturer Broadcom Corporation 15 Now we will set up the dongle to begin what is known as advertising in the BLE parlance We will perform this in the low energy 1e mode using the flag 3 this sets the connection mode sudo hciconfig hci0 leadv 3 Note A further word about nomenclature in the iBeacon BLE landscape is that you will often see references to the word advertising when you develop with BLE The term is used generically to refer to a packet of data that is being sent from a BT device to make its presence known it has nothing to do with Apple s orig
96. type cyclictest from whatever directory you find yourself cp cyclictest usr bin 6 Bang on the tool s documentation to make sure it installed properly cyclictest help 7 Now let s run a simple test to see what kind of data that cyclictest captures cyclictest smp p95 m The sample output should look like the following dev cpu_dma_latency set to 0us policy fifo loadavg 0 00 0 01 0 05 1 221 4471 T O 4464 P 95 1 1000 C 31326 Min 39 Act 58 Avg 69 Max 785 This output tells us that our CPU had an average latency of 69 microseconds which is a decent value Yet we also had a maximum latency of 785 microseconds Ouch What s happening there Let s debug or trace that Alas we can t do a trace until we ve customized the kernel to run a trace routine with cyclictest So that s what we ll do in the next section since we also need to modify the kernel to accommodate a new patch In the meantime let s quit the program with Ctrl C See also e FAQ on real time with PREEMPT RT https rt wiki kernel org index php Frequently_Asked Questions e The home of the developers of cyclictest https rt wiki kernel org index php Cyclictest e More details on how to set up and configure cyclictest http people redhat com williams latency howto rt latency howto txt e Long but useful video explaining the deeper functionalities and virtues of cyclictest https www youtube com watc
97. user gaining in complexity as the material progresses In a nutshell these are the chapters and their topics Chapter 1 Setting Up for the First Time starts by booting up your board out of the box getting it connected online teaching how to control it remotely and then diving into the essential Linux command line commands Chapter 2 Basic Programming Recipes moves briskly along to scenarios using several flavors of programming ingredients on BeagleBone Black including BoneScript an easy JavaScript variant for BeagleBone Node js Python and Johnny Five Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python tells it like it is as we will take the recipes discussed in Chapter 2 Basic Programming Recipes and apply them to the use of buttons sensors LEDs and motors Chapter 4 Exploring GNU Linux Recipes Using Bash Autotools Debugger and systemd looks at some foundational Linux tools that you will need to bend the board to your will tools that come in handy for a wide variety of use cases Chapter 5 Basic Programming Recipes with the Linux Kernel helps you start putting your arms around the system kernel by installing the latest version and then building a custom kernel We will also will cook up some mischief with one of the hallmarks of all ARM devices Device Tree which makes it easier to add peripherals and daughterboards to your system We will finish using the universal cape overlay
98. website at http www hudsonwerks com beaglebone black recipe book images Errata Although we have taken every care to ensure the accuracy of our content mistakes do happen If you find a mistake in one of our books maybe a mistake in the text or the code we would be grateful if you could report this to us By doing so you can save other readers from frustration and help us improve subsequent versions of this book If you find any errata please report them by visiting http www packtpub com submit errata selecting your book clicking on the Errata Submission Form link and entering the details of your errata Once your errata are verified your submission will be accepted and the errata will be uploaded to our website or added to any list of existing errata under the Errata section of that title To view the previously submitted errata go to https www packtpub com books content support and enter the name of the book in the search field The required information will appear under the Errata section Piracy Piracy of copyrighted material on the Internet is an ongoing problem across all media At Packt we take the protection of our copyright and licenses very seriously If you come across any illegal copies of our works in any form on the Internet please provide us with the location address or website name immediately so that we can pursue a remedy Please contact us at lt copyright packtpub com gt with a link to the suspected pi
99. well regarded and ubiquitous PCB http www adafruit com product 746 at around USD 40 00 Antenna Again Adafruit s suggested SMA to the uFL adapter antenna is the simplest and cheap at USD 3 00 https www adafruit com product 851 5V power Powering via the 5V DC in lieu of simply connecting via the mini USB is advisable The GPS modules consume a good bit of power a fact apparent to all of us given how the GPS functionality is a well known drain on our smartphones Internet connectivity via Wi Fi or Ethernet Breadboard 4x jumper wires How to do it For the GPS setup the steps are as follows 1 Insert the PCB pins into the breadboard and wire the pins according to the following fritzing diagram BeagleBone fritzina P9_11 blue wire This denotes RX on BBB and TX on GPS PCB At first it may seem confusing to not wire TX to TX and so on However once you understand the pin s function the logic is clear a transmit TX pin pairs with a pin that can receive data RX whereas a receive pin pairs with a pin that transmits data P9_13 green wire This specifies TX on BBB and RX on GPS PCB P9_1 This indicates GND P9_3 This specifies 3 3V 2 Now carefully attach the antenna to the board s uFL connector 3 Next power your BBB Here s where it gets a bit tricky When your BBB starts you will immediately see the Fix button on the GPS board that will begin to flash quickl
100. which allows that app to determine its location in a venue or outdoor spot and in turn sends the user location specific data Alternatively it can capture and make use of that data in other ways Furthermore iBeacons do not track users based on any kind of profiling requirements the interaction can be and generally is completely anonymous so concerns about privacy are negligible With Beacons there are several data fields that you typically want to watch This helps in differentiating one beacon from another For instance let s say that we are in the Museum of Natural History in New York City that has a beacon network Here are the relevant data fields e UUID Services are identified by unique numbers known as UUIDs Universal Unique Identifier which you may be familiar with from other projects Therefore the museum would have its own unique UUID string e The major field ID Inputting a specific value in this field can specify a more general location for example a particular floor in the museum e The minor field 1D Inputting a value in this field will specify a particular gallery on a specific floor e TX Power This is used to try to estimate the distance based on the signal strength of the Wi Fi connection the RSSI value in a particular room The major and minor IDs can be used to trigger certain behaviors in your application when it discovers one of your beacons All of these fields come together to make pinpointing
101. while waiting for the BBB to complete its tasks Why don t we just make something on one box and move it over to another box Hmm Not so fast If you want to create or debug an application on a nonBBB board and output a binary or chunk of code to run it on an ARM Linux board like the BBB s then you have to have the right toolset This toolset will juggle between differing board architectures and operating system requirements Unfortunately getting this toolset set up properly can be quite unpleasant Not only does it take a fair bit of time the process is also fraught with many opportunities for error So be patient and persistent in following this recipe Before going into the minutiae here are the high level steps to get remote debugging going on BeagleBone Black 1 Install and set up a virtual machine you can skip this if your client development box is Linux 2 Install and set up a cross compile and debug toolchain Install and set up the GDB server on your BeagleBone Black 4 Install and set up Eclipse our IDE of choice w Nothing to it right Not quite How to do it Part I Set up Virtual Machine Mac OSX On your client box we will set up a virtual machine VM with a Linux distribution on board There are a number of sources for this but we will use Oracle s free virtual box once again if you are already using this book and its recipes with a Linux box as your client machine installing a VM is not ne
102. 1_DAT7 VDD_5V DD_5V Wi C1 DAT2 06 MMC1_DAT3 SYS_5 j nai i E aoe 08 GPIO_67 PWR_BUT 10 GPIO 68 GPIO_30 12 GPIO_44 GPIO_31 14 GPIO_26 GPIO_48 16 GPIO_46 GPIO_04 18 GPIO_65 12C_2 SCL 20 MMC1_cMD GPIO_03 22 MMC1_DATS GPIO_49 24 MMC1_DAT1 GPIO_117 26 GPIO 61 GPIO_125 28 LCD PCLK SPI_1_DO 30 LCD_AC BIAS E SPI_1_SCLK 32 LCD DATA 15 AIN_4 34 LCD DATA 11 AIN_6 36 LCD DATA_10 AIN_2 38 LCD DATA 09 AIN_O 40 LCD_DATA_07 GPIO_20 42 LCD_DATA_05 DGND a 44 LCD DATA_03 DGND 46 LCD DATA 01 PATAOO ves Er UE gt www insigntech com The process of pinmuxing A common frustration among new BBB users is that the pins do not always respond as expected This is because by default some header pins are assigned to specific tasks such as the HDMI output some are used for multiple purposes and many of its functions are only available after some tweaking For example pin 21 on the P9 header wants to be a GPIO at some time whereas at other times it wants to be a PWM a UART an I2C or a SPI pin So how do you get around this pin schizophrenia Well you have to reconfigure it for this purpose a process known as pin multiplexing or pinmux Pinmuxing is fairly straightforward and can be easily handled from the command line We will encounter this technique later in this and subsequent chapters Although the BBB s sophisticated pin design can accept different types of signals in this chapter we will mainly take a look at the two typ
103. 36 3592 Apr Apr May May Apr Apr Apr Apr 23 23 18 18 23 23 23 23 16 57 16 57 2014 2014 16 57 16 57 16 57 16 57 BB ADC 00A0 dtbo BB BONE AUDI 01 00A0 dtbo BB BONE AUDI 02 00A0 dtbo BB BONE AUDI 02 00A0 dts BB BONE BACON 00A0 dtbo BB BONE BACONE 00A0 dtbo BB BONE BACONE2 00A0 dtbo BB BONE CAM VVDN 00A0 dtbo There s more Here are a few other key things to keep in mind about Device Tree and the BBB Many embedded architectures have a wide variety of nondiscoverable hardware daughterboards add ons and so on Depending on the architecture this hardware is described using either C code directly within the kernel or a special hardware description language in Device Tree Other architectures besides the BBB s ARM also use Device Tree including PowerPC OpenRISC ARC and Microblaze A DTS is compiled into a binary Device Tree Blob DTB data structure and passed at boot time to the kernel The bootloader must load both the kernel image and Device Tree Blob in memory before starting the kernel Device Tree basic build On the BBB there are three essential steps to create and run a Device Tree file 1 Create a source file dts 2 Compile it and make a binary dtb also known as blob of the file 3 Ensure that the kernel knows where to find the new blob Let s start with a simple recipe one that turns off one of the onboard LEDs specifically USRO which is the LED that blin
104. 42 pin on the BBB and the other end to the breadboard in the same row and on the left hand side of the resistor following the diagram s position We could also have used P9_14 P9_16 P8_13 or P8_19 o Finally attach the servo jumper wires to the breadboard as follows GND black wire into the GND rail coming from the BBB 3V red wire into the 3V power rail coming from the BBB PWM yellow wire into breadboard on the other side of the resistor 3 Open the Cloud9 IDE at http 192 168 7 2 3000 Use the following code to begin firing up the servo In order to control the PWM signal we need to specify the period run and duty cycle Here s the script to run the Servo usr bin env node Include the bonescript library var b require bonescript Servo motor s PWM pin var servo P9_42 var duty_min 0 03 var duty_max 2 5 var position 0 1 var increment 0 1 Set up the mode for the servo pin b pinMode servo b ANALOG_OUTPUT updateDuty console log Use keyboard Control C to stop function updateDuty This function calculates and adjusts the duty cycle based on a desired position in range 0 1 var duty_cycle position 0 115 duty_min b analogwrite servo duty_cycle 60 scheduleNextUpdate console log Duty Cycle parseFloat duty_cycle 100 toFixed 1 Position position function scheduleNextUpdate adjust position by increment and reverse if
105. 5S5 5 5 5595 9595 95 995 m A y 240000000 uy uy uy y un e 200000000000000000000 eooeroecocooce0n oececoeroooow 63 45 58 usr bin python 0 usr s lib systemd systemd lib systemd systemd jour sbin udevd avahi daemon running be usr bin dbus daemon sy sbin wpa_supplicant u usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin ruby1 9 1 usr l usr bin node autorun js usr bin node autorun js usr bin node autorun js As you can see it has an output that is much cleaner and easier to read Device and system insight quitting processes kill The typical way to force quit or kill an application is to use the kill command and combine it with the process ID PID which you can derive from any of the preceding recipes to capture process information Let s take a look at the basic method How to do it Use the following command to kill processes kill lt process_id gt Here s a real example which would force quit the top process shown in our prior recipe kill 4569 When you know the name of a process you can use the pkill command which operates on the process name instead as follows pkill 9 gdb Naturally there is yet another way to skin the cat while killing a pro
106. 9 gpiochip0 gt devices virtual gpio gpiochipo Irwxrwxrwx 1 root root O Dec 31 1999 gpiochip32 gt devices virtual gpio gpiochip32 Irwxrwxrwx 1 root root O Dec 31 1999 gpiochip64 gt devices virtual gpio gpiochip64 Irwxrwxrwx 1 root root O Dec 31 1999 gpiochip96 gt devices virtual gpio gpiochip96 W 1 root root 4096 Oct 21 10 32 unexport 6 Once this is done send an echo command as follows echo 26 gt sys class gpio export 7 Now take a look at the directory to see how it has changed ls 1 total 0 W 1 root root 4096 Apr 23 16 24 export Irwxrwxrwx 1 root root O Apr 23 16 24 gpio26 gt devices virtual gpio gpio26 Irwxrwxrwx 1 root root O Dec 31 1999 gpiochip0 gt devices virtual gpio gpiochip Irwxrwxrwx 1 root root O Dec 31 1999 gpiochip32 gt devices virtual gpio gpiochip32 Irwxrwxrwx 1 root root O Dec 31 1999 gpiochip64 gt devices virtual gpio gpiochip64 Irwxrwxrwx 1 root root O Dec 31 1999 gpiochip96 gt devices virtual gpio gpiochip96 W 1 root root 4096 Dec 31 1999 unexport This echo command has created a virtual directory which now allows you to directly interact with the Linux kernel from user space The kernel s virtual file system VES is an abstraction of a filesystem and gives you a way to use standard functions for manipulating anything that could be a file on your system You should also note that p
107. DMI_ Adapters You may also develop an embedded prototype device that only needs a small LCD and no HDMI Here s one recipe for a scenario using a 3 5 inch screen from Circuitco http elinux org CircuitCo BeagleBone_LCD3 that I ve used in my own projects The display is in the category of add ons to the BBB called capes which are akin to the shields on an Arduino board Capes are typically robust daughterboards and unfortunately tend to be much more expensive than Arduino add ons CircuitCo LCD3 cape How to do it Perform the following steps 1 Power down your board 2 Examine the header pins at the bottom of the LCD3 and note the pin layout one short row and one longer row Also note the Power PWR button at one end The pin line up at the bottom of the PCB printed circuit board 3 Position the long row of pins on the LCD on top of the P9 pin slots on the BBB and the short pin row on the P8 row Don t push the pins in yet The PWR button should rest between the Ethernet port and the 5V barrel jack as in the following image 4 Next slowly push the pins into the BBB headers All pins should go in more or less simultaneously It s a little tricky as you also have to squish the PWR button in place at the same time so that it lodges snugly between the 5V barrel and the Ethernet jack as in the following image 5 All pins on both sides of the LCD should be firmly pushed into place on the boa
108. Getting ready upgrading Getting ready PCB amp o URL How to do it pin layouts o o sources There s more references There s more pinmuxing o o about Header pins and pinmuxing process The process of pinmuxing playlist PLS files Creating a high quality audio platform with Volumio Programmable real time units PRU o o o about Programmable real time units an introduction How to do it test with assembler A simple PRU test with an assembler Getting ready How to do it ultrasonic range sensor running Running an ultrasonic range sensor with the PRUs How to do it Python using with Using Python with the PRUs How to do it See also projects o o video using Using videos and displays in projects Getting ready How to do Ls displays using Using videos and displays in projects Getting ready How to do mini OLED hooking up Using videos and displays in projects Getting ready PRUCAPE See also Python o o o o basic recipes Python basic recipes libraries adding Adding libraries How to do it used for writing alternative script Writing an leal script with Python using with PRUs Using Python with the PRUs How to do it See also Python script o running to control LEDs Running a Python script to control the LEDs How to do it There s more R e Resin io o URL See also
109. Git the illustrious software version control system We could have cheated and just stuck with the version of Git that is already handily installed on the current Debian distro for the BBB Let s check it git version git version 2 0 2 This tells us that the current prebuilt Git binary offered for armh on the Debian repository is version 2 0 2 Yet if we go to the Git website http git scm com you will learn that there is a newer version So let s install the latest and greatest from the source How to do it Perform the following steps 1 To get the dependencies or associated libraries we 1l need to start by grabbing the libraries that Git requires curl zlib openssl expat and libiconv with the following command sudo apt get install libcurl4 gnutls dev libexpati dev gettext libz dev libssl dev 2 As we are about to download the package source files and the compiled code we should set up a directory where we can consistently manage everything as shown in the following command mkdir home debian packages 3 With the libraries installed it s tarball time so get Git using the following command wget P home debian packages https www kernel org pub software scm git git 2 6 2 tar xz The P option points wget to the specified directory Note The preceding tarball version will likely be superseded by the more current code Check for the latest Git tarball at http git scm com This link wil
110. LED should now be blinking Change the interval value to speed it up or slow it down Note If you get an error in the IDE s console window sometimes the fix is as simple as clicking on the Resume button in the upper right corner panel or just restarting the script You can also turn off the debugger to keep the script running There s more The ultimate circuit resistor capacitor cheat sheet we recommend a couple of very useful smartphone apps that serve as exceptionally handy reference tools for resistor and capacitor codes circuit calculators and other useful component values First is AdaFruit s Circuit Playground app for iPhone and Android Although not free but available for just a few dollars it sure beats getting it wrong on those resistor color value bands Second for the Android platform only is Electrodroid which has free and pro USD 2 99 versions available in the Google Play store Using analog sensors Now it s time to grab some analog data Wait a second Analog Isn t the world we live in including the BBB s all digital Mostly yes But the world of sensors is vast and many of the most ubiquitous most useful and least costly sensors are analog devices A great deal of the embedded sensing world motion temperature humidity light intensity pressure and accelerometers consists of analog animals So how do we capture all that analog data goodness With ADC analog to digital converter pi
111. Magazine 1877 Image composite by Charles Hamilton To discover the answer to these and other potentially board burning questions you need to know a bit about the three pillars of electronics wisdom and wiring current voltage and resistance e Current The continuous flow of electrons or the rate of charge through a given point in a circuit e Voltage potential difference This indicates the size of the electrical potential in your circuit that allows electrons to flow Specifically voltage is the difference in the electrical potential between two given points that allows electrons to move This is why it is known as the potential difference e Resistance This denotes that electrons get hung up from Point A to Point B that is there is friction that can impede their free flow of current which we call resistance How do all these things relate to one another when it comes to circuitry The easy answer is Ohm s law Much ink has been spilled in explaining this foundational principle of electricity we will only say a few words and quickly throw a formula at you the only one you will see in this book V Ix R Knowing how to use this basic formula will help you determine the right combination of current and resistance to apply when you wire up your BBB circuits Here is the breakdown of the formula e V This specifies voltage expressed in volts e I This indicates current expressed in amps e R This denotes resis
112. S sh This will run our script at 30 minute intervals Change 30 to 1 in order to test it right away We ve done it A talking BeagleBone Black that captures dynamically generated tracking data and tells us when the International Space Station gets within striking distance There s more Text to Speech e The TTS options on Rpi most of which can be ported to the BBB can be found at http elinux org RPi_Text to Speech Speech Synthesis e E Speak For install and setup instructions refer to http hudsonwerks com beaglebone black recipes voice recognition tts e Festival This is a quick and easy option commonly used on Rpi with various tutorials available e Google Voice This is a great reference for higher quality voices and variety However the engine is cloud based so you need continuous internet access to use it Additionally Google will often throttle usage from scripts by pinging the service so you may encounter difficulties using it Voice recognition The other leg of a voice user interface is voice recognition which is beyond the scope of this book However several tutorials are out there for both the BBB and the RPi that can take you down the path of voice actuated device control Take a look at the Jasper project through the following links e http blog oscarliang net raspberry pi voice recognition works like siri e http jasperproject github io documentation installation e https teslafly word
113. TG1672GD2 100 WPA2 Channel 6 Automatically connect to this network Pr Never connect to this network ike 7 Properties 2 Connect DG1670AD2 95 WPA2 Channel 6 Automatically connect to this network af Never connect to this network ASS at gt 3 E Connect 7 Properties 5 Choose your local network Enter your password in the popup window according to the type of encryption your network uses Then click on OK After a few moments your dongle will be connected Check the connection with the ping command ping www google com If all is well you will be getting solid pingback messages Although the preceding steps are straightforward you might find that your dongle will not work with this recipe or that you are using a different version of the kernel and easy connectivity eludes you If so here are other recipes to get connected Method Two command line option 1 Consult the table at the beginning of this section for the tested models that use Method Two Note that they all use the same RTL8188CUS chipset This means that you will likely be able to use other dongles with the following steps as long as they use the aforementioned chipset Now to the steps 1 2 From your BBB s desktop open up LXTerminal In the command prompt window open the file in the directory specified in the following path sudo nano etc network interfaces Among other settings you
114. To further clarify the PRU subsystem is not a hardware accelerator that speeds up algorithm computing However PRUS do e Reduce latency Digital I Os respond in nanoseconds not milliseconds like we saw in our software RT scenarios e Extend connectivity and add ons Although the BBB is often positioned as a hobbyist or prototyping platform PRU capability opens up use cases to professional embedded computing scenarios unlike other players in the market such as the Raspberry Pi e Manage power With the ability to reduce power consumption in real time far better control over the system and its uses becomes possible For the embedded dev crowd that s a real boon e Deliver 100 percent hard real time Note Texas Instruments the inventor of the BBB doesn t actually support your use of the board with the PRUs They provide examples and even encourage use of the PRUs but still caveat the whole thing by saying that the code is for DIYers to use at their own risk Maybe they re afraid someone will use the PRUs to make a flux capacitor On one level it only takes two things to make the PRUs fly you enable them and then you run a C program or another wrapper with Python to make use of them Easy right However buried within those two seemingly straightforward tasks are some challenges Because we are manipulating an entirely second set of hardware separate from the main processor handling PRUs on the BBB is
115. UI on your desktop client go to http volumio local Then navigate to MENU LIBRARY and click on the UPDATE LIBRARY button At this point if you have the media from this simple recipe the update will take only a few seconds It s time to test our files we will begin by using the m4a file Again on the web GUI go to the Browse USB tab Then click on Space Oddity Hadfield CLIP twice You should hear a brief sample of a remix of David Bowie s song Major Tom from the album Space Oddity In this case it will be sung by US astronaut Chris Hadfield on board the International Space Station It is a remake of a classic but the astronaut does a great job of it Note We would have preferred using the whole track but we limited the length of the clip to conform to the Fair Use legal restrictions For a longer version of the song the video is available online at https youtu be KaOC9danxNo 20 21 22 23 Now let s test our newly downloaded web radio station playlist On the web interface go to Browse WEBRADIO Then click on wbgo_jazzFM_NJ With a nearly finished setup we can cut the Ethernet cord and run Volumio via Wi Fi Go to Menu Network and input your network s name and password in the appropriate fields Then click on Save Changes and Volumio will reset the web interface Next remove the Ethernet cable If you do not already have it open type in the Volumio server address http volum
116. You may encounter the following error File usr lib python2 7 1ib tk Tkinter py line 1712 in _ init __ self tk _tkinter create screenName baseName className interactive wantobjects useTk sync use tkinter TclError no display name and no DISPLAY environment variable If so here is how you can fix it sudo xauth add xauth list If all goes as expected your screen output over the X session terminal will look similar to this Figure 1 ISS Location for 22 Apr 2015 17 33 54 Lat 32 44 Long 143 62 NOt em HR The blue dot shows the current location of the ISS with its coordinates updated every minute 18 Quit the script by pressing Ctrl C There s more High definition camera views from the ISS can be found at e http eol jsc nasa gov ForFun HDEV e http columbuseye uni bonn de Tracking using RTL SDR One of the more exciting add ons to our BBB satellite and object tracking recipes is an extremely low cost USB dongle called RTL SDR RTL is short for Realtek RTL2832U controller and tuner chipset which is inside this dongle and can be purchased for around USD 20 00 Besides being cheap the best part of the story is SDR which stands for Software Defined Radio SDR is kind of what it sounds similar to instead of using hardware components such as amps mixers filters and modulators it is radio with its key functions driven by software SDR can receive signals over a very wide band of fre
117. a look at which audio devices are available through the following command aplay 1 List of PLAYBACK Hardware Devices card 0 Black TI BeagleBone Black device 0 HDMI hdmi hifi 0 Subdevices 0 2 Subdevice 0 subdevice 0 card 1 Device USB PnP Sound Device device 1 USB Audio USB Audio Subdevices 1 2 Subdevice 1 subdevice 1 On the BBB ALSA gives preference to the HDMI port s audio channel which we need to change to the USB sound dongle First we have to disable the HDMI audio output with this command sudo nano boot uEnv txt Edit the following line Disable HDMI cape_disable capemgr disable_partno BB BONELT HDMI BB BONELT HDMIN 10 11 12 13 After editing the preceding line should look similar to this Disable HDMI cape_disable capemgr disable_partno BB BONELT HDMI BB BONELT HDMIN Save the open file by pressing Ctrl O and then enter and exit nano by pressing Ctrl X Next we will modify the ALSA configuration file so that it recognizes our audio dongle as the default device sudo nano etc modprobe d alsa base conf Duplicate the following line Keep snd usb audio from being loaded as first soundcard options snd usb audio index 2 Then comment out one of the lines and change 2 to 0 in the uncommented line Keep snd usb audio from being loaded as first soundcard options snd usb audio index 2 options snd usb audio index 0 S
118. a pin HIGH or LOW in rapid succession Often you will find that three control parameters can be set e Duty cycle This is the percentage of time when the pin is HIGH or on over a specific span of time In your code you express duty cycle as a percentage For example 100 percent would be high power being applied and would be fully on Whereas a low duty cycle of 1 percent would result in low power since power is off for most of the cycle e Period This is the combined time it takes to complete an on off cycle e Frequency In our case frequency is how many times per second the pulse signal went ON HIGH and OFF LOW Taking the inverse of the period gives us the frequency Getting the frequency setting right is crucial since some devices may not work properly if your setting is too high or too low Working with servos comes with taking care with the power input into your board Under no circumstance do a 5V draw to run the motor or you will likely meet Merlin s magic smoke And nothing cuts BBB recipes down to size like magic smoke Note Inside every servo there is a potentiometer that provides feedback to the motor about its position on its 180 degree sweep Getting ready You ll need a few things for this recipe e Servo These small but mighty motors come in many varieties and price ranges If you already have fancy ones in your kit congratulations If not purchase either a standard or mini size because our recipe will
119. ab Create a new file by clicking on the sign Tools Window New File New Terminal Open Preferences New Immediate Window Copy and paste the following code in the new window var b require bonescript var ledPin USRO b pinMode ledPin b OUTPUT var state b LOw b digitalwrite ledPin state setInterval toggle 1000 function toggle if state b LOW state b HIGH else state b LOw b digitalWrite ledPin state For you Arduino users the code feels kind of familiar right For those of you who are brand new to physical computing and hardware let s break down some of the lines before executing the script At the outset of the code we needed to establish certain ground rules namely that we will be using the functionality of BoneScript So we had to include the BoneScript library with all its functionalities and coding shortcuts with the following script var b require bonescript Next we needed to establish which pin or pins we intended to use USRO and then create a variable of it so as to not have to write the pin name repeatedly throughout the script The following code helped us do this var ledPin USRO Once we had an anointed pin to play with we needed to set its mode in other words initialize it so that we could interact with it and declare whether it will be an input or output pin If we were controlling a button the pin would need to be recognized a
120. achine is full of activity So limiting dmesg to output smaller chunks of information with a command option is primarily the course followed In this case we want to show the last ten events on the system so we will use the following dmesg tail Alternatively we can use the less option which allows us to advance forward in the list more methodically as follows dmesg less Device and system insight shows disk space df h This command outputs information on your board s available disk space and displays it in human readable format How to do it Use the following command to find out the disk space debian beaglebone Filesystem rootfs udev tmpfs dev mmcb1k0p2 tmpfs tmpfs tmpfs tmpfs dev mmcb1k0p1 dev mmcb1k1p2 dev mmcb1k1p1 Size 7 26 10M 100M 7 26 249M 249M 100M 5 0M 96M 1 76 96M df h Used 1 66 0 824K 1 66 Avail 5 46 10M 99M 5 46 249M 249M 100M 5 0M 25M 0 86M Use 22 0 1 22 0 0 0 0 75 100 11 Mounted on dev run dev shm sys fs cgroup run user run lock boot uboot media rootfs media boot Device and system insight explore network Ifconfig This lists all the network devices with network information You will commonly find yourself using this command on the BBB when you need to troubleshoot a problem or set up network connections How to do it Use the following command to explore n
121. ake a look at how we can have systemd send us this magical IP addressed e mail How to do it Perform the following steps 1 Log in as root with the following code sudo i 2 Then create a new Python file called email ip py and save it as shown in the following code sudo nano email ip BBB py 3 Here is the Python code the code is derived from the example code on stackoverflow at http bit ly 1kUppmT usr bin python Look up your BBB s ip address and email it import socket import datetime time import sys Import smtplib for the actual sending function import smtplib Import the email modules we ll need from email mime text import MIMEText try b socket socket socket AF_INET socket SOCK_DGRAM b connect 8 8 8 8 80 bbb1_ip b getsockname 0 b close except SocketError print sys exc_info 0 except print error time sleep 5 msg MIMEText Beaglebone Black ip address s bbb1_ip From yourname youremaildomain com To recipientemail recipientdomain com include module for date and time msg Subject BBB ip address at str datetime datetime now msg From From msg To To Send the message via our own SMTP server but don t include the envelope header s smtplib SMTP smtp gmail com 587 10 11 starttls Login your name gmail com your password sendmail From To msg as_string quit In our recipe we ve u
122. an now see the blank slate charts that have been created for the channel that will receive data from the BBB s sensor CJ ThingSpeak channeis Apps Plugins Account Field 2 Chart ID A Channel N 3 4 La ad o 3 rra Date ThingSpeak com Field 1 Chart nee Channel 3 2 n a o E ra Date ThingSpeak com 8 From your GitHub repo download the BoneScript Node js code for this recipe to 10 11 your BBB with the following command git clone https github com HudsonWerks tmp36 sensor thingspeak git Note The repo also includes a Python script example however we will only review the node version of the recipe here Navigate to the new directory that we just created and open the Node js file with the following command cd tmp36 sensor thingspeak sudo nano tmp36 thingspeak js In a browser on your client desktop open the Cloud9 IDE and create a new JavaScript file Then copy and paste the code from the open nano window on your BBB to the Cloud file Before trying to send data to ThingSpeak we should first verify that our sensor wiring and basic code are functioning properly Now in your Cloud9 window click on the RUN button If all goes well the console output in the IDE should show readings similar to the following code debugger listening on port 15454 Sensor reading started Output at 10 sec intervals Temperature at Ground Control for Tue 11 Aug 2015 19
123. and design challenges in the arenas of IoT space technologies and next generation health and wellness devices He writes and blogs at http www hudsonwerks com He is a former creative director at AT amp T and product developer at a New York City based new product development agency Charles development expertise spans devices in the consumer electronics digital media display voice recognition and telecommunication markets He is also a proud papa to his 4 year old son Hudson I would first like to acknowledge the support of Jason Kridner the Texas Instruments embedded applications Evangelist and founder of Beagleboard org without whom this book would never have achieved liftoff Additionally immeasurable thanks need to go to John Reaves of Learning Worlds and Masuo Kitano of Seiko Epson Corporation who ignited the prototyping and build something crazy spark in me Jonathan Hirschman of PCB NG gave it a further push by showing us the way to cook up PCBs from scratch literally Finally more than thanks are necessary to the two people that showed the greatest forbearance in seeing this project to its conclusion my wife Mary and little boy Hudson Without their encouragement patience and love this book would never have happened For this I am humbled and grateful About the Reviewers Nathan Burles is a postdoctoral researcher with a PhD in computer science He is currently working for University of York on subjects as diverse a
124. and first time connectivity we suggest that you have your board connected to a monitor for this recipe After you gain confidence and learn more about connectivity methods you will be able to dispense with using an external monitor How to do it Perform the following steps for Ethernet connectivity 1 With your BBB powered down plug in one end of an Ethernet cable to the BBB and the other end to your router Power up your board via the 5V power supply The connection should occur seamlessly assuming your Ethernet cable is sound your internet connection is reliable and the BBB has no defects At your screen s login prompts enter your login name and password You will be taken to the desktop Next we will check our connection via a terminal session In the lower left hand corner of your screen click on the bird like icon and then navigate to Accessories LX Terminal In the open terminal window type the following ping www google com You should be getting ping responses back that look similar to the following output debian beaglebone File Edit Tabs Help ttl 41 ttl 41 time 90 3 ttl 41 time 89 3 ttl 41 time 93 5 ttl 41 6 ttl 41 7 ttl 41 time 105 qF8 ttl 41 time Connectivity Wi Fi Since its original release in the spring of 2013 Wi Fi on the BBB has been a bit of an Achilles Heel for the platform Compared to the typical experience with Raspberry Pi you could pull out your hair getti
125. ange it to Cloud9 Bright Theme instead Note Not all UI screens change to the new color scheme there s a temporary bug in this beta release of Cloud9 s IDE Firefox Histo Bookmarks Tools Window _ Help BATO ARE 7 52PM Q 3 eoo cloud9 Cloud9 F cloud9 Cloud9 lz ajel E i 192 168 7 2 3000 ice ht G cl B Q S A D 119 118 i Arch Linux C sss C CHAT Clients _ Chromium _jekiga C Empathy Chat _ Gajim XMPP gt CStreamer 7 Jitsi C linphone RPI Misc _ WebRTC Clear Modem co File Edit Find View Goto Run Tools Window Beta Feedback C John Doe 5 a o Untitled Preferences gt D attic ee Maximum of Undo Stack Items in Meta Data aumo gt D autorun D demo GENERAL SETTINGS Enable Preview on Navigation s Navigate Workspace 2660990 Command E f i gt 5 README m Main Theme Cioud9 Bright Theme 8 Ltd testace htm Cloud9 Dark Theme Cioud9 Bright Theme Defaut Find in Files Ih Preview Pt bash vbeaglebone immediate root beaglebone var lib cloudge x O OE now 54 F 8 Sun 37 F 2 Mon 33 F lt 5 One handy feature in the lower portion of the screen is a command shell window This gives the user an integrated command line control within the IDE proper without the need to pop open another window for a shell application Unless you want to customize the UI or listen to the audio tutorials close the Welcome t
126. appear in the directory s lineup Back in the Eclipse window select Window Open Perspective Other Then select Debug This will shift the window views to a debug centric UI From the top menu select Run Debug Configurations In the window that opens select C C Remote Application bbb_ground_control Debug Hold on tight Almost done Select the Debugger tab This shows us more tabs because we haven t had our fill of tabs or options yet Now select the Main tab Here we need to populate the two fields GDB Debugger the executable in the toolchain directory and the GDB command file the directory where we created the gdbinit file To facilitate this step you should be able to browse the relevant directories and grab the right paths as follows GDB Debugger home user bbb tools gcc linaro arm linux gnueabihf 4 8 2013 10_linux bin arm linux gnueabihf gdb GDB command file home user bbb eclipse workspace bbb_ground_control Debug gdbinit 48 49 50 51 52 Then click on Apply I like this part Now we finally get to test the whole shebang with Debug run Let me repeat and this time with bugles and proper fanfare we will test everything we just did and start a Debug session So at the bottom of the still open window click on Debug Hold your breath This will start the remote session with the BBB and finish the cycle just after the main line in your c file Note You may get another login
127. ase the 8081 port With this option enabled we can open a browser and access a web page with some JavaScript and the Google Map API is available as part of the installed package So open a browser and paste the following address into the window using one of the following http beaglebone local 8081 http 192 168 7 2 8081 http your_bbb_ip 8081 You will immediately see a Google Map along with a sidebar window showing a rollup of the data Move the map around until it is positioned at your current location and you should see plane icons appearing Clicking on an icon pulls this particular flight s data into the frame Watch the icons closely to see what kind of general range your receiver and antenna are getting before the aircraft disappears from the screen To quit the program type Ctrl C in the BBB s terminal window There s more e Check out the Raspberry Pi version of RTL SDR used as a portable SDR scanner at https learn adafruit com freq show raspberry pi rtl sdr scanner view all e Public Lab has a wonderful write up describing how plane tracking using RTL SDR yielded information about FBI s surveillance aircraft at http publiclab org notes ajawitz 06 11 2015 raspberry pi as marine traffic radar Satellite tracking using GPredict and RTL SDR SatNOGS is an open source initiative to build a network of ground stations around the world to track satellites Thousands of low Earth orbit LEO sate
128. ates files called Makefiles that track the dependencies for the code that you run with a make utility Libtool This is a script that provides a frontend to the often complex assortment of shared objects such as compilers linkers and libraries that an application requires In the Windows world developers more commonly know this animal as dynamic link libraries or DLLs For most occasions when you compile and install a source file package you will rely on three common commands which must be run in the directory where they reside 1 configure This runs a script that configures the make file It serves to customize the package to the system where it will be running The tells the Linux shell that the script is in the current directory make This is the command that executes the make files in your source code The make files contain the shell commands that compile the necessary files for assembling the software package make install This is simply the make command but with an additional option Called target It takes the compiled files from Step 2 and installs them The make and make install commands almost always require super user privileges to execute so sudo make and sudo make install is your frequent companion When you run make you can further refine what the script does with other targets Here are other commonly used options make all This is somewhat redundant to just using make but you may occasionally f
129. ave the open file by pressing Ctrl O and then enter and exit nano by pressing Ctrl X Reboot your BBB with this line sudo reboot Verify that the HDMI audio is no longer present and that only the USB dongle appears by pasting this command aplay 1Ns List of PLAYBACK Hardware Devices card 0 Device USB PnP Sound Device device 0 USB Audio USB Audio Subdevices 1 1 Subdevice 0 subdevice 0 Confirm that it loaded properly and is available to ALSA with this command cat proc asound cards 0 Device USB Audio USB PnP Sound Device C Media Electronics Inc USB PnP Sound Device at usb musb hdrc 1 auto 1 5 full Open up alsamixer so that we can tweak the volume settings You should see your sound dongle as the default device in the upper left corner of the GUI alsamixer Choose the Speaker option and use the up arrow to increase the volume Help System information F4 Capture F5 All Select sound card Exit The Alsamixer window 14 Close the window with the Esc key 15 Do a simple test to check audio output with the following command aplay usr share sounds alsa Front_Center wav D sysdefault CARD 0 You should hear the nice lady say in English Front Center Whew Not exactly Plug and Play but that s open source for you Part II Installing TTS Let s move along to making the BBB speak using the text to speech TTS engine SVOX Pico Although there are
130. b by adding a toolkit to plot 2D data on maps in Python So now install the Python libraries as follows sudo apt get install python matplotlib sudo apt get install python mpltoolkits basemap Create a python file that will serve as our test ISS tracking tool based on the output from the spreadsheet that we will generate on Dropbox using the following command 14 15 16 17 sudo nano iss_track1 py From our Github repo download the code for this recipe with this command git clone https github com HudsonWerks space satellite git Browse the new directory and open up the following tile cd space satellite sudo nano iss_track1 py Take a look at the opened code It piggybacks on the wonderful Open Notify API developed by rocket maker and satellite wonk Nathan Bergey and is nicely commented and broken down into clear sections including a call to an API the visual map projection code the color values for the map the coordinates that we want to track and the timing for the data updates If you are running headless we will use a method here that you may not be familiar with called X session This is basically an SSH remote session that can run X commands and load graphical windows within your regular SSH terminal So on your desktop client box open up another terminal window this time with the following ssh X debian lt ip address_here gt Run the Python script sudo python iss_track1 py
131. bian beaglebone mkdir test Now is a good time to check your work with the 1s command as follows debian beaglebone 1s Desktop test Modify content data commands remove a file or directory rm As the name implies this command removes a file or directory that you designate How to do it Removing a file is very simple You just need to type out the following rm filei Adding the i option is good practice especially for beginners as it prompts you to confirm the file s removal as follows rm ir filei rm remove regular file file1 To remove directories there are principally two commands you can use Firstly when you have an empty directory the command is similar to the following rmdir dir1 However rmdir works only if the directory is empty If you want to remove a directory with all its contents you can use rm with the r option This option tells rm to remove a directory recursively as in the following command rmdir r dirt Tip Red Alert Obviously rm r can wreak havoc on your system and delete files and directories that you may actually need To be cautious the first few times you use this command you might want to include the i option This way each time you delete a directory and its contents you will get a prompt before each file is deleted Modify content data commands download files wget Running this command gives you control over grabbing and downloading files
132. bone black gpios A quick guide on how to pinmux is available at http beaglebone cameon net home pin muxing Derek Molloy s Beaglebone GPIO Programming on ARM Embedded Linux tutorial and video is another comprehensive and thoughtful introduction available at http derekmolloy ie beaglebone beaglebone gpio programming on arm embedded linux Controlling external LEDs In the last chapter we looked at a quick blink recipe on how to control our on board LEDs Now the objective is to have an external LED on a breadboard blink First we will take a look at the circuit symbol of a basic LED so that we can recognize its proper usage as shown in the following diagram 77 ANODE CATHODE The typical symbol for a light emitting diode LED In the following image you will see what a real life LED actually looks like Not so straightforward as looking at the symbol right anode cathode Note With LEDs polarity matters to have a working circuit Pay attention to the fact that the anode is the longer end whereas the cathode is the shorter end Although mixing them up will not cause any damage the circuit will not work Getting ready You ll need the following items to supplement your now happily perking BBB e LED Just a plain vanilla inexpensive LED is fine this is the type you ll find for pennies at your local hobby store or online You may already have a bunch in your kit e Resisto
133. cess For example you may discover that there are several processes associated with one application and killing them one by one gets a bit slippery Instead use killa11 and kiss them goodbye killall chromium Device and system insight message reports dmesg As you already know every time you boot up your device a ton of messages quickly scrolls past on the screen Unless you wear a blue leotard with a red cape and possess exceptionally fast eyes you likely will not catch all these pearls of ASCII wisdom Yet these messages can be extremely useful at times particularly when you need to troubleshoot a system problem How to do it The dmesg command is used as follows dmesg Typically the output looks similar to this 0 000000 Booting Linux on physical CPU 0x0 0 000000 Initializing cgroup subsys cpu 0 000000 Linux version 3 8 13 bone47 root imx6q wandboard 2gb 0 gcc version 4 6 3 Debian 4 6 3 14 1 SMP Fri Apr 11 01 36 09 UTC 2014 0 000000 CPU ARMv7 Processor 413fc082 revision 2 ARMv7 cr 50c5387d 0 000000 CPU PIPT VIPT nonaliasing data cache VIPT aliasing instruction cache 0 000000 Machine Generic AM33XX Flattened Device Tree model TI AM335x BeagleBone 0 000000 Memory policy ECC disabled Data cache writeback 0 000000 On node O totalpages 130816 0 000000 free_area_init_node node 0 pgdat c0824280 node_mem_map c089f000 The list goes on and on as your m
134. cessary Note All the steps in this section occur on either your desktop client box or a virtual machine not on BeagleBone Black Download and install the VM from https www virtualbox org When finished open the application Perform the following steps 1 10 Download a Linux distribution that you will load to Virtual Box s virtual machine environment We used an i386 net install of Debian Wheezy available from debian org at https www debian org releases wheezy debian installer download is available at http cdimage debian org debian cd 7 6 0 i386 iso cd debian 7 6 0 i386 netinst iso Note You do not need to have the VM run Debian Wheezy for ARMH as the BBB does but can use almost any flavor of Linux Next install and set up a Linux environment on the VM In the open Virtual Box window click on New VM Give the VM a name something clever like Debian Wheezy From the drop down options 1 Choose Linux 2 Then choose Debian 32 bit according to the type of iso you downloaded Then click on Continue Allocate 1024 MB of memory instead of the default 512 MB Then click on the Next button For the hard drive unless you have another virtual hard disk set up and want to use it leave it with the default setting Create a virtual hard drive now Then click on Create For the hard drive file type leave the default VDI setting Then click on Continue For the storage on the
135. ch we ll define in the next section of code Then flash on off according to whatever interval we specify in this case every 500 milliseconds This line is analogous to the commonly seen loop function in Arduino scripts However JavaScript and the event driven Node js environment greatly simplifies the code as follows setInterval blink 500 Finally we will define the blink function The before the state value inverts the value and as the LED begins with a 0 off state this isn t the same as changing to 1 on The last line b digitalwrite which happens to be Arduino friendly syntax establishes an output statement for the LED and its on off state as shown in 11 the following code function blink state state b digitalwrite LED state Finally let s see what the script does Click Run in the Cloud9 IDE Your LED should now be blinking merrily at 500 millisecond increments Note You can find more documentation on the BoneScript library functions at http beagleboard org support bonescript Writing an alternative script with Python Starting from step 3 here s the Python version of the recipe that uses the Adafruit library 1 2 In the Cloud9 IDE terminal window open a new file window in the editor and name it blink_LED py Copy and paste the following code to the window import Adafruit_BBIO GPIO as GPIO import time GPIO setup P8_15 GPIO OUT while True GPIO
136. compatible converters o URL Connecting a non HDMI LCD or cape compile and install o about Compile and install o documentation standards Compile and install o BeagleBone Black compiling on Compile and install o Git from source Compile and install Git from source connectivity o about Connectivity o ethernet Connectivity Ethernet How to do it o Wi Fi Connectivity Wi Fi Getting ready How to do it There s more content data commands modifying o new directory creating Modify content data commands make a new directory mkdir o file removing Modify content data commands remove a file or directory rm How to do it o directory removing Modify content data commands remove a file or directory rm How to do it o files downloading Modify content data commands download files wget There s more o tar file opening Modify content data commands open a tar file tar options How to do it o files cleaning up Modify content data commands clean up files autoclean o package purge Modify content data commands purge a package apt get purge apt get remove purge How to do it o system shutting down Modify content data commands shutdown the system options See also e conventions Getting ready e current OS kernel o updating Updating your current OS kernel See also e custom kernel o installin
137. cond intervals on the screen plotting the fluctuations of Ground Control Temperature of your room as shown in the following screenshot E ThingSpeak Channels Apps Plugins Account Field 1 Chart Ground Control Temperature Temperature Fahrenheit 11 52 15 11 52 20 11 52 25 11 52 30 Time ThingSpeak com Field 2 Chart Ground Control Temperature Temperature Celsius 11 52 15 11 52 20 11 52 25 11 52 30 Time ThingSpeak com 15 Last but not least we want to make the sensor data visible through yet another method this time using Twitter As Twitter is free and readily available on your smartphone it serves as a useful channel to funnel IoT data ThingSpeak simplifies the process considerably by having a web hook that lets you plug into a Twitter account If you do not have a Twitter account set one up now And even if you do have one create a new development account that is separate from your primary feed Otherwise your followers may not appreciate getting your temperature sensor tweets 16 On the ThingSpeak site select Apps from the menu and then ThingTweet 17 Under the ThingTweet App select Link Twitter Account This will redirect you to Twitter so you can authorize ThingSpeak access to your account If you want to proceed with the rest of this recipe you will need to give permission for authorization Once you have confirmed the right Twitter account Twitter will send you back to ThingSpeak 18 A
138. d you need a powered hub to do the job If you don t use a powered hub you may be able to get away with decent stability but you are just as likely to get poor results e Wi Fi dongle refer to tables to test compatible versions We will divide this recipe into three different setup methods as some dongles are happy with one method while others prefer the second one We will also include the setup for Debian 8 0 Jessie as this distribution has greatly improved and simplified the process Some of the setup instructions are derived from http elinux org BBBWiFiConfigs The micro USB dongle models The universe of low cost Wi Fi dongles available on the market is fairly large the following table being a very small subset The mini dongles we used in these recipes have been historically problematic with the BBB but are now more reliable with the current Debian distribution Your best results however may be with a standard sized nonmicro dongle that also comes accompanied by an antenna The following table shows the tested and working models of micro USB dongles for our recipes Note that the first three models use Method Two for setup and the last two use Method Three All dongles are priced around USD 10 00 12 00 Method Two Product Supplier Chipset Powe NOTES Name requirements RTL8188CUS powered USB fThis is the same product as 2 802 11b Adafruit po fr none SH po RTL8188CUS powered USB Method Three EE A
139. dB amixer set Right PGA Mixer Mic3R on amixer set Left PGA Mixer Mic3L on Additionally if you want to plug in a music player or another audio source you need to switch audio from in to out amixer set Right HP Mixer PGAR Bypass on amixer set Left HP Mixer PGAL Bypass on Finally use these commands to adjust the gain 1 To increase volume for example to 10 run the following amixer set PGA 10 2 To decrease the volume for example to 5 run the following amixer set PGA 5 3 To toggle mute run the following amixer set PGA toggle See also There is a wealth of supporting information to satisfy your curiosity and take your understanding of Device Tree to new heights Entire LINUX KERNEL IN A NUTSHELL O Reilly is available as a downloadable PDF at http free electrons com doc books Ikn pdf A general overview of DT with examples can be found at http www circuidipity com bbb dt html A discussion about using DT overlays and its relevance to controlling GPIOs can be found at https groups google com forum topic beagleboard c2LFLEUg6Aw Enabling Device tree overlay on startup on BeagleBone Black can be found at http hipstercircuits com enable device tree overlay on startup on beaglebone black Lots of good tips on DT and overlays are available at http hipstercircuits com category device tree The canonical reference site for Device Tree is at http devicetree org Device Tree U
140. ddle of the window to create a project debug run configuration Click on the New button next to Connection in the Main tab This brings up the New Connection window Select Linux and click on Next This brings up a window with the connection information Enter BeagleBone Black IP address for Host name and name the Connection name and Description both as BeagleBone Black o Host name 192 168 2 7 o Connection name Beaglebone Black o Description Beaglebone Black Click on Next In the New Connection Files window select the select ssh files and then click on Next In the New Connection Processes window select processes shel linux Then click on Next In the New Connection Shells window select ssh shells Then click on Next 26 27 28 29 30 31 32 33 34 35 36 37 38 39 In the New Connection Ssh Terminals window select ssh terminals and click on Finish You will end up back at the Run Configurations window For Connection choose BeagleBone Black not Local Click on Properties next to Connection A window will come up so select Remote workspace location Enter a path to your project on BeagleBone Black For the sake of simplicity you should probably follow what we did and input root Click on OK This takes you back to the Run Configurations window In the following steps we will perform two key things configure our remote paths on the BBB and give our application permission t
141. desktop client PC or Mac This app will hook to the Dropbox Uploader script Perform the following steps 1 Open the following URL on the desktop in your browser and log in using your Dropbox account at https www2 dropbox com developers apps 2 Click on Create App and then select the Dropbox API app 3 Select Files and Datastores The rest of the fields should be filled out in the following manner Can your app be limited to its own folder No What type of files does your app need access to Specific file types My app only needs access to certain file types like text or photos Last question what type of files will your app use Images 4 Give the app a name in the last text field Mine is called NowPix to remain consistent with the directory album name that we set up on the iPhone Then finish by clicking on the Create App button 5 Now generate an App key Back to the BBB The next series of steps continue with the verification authentication process using Dropbox Perform the following steps 1 2 In the open terminal window and at the appropriate prompt paste the App Key generated in the previous step and follow the onscreen prompts When your new app is successfully created enter the App Key App Secret and the permission type shown in the confirmation page as follows App Key YOUR_API_KEY_HERE Hit the return Enter key after you input the appropriate data given the next several terminal pro
142. dict uses the term module for what you use as your dataset of the satellites you want to track So create one by navigating to File Create New Module MODULE NAME XX 8 From the little down arrow button in the upper right corner of the screen select Clone This will create a clone of the module that you will customize and configure for this recipe 9 Next go to Configure Ground Station and give yours a name Mine is NYC because that s where I live 10 Determine your location either using a preset value from the Select option or by filling in the Latitude and Longitude fields I ve done the latter to get a more precise location Various websites can provide you with GPS coordinates I used http mygeoposition com as it includes elevation as a variable 11 Now we want to choose our satellites Although there are countless birds up there in the heavens for simplicity s sake we will stick with our touchstone the ISS If you cloned the module as described in the preceding steps you will only need to remove the nonISS satellites as the ISS is already in the list However you may also choose from the more than 1200 satellites listed in the GPredict database 12 Once you make your selection the main window will begin populating the data with the ISS s position There are numerous options to customize the views of your modules which you can learn from the very thorough user manual The Gpredict user inter
143. directly into the kernel from the user space added a virtual directory to enable control over a pin and then controlled this pin via the command line Seeing it work here at a deeper level will bear fruit as we advance toward fancier recipes in later chapters There s more For more information refer to the following sources Pin states Understanding pin states can be quite challenging According to your use case not only can they be set as input or output pins but they can also be set as pull up pull down or floating For more discussion and background on configuring your pins for these purposes review Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python where we discussed GPIO pins Other tutorials For a couple of interesting sysfs methods to turn off the USR LED heartbeat pattern which many find annoying follow along with one of these tutorials e Howto Disable BeagleBone USR Heartbeat LED lights http experimentswithlinuxrelatedtech blogspot com 2014 12 how to disable beaglebone usr heartbeat html e Professor Mark Yoder s class EBC Exercise 10 Flashing an LED http elinux org EBC Exercise 10 Flashing an LED Device Tree and its roots Linus Torvalds was sad and mad ARM was making Linus sad and mad There were too many cooks too many ingredients too many new hardware variations in the world of ARM devices The architecture had become so popular in the embedded computi
144. dit as follows sudo nano linphonerc 21 22 23 24 25 26 With this file window open find the video section and type or replace the following at the end of the section displaytype MSVideo0ut We are now ready to launch Linphone When you launch the application for the first time you may encounter the following error or something similar liblinphone so 6 cannot open shared object file If so you need to reset the location of the Linphone libraries as the error indicates that you have installed the package in a nonstandard directory on your BeagleBone Black board This command will help Linphone relink the shared library location export LD_LIBRARY_PATH _the_path_to_your_linphone_libs You can now launch Linphone from its command line tool as follows linphonec In the terminal window Linphone will launch and allow you to configure the settings in the next two steps Setting up an SIP account Unlike the GUI based wizard that you experienced with the initial prepackaged install setting up and registering is a bit more minimal As you have already registered an SIP account you can just register your SIP address with the following command gt linphone register lt sip address gt lt sip domain gt lt password gt Making a video call To test your connection make a call to your client box which should already have an installed and registered version of Linphone from the first
145. dow into the IDE file window From here you can begin customizing the code starting with the messages displayed on the screen Once appended save the file and click on the RUN button in the IDE An updated scrolling text message will appear on your OLED display Note Before running a Python script in the Cloud9 IDE remember to save the document each time Otherwise the IDE may run a cached version that does not contain your new changes There s more The following is some supporting information e You can dig deeper into the nuances of modifying the SPIdev pins at http elinux org BeagleBone Black Enable SPIDEV e You can also experiment with py gaugette a Python alternative to the Adafruit Python library to control SPI and other GPIO pins including a thorough explanation of using higher quality fonts with the display at http guy carpenter id au gaugette 2014 01 28 spi ssd1306 oled for beaglebone black Testing a mini LCD cape In this section we will cook up an introductory recipe to use the mini LCD display cape designed by CircuitCo With a mere 1 8 inches of screen territory you might wonder what kind of scenarios would be relevant for an add on such as this You might also think that the design is a bit odd as the PCB board space dwarfs the actual screen size Keep in mind a couple of things though when deciding to purchase the cape and testing it e The BBB is an embedded computing centric development envi
146. drink a sandwich or go for a jog a long one If all went as planned your music library should now be catalogued Go to Library select the your USB music directory and verify that everything s visible 26 We also have a potential bug fix Depending on your version of Volumio this is where you may encounter some quirks Because of a lingering bug in the in the last few versions of the MPD server environment which is not Volumio s fault many file types compatible with FFMPEG are disabled by default This means that the GUI based update MDB database function that we just executed may capture some of the metadata for a music file including its name but not the actual media data itself So let s fix this in the command line as follows nano etc mpd conf Scroll down to the FFMEG disable line and change disable to enable Following this save the mpd conf file and close it 27 Now let s test our media files via the GUI go to Browse USB select your album or music track and choose a favorite music file Note that it doesn t have to be a David Bowie track With all this done we are left with one thing to do turn it up to 11 There s more Here is some supplementary information about playlists which you can use to extend this recipe As in most music library environments Volumio uses playlists p1s files as a means to categorize or organize your media into custom play sequences Here are two basic me
147. drive eMMC or via an SD card First boot up BeagleBone Black BBB designers have worked hard to simplify the user s first out of the box experience Although things get more challenging later which is natural it is pretty close to Plug and Play at the outset You do not even need to load any software as the platform arrives preloaded with a custom distribution of Linux Debian on the internal solid state drive eMMC Getting ready Here s what you need e Desktop client PC As noted in the introduction we will principally be using a Mac box as our client machine However the following steps apply equally to a Windows or Linux machine e USB cable A mini USB B to USB cable is required which is typically supplied with your board e BeagleBone Black Rev C To reiterate a point from this book s introduction our recipes use Rev C which is the currently shipping version of the board If you have an earlier board you may run into occasional conflicts with the recipes How to do it Perform the following steps 1 To power up plug the USB cable into the BBB and your client box 2 Wait for the three blue LEDs to light up each of them functions as a useful indicator of the board s health o Power Once power is supplied to the board the LED next to the 5V barrel jack will remain on without flashing o USRO Next to the tiny reset button S1 this light maintains a continuous solid heartbeat blink when po
148. e are the steps you need to perform 1 Check that pip is installed and the package management system used to install and manage packages is written in Python through the following command pip list As Python 2 7 9 and later versions on the Python2 series and Python 3 4 and later versions include pip by default you may have pip already If not you can install it this way 2 Download get pip py at https bootstrap pypa io get pip py 3 Then run the following sudo python get pip py 4 Install package dependencies via the following command sudo pip install virtualenvwrapper Note virtualenv is a tool designated to address the problem of dealing with packages dependencies while maintaining different versions for different projects For example if you work on two Python Django websites one that uses Django 1 2 and another 0 96 there is no way to keep both versions if you install them into the standard usr lib python2 site packages virtualenv creates two isolated environments vitualenvwrapper takes virtualenv a step further by providing commands that can be invoked from the terminal window 5 So that your program knows where to find virtualenvwrapper modify your bash profile with the following command sudo nano bashrc 6 At the end of the open file append it with the following export WORKON_HOME HOME virtualenvs source usr local bin virtualenvwrapper sh 7 Reload the bash script with the follow
149. e capemgr bone_capemgr 9 slot 7 dtbo bspm_USRO_10 00A0 dtbo loaded converting to live tree 153 834620 bone capemgr bone_capemgr 9 slot 7 2 overlays 153 835294 bone capemgr bone_capemgr 9 slot 7 Applied 2 overlays When we run dmesg it tells us more about the sequence of events including whether the previous commands were successful The 10 option outputs the last ten messages from the kernel You can make the number higher or lower according to how many messages you want stdout to display 9 Further forensics are useful for a greater insight into the process so navigate to the following designated directory and run the following cd sys devices bone_capemgr cat slots 54 PF 55 PF 56 PF 57 PF ff P O L Bone LT eMMC 2G 00A0 Texas Instrument BB BONE EMMC 26 ff P O L Bone Black HDMI 00A0 Texas Instrument BB BONELT HDMI ff P O L Override Board Name 00A0 Override Manuf bspm_USRO_10 No BWNEF O The preceding output tells us something important that the Device Tree blob that we just built is recognized by the kernel and slotted into position Beautiful kernel magic Device Tree advanced adding DT overlay to run a custom cape BeagleBone Black introduced the idea of Device Tree overlays that provide even more functionality to DT by modifying the tree in user space typified in our prior example With DT overlay there is no need to reboot We saw in our earlier section on sys
150. e detail than you ll likely need but good context and a helpful table of commands for PASM https github com beagleboard am335x pru package blob master Documentation AM335x PRU ICSS Overview pdf e Texas Instruments official overview of PRUs http processors wiki ti com index php Programmable Realtime Unit Software E e PRU C project from device tree to program execution an extensive and useful thread on PRU usage https groups google com forum category topic beagleboard pru VW361VUKkCcI e An assortment of PRU centric projects http processors wiki ti com index php PRU_Projects e Another take on setting up and running PRUs http www embeddedrelated com showarticle 586 php e An early some consider seminal post on using PRUs with the BB White not the Black http boxysean com blog 2012 08 12 first steps with the beaglebone pru e Debuggers and editors o VisualPRU a sexy browser based editor and debugger for the PRUs https github com mmcdan visualpru o PRUdebug a functional CLI centric app for debugging your PRU code http sourceforge net projects prudebug e BeagleRT Most projects on the subject of using RT on the BBB focus on driving motors for machine tools or other industrial applications BeagleRT however is a fascinating project that uses Xenomai and PRUs on the BBB in the service of creating hackable Digital Musical Instruments DMIs This novel use case for an ultra low latenc
151. e formula Temp C 100 x reading in V 50 function writeTMP x var millivolts x value 1800 1 8V var temp_c millivolts 500 10 var temp_f temp_c 9 5 32 console log Current temperature is temp_c C and temp_f F 4 When you are ready to run the code just click the Run button in the IDE Your output should look like the following with your local temperature of course Current temperature is 20 C and 68 F Current temperature is 22 4 C and 72 32 F Note If you get some funky temperature readings reboot your board and rerun the script There s more You can try exactly the same exercise this time with Python https learn adafruit com setting up io python library on beaglebone black adc See also e More support for analog inputs can be found at Reading the analog inputs http beaglebone cameon net home reading the analog inputs adc Variable resistance sensor photocell Capturing the data generated from light sensors is one of those satisfying and highly useful examples of physical computing Some of you may have used light sensors also known as CdS cells photoresistors and photocells in your Arduino or Raspberry Pi projects If so this recipe will be a snap for you A photocell is a variable resistor which in this case means that it varies its resistance according to the intensity of light exposed to it The value of that variable resistance is turned
152. e most powerful and fully featured However the vim command is not a good starting point for neophytes as it is more complex Instead our text editing tool of choice for the rest of this book will be nano In this section you will learn your way around the editor and then create and edit a text file How it works When you re using nano take note of all the options at the bottom of the screen Exit Get Help Read File and so on You access these functions with the keyboard shortcuts shown next to each option Beware that these shortcuts actually may change their function or mode when you navigate to another screen or choose an option So remember what the bottom menu says before assuming that the shortcut you just used remains in the same mode In the main default window here s a quick rundown on the most commonly used functions and their shortcuts Ctrl X Closes the file Ctrl V Takes you to the next page Ctrl Y Takes you back to the previous page Ctrl K Cuts text deletes the line of text where your cursor is Ctrl U Uncuts text undoes the line deletion from the last line that you cut Repeating this command will keep adding the same line of text that you cut Ctrl G Help menu e Ctrl C Shows the current position gives you line column and character coordinates e Ctrl R Inserts a file into the file you have open Now that s a time saver huh I recommend using Ctrl G periodically wh
153. e worth mentioning for their ease of use or their strong positioning on the marketplace Cloud deployment Deploying software updates to multiple remote devices will become an increasing challenge as the IoT continues to grow Two players Resin io https www resin io and Docker https www docker com are leading the charge in creating a platform for containerizing your applications making it easy to deploy packages to all your devices over the cloud Data display and hosting Many businesses in the IoT space are trying to make it easier for you to manage and display your IoT data in a slicker package and simultaneously host with them Here are a couple of them o Initial state https www initialstate com o Ubidots http ubidots com Messaging and alerts Dweet io Freeboard http dweet io Connecting to web services through open APIs Ship iot https shipiot net Toolsets to hook up IoT devices including the following sample o IBM s Nodered js http nodered org o Adafruit I O https www adafruit com io Making things smarter building a wireless digital picture frame Taking mundane objects and connecting them to one another is one of the key intentions of the whole IoT phenomenon In our next recipe we will create a digital picture frame However ours is is not the typical off the shelf version where you load images from an SD card Instead we will use a combination of web services that are commonly used i
154. eacon can be found at http tiletogether tumblr com post 98897004442 tile is coming to android notes Troubleshoot your Bluetooth installation https wiki archlinux org index php bluetooth Bubble app This app that strives to simplify the process of setting up and interacting with iBeacon content by using tags to connect websites to things in the real world Learn more at http discoverbubble com Using sensors and data with ThingSpeak Having some facility to hook up sensors is almost de rigueur when you talk about the Internet of Things Furthermore learning how to get your arms around the large datasets that typically pour out of these sensors has become a crucial piece of the IoT puzzle In the next section we will take a look at a recipe that introduces one method for managing this data We will be piggybacking on a recipe from Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python and will use the TMP36 temperature sensor in particular However this time you will learn how to use the data coming out of the sensor and display it in a more accessible IoT style manner Getting ready The following materials will be needed BBB powered via 5V supply Ethernet or Wi Fi connectivity Breadboard 3x jumper wires The TMP36 temperature sensor this is the same sensor as the one we used in Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python As a re
155. ebian VM is selected click on the Start button On your first bootup you will be presented with a Debian setup window Choose INSTALL You will then be taken through quite a few setup windows including choosing language region and keyboard preferences network options password and user setup and other configuration options that I will not elaborate here Configure as you see fit while clicking on the Continue button until you end up with the hard disk partitioning sequence Make your choices there according to your preference In most cases choosing the default option should be fine Note Keep in mind that an entire OS is being installed on your host machine so this step willtake a while Also remember that this new OS is being installed on the Virtual Machine environment and not affecting or modifying your client desktop Once the Debian installation and setup is completed you will end up at the Debian GUI login screen Log in and you will finally arrive at the desktop Let s open the terminal window in our new Debian environment and perform a basic ping test on BeagleBone Black We want to make sure that we can communicate with it via our VM as follows ping 192 168 7 2 You should get consistent pings Adding cut and paste to VM We now need to implement an additional functionality to the virtual box that will drive you mad if you do not add it the cut and paste function When you use Mac OS X as your client
156. ebugger tutorial is available at http www unknownroad com rtfm gdbtut gdbtoc html e For a deeper understanding of GDB and the gdbinit file refer to http www dirac org linux gdb 03 Initialization Listing And Running php systemd services First it wasn t a typo to label this section as systemd in all lowercase letters It is one of the mandates of Linux that any daemon which is what systemd is should be in lowercase Also daemons must also come with the lowercase suffix d So what is systemd exactly Briefly it is a background process and a system management daemon for managing user space system services Systemd will become standard plumbing for most major Linux distros and is an integral part of the BBB Debian distribution It is the first process initiated on bootup in the Linux user space and the last process to terminate on shutdown Basically systemd starts the show on your Linux OS and turns out the lights as it s leaving Sound familiar If it does that s because systemd is the heir to init Linux s longtime daemon of daemons Mastering systemd on your BBB helps us better understand system dependencies because systemd serves as a robust framework for these dependencies Here are a couple of examples of why you d want to manipulate systemd processes e Bootup Since much is happening with your system at bootup it makes sense to have tighter control and deeper insight into the startup processes For example you
157. ecipe is pin P9_38 or AIN3 Pin 3 right pin Ground pin on the BBB 2 Open up Cloud9 IDE at http 192 168 7 2 3000 and use the following code to begin capturing temperature readings Setup var b require bonescript Read library var TMP36 P9_38 Pin location for sensor Check the temperature every 4 seconds setInterval readTMP 4000 Define the readTMP function function readTMP b analogRead TMP36 writeTMP Define the writeTMP function function writeTMP x var millivolts x value 1800 1 8V var temp_c millivolts 500 10 var temp_f temp_c 9 5 32 console log Current temperature is temp_c C and temp_f W F 3 The code is broken down as follows o Evoke the BoneScript library Setup var b require bonescript o Now choose the pin number where your sensor is wired See the pin layout reference diagram at the end of this section for more background on the ADC input options var TMP36 P9_38 Pin location for sensor o Then we ll check the temperature at specific intervals in this case every four seconds setInterval readTMP 4000 o Now we define the readTMP function function readTMP b analogRead TMP36 writeTMP o Finally we define the writeTMP function which is where the voltage data captured is turned into temperature readings We calculate the temperature from the voltage in millivolts with a simpl
158. ed on our smartphone Here we will use it to help us track the International Space Station ISS but we will take the interaction a bit further Getting ready The materials needed are as follows e The BBB headless or connected to an external monitor and tethered over USB with Ethernet or Wi Fi if you choose e A smartphone with cell or Internet connectivity How to do it Perform the following steps 1 The easiest most basic way to get the ISS s flyover data is by signing up for SMS alerts from NASA s website at http spotthestation nasa gov index cfm The first few times you get the alert it is a thrill to know when you can potentially go outside and watch the space station fly over your head Here is a typical message showing the directional data points Subject SpotTheStation Time Tue Apr 21 8 18 PM Visible 4 min Max Height 80 degrees Appears NW Disappears SE Soon however you may want to do more with this information To do this the next steps will build on recipe of pulling images into a rotating screensaver cycle using the feh package from Chapter 8 The Internet of Things However this time we will use fresh space imagery Additionally we will add ingredients to grab flyover data and display it So let s slightly modify the steps and code from the earlier chapter From your smartphone go to the IFTTT Space Channel https ifttt com space and activate the version according to wh
159. ee also The following are some key links to gain more information about Volumio which also illustrate many ways to troubleshoot issues e The very active Volumio support forum is available at http volumio org forum e MAA file support is available at http volumio org forum m4a support t14 html e To fix Wi Fi drop off freezing issues navigate to http volumio org forum volumio for feeback thread t781 70 html Using videos and displays in projects It s one thing to just plug an HDMI monitor into the mini HDMI port on your BBB and get a picture In many cases this is may be all you care about for a project However for bona fide embedded or mobile scenarios where you need a display using the HDMI option can be overkill your needs are low power small form factor and just enough display to convey basic information In this section we will take a look at two other options for display a mini OLED display available as a breadboard able PCB and a custom BBB cape designed with a very small LCD panel Hooking up a mini OLED In this recipe we will take a look at a very small 1 3 inch OLED display with a resolution of 128 x 64 pixels It has a monochrome screen which means that we will not be watching Lawrence of Arabia on this device Instead we will explore some methods for basic control and input and take a preliminary peek at typical design choices for embedded devices The nice thing about experimenting with a device like
160. eful sudo shutdown r now However if you simply want to shut down the system and power down completely then either of the following two options will do the trick sudo shutdown h now You can alternatively use the following command sudo poweroff See also e Linux in A Nutshell The online version of this book delivers an abbreviated list of 687 commands http www linuxdevcenter com cmd e Working with commands You can work with commands at http linuxcommand org lc3_lts0060 php You will find some of the best one page cheat sheet references for Linux commands Print them out and post them in an honored place e The table from Make use of http www makeuseof com pages linux commands reference pdf e Free electrons command memento This is well designed and comprehensive and can be found at http free electrons com doc training linux kernel command_memento pdf e An excellent cheat sheet that comes in different languages and printable PDFs can be found at http fosswire com post 2007 08 unixlinux command cheat sheet e You can read up more on cleaning up packages at http www stchman com cleanup html Edit a text file from the command shell There is nothing pretty about the text editing tools in Linux After all it is a command shell environment how pretty can it be But if you are a minimalist at heart you will feel right at home Two editors mostly dominate Developerland nano and vim The latter is th
161. ement or response time Further engineers and developers often have their own spin on what they define as real time which is once again determined by their own scenario requirements However for our purposes we ll define real time using the following spectrum of categories e Soft This is where use case requirements for real time are met most of the time Consider the example of music playback on your system It s mostly smooth but hiccups happen sometimes on playback This standard is typically adequate for most desktop use cases e Life safety hard This specifies that the system must deliver on real time requirements 100 percent of the time If it doesn t it might result in death or injury None of our recipes and certainly not our lovely BBB will deliver this standard of response or reliability I repeat that our recipes and use cases do not cover these scenarios Only custom dedicated systems and certainly the ones that cost more than USD 45 00 can perform this way e 100 percent hard This indicates that the system delivers real time performance 100 percent of the time This may sound like Life safety hard but the only thing at stake is nonhuman The worst thing that can happen is that a product gets botched in a milling machine or your UAV fell down and went boom But nobody got hurt and nobody died e 95 percent hard This denotes that our system is nearly perfect with only 5 percent error margin This is commonly acc
162. en you re just beginning as a reminder for the additional functions available many of which are powerful and useful Overall you will find that even a simple Linux based text editor such as nano comes loaded with features that most Wintel Mac desktop versions don t typically include How to do it This function can be performed through the following steps 1 Let s begin by opening nano and simultaneously creating a file named major_tom nano major_tom Pow A window opens That s the nano interface in all its glory All right not so sexy But very functional as you can see in the following image debian beaglebone File Edit Tabs Help GNU nano 2 2 6 File major tom Get Help e WriteOut Read File Prev Page Cut Text e Cur Pos Exit Justify where Is Next Page UnCut Textil To Spell 2 On the first line which is where your cursor should be by default type or paste the following I love my Beaglebone Black so much I want to send it into orbit with Major Tom Quickly looking around the window you will notice the following At the top of the window you will see the version of nano that you re using and the file name major_tom At the bottom of the window is an assortment of options If you ve played around with any of the options in the menu ensure that you re back in the main screen where we began with our typed line about Major Tom 3 Next save the file by pressing Ctrl x when prompted ty
163. eptable for example when you re capturing data from sensors There may be some gaps in the data stream but nothing egregious that throws off your outcomes or analysis You can just resample for another dataset Note The preceding definitions are inspired by the paper How fast is fast enough Choosing between Xenomai and Linux for real time applications https www osadl org fileadmin dam rtlws 12 Brown pdf On the subject of real time systems embedded developers like to throw around the term determinism They aren t getting philosophical In a real time context they re referring to event and temporally driven outcomes that are precisely determined That is with an event you have an input and a determined locked set of outputs whereas in the temporal piece for a real time environment the timing is determined as well So why wouldn t you use real time all the time The answer is effort money time and project requirements And sometimes there are distinct trade offs when using a real time variant in your kernel or system For example an event you mark for real time response may hum along perfectly however this can end up being a drag on overall system performance The following table is a latency table system Typical instruction interrupt cycle latency nos This specifies 1 second PREEMPT_RT This denotes 200 milliseconds xenoma This denotes 20 50 milliseconds PRU This specifies 5 10 nanoseconds
164. equently used to dig into problems you may have with a C or C program that you may have written Alternatively you can run GDB to debug an executable or binary In this section we will perform the former One of the most typical entry points to understand how to debug using GDB is by running simple examples of executables written in C or C Many of the software resources available for developing on hardware platforms such as BeagleBone Black commonly rely on C or C These are the core low level and mid level languages needed for deep manipulation of the machinery Indeed most of the binaries that you will often load to your BBB are written in one or both of these two languages They also serve as a vital bridge between high level and low level programming which we will see in later chapters If you are already an Arduino user or even a Raspberry Pi developer this is old news because you already know that the Arduino processing language is largely a simplified version of C C If you are a newcomer don t worry because the examples we use are very basic and will not require advanced knowledge of C or C Also any kind of in depth analysis at either of these two programming languages is beyond the scope of this book We will begin by serving up a small piece of C code on the BBB so that you can see what the debugger output can show us Then based on GDB s forensics we will fix the code How to do it Perform the following
165. er to the recipe mentioned before to set up this configuration including the images and the Fritzing diagram Note For audiophiles one of the attractive features of Volumio is that it supports the use of DAC boxes Although sexy useful and powerful DAC boxes can be quite expensive We don t have one so we re not including the hookup methodology in this recipe At Volumio s support forum http volumio org forum you will find ample discussion around using DAC boxes Speakers Connect the speakers that you used in the prior recipe or use the audio out jack on a USB audio dongle e Speaker cable You can use mono or stereo jacks e Media storage Audio files can be served from a variety of storage devices such as USB NAS and so on Since we had it on hand we used a powered USB hard drive How to do it Now that you re ready let s begin 1 Start by downloading the Volumio BeagleBone Black disk image on your client machine not your BBB The current version is available at http volumio org get started Following the download extract the downloaded archive You should end up with a img file on your local box Insert an SD card reader with a minimum 4 GB microSD card installed As Volumio claims to require a very minimal install piggybacking on Debian Wheezy you may be able to get away with a smaller amount of storage than 4 GB Flash the img file to your SD card As we are using a Mac box we w
166. erful and potentially becoming overly complicated for users Here is some background on this controversy e A robust slashdot thread provides plenty of rants on the pros and cons at http news slashdot org story 14 02 14 166255 ubuntu to switch to systemd e Eric Steven Raymond ESR an open source guru is currently on the fence about systemd at http interviews slashdot org story 14 03 10 137246 interviews esr answers your questions Despite the disagreements over its long term impact on Linux systemd is here to stay at least for the foreseeable future So it behooves you to learn some recipes Basic commands for systemd services systemd is modified via a configuration file rather than a shell script Before you perform anything too ambitious we will take a look at how we stop start enable and disable a service Our example will reset and reconfigure a key service that will run in your Debian distribution the systemd timedated service by default How to do it Perform the following steps 1 Navigate to the systemd directory root user with the following code cd 1ib systemd system Let s see what services are running using a command that serves as the control utility for systemd as shown in the following code systemctl You should see a long fat list of services that show their current status on the system The items appended with the service filename are systemd services and controllable via
167. es that are commonly used in physical computing e Pulse width modulation PWM e Analog to digital converter ADC Within our toolset is another software application that electronics and hardware makers rely heavily on Fritzing You may already be familiar with it but if not Fritzing is an extremely handy open source graphical tool for creating diagrams of breadboards schematics and PCB layouts without the need for traditional engineering schematics Note Before wiring up your breadboard it s a good idea to reset the BBB each time you perform a new recipe by powering it down This ensures that the pins are reset to their input state Otherwise if the pin is being used as an input in a new recipe that was previously used as an output you may damage your BBB There s more Here are some of the sources and links to the BeagleBone Black s pin layouts One of the best pin mapping guides is Eskimon s interactive overlay at http eskimon fr beaglebone black gpio interactive map The full expansion header layout is at http elinux org Beagleboard Cape Expansion Headers A more succinct diagram of GPIOs is available at http stuffwemade net post beaglebone pinout new Collars that you can attach to the BBB that provide easy call outs for the GPIO pins is available at http www doctormonk com 2014 01 beaglebone black collars html Take a look at how to use BeagleBone Black GPIOs at http www armhf com using beagle
168. et started To do this perform the following steps 1 Firstly log in as root with the following command sudo i Following this check the current version of your kernel through the following command uname a Linux beaglebone 3 8 13 bone67 1 SMP Wed Sep 24 01 36 09 UTC 2014 armv71 GNU Linux Note Write down the version number so that we can refer to it at the end of the recipe 2 You then need to go to the scripts directory that comes preloaded with your version of Debian for the BBB You can do this by typing out the following command cd opt scripts tools 3 Run the following git command to update your local files git pull 4 You have several options for the type of install you prefer the stable testing or custom release According to your preference append the command with one of the following options o For the stable release use the following command update_kernel sh o For the testing release the following command will be useful update_kernel sh beta kernel Running this script installs a version of the kernel that is still in the test phase Although technically not a release the testing versions of the kernel can still be quite stable and robust albeit with some bugs o For the custom release run the following command this has to be on rcn ee net update_kernel sh kernel v 0 00 bone00 For the custom option you can replace the version number with the exact version you want t
169. ether you use an Android or iPhone Once you ve done this IFTTT suggests useful trigger pairings This channel goes well with Choose Google Drive as the pairing Activate the following two triggers Add NASA s Image of the Day to my Dropbox Log each time the ISS passes overhead to a Google Docs spreadsheet Now we will tweak our Dropbox Uploader script and cron jobs from the last chapter As a reminder the cron job looks for a new image file in Dropbox at specified intervals and cycles it into a feh image playback queue on your screen while the Dropbox Uploader script actually downloads new images into a specified directory on your BBB So if you successfully executed the recipe for NowPix in Chapter 8 The Internet of Things proceed to the next steps Otherwise return to Chapter 8 The Internet of Things and follow the steps to download and display the images Create a Space directory on your BBB that mirrors your Space directory created by IFTTT on your Dropbox account using the following command mkdir Space Now confirm that the content of your IFTTT directory on Dropbox can be accessed and read properly list the images that are there This is why we put a dummy image here in an earlier step as follows 10 11 12 13 cd Dropbox Uploader dropbox_uploader sh list IFTTT Space Your terminal output should look similar to this gt Listing IFTTT Space DONE F sample_i
170. etween your client host box in our case Mac OS X and your virtual machine environment should now be enabled Before moving one though we need to verify that the cut and paste function is working From your Debian Wheezy virtual machine window navigate to Applications Accessories gedit Text Editor and open a new file as shown in the following screenshot Applications Places Tue May 26 4 26 PM A Accessories gt da Archive Manager ed Games gt E Calculator Graphics gt Character Map Internet gt 3 Contacts Y Office gt Q Desktop Search lt T Programming gt EN Disk Utility Hy Sound amp Video gt 2 Documents System Tools gt E Files x Universal Access gt A gedit Text Editor Main Menu Root Terminal amp Screenshot m Terminal a Time Tracker a Time Tracking Overview E Tomboy Notes 15 From the open file window enter Ground Control and then select Edit Copy Then navigate to your client desktop Mac Windows machine and so on open a simple 16 17 18 19 20 text editor and select Paste Hopefully Ground Control will be pasted to the window We want to check the bidirectional functionality so now enter Major Tom in Mac Windows text editor on the desktop and press Ctrl c copy Now switch back to the VM editor window and then select Edit Paste Major Tom should be pasted successfully to the gedit window Reboot the VM and the
171. etwork configuration ifconfig The output is as follows eth lo usb debian beaglebone ifconfig Link encap Ethernet HWaddr 90 59 af 65 5b ba inet addr 192 168 15 100 Bcast 192 168 15 255 Mask 255 255 255 0 inet6 addr fe80 9259 afff fe65 5bba 64 Scope Link UP BROADCAST RUNNING MULTICAST MTU 1508 Metric 1 RX packets 34715 errors dropped overruns frame TX packets 19912 errors dropped overruns carrier collisions txqueuelen 1000 RX bytes 6195835 5 9 MiB TX bytes 7328600 6 9 MiB Interrupt 40 Link encap Local Loopback inet addr 127 0 0 1 Mask 255 0 0 0 inet6 addr 1 128 Scope Host UP LOOPBACK RUNNING MTU 65536 Metric 1 RX packets 11284 errors dropped overruns frame TX packets 11284 errors 0 dropped overruns carrier collisions txqueuelen RX bytes 1429208 1 3 MiB TX bytes 1429208 1 3 MiB Link encap Ethernet HWaddr ce eb cb d1 4a c3 inet addr 192 168 7 2 Bcast 192 168 7 3 Mask 255 255 255 252 UP BROADCAST MULTICAST MTU 1500 Metric 1 RX packets errors dropped 0 overruns frame 0 TX packets errors dropped overruns carrier collisions txqueuelen 1000 RX bytes 0 0 0 B TX bytes 0 0 0 B Modify content data commands make a new directory mkdir This command helps you create a directory folder where you want to work or place files How to do it Use the following command to make a new directory de
172. f a device is one of the most typical features of many IoT use cases So we will first take a look at a recipe on how to use everyone s favorite location tech GPS Then we will explore one of the newer innovations that has spun out of Bluetooth 4 0 beacons a technology for capturing more precise location based data than GPS The UART background In the galaxy of embedded systems developers use dozens of different serial protocols More common and familiar to most consumers are components such as USB and Ethernet Then there are protocols familiar to engineers such as SPI and I2C which we have already explored in this book For this recipe we will use yet another flavor of serial UART an asynchronous or clock less protocol This comes in handy in a variety of scenarios to connect IoT centric devices Universal asynchronous receiver transmitter UART is a common circuit block used for managing serial data and hardware As UART does not require a clock signal it uses fewer wires and pins In fact UART uses only two serial wires RX to receive packets and TX to transmit them The framework for this recipe comes from AdaFruit s tutorial for the RPi However the difference between these two boards are nontrivial so this recipe needs quite a few more ingredients than the RPi version Getting ready You will need the following components for this recipe GPS PCB You can probably find cheaper versions but we will use AdaFruit s
173. face What a beautiful view you ve got on your BBB There s more e To learn more about TLEs the venerable Radio Amateur Satellite Organization aka AMSAT explains it well at http www amsat org amsat new tools keps_tutorial php e Other amateur and educational satellite tracking projects can be found at http funcube org uk Satellite tracking using the SatNogs Network client ground station and RTL SDR In the previous recipe we compiled and installed the part that actually tracks the satellite Now we need to add the piece of the system that allows us to manage the potential flood of data share it with others and have them share their data back with us Note that this has been tested successfully on Debian Wheezy 3 8 and Debian Jessie 13 4 Getting ready The materials needed are as follows An RTL SDR dongle An antenna for the recommended low cost antenna that we are using refer to the Diamond Antenna in the prior recipe on plane tracking http www aesham com glass magnet diamond antenna mr 75s An antenna adapter if you use an antenna other than the small one that often comes with the dongle such as the one mentioned before you will need to buy a separate adapter Don t worry They re cheap too and ours was only about USD 6 00 http amzn to 1WoB7Lg Attach the antenna to the RTL SDR dongle via the usML adapter Powered USB Ethernet or Wi Fi connectivity How to do it Her
174. for all users Historically ps requires different syntax depending on our flavor of Linux or Unix This option simplifies the method required to add options e Using the u option tells the command to display the user or owner of the process in the output The reason you want to do this is that there are processes typically running at the root level and other processes running at a non root user level However we frequently want to see all processes running regardless of user so this option is important e The x option ensures that processes that are not currently running in a terminal window which form the majority of running processes are also in the output that we want to see Device and system insight find out the resources used by running processes top and htop This command takes it a bit further than the ps command as it dynamically updates not only the processes running but also the CPU resources used by the processes The status is continuous and in real time How to do it Use this command line top The output is as follows PID USER PR NI VIRT RES SHR S CPU MEM TIME COMMAND 549 messageb 20 0 2736 1424 1008 S 9 3 0 3 6 12 02 dbus daemon 1086 root 20 3160 696 572S 9 3 0 1 0 32 40 agetty 1087 root 20 0 23884 7004 1824 S 9 3 1 4 0 28 78 wicd 1107 root 20 0 14708 7596 3456 S 0 3 1 5 6 13 48 wicd monitor 1393 root 20 4448 1400 832 S 0 3 0 3 0 24 32 tmux 1784 root 20 0 0 0 OS 0 3 0 0 0 04 39 kworker 0 0
175. fs usage the directory extension capemgr which refers to cape manager The BeagleBone kernel uses cape manager as a way to provide dynamic loading and unloading of device tree fragments both at compile time and from user space after the device has booted We will demonstrate this again here except this time we will use DT to enable a custom cape one which delivers audio I O functionality to the BBB Getting ready In addition to your usual BBB setup we will use Audio Cape Rev B available from CircuitCo http boardzoo com index php beaglebone black bone audio html Attach the cape to your BBB s header stack following the orientation shown in the following pictures Note If you ran the recipe in the previous chapter to send the IP address of your BBB to your email address you can run your system remotely and in a headless way ve RAA u u VD Ca Y Be sure to match the header pin rows P8 and P9 on the audio cape to those of the BeagleBone Black The output jack is green and the input jack is light blue In order to do the last part of this recipe you may also want to either plug a microphone into the input jack on the cape or use a USB mic in the USB port How to do it Now that you re prepared let s get started 1 First download and unzip the DT overlay from the manufacturer http elinux org images 1 10 BB BONE AUDI 02 00A0 zip For the fastest method just download it to your
176. fter the authorization process the ThingSpeak app generates a ThingTweet API Key that we will need to use in our code as shown in the following screenshot fal ThingSpeak Channels Apps Plugins Account Twitter Account BR Unilink Account 19 Copy and paste this new API Key to line 33 of the code in the Cloud9 window where it says THINGTWEET_TWITTER_API_KEY_HERE and the two CHANNEL IDs to the designated spots in the code request post https api thingspeak com apps thingtweet 1 statuses upd ate form api_key THINGTWEET_TWITTER_API_KEY_HERE status The current Ground Control temperature is channel_CHANNEL ID_field_1 F channel_CHANNEL ID_field_2 C Note All the parameters from the Twitter API statuses update are possible including geolocation You can learn more about the ThingSpeak API and its Twitter app on their site at https thingspeak com docs thingtweet 20 Last but not least click on RUN in the IDE Let s keep our fingers crossed because your BBB s Ground Control Temperature will begin to send temperature updates to your Twitter account Three cheers for Ground Control Temperature See also You will soon learn that there is a vast array of new ventures playing in the IoT cloud services sandbox As most of them are nascent businesses in a newly emerging industry it is difficult to predict who will emerge as go to platforms in the future However a handful of players ar
177. fy the dts file to include the target GPIOs seen in our fritzing diagram sudo nano rangepru dts In the open edit window scroll down to the following section exclusive use lt TRIGGER PIN HERE gt lt ECHO PIN HERE gt GPIO44 GPIO45 Change it to the following exclusive use P8 12 P8_11 GPIO44 GPIO45 Save your changes and close the nano window Ctrl X then type y for yes and press Return Enter key Next we need to compile a Device Tree overlay file dtbo with the DT compiler adding all appropriate flags dtc O dtb o rangepru 00A0 dtbo b rangepru dts 10 11 12 Note See Chapter 4 Exploring GNU Linux Recipes Using Bash Autotools Debugger and systemd for a refresher on Device Tree the compiler and its options Now we need to copy the compiled output file rangepru 00A0 dtbo to the directory where the overlays are referenced cp rangepru 00A0 dtbo lib firmware Although we put the overlay in its proper directory we have to load it just like a driver has to load in order to recognize a new piece of attached hardware So run the following echo rangepru gt sys devices bone_capemgr slots Take a look at the slots and see that the overlay is ready for action cat sys devices bone_capemgr 9 slots Your output should look similar to this 54 PF 55 PF 56 PF 57 PF ff P O L Bone LT eMMC 2G 00A0 Texas Instru
178. g Installing and building a custom kernel How to do it D e data o using with ThingSpeak Using sensors and data with ThingSpeak How to do lts DC motors o o about DC motors Getting ready How to do it How it works requisites Getting ready Debian o URL How to do it debugging o about Debugging See also device and system insight o directory content displaying Device and system insight shows what s inside a directory ls How to do it connected USB devices finding Device and system insight find out what USB devices are connected lsusb connected devices finding Device and system insight get information about connected devices cat proc bus input devices There s more Linux version getting Device and system insight get your version of Linux How to do it running processes finding Device and system insight find out running processes ps How to do it resources used by running processes finding Device and system insight find out the resources used by running processes top and htop How to do it processes killing Device and system insight quitting processes kill How to do it message reports Device and system insight message reports dmesg How to do it disk space showing Device and system insight shows disk space df h network exploring Device and system insight
179. gh we could find some answers it is always a struggle to get to an answer quickly As we proceed our intention is to do our best to give you clear and simple introductions to concepts So for example if you already know your way around things such as i2c sysfs and GPIO pins and know how to write custom functions in Python you may find this book a bit too slow Given the speed of changes in the small board computing sector many online tutorials are quickly aging out or just too advanced for a beginner Thus we believe that there is a dearth on the market of good easy to succeed introductory books and material on BeagleBone Black Furthermore unlike Raspberry Pi which is surrounded by warm and fuzzy support forums the BeagleBone community forum is comparatively sparse Worse it is often intimidating and unwelcoming to a new user Our intention is to be light hearted fun and inviting for a first time user Sections In this book you will find several headings that appear frequently Getting ready How to do it How it works There s more and See also To give clear instructions on how to complete a recipe we use these sections as follows Getting ready This section tells you what to expect in the recipe and describes how to set up any software or any preliminary settings required for the recipe How to do it This section contains the steps required to follow the recipe How it works This section us
180. gr 9 slot 7 Requesting part number version based BB UART4 00A0 dtbo 188 335370 bone capemgr bone_capemgr 9 slot 7 Requesting firmware BB UART4 00A0 dtbo for board name Override Board Name version 00A0 188 335400 bone capemgr bone_capemgr 9 slot 7 dtbo BB UART4 00A0 dtbo loaded converting to live tree 188 335673 bone capemgr bone_capemgr 9 slot 7 2 overlays 188 343353 481a8000 serial tty04 at MMIO 0x481a8000 irq 45 is a OMAP UART4 188 343792 bone capemgr bone_capemgr 9 slot 7 Applied 2 overlays Note Tips to get a GPS Fix Your best method to get the GPS module connected is to take it outdoors However as this is not a likely option when you develop a project putting it against or even just outside a window will often suffice If it is cloudy and if you don t have a reasonably clear sky view from your module s antenna do not expect a quick connection Be patient When a fix is made the flashing LED will cycle very slowly at about 15 second intervals Even if GPS modules do not have a fix be aware that they will still send data This can be confusing because you may run some of the following commands and think that your connection is fine but you just keep getting junk blank data However to reiterate the flashing LED needs to have slowed down to 15 second intervals to verify that you have a fix 8 Although the output is not pretty the following command is a useful first s
181. gulates its speed More details about this IC are described later in this recipe 13x jumper wires 1x pushbutton switch 1x 1k resistor 9V battery and holder Breadboard O O O 0 0 How to do it Perform the following steps to test the DC motors 1 Make sure that your BBB is powered down first and then wire your breadboard as follows Clearly this is a thicket of wires so be methodical as you follow the diagram s rn eee eee ee ef en ee a a ee eee 1 0 0 c0 0 0 0 s6 0 AIA X A n n0 0 0 0 0 0 0 0 0 0 0 eee ee eee em err eee eee eee fritzing To help with the diagram above here are some further details for the wiring setup Jrardware pin Color Location purpose BBB P8_8 iBlue IGND on breadboard button aligned with 1k resistor BBB P9 1 Black IIGND on breadboard rail 5V power to button Attached at pin 3 1Y on H bridge nn 6S6 amp w w tu nu Open the Cloud9 IDE at http 192 168 7 2 3000 and navigate to File New From Template Javascript Save the new file as DC_motor1 js Paste the new document to the following BoneScript code var b require bonescript var enablePin var motorPini var motorPin2 var buttonPin P8_13 pin 1 1 2EN PWM on H Bridge P8_7 pin 2 1A motor logic 1 on H Bridge P8_19 pin 7 2A motor log
182. h caveats as no open source tool is ever finished Volumio in some respects typifies the pleasures and perils of open source tools and bending them to your will on microcomputers There s no out of the box perfection Some of the recipes in this chapter use a number of prepackaged toolsets to get you where you want to be faster and Volumio is still technically a beta release For example other than a perfunctory setting up and installing procedure developers do not have a nice handy set of obvious instructions Instead you have to spend a fair amount of time perusing their forum volumio org forum to find answers to common questions Examples include how do I SSH into Volumio What s the password for remote login How do I add a new internet radio station Why is my external hard drive which is chock full with music files not recognized by Volumio How do I gracefully shut down my BBB if Volumio crashes These are burning questions indeed Thankfully you bought this book so the answers to these questions are right here Getting ready To get Volumio up and running you need the following e A USB powered hub As we need several USB devices to get the system operating reliably you will need to add a powered hub to your configuration e A keyboard Plug one into the USB hub We will use it for terminal access in case we lose or cannot get a remote SSH session and want to do a graceful shutdown of the system However
183. h v f_u4r6ehZKY Modifying the kernel using RT PREEMPT To dive into the real time realm we ll begin by exploring a piece of code that you apply to the Linux kernel directly one which is often considered the de facto standard for real time applications a patch called PREEMPT_RT First nomenclature In the literature our patch can be found referred to as CONFIG_PREEMPT_RT PREEMPT_RT RT Preempt or simply Linux RT patch Whew Can t anyone decide We ll default to calling it RT PREEMPT since that is the most common usage The RT PREEMPT patch forces onto our system what is known as native real time pre emption This means that the patch is applied directly or natively onto the kernel and allows you to preempt the entire kernel s events and processes in favor of targeted events or tasks It makes sections of the Linux kernel pre emptible that are ordinarily blocking For example let s say we have two processes We assign a higher priority to the second process than the first one The patch enables a time tick interrupt to preempt the first or any other process since the second one is given the highest priority This way the process fires and finishes exactly on schedule RT PREEMPT also happens to enjoy the least real timeliness in this chapter s basket of tricks Because the patch utilizes a pre emption process the kernel stops whatever it is doing and focuses on delivering the real time event This is good for yo
184. handle requests from client applications and apps that are authored in Javascript It s Javascript on the server More specifically it s an I O framework that Is event driven Is nonblocking Runs on the V8 JavaScript engine Executes JavaScript code on the server side Is rich in robust developer libraries and modules Node s speed makes it particularly useful in physical computing scenarios as it can handle requests in real time After all when a gust of sudden wind blows and your BBB powered drone starts teetering midair you don t want to rely on a poky LAMP stack and keep those gyros compensating The good news about Node js and we ll often just call it node is that you don t have to install it because it comes preloaded on the BBB firmware The bad news about Node js is that it can be a bit confusing to understand for beginners its sheer simplicity is daunting However once you review some recipes you ll likely find yourself a new fangirl fanboy of node Adding a new module to Node js Here is a recipe to add a new module into Node js In this case we ll use Nodemailer a powerful and highly customizable API e mail engine We chose this module because we wanted to actually have the script do something interesting and not just spit out another onscreen print command At the end of this recipe you will be able to run a script that sends an e mail to your inbox Getting ready Open up LX Terminal Alternatively
185. he BBB without a display later in this chapter Connecting an HDMI LCD Running your board with an HDMI monitor is the default method to use your BBB How to do it ll Check the compatibility list for your HDMI LCD monitor at http elinux org Beagleboard BeagleBone Black Accessories Monitors_and Resolu Given the large universe of LCDs out there this is not a definitive list However it does lend guidance on displays that will work with the BBB You will also be pleasantly surprised that most consumer grade HDTVs work pretty well out of the box with your board Check your resolution at http elinux org Beagleboard BeagleBoneBlack HDMI Plug in one end of your HDMI cable to your monitor and the other end which is the micro HDMI end into your powered down BBB Fulfill the power requirements power up your board with a 5V adapter Note Since HDMI displays can draw a lot of power don t try to run off your desktop s USB slot Otherwise you will get flaky results at best and more likely no picture at all You should get a straightforward boot up into the default desktop beagle screen Connecting a non HDMI LCD or cape There s no obligation to use only an HDMI display on BeagleBone Black For example with the right HDMI to VGA converter cable you can actually attach a standard VGA monitor to the BBB Compatible converters can be found at http elinux org Beagleboard BeagleBone Black Accessories H
186. he version of BoneScript that you are running on your board using the following code node pe require bonescript getPlatform bonescript 2 Install the latest version of BoneScript to do this you need to be the root user first Then you can execute the following command sudo i TERM none npm install g bonescript Using the Cloud9 IDE As the name implies Cloud9 is a cloud hosted toolkit For BBB it provides an integrated open source development environment to build BoneScript powered JavaScript code Its strengths are JavaScript and Node js which it actually uses on the backend we 1l discuss this in the next section though it is also very flexible with other programming languages such as PHP Ruby and Python The IDE comes preloaded and ready to use immediately on the BBB firmware with no setup necessary With your board still connected via USB let s do a snappy recipe How to do it 1 To load the IDE open a browser window to the following URL http 192 168 7 2 3000 ide html The IDE will open to a window like this Firefox File Edit View History Bookmarks Tools Window Help SATO i xe Sat 7 16PM Q i en cloud9 Cloud9 y cloud9 Cloud9 2 192 168 7 2 bash beaglebone root beaglebone var lib cloud9s x 5 Now 55 F Sun 37 F y Mon 33 F a 2 Next change the color settings to improve readability in the UI The default black scheme is funereal let s ch
187. hen you do so the routine will run and may take several minutes depending on the amount of data you re backing up OS image flashing the SD card boot In this section you will learn the recipes to load the OS and boot from a microSD card Much of the process is similar to how we flash the eMMC internal drive however it is important to take note of the differences Getting ready You will need the following BeagleBone Black powered down A 5V DC power supply or a USB tethered to the BBB A MicroSD card 4 GB or greater An SD card reader You will insert the microSD card into the card reader and the card reader into an SD port on your desktop machine e A board connected to either an HDMI monitor or an LCD cape as explained earlier in this chapter How to do it Perform the following steps 1 Using the wget command get the latest software image and put it on your desktop computer The latest version of the shipping OS is at http beagleboard org latest images So you will need to get the exact URL and append it accordingly in the following command Note the URL difference from the prior recipe for flashing the internal drive wget https rcn ee com rootfs bb org release YEAR MONTH DAY 1xde 4gb bone debian 7 8 1xde 4gb armhf YEAR MONTH DAY 4gb img xz The preceding link references a Rev C board which is the currently shipping version If you have another version of the BBB you can find software for pri
188. hon with the PRUs Contrary to popular geek belief ancient Egyptians did not write on PyPRUSS But if they d known Python they might have Actually the oldest thing about PyPRUSS a Python library for the PRUs is that it was primarily focused on the earlier Angstrom firmware for the BBB a distribution now looking increasingly mummified Which is not to say that PyPRUSS does not still remain a great userland touchstone for Pythonistas and PRU ophiles In fact even though there is no pre compiled binary in the Debian repositories for PyPRUSS it takes all of 90 seconds to compile and install from source and begin running Python on the PRUs quickly Getting ready The usual minimal setup is all you need a BBB powered over mini USB with Internet connectivity You will also need to have done the first recipe in this section on prepping and enabling the PRUs How to do it 1 10 11 Log in as root sudo i Grab the source files git clone https github com HudsonWerks pypruss git Navigate to the directory we just created cd pypruss Run the script for installing the PyPRUSS library python setup py install Make sure your library is mapped properly export LD_LIBRARY_PATH usr local lib Browse the example directory cd examples Take a look at what is available in that directory 1s Now we will run some examples We begin with everyone s favorite blinky thing
189. ia vnc as follows feh x Now we can view all our photos taken on our smartphone as a slide show feh FD10 home debian NowPix FD is the command to run a slideshow whereas the number after FD is an adjustable play duration for the image The program must also point to the directory with the images that will run as a slideshow Use the Esc button on your desktop to exit from the slideshow You may see another permissions related error when you try to execute the feh program The error may say something similar to the following code Invalid MIT MAGIC COOKIE 1 10 11 12 13 14 15 16 If so run the following command to delete the Xauthority file rm Xauthority Next we will create a systemd service remember that that runs the command to load the images and display them in a loop on bootup So log in as root as shown in the following code sudo i Navigate to the systemd directory with the following code cd lib systemd system Now create a new service file as follows sudo nano nowpix service Then paste the following code to the editor window Unit Description Run NowPix images using Feh on boot Service Type simple ExecStart usr bin feh FD10 home debian NowPix Environment DISPLAY 0 SyslogIdentifier fehslideshow Restart on failure RestartSec 5 Install WantedBy multi user target Start the systemd service with the following code systemctl start no
190. ic 1 on H Bridge P8_8 pin for button b pinMode enablePin b OUTPUT b pinMode motorPin1 b OUTPUT b pinMode motorPin2 b OUTPUT b pinMode buttonPin b INPUT function loop if the button is high motor will turn off if b digitalRead buttonPin b HIGH b digitalWrite enablePin b HIGH b digitalWrite motorPini b LOW set pin 2 on H Bridge low b digitalWrite motorPin2 b HIGH set pin 7 on H Bridge high if the button is low motor will turn on else b digitalWrite enablePin b LOW b digitalWrite motorPini b LOW b digitalWrite motorPin2 b HIGH setInterval loop 50 To start your engines click on the Run button in the IDE The motor should rotate when you press the button and stop when you release it How it works Here is some context for what s happening with the wiring 1 H Bridge motor driver Although our component can drive two motors one on each side of the chip in our example we will only run one Besides controlling the direction and speed the motor driver also protects the BBB from the higher output needed to drive the motor The name H Bridge is derived from the way the circuit is typically drawn with four switches When switch 1 s1 and switch 4 s4 are closed and switch 2 s2 and switch 3 s3 are open then a positive voltage flows across the motor To reverse the direction of the motor the switches are then reversed from their open or closed state
191. ic range sensor Using the Makefile script we will run two actions one will create an Assembly code binary to interact with the PRUs from the file rangepru p the other will generate a compiled C program from the file rangepru c that serves as both an interface to the assembly binary while taking the sensor data and displaying it in a human readable fashion make Note Using sudo nano make it might be useful to look under the hood for a moment to see what the script is doing The magical make command creates a new executable file rangepru in our directory We will now run it to monitor and output data being captured by our ultrasonic range sensor rangepru If all is well in BBB land you should be getting screen output that looks akin to this Carefully move the sensor around to watch the distance change note your numbers will vary according to the distance your sensor is from an object gt gt Initializing PRU gt gt Executing range sensor code 1 Distance 70 21 cm 2 Distance 71 95 cm 3 Distance 71 95 cm 4 Distance 7 68 cm 5 Distance 64 27 cm 6 Distance 4 09 cm 7 Distance 5 20 cm 8 Distance 53 25 cm 9 Distance 6 62 cm 10 Distance 2 28 cm 11 Distance 2 34 cm 12 Distance 10 13 cm gt gt PRU Disabled Outstanding You have now successfully hooked up a sensor that is ubiquitous in robot building and taught it how to dance with your BBB and its fancy PRUs Using Pyt
192. ill use our trusty tool PiFiller which we used and explained in prior chapters On a Windows box you can use Win32DiskImager Confirm that you have adequate storage remaining on your SD card To do this run the check from a terminal window on your client machine with the following command df ah Your output should show somewhere around 22 percent capacity used From the preceding Getting ready section you should have all the required hardware connected Remove the SD card from your client machine insert it in the BBB and boot I have seen some flaky performances on first boot so you may need to reboot again to get the login screen to appear If you have used Volumio on Raspberry Pi you will find booting up on the BBB considerably faster You now need to set up terminal access first directly on the BBB and then remotely Technically neither is a requirement to run Volumio as there s a lovely web based GUI to control the tool we ll get to that next However you will inevitably need to troubleshoot various issues and terminal access is really the best way to do so So first type the following command on the BBB user root pw Volumio You should now see the following screen output date and version may vary of course La 10 Now repeat the previous step on your client desktop box for SSH access with the same user root and password volumio credentials ssh volumio0xXX XXX XX XXX
193. ime sh 2 Then paste the following code in the new window Epoch time in milliseconds CTRL C TO STOP WRITTEN BY CHARLES HAMILTON Simple script for showing the epoch time at 10 second intervals ona BeagleBone Black running Debian bin bash Resets the RTC from the system clock sudo hwclock systohc sudo hwclock show Runs command for determining epoch time for do echo n Since Epoch in milliseconds OPTION 1 command Comment out if running OPTION 2 echo date s N 100000 OPTION 2 command Uncomment to run this version and comment out OPTION 1 cat sys class rtc rtco since_epoch sed s sleep 10 done Note If you run into problems while copying and pasting the code download the script available at https github com HudsonWerks bash script samples blob master epoch time sh 3 Now run the following script sudo bash epoch sh 4 Your screen output should look similar to this Tue Oct 27 14 13 53 2015 0 062322 seconds Since Epoch in milliseconds 1445969632617 Since Epoch in milliseconds 1445969642630 The script determines the Epoch time in milliseconds relative to the UTC time 5 Stop the script by pressing Ctrl C There s more For some all you can eat is buffets with shell scripts on the menu e http linuxcommand org writing shell scripts php e http www tldp org LDP abs html why shell html Compile and install In Chap
194. in 26 on which we just ran echo corresponds to pin P8_14 that we wired up on the BBB 8 Go to the new directory created from the echo command and take a look inside using the following command cd gpio26 ls The output shows the options now available to control the pin as follows active_low direction edge power subsystem uevent value 9 Determine the current GPIO value You should see its initial value as or off as follows cat value 0 10 Now let s light her up by sending the following commands echo out gt direction echo 1 gt value Voila You should get a sexy glowing red thing on your BBB 11 Repeat the same command but change the value back to 0 which should turn the LED back off with this command echo 0 gt value 12 A variation on this is to use another one of the VFS options in this case this will be the high low direction This turns the LED on echo high gt direction And then it turns off echo low gt direction 13 To finish up it is considered good practice to clean up your pin usage before moving on to some other task Use the following command lines for this cd sys class gpio echo 26 gt unexport Note that the exported gpio26 has now evaporated ls export gpiochipO gpiochip32 gpiochip64 gpiochip96 unexport You may think that this exercise is just another blinking LED yawn But really we did something quite different this time we reached
195. inal advertising marketing centric purposes for iBeacon By default the BLE dongle will scan for other devices However we want to turn this function off because it can interfere with advertising as follows sudo hciconfig hci noscan 11 The last command adds the UUID as shown in the following command sudo hcitool i hci0 cmd 0x08 0x0008 1E 02 01 1A 1A FF 4C 00 02 15 37 84 B5 BO 2D A7 11 E4 8C 21 08 00 20 OC 9A 66 00 00 00 00 C8 The instant you send the preceding command you should see a notification popup on your smartphone With the iLocate app on the iPhone it should say Entered region BBB beacon 1 This assumes that a smartphone app is already installed and set up to recognize the BBB beacon UUID Congratulations You are now able to broadcast hyperlocal data without the need for a big GPS satellite There s more The following references provide more detail on BTLE Classic versus BTLE discussion This gives you an excellent drill down into the nature of BLE s distinctiveness from Bluetooth Classic at http makezine com 2014 06 16 the bluetooth le doc a thon at itp camp BTLE documentation This provides various examples from a Doc a thon at https github com tigoe BLEDocs wiki Estimote teardown Make magazine takes apart an Estimote iBeacon a commercial mostly closed product at http makezine com 2014 01 03 reverse engineering the estimote Tile Information on this new very cheap and small B
196. ind a README file recommending it Target compiles the entire program including its libraries and documentation make install strip This is the same as make install strips out debugging symbols and is not typically recommended unless you re certain that the program has no bugs make uninstall This is the opposite of make install because it deletes all the installed files make clean This cleans and erases what has been built the opposite of make all make distclean This erases anything that the configure command created make check This runs a test suite if one exists for the source make installcheck This performs installation checks on the installed program if needed make dist This creates a distribution tarball for the program and outputs PACKAGE VERSION tar gz See also e Fora more detailed usage of the autotools toolset and further explanation on how to change the default behaviors and the options to build customized packages in order to suit your specific purpose refer to https autotools io index html e Refer to https www gnu org software libtool for more details on Libtool e You can deep dive into autotools arcana with a bazillion examples at https www lIrde epita fr adl autotools html Now onward and upward with the recipes Compile and install Git from source Our first recipe is a basic scenario of building from a source file and then installing it on your BBB In this case we will work with
197. ing code Starting program home debian bbb_recipe_book projects debug majortom_gdb Program received signal SIGSEGV Segmentation fault 0xb6f45904 in strlen from lib arm linux gnueabihf libc so 6 gdb The good news is that GDB just told us that the problem lies with strlen a standard C library function that determines the length of a string However the function requires a nonNULL string in order to run properly Thus our NULL value threw off the bug So now we can fix it 7 Now exit out of GDB with the following code gdb quit 8 Then open your C file again as follows projects debug sudo nano majortom_gdb c In line 13 change NULL to the Ground Control to Major Tom string with double quotes as shown in the following code const char a Ground Control to Major Tom 9 Now save close and press Ctrl x when prompted type y for yes and then press return Enter key 10 Recompile the file as follows gcc majortom_gdb c g o majortom_gdb 11 Then run the compiled file in GDB again as shown in the following code gdb majortom_gdb 12 Now let s begin the debug session with the following code gdb run If all goes as planned your code should no longer segfault but show the output similar to the following code Starting program home debian bbb_recipe_book projects debug majortom_gdb The number of characters in Major Tom string a 27 Inferior 1 process 6020 exited normally
198. ing command sudo source bashrc 8 Time to install the dependencies Use the following commands sudo apt get install libxml2 dev libxsl1t1 dev python dev sudo pip install django sudo pip install django dotenv 9 Now it s time to get the custom package created by the SatNogs team First we will 10 11 12 13 14 15 16 17 clone the source code from the repository as follows git clone https github com satnogs satnogs network git Set up the virtual environment On the first run you should create it and link it to your project path The following commands will do this cd satnogs network mkvirtualenv satnogs network a Note the symbol at the end of the command and don t use sudo Set your environmental variables as follows satnogs network debian beaglebone satnogs network cp env dist env Note Take note that you are now in a virtual directory satnogs network debian beaglebone satnogs network Activate your python virtual environment with the following command workon satnogs network Install the local development requirements as follows pip install r requirements dev txt This step may take a while and consume most of your BBB s resources as it downloads compiles and installs the development platform to share your SatNog tracking data Create and set up the database with the following command sudo manage py migrate We are nearly there now
199. ing it to the BBB such as the one at http bit ly LHQMc1N Getting ready Here are the materials we need PCB amp kit This can be TPA2016 or similar Adafruit has several choices which you can access at https www adafruit com search g amplifier Speakers You can use any set of speakers that take mono or stereo mini connector cables Audio input jack Either one of the following two methods will work o 3 5mm Stereo Headphone Jack breadboard ready This is very cheap and available at Sparkfun https www sparkfun com products 8032 or Adafruit https www adafruit com product 1699 for around USD 1 00 o 3 5mm stereo plug to pigtail cable This is basically a simple stereo mini cable using a standard plug on one end and a left and right speaker with wire stripped tinned leads on the other The leads break out so you can plug them into a breadboard easily It is cheap and available at Adafruit https www adafruit com product 1700 for USD 1 95 Mp3 or portable music player This can be an iPod or smartphone with 3 5mm audio jack output and containing sample music or audio files 2 plug male audio cable A standard 3 5mm cable that you likely already have around the house Soldering iron Lead free solder Mini Philips head screwdriver Jumper wires Breadboard How to do it To prep the PCB amp we followed some of the guidance provided by Adafruit s tutorial to work with their board https
200. ink about this book what you liked or disliked Reader feedback is important for us as it helps us develop titles that you will really get the most out of To send us general feedback simply e mail lt feedback packtpub com gt and mention the book s title in the subject of your message If there is a topic that you have expertise in and you are interested in either writing or contributing to a book see our author guide at www packtpub com authors Customer support Now that you are the proud owner of a Packt book we have a number of things to help you to get the most from your purchase Downloading the example code You can download the example code files from your account at http www packtpub com for all the Packt Publishing books you have purchased If you purchased this book elsewhere you can visit http www packtpub com support and register to have the files e mailed directly to you In many cases you will also be downloading code from the author s github site at https github com HudsonWerks Downloading the color images of this book We also provide you with a PDF file that has color images of the screenshots diagrams used in this book The color images will help you better understand the changes in the output You can download this file from https www packtpub com sites default files downloads 29290S_GraphicBundle pdf Where noted you may also download some of the images and diagrams from the author s
201. io local again on your desktop client browser You should be able to control Volumio fluidly now without the Ethernet connection Assuming you have a smartphone pull it out and open up a browser to the same address that you just entered on your desktop volumio local Voila You are now freed from the desktop and have remote control of your media library from any smartphone Vodafone de 07 09 100 An SES Ze 7 MENU 2 The Chemical Brothers Exit Planet Dust Although the Volumio interface can be a bit crowded on small smartphone screens you should see a tighter highly usable design on tablet clients 24 Next we need to check the version of Volumio Doing this will output the compatible file types that the software can play mpd version Tip The screen output should yield not only the usual copyright boilerplate but an extensive list of the audio file types that are playable with Volumio Check that your music library s file types are in the list particularly in the very lengthy ffmpeg section 25 Next you need to update the MPD database so that it catalogues all files on your attached storage drive You can use the Volumio GUI for this navigate to MENU Library Update MDB database You can also do the same thing with the following command line sudo service mpd restart Depending on the size of your library and regardless of the method you use the database update may take a while So get a cold
202. ion 3 8 13 xenomai sica Linux kernel version 3 8 13 xenomai een Linux kernel version 3 8 13 xenomai ee aida Linux kernel version 3 8 13 xenomai ee Linux kernel version 3 8 13 xenomai r72 Now we will install the Xenomai kernel Replace the x with the version of the bone kernel that you have on your board Take a look at step 6 if you do not remember Wheezy sudo apt get install linux image 3 8 XX xenomai rX Jessie sudo apt get install linux image 3 14 XX ti xenomai rXX Install the toolset for running basic Xenomai tests sudo apt get install xenomai runtime Confirm that we installed Xenomai uname r Wheezy 3 8 XX ti xenomai rXX Jessie 3 14 XX ti xenomai rXX Check the version of Xenomai you may have a later one cat proc xenomai version 2 6 4 It s looking good You now have a real time Xenomai environment set up on your BBB To round out the recipe we want to run a couple of tests to both check that the kernel layer is installed and determine latency First log in as root user sudo i Run the user mode latency test xeno latency Your output should look something like this RTT 00 00 01 periodic user mode task 1000 us period priority 99 RTH lat min lat avg lat max overrun msw lat best lat worst RTD 1 583 1 999 6 541 ol ol 1 583 6 541 RTD 1 583 2 958 35 916 ol ol 1 583 35 916 RTD 0 916 2 083 30 624 ol ol 0
203. ion development embedded systems parallel computing networks and security Lately he has been heavily involved in IoT projects and is working with World Wide Web Consortium W3C to help standardize Internet of Things by contributing to their WoT platform Apart from writing code Deepak loves teaching and working out You can catch him at github com deepakkarki or on beagle freenode IRC as nick karki_ Agrima Seth is currently a senior year student pursuing a bachelor s degree of engineering in information technology at University of Pune India Her research interests include machine learning and information retrieval systems She is currently an intern with the SIG Generalized Information Systems research team under Professor Josiane Mothe at IRIT France Here Agrima is working on performing effective data indexing and query reformulation on TREC datasets to study and create better information retrieval systems She has been the recipient of Sir Ratan Tata Memorial Scholarship and other merit scholarships Apart from machine learning Agrima has also worked on computer graphics and computer vision at Indian Institute of Space Science and Technology India Her work is published at arXiv http arxiv org abs 1409 5024 Agrima has worked on a project for Thermax India on making a mini solar tracker using MSP430 She has been involved in the creation of a machine learning group at her institute where she trained undergraduate student
204. ion side you could again use GPredict which includes this kind of functionality However in our recipe we will build the SatNogs Network custom client as it lets us taste some new coding flavors Once installed the tool gives operators an efficient way to both plan their observations and combine their tracking data with multiple ground stations around the world GPredict SatNogs suggests two tools for satellite tracking their own custom package and GPredict We will only look at how to use GPredict as this package is more widely used and can serve as a jumping off point for satellite tracking beyond just the SatNogs initiative Gpredict is a real time satellite tracking and orbit prediction application that can track an unlimited number of satellites and display the data in tables and numerous graphical views The application actually exists for more than just Linux distributions it includes the Windows and Mac OS X versions However unlike the commercial OS versions we will build a recipe set on our open source microcomputer that gives us greater flexibility on several fronts such as the following e Dedicated device A BBB SatNogs platform gives you the ability to create a dedicated satellite tracking device in lieu of turning over your desktop or laptop exclusively to satellite tracking e Optimal placement The position of your ground station s antenna is critical as it impacts the quality of your data and experience Creating a de
205. ion you want you can also update or modify your kernel with an alternative method using a series of command line steps 1 Log in as root as follows sudo i Check the kernel version with this command uname r Update your repositories with this command apt get update Find available kernel versions using this apt cache search linux image The screen output will deliver a long list of kernel options Scroll the list until you find one with the label Linux kernel version 3 8 13 boneXX with the XX being a two digit number Install the kernel you want by explicitly specifying a version number from the list in the prior step as follows apt get install linux image x x x xx Reboot your board as follows reboot uname r Your new kernel should now be installed on your board Chapter 2 Basic Programming Recipes As the next step in learning how to control and manipulate your BeagleBone Black we will take a look at the following languages tools and simple programming recipes in this chapter Introduction to BoneScript Toggle LED Using the Cloud9 IDE Node js basic recipes Adding a new module to Node js Using Node js with Johnny Five Python basic recipes Adding libraries Running a Python script to control the LEDs Introduction In the first chapter our objective was to ensure that all you new chefs were ready with sharpened knives and the right combination of seasonings
206. ions of commands available to the Linux user And this book is not intended to be about Linux commands So instead I will give you a handful of basic commands that I find myself consistently using on the BBB and also provide you with some of my favorite reference materials and cheat sheets that will give you a more comprehensive list of important commands Getting ready Of course we assume that if you intend to use some command line interface CLI commands you have to have your command shell window open and gain root access sudo Using sudo as part of your command syntax is a requirement that often bedevils new Linux users It is important to understand that many Linux commands demand what are known as superuser privileges which grant you total control over the board and its software Having full admin rights within a command prevents any casual user from coming along and destroying your hard work by design or accident The open sesame of Debian Linux the magic sudo command pronounced soo doo means Super User do x command when dissected If you don t append your command at the beginning with sudo your mkdir command for example will return a bad command error sudo i and root Adding the i option the sudo i command provides even more control over the environment the root user access When running commands as a root user there are ample opportunities to completely mangle your system so exerc
207. is Your readings of course will vary according to the strength of your light source Light output in millivolts 1387 Light output in millivolts 1386 Light output in millivolts 1159 Light output in millivolts 608 Moving your hand over or close to the sensor should make the output numbers rise and fall based on how the light source hits the sensor Notice that doing all this requires very few lines of code So let s take a quick look at what some of the parts of the script are doing Besides evoking the BoneScript library the first section defines a read function on a specific analog pin that we will reference on the BBB var b require bonescript function lightSensor b analogRead P9_37 lightValue In the next section we define a function that determines how the sensor data being captured will be crunched That data is expressed in millivolts and varies at a constant rate function lightValue reading var millivolts reading value 1800 console log Light output in millivolts millivolts An The n in the code simply creates a space between each output for better legibility Optional Python code Besides the code above you can also test your light sensor with a Python script available on our Github repository There is a ReadMe file on the repo but here are the basic steps 1 Download the Python code with the following command git clone https github com HudsonWerks light
208. ise extreme caution in its use However not all commands require superuser privileges For instance when you re really just poking around the system and not modifying files directories or the system itself sudo isn t necessary You should keep in mind several things when working with the command line e Lowercase Using lowercase syntax is the shell s required expectation with the exception of some options and arguments that are uppercase e Arguments and options Most commands have multiple options or arguments that can be used to fine tune your command We will only be able to touch on a few instances of how and when these options are used e Help o Help no hyphens Typing help before a command outputs information about this command An example of this is help cd o Help hyphens Many executable commands have more help and information about their options or arguments An example of this is mkdir help o Man pages Short for manual pages adding man to the beginning of many Linux commands opens up a manual for these commands It can often yield too much information but it can be helpful if you re looking for a deeper understanding of a command An example of this is man chmod e Tab command This lists recent commands In order to use this you need to do the following o Type a letter or a string of letters and then press the Tab button All commands that begin with this letter or string will be shown
209. ishing cannot guarantee the accuracy of this information First published November 2015 Production reference 1121115 Published by Packt Publishing Ltd Livery Place 35 Livery Street Birmingham B3 2PB UK ISBN 978 1 78398 292 9 www packtpub com Credits Author Charles A Hamilton Reviewers Nathan Burles Anuj Deshpande Deepak Karki Agrima Seth Commissioning Editor Edward Gordon Acquisition Editor Richard Brookes Bland Content Development Editor Rohit Kumar Singh Technical Editor Vijin Boricha Copy Editor Shruti Iyer Project Coordinator Mary Alex Proofreader Safis Editing Indexer Monica Ajmera Mehta Production Coordinator Conidon Miranda Cover Work Conidon Miranda About the Author Charles A Hamilton is the owner of HudsonWerks a New York City based DIY hardware and development shop for new products Passionate about emerging technologies open source hardware and the maker movement his background as a technology creative entrepreneur and maker provides readers with a unique perspective Besides BeagleBone Black Charles works frequently with other hardware platforms including the Raspberry Pi Arduino and UDOO development boards open source board architecture and PCB design micromechatronics and sensors He is also an advocate and keen user of emerging low cost manufacturing and design tools such as 3 D printers and laser cutters Among other subjects Charles keenly follows advances
210. istro When the kernel begins running it performs several key tasks such as process management file management and I O management The latter is what we will mainly look at in this chapter as it is the most clearly recognizable and relevant function that the kernel performs for physical computing or while building hardware prototypes For us I O means mostly GPIO pins peripheral devices such as capes and daughterboards and other add ons as this is where most of the action is for this book See also Understanding the boot sequence gives you a deeper understanding of the various processes and events occurring on your BBB and can play a key role in development and debugging The following provide an excellent background on the boot cycle e In the context of using ArduPilot a drone centric toolset developer Anuj Deshpande takes you through the steps at http diydrones com profiles blogs booting up a beaglebone black e Although this example from professor Mark Yoder shows an Angstrom distribution boot with an earlier kernel one of the better tutorials to describe the BBB boot can be found at http elinux org EBC_Exercise 21a Boot Sequence e A commonly referenced process map created by Alexander Holler delivers an excellent graphical representation of the boot sequence at http ahsoftware de Beaglebone Black Boot explained svg Kernel application binary interface Now let s do a quick simple task with a command to find
211. it exceeds range of 0 1 position position increment if position lt 0 position 0 increment increment else if position gt 1 position 1 increment increment call updateDuty after 500ms setTimeout updateDuty 500 4 The motor will begin by first moving to a starting position then move forward in small increments Then it will reset its starting point and begin moving backward in small increments In the IDE terminal window press Ctrl C on your keyboard to stop the script There s more To check your PWM pinmux run the following commands sudo i cat lt sys kernel debug pwm Your output should look something like this platform 48304100 ecap 1 PWM device pwm 0 null plat form 48304200 ehrpwm 2 PWM devices pwm 0 null J pwm 1 null plat form 48302200 ehrpwm 2 PWM devices pwm 0 null pwm 1 null platform 48300100 ecap 1 PWM device pwm 0 PWM_P9_42 requested enabled platform 48300200 ehrpwm 2 PWM devices pwm 0 null pwm 1 null E Note that our referenced pin in our code that we just ran P9_42 is marked as requested enabled For an alternative method of driving the servo using Python check out Adafruit s tutorial at https learn adafruit com controlling a servo with a beaglebone black Chapter 4 Exploring GNU Linux Recipes Using Bash Autotools Debugger and systemd Here is what we ve got in store as reci
212. ithout full cape support use the following command bb kernel git checkout origin am33x v3 14 b tmp 4 Now we will build the kernel with this command bb kernel build_kernel sh Be sure to take note of the space between and in the command Otherwise your command will not be executed Also beware that this build cycle may take a while so be patient for it to finish Note Since Linux BeagleBone Black and the open source community at large move pretty fast what we deem experimental in this book may be nearly mainstream within a short period of time For example note that the current move toward the new Debian 8 Linux kernel Jessie as opposed to the current version 7 nicknamed Wheezy is well underway In 2015 it will likely have moved from the Debian testing repos to the stable repos and is expected to be part of the BBB shipping firmware Interactions with the kernel sysfs entries and controlling the GPIOs When first starting out with physical computing and a Linux board such as the BBB in particular it is less daunting to use preexisting libraries along with familiar programming tools This is why we used tools such as Python libraries and BoneScript to gain access to BeagleBone Black s GPIO pins methods that abstract the kernel layer from the user space layer However it is useful to understand the nature of this abstraction a bit better particularly when it comes to the GPIO pins The Linux
213. ive require johnny five var BeagleBone require beaglebone io var board new five Board io new BeagleBone 3 board on ready function var led new five Led turn the LED off and on in 1000ms increments led blink 1000 this repl inject led led 3 Note If you run into problems copying and pasting the code you can download the code from https github com HudsonWerks Johnny Five blob master johnny5_led1 js 6 Save the new file using the following keyboard command with nano Ctrl x when prompted type y for yes and then press return Enter key 7 Now run the following script sudo node johnny5_led1 js The onboard LED USR3 should begin blinking at 1 second 1000ms intervals We will not break down every part of the script here you can further investigate Johnny Five in the There s More section However one thing we will point out is a feature of the code that expresses Johnny Five s modularity over BoneScript specifically the following line var board new five Board io new BeagleBone With Johnny Five this code snippet is all you need to change if you want to run the same script on the Raspberry Pi Arduino or UDOO board or a huge range of other SOCs Write once run anywhere is getting closer There s more For more insight into Johnny Five it s best to start by exploring their wiki which is full of examples and documentation at http joh
214. iverse of information about autotools and the build and compile process for the source code As this book is a mere dust mote in that universe we can only cover the basics here Note Most of the software you 1l want is only released in the tarball source code form These are just compressed archives with extensions such as tar gz tar xz or tar bz2 Documentation standards In the open source world developers generally ship their source code with the README files intended to provide guidance on the compile process for their tarball The README file can serve as a Starting point to build the package from scratch Unfortunately these README files can often be cryptic or poorly written Although frustrating it is inevitable that you will frequently find yourself Googling for more information about how to install a package Compiling on BeagleBone Black Although the board s 1 7 GHz ARM chip is pretty snappy for most embedded applications compiling and installing software directly on the BBB can be pretty poky and even painful Ideally building a large package with multiple dependencies will be far speedier on a dedicated desktop with bushels of RAM However for the purposes of simplicity we ll forge ahead with how to compile on our board Autotools contains several utility programs Autoconf This creates a configure shell script for the source code that runs tests to determine the build environment Automake This gener
215. just recorded Alternatively we can use another audio package aplay Although it is not as full featured as mplay it is easier to use as it requires fewer settings Run the following command for this pico2wave w test wav This is Ground Control amp amp aplay test wav Regardless of the player you use you should get a female speaker saying This is Ground Control in the English language out of your speaker You can change the output of course including the speaker s language as long as it is English UK or US German Italian French or Spanish Part III Python coding to calculate the ISS s current distance from your location Next we will use some Python code to track the International Space Station 1 If you did the earlier recipe in this book with GPredict to track the ISS you would already have the repo downloaded If not get it from our GitHub repo and then browse the directory as follows git clone https github com HudsonWerks space satellite git cd space satellite 2 Let s take a look at what the code does You can open it up in a nano editor window by running this command sudo nano ISS current_distance py Alternatively you can copy and paste the code into a new Cloud9 file Note For simplicity s sake we will use a different set of code to track the ISS than we did an earlier recipe in this chapter Here we do not want to run an X session as in the previous example instead we want to focu
216. k Continue Select Connect You will now be logged in to your BBB be able to see the desktop and have full control over the device using the mouse on your client box There s more e Security Using the default or basic settings in VNC is not secure Unless you re familiar with doing so the sessions are not encrypted One quick though imperfect measure is to change from the default server port 5900 to a spare randomly chosen port e Getting the IP address on a headless BBB From another computer on the network use the following steps to list a network s basket of IP addresses ifconfig grep inet o Note that this will show the IP address range and only name specific host devices but not other addresses o This method may only be feasible in a smaller network where the number of addresses is more limited and you do not have to look for a needle in a haystack o You will likely need to install the NMap security scanner http nmap org Check whether it s installed first o Then type in sudo nmap sn PE 192 168 1 0 24 with the IP address of the host machine and then xxx from the end range shown in Step 1 e Browse to the local router admin address Find the configuration options that show all computers devices on the network with their IP addresses e Set a static IP address This takes several steps but one of the best tutorials is Derek Molloy s at http derekmolloy ie set ip address to be static on the beag
217. kernel is for another very large set of books and discussion We won t be doing that here What we do want to explore is how to update build and modify the kernel in ways that will give us tighter control over our hardware and make the development process less opaque Then we ll conclude the chapter by working with one of the key differentiators for BeagleBone Black the Device Tree which is a clever way to describe the hardware in our system The best part is that if you do all the recipes you ll be forever known as Colonel kernel Well lieutenant kernel All right maybe private kernel But it s a start Kernel building basics What is this mysterious kernel thing of which we speak What does it look like Where does it live Well on one level it is merely a file Let s take a peek Open up a terminal on your BBB and type the following commands cd boot ls The command should deliver this output debian beaglebone cd boot debian beaglebone boot ls System map 3 8 13 bone67 dtbs uboot config 3 8 13 bone67 initrd img 3 8 13 bone67 vmlinuz 3 8 13 bone67 debian beaglebone boot F There it is the kernel the file that begins with the name vmlinuz However the file itself an executable one does not really do anything until you load it into memory and have it run That happens of course when you have the right boot sequence established which should be happening by default on your BBB Debian d
218. ket even RPi e Out of the box simplicity As the BBB comes preloaded with a Linux OS Debian all you need to get going quickly is a mini USB cable to power up the board There is no futzing around with installing software or adding peripherals to operate it e Internal drive While other small board computers of this ilk can only run from an SD or microSD boot BeagleBone Black comes with an internal solid state drive referred to as eMMC to run the OS e Open source design If you want to knock it off for a custom project you can do it all board designs and schematics are freely available e Real time applications Unlike other boards such as Raspberry Pi BeagleBone Black has a set of separate processors that can ensure that your code runs rock solid and according to your expectations which is an extremely unique feature for a computer at such a low price point As you begin tasting the various recipes throughout this book perhaps a key difference worth keeping in mind is that the designers of BeagleBone Black regard the board as a prototyping platform to build embedded applications and products An embedded computing device is typically part of a larger electronics system This is quite unlike the design strategy of other boards such as Raspberry Pi which is a device specifically created as a full blown desktop system and targeted at the grade school market What this book covers This book explores a range of recipes for the novice
219. ks with the heartbeat pattern There are simpler ways to do this as we did the same thing with BoneScript in Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python However it remains a useful introductory recipe to understand Device Tree s interaction with the kernel Getting ready For the next recipe simply power up your board via the USB port Internet connectivity is not required How to do it You need to perform the following steps 1 Log in as root with this command sudo i 2 Grab the file that we need for this recipe Going forward in the book we will more commonly have you use our GitHub repository to get the code instead of downloading a file directly as we did in earlier chapters Use this command git clone https github com HudsonWerks device tree git 3 Browse the downloaded folder and open up the following file cd device tree nano bspm_USRO_10 00A0 dts Take a look at the code visible in the nano window The intention of this step is for you to review the code structure before we actually move it to its appropriate directory This is a mostly template generated file from BoneScript modified from Kilobaser com s Device Tree Overlay Generator eS dts v1 plugin compatible ti beaglebone ti beaglebone black identification part_number BS PINMODE_USRO_0x0 state the resources used exclusive use
220. l ABT Basically it is an interface layer between the kernel and user space applications One way of understanding it is by comparing it to an API a familiar concept to any programmer When you use an API you can access the features of an external component a third party software feature or an OS An ABI is kind of similar to a compiled version of an API Think about the software that we built and compiled from source in our prior chapter Once code is compiled at the kernel level an application accesses the binary data through the ABI Just like an API an ABI defines the structures and methods that your compiled application will use to access an external library for instance Except with the kernel ABI it happens at the lower machine language level Installing the latest kernel image All the way back in Chapter 1 Setting Up for the First Time we used a set of tools that came with our Debian distro In that case we used a tool a bash script to expand our partition In this case we ll use another script from that toolset that runs a routine to update our kernel image Let s go get it With developer Robert Nelson s slick scripts https eewiki net display linuxonarm BeagleBone Black the process to update or build the kernel on Debian for the BBB has become a snap Getting ready As in our preceding recipe connect your board via USB to your host computer boot up and then open a terminal window How to do it Let s g
221. l audio amplifier Other than its power leads the bus only uses two wires to communicate SCL and SDA The first one is the clock line SCL which is used to sync any data passing over the bus The second line SDA carries the actual data I2C also utilizes a simple master slave relationship between devices with the bus allowing the roles to be interchangeable I2C is also good at noise filtering which is a relevant feature for our recipe Working with I2C pins on the BBB is pretty straightforward There are three I2C buses implemented on the BBB but only one of these is easy to use e 12C0 This is used for some onboard components such as HDMI EEPROM and power management If we disable it it will interfere with these components so it is typically not used unless needed e 12C1 This is available for use but requires enabling e 12C2 This is usable out of the box Expansion port P9 refer to table 11 in the SRM These are the pins that we will use Note 12S bus I2C should not be confused with Integrated Interchip Sound 125 another serial bus available on the BBB Unlike I2C which is bidirectional I2S only handles data in one direction Coincidentally 12S is typically used as an interface to communicate PCM audio data between devices commonly with a Digital to Analog Converter DAC audio device though we will not use it in our audio recipes There are several helpful tutorials on making a DAC interface with I2S and connect
222. l identify more information about an unused pin To get the code you can cut and paste the code below into the IDE or follow the same step described in the prior step of getting it from our GitHub repo Look for the file findGPIO js in the device tree directory that you downloaded usr bin node Program to test looking up information in usr share bone101 static bone js Usage findGPIO js 7 Look up info for gpio7 internal pin number findGPIO js P9 12 Look up using header pin number external findGPIO js P9 12 P9_13 Look up multiple pins and use one line output for each Returns current pin mux var PINS sys kernel debug pinctr1 44e10800 pinmux pins PINMUX sys kernel debug pinctr1 44e10800 pinmux pinmux pins b require bonescript exec require child_process exec process argv forEach function val index array console log index val af function pinMux gpio flag var addr 0x44e10800 parseInt gpio muxRegOffset 16 toString 16 A3 console log grep addr PINS exec grep addr PINS function error stdout stderr var mux Current mux setting out output string dir down Direction of pullup or pulldown if error console log error error if stderr console log stderr stderr stdout stdout substring 0 stdout length 1 Get rid of extra n console log
223. l kernel mix composed of the primary Linux kernel and the secondary Xenomai kernel e A subsystem underneath Linux that does not rely on the kernel to pre empt designated events like our previous method But why should we use it instead of PREEMPT_RT With its focus on embedded systems Xenomai is useful for several reasons e Lowers system overheads e Legacy porting Easier to port legacy real time systems As a budding BBBer and embedded Linux neophyte you may not be porting legacy systems anytime soon But if you were then Xenomai would be an easier way to do it since you can lash your old system together to the Linux kernel by using Xenomai as a binding interface e Highly configurable Xenomai can be configured to set thread priorities timer IRQ for example to high or low based on your preference 99 is the highest in Xenomai with the result that events never get interrupted e Works better with version 3 8 of the kernel and above Getting ready The usual minimal setup is all you need a BBB powered over mini USB with Internet connectivity enabled How to do it Although there are methods noted later in this section for installing Xenomai from source our recipe will illustrate a simple method for getting your kernel modified 1 In order to run this recipe properly you will need to start by appending your repositories Begin by opening up your source list sudo nano etc apt sources list In the open edit windo
224. l likely refer you to a code repository There you ll look for a file with the git 0 0 0 tar xz naming convention along with another possible digit depending on the version 4 Navigate to the directory and untar it as follows cd packages tar xf git 2 6 2 tar xz 5 Then go to the new directory created with the following code packages cd git 2 6 2 Note In the untarred folder search for the INSTALL file This file provides guidance on alternative directories for installation purposes than the one we will perform here 6 Now we are ready to install git For each stage of this process wait for the terminal window to default back to your working prompt before proceeding We will begin with configure configure 7 Next the make file needs our attention with the command sudo make In this case and if you re building the package directly on your BBB the compilation may take more than 20 minutes other packages can take considerably longer So be patient and wait for the default prompt 8 Once all the files have been crunched and compiled we need to install the package a step that can often finish quickly as shown in the following code sudo make install 9 Finally let s see how we performed compared to our prior 2 0 2 version with the following command git version git version 2 X x Voila The freshest baked version of Git is now at your board s disposal Debugging Reality check st
225. lebone black System images In this section we will give you the recipes to download install and update the Debian distribution firmware and software kernel that comes preloaded on your board Finally we will walk you through changing over from the currently shipping Debian 7 0 Wheezy to the newer Debian 8 0 Jessie There are two basic methods to install and update your board s software install the OS onto the eMMC solid state internal drive or a compatible SD card refer to the compatibility list in further chapters In either case the process is commonly called flashing the image which is how we will refer to it Note One of the signature features of the BBB is its ability to use many different flavors of Linux to run the board In the further chapters you will find references and material to install various versions of Linux including Ubuntu ArchLinux and Android OS image flashing internal drive boot Although your board comes preloaded with a shipping version of Debian 7 you certainly want to understand how to replace it or update it when necessary Here we will discuss the recipe to flash the OS to your internal solid state drive along with how to update to Debian 8 As of the writing of this book Debian 8 Jessie is still considered a testing option whereas Debian 7 Wheezy is the official shipping firmware OS for the BBB Additionally you will notice LXQt as part of the URL download link LXQt is a
226. ll it with the following command make install Head back up to the root directory where we need to bring the aircraft scanner specific package on board This requires another series of downloading setting up and installing ingredients which goes as follows cd git clone https github com antirez dump1090 git 11 12 13 14 15 cd dump1090 make Configure the path for the shared libraries echo usr local lib gt gt etc ld so conf Let s run a test ensuring that we are in the dump1090 directory cd home debian dump1090 dump1090 If your RTL dongle scanner is operating as it should the command will begin quickly dumping any nearby aircraft to standard output If you use the small antenna that came with your dongle its range will be very limited Press Ctrl C to interrupt the command The last step is to put this galloping data in an easier to read format In the terminal window paste the following command dump1090 interactive net net http port 8081 This last command and its options tell dump1090 to begin outputting data in a more viewable form One version of this output is immediately visible in your terminal window with the data refreshed continuously and sorted into tidy columns by flight number altitude speed of aircraft latitude and so on Even more interesting is the net http port 8081 option which sends the data via HTTP to a specified port in this c
227. llites are its principal focus Its goal is to provide a toolset and tech stack hardware and software that is low cost and easy to build The project supports VHF and UHF bands for satellite reception with the default configuration Its software automatically tracks receives and records satellites as they pass overhead while automatically scheduling observations and recording them to an online database shared among other participating ground observers For the purpose of simplicity we will not cover how to build the whole hardware part of the system which includes a high gain antenna tracking motors and a standard RTL SDR dongle as a receiver In our recipes we will only use the dongle and a low cost antenna You are welcome to get more ambitious with the hardware More details are at the SatNogs website https satnogs org Setting up the software stack requires two pieces a satellite tracker and a ground station Satellite tracker For the tracking software they suggest one of two packages either GPredict a popular and venerable open source solution for satellite tracking and orbit prediction or a custom open source client that the SatNogs team built in Python The latter is more robust and interoperates more easily with the antenna and rotor mechanism However since we will not illustrate the build out of the rotor and the hardware parts of the system we will do a recipe around GPredict Ground Station On the ground stat
228. llowing steps 1 Log in as the root user with this command sudo i Using the following command ensure that you update your package list apt get update Now install the library s dependencies through the following command apt get install build essential python dev python setuptools python pip python smbus y Note For instructions on installing a software patch to make extra pins accessible with the library the SPI and UART pins in particular refer to the further chapters Now we can install the library itself with the following command pip install Adafruit_BBIO Test your package installation by typing out this command python c import Adafruit_BBIO GPIO as GPIO print GPIO Your output should look similar to this lt module Adafruit_BBIO GPIO from usr local 1lib python2 7 dist packages Adafruit_BBIO GPIO so gt Part Two Installing PyBBIO library Perform the following steps 1 Log in as the root user with the following command line sudo i Ensure that you ve updated your package list using the following command apt get update Now install the library s dependencies with this command apt get install python serial python setuptools python dev python smbus python pip Now we can install the library itself Use the following command for this pip install upgrade PyBBIO Test your package installation via the following command line
229. low powered device whereas the client is typically a more sophisticated device such as a smartphone a laptop a tablet or other wireless device e Not one to one BLE allows multiple simultaneous connections to the same server or peripheral device e Low power The connections between devices are very short in BLE This results in extremely low power usage Devices can operate with simple lithium coin cell batteries e Broad services and characteristics schema The data presented by a peripheral is structured as services which are then subdivided into characteristics Services are akin to the notices on a bulletin board whereas characteristics are similar to the individual paragraphs of these notices You can easily hook up to different services and characteristics with a few lines of code For example you can interact with a battery service and easily determine the power levels remaining for a device Alternatively your use case may be related to health or fitness which means that you can leverage the onboard health service that includes a characteristic such as heartbeat data Beacons and iBeacons Where GPS leaves off Beacons begin This emerging BLE technology is quickly becoming the next big thing in location sensing Although proven powerful and ubiquitous GPS can only determine the coordinates of an object within 20 30 feet However the BLE Beacon technology is commonly referred to as hyperlocal in its sensitivity because
230. ls to use a command shell LX Terminal and Root Terminal Although there are others with more robust and colorful interfaces that you can install such as xterm and eterm for simplicity s sake we will use LXTerminal In the next section you will learn about the command syntax required within the tool Finally we will create edit and save a text file from the command line Getting ready Ensure that your BeagleBone Black is set up and running in the manner described in the Introduction section Note that here we will show the two different methods of running the board powered via USB and powered via 5V How to do it 1 Begin by opening up LXTerminal which you will find in the Accessories application on the lower left hand side of the screen File Manager a Internet gt Leafpad Yao Preferences gt N terminal Ed Root Terminal Run Logout MA debian beagle 2 You will now see a command prompt that looks similar to this on your screen E debian beaglebone File Edt Tabs Help debian beaglebone E N M debian beaglebone 3 Just for fun let s type in the following at the command prompt debian beaglebone echo Can you hear me Major Tom This will show the following output debian beaglebone Can you hear me Major Tom ar me Major Tom aglebone Congratulations You ve just sent your first command to BeagleBone Black and it wasn t Hello World But we re get
231. ly want to determine whether the GPS module is speaking correctly to the port 2947 and if there are any conflicts So we will run the following command sudo lsof i 2947 This is how the output should look COMMAND PID USER FD TYPE DEVICE SIZE OFF NODE NAME systemd 1 root 24u IPv4 6907 oto TCP localhost gpsd LISTEN gpsd 5960 nobody 4u IPv4 6907 oto TCP localhost gpsd LISTEN 4 You may also want to check whether any instances of the GPS are running and then kill them with the following command ps aux grep gps sudo killall gpsd For a final bit of cooking with the GPS board we want to run a Python script and display the data in tidy parsed output The code was originally written for the RPi but it is useable on the BBB as well 1 Go get it with the following command git clone https github com HudsonWerks gps tests git 2 Now browse to the new directory that we just created and take a look at the file that we will use with the following code cd gps tests sudo nano GPStest1 py 3 Let s peruse the script a bit to understand some of its key parts The script requires a number of Python libraries import os from gps import from time import import time import threading Keep in mind that getting a fix and then obtaining a good GPS data can take several moments before the system settles into a comfortable flow as shown in the following code It may take a second or two to get good data
232. machine Virtual Box like most virtual machine software does not include cut and paste by default Instead they have given us a series of 15 steps yes 15 Oracle Virtual Box refers to this function as Guest Additions Here we go 1 Let s begin by installing some external kernel modules on your VM So with a terminal window open in the Debian virtual machine on your client desktop run the following command as a root user sudo i apt get install dkms 2 Next back on your client desktop Mac OS X we have to locate a very buried iso file that contains the code to add the guest additions with its cut and paste feature In Finder navigate to Applications Virtualbox app Show Package Contents This will open all the hidden directories in the package including our target directory and file Then navigate to Contents MacOS VBoxGuestAdditions iso 3 Find and copy the vBoxGuestAdditions iso file to a place where you can find it on your machine 4 Back in your open Virtual Box in Debian Wheezy Settings Storage click on the small CD icon at the bottom of the screen and select Choose a Virtual CD DVD disk file Debian_Wheezy Running Applications Places Tue May 26 10 29 PM e 4 e M Charles Hamilton doi Ol Left se Another way to perform the same thing is from the drop down menus at the top of the screen not in the VM Debian window but the virtual machine menu options at the very top of your deskto
233. mage_name_here jpg Download the actual images to your BBB s directory with the following command dropbox_uploader sh download s IFTTT Space home debian Space Your terminal output should look similar to this gt Download IFTTT Space DONE F sample_image_name_here jpg Check that you did in fact get the images through the following code cd NowPix ls Set up a cron job refer to the prior chapter for more information on running a cron job to run the downloader script as follows crontab e Append the open file with the following line 3 home debian Dropbox Uploader dropbox_uploader sh s download IFTTT Soace home debian Space Next we want to have our space images display on screen whenever a new one is added This will use feh the package we explored in Chapter 8 The Internet of Things So if you successfully executed the recipe for NowPix in previous chapter proceed to the next step Otherwise return to Chapter 8 The Internet of Things and follow these steps to use feh Modify the feh script accordingly feh FD10 home debian Space Next we want our BBB to parse the flyover time data both archived and near future and turn it into nice visual displays So at this point we will depart from the earlier steps and add a powerful data visualization library used in Python matplotlib We will also add the basemap library which extends the functionality of matplotli
234. mailer var transporter nodemailer createTransport service Gmail auth user gmail user gmail com pass user_password 3 setup e mail data with unicode symbols var mailOptions sender address from Ground Control lt your_name gmail com gt list of receivers to sender_name1 some_domain com another_address anotherdomain com Subject line subject This is Ground Control to Major Tom plaintext body text Can you hear me Major Tom html body html lt b gt Can you hear me Major Tom lt b gt 4 send mail with defined transport object transporter sendMail mailOptions function error info if error return console log error console log Message sent info response Note The preceding code is a modification of nodemailer s GitHub example Also note if you run into problems copying and pasting the code you can download the code from https github com HudsonWerks Nodemailer blob master examples nodemailer test js Finally if you use Gmail for your account in this example and run into login errors there are numerous troublehooting tips here https github com andris9 nodemailer wellknown issues 3 Save the new file using the keyboard command Ctrl x with nano and then type Y for yes Then press the return Enter key Now run the following command node nodemailer test js Ta da If all went well you should receive a
235. ment BB BONE EMMC 2G Ff P O L Bone Black HDMI 00A0 Texas Instrument BB BONELT HDMI Ff P O L Override Board Name 00A0 Override Manuf rangepru NoB WON EF Confirm the overlay took hold dmesg Your output should look similar to this 1462 225670 bone capemgr bone_capemgr 9 part_number rangepru version N A 1462 225742 bone capemgr bone_capemgr 9 slot 7 generic override 1462 225758 bone capemgr bone_capemgr 9 bone Using override eeprom data at slot 7 1462 225773 bone capemgr bone_capemgr 9 slot 7 Override Board Name 00A0 Override Manuf rangepru 1462 225856 bone capemgr bone_capemgr 9 slot 7 Requesting part number version based rangepru 00A0 dtbo 1462 220878 bone capemgr bone_capemgr 9 slot 7 Requesting firmware rangepru 00A0 dtbo for board name Override Board Name version 00A0 1462 230469 bone capemgr bone_capemgr 9 slot 7 dtbo rangepru 00A0 dtbo loaded converting to live tree We should also check that the PRU module is loaded as expected lsmod Your output should look similar to this You should see the uio prussdrv driver Module Size Used by 13 14 uio_pruss 4058 0 g_multi 50519 2 libcomposite 15032 1 g multi 8192cu 449177 0 cpufreq_userspace 2013 0 evdev 7244 2 omap_rng 4054 0 Whew That was the first part of the recipe completed Okay let us now move right along to creating the actual file we will use to capture data from the ultrason
236. minder this low cost sensor is readily available from numerous sources including suppliers such as Sparkfun https www sparkfun com products 10988 How to do it Perform the following steps to use sensors and data with ThingSpeak 1 If BBB is not already off turn it off 2 Using the following fritzing diagram wire your powered down BBB A BeagleBone You may remember this configuration from Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python as the wiring is exactly the same GND uses the analog ground P9_34 GNDA_ADC 3V PWR at P9_3 and the sensor pin at P9_38 3 Power your BBB and log in via SSH 4 Sign up for a new account at ThingSpeak https thingspeak com a free cloud service for data publishing and creating IoT style products 5 Follow the prompts on the ThingSpeak site on how to set up a channel for your account Just for fun let s name the channel as Ground Control Temperature Ki ThingSpeak Channels Apps Plugins Public View API Keys f Percentage Complete 15 Channel ID Name Ground Control Tempe 6 Atthe bottom of the same Channel Settings screen create a second field called Field Label 2 as shown in the following screenshot Make Public URL Video ID YouTube Vimeo Field 1 Field Label 1 remove field Field 2 Field Label 2 remove field Field 3 add field 7 You c
237. mpts Now App Secret has been generated Cut and paste that string from the Dropbox to the terminal window as shown in the following code App secret abcdefghijklmnop1234 Permission type App folder or Full Dropbox a f App folder f App key is abcdefghijklmnop1234 App secret isabcdefghijklmnop1234 and Access level is Full Dropbox Looks ok y n y n y Hit return and you are finished at least with the installation Note If you accidentally input the wrong App Key and App Secret which I did since I have several Dropbox apps you can reset the access by running the following script dropbox_uploader sh unlink Testing and running the script We now need to verify that the script operates as expected downloading images from Dropbox and placing them in a specified directory 1 First we will verify that the content of our IFTTT directory on the Dropbox can be accessed and read properly so we will list the images that are there cd Dropbox Uploader dropbox_uploader sh list IFTTT i0S_Photos NowPix 2 Go get the actual images and download them to your directory using the following command dropbox_uploader sh download s Apps NowPix home debian NowPix We added the s option that skips the already existing files when you download upload otherwise the default parameter is to overwrite the files in the target directory 3 Verify that you did in fact get the images with the following command
238. n IoT together with a wireless image player to update the digital picture frame dynamically and seamlessly from a smartphone Getting ready The materials needed are as follows A smartphone with internet connectivity The BBB powered by 5V A Wi Fi dongle An LCD 5 inches or larger You will also need to set up two web service accounts e Dropbox The free plan is adequate http www dropbox com e IFTTT This is a free service http www ifttt com Using IFTTT For this recipe we will incorporate the If This Then That IFTTT web service Although not perfect IFTTT is a fun rapid development tool for prototyping IoT scenarios and use cases There are other ways to perform what I will outline later you could hook up other popular third party apps such as Instagram Flickr and Twitter However I prefer to keep the additional installations at a minimum and establish more of a least common denominator environment that provides a simpler development path For long term serious product builds IFTTT is not a good choice because it is too black box too opaque in its functionality to rely on for final designs However for rapid protoyping and idea generating it is highly useful With IFTTT you can iterate quickly and nimbly using a host of different web services that will always lead to new ideas and directions for your development How to do it Part one The smartphone setup Perform the following steps 1 2
239. n distribution running VNC is easier than ever as the BBB arrives preloaded with the relevant package the TightVNC server On your client box you need to install a remote viewer Getting ready For your client box download and install one of the following remote viewer applications e The Windows Mac and Linux boxes http www tightvnc com e VNC Viewer http www realvnc com download viewer Once again we re cooking up a recipe from a Mac perspective so VNC Viewer it will be How to do it As noted the BBB now comes with the remote server installed so the only new installation required is the one for your client box For this perform the following steps 1 2 5 6 7 Install the client app on your desktop box From the terminal window run the VNC server on the BBB through the following command vncserver Next you will need your BBB s port address You will find it in the status message now running in the CLI window New X desktop is beaglebone 1 Note Your port number may differ On your desktop box o Open up VNC viewer or whichever client app you re using o Type in the IP address of your BBB and the port number at the end of the VNC server field 123 456 78 9 1 The default my be beaglebone 1 60 VNC Viewer VNCO Viewer Va Encryption Let VNC Server choose v About Options Connect You will then have a window pop up Unencrypted Connection Clic
240. n e mail from Ground Control in your inbox There s more e 6 things you should know about Node js This is perhaps the best and most succinct article on why Node js has become a freight train for rapid robust development and can be found at http www javaworld com article 2079190 scripting jvm languages 6 things you should know about node js html e The Node Beginner Book The author of this book provides the first 21 pages for free and charges for the rest of the book which is definitely worth the 20 00 You can find it athttp www nodebeginner org e Mixu s Node book Although it was originally written several years ago it remains an excellent in depth introduction to Node js This can be easily found at http book mixu net node e From Java to Node js You can find this at https nOtwOrthy wordpress com 2012 01 08 from java to node js e For further ideas on which modules are out there explore the extensive list of node modules found at https github com nodejs node wiki See also To explore this particular module including nodemailer s wide variety of features and customization options check out https github com andris9 Nodemailer Using Node js with Johnny Five In this section we will cover a recipe for Johnny Five a unique library built in JavaScript Node js that is increasingly getting the attention of the open source software world Although positioned as a robotics library Johnny Five is
241. n its code You may have little experience with Assembly you may have none Don t despair after running the command above the tool comes ready to use o libprussdrv This consists of the driver library and library headers 3 In a similar vein as we do with GPIO pins to make use of the PRUs we have to enable them And interaction with the PRUs requires the use of a Device Tree fragment With the current Wheezy and Jessie distributions the DT overlay comes pre compiled and ready to use on your system a huge time saver over earlier versions of the software Before loading a fragment let us first look at the system s Device Tree slots where it will appear so we can see understand the before and after output ff P O L Bone LT eMMC 2G 00A0 Texas Instrument BB BONE EMMC 2G Ff P O L Bone Black HDMI 00A0 Texas Instrument BB BONELT HDMI ff P O L Override Board Name 00A0 Override Manuf BB UART4 cat sys devices bone_capemgr 9 slots 0 54 PF 1 55 PF 2 56 PF 3 57 PF 4 5 7 Nothing shows yet in the output above that indicates PRU visibility or communication with the kernel The next command changes that status 4 Using the echo command load the device tree fragment This enables the PRU echo BB BONE PRU 01 gt sys devices bone_capemgr 9 slots The command should return you to the prompt without any message or error 5 With the cat command again check to make sure that the fragment loaded
242. n log back in as the root user with the following code sudo i Add your username to the sudo group as follows adduser username sudo Then use the fdisk command to check whether sudo is working properly The v option will check the version of fdisk installed on your VM You should get a prompt for a user password as shown in the following code sudo fdisk v The screen output should show the version of fdisk that is installed and there should be no errors about permissions Install ssh We already use it on the BBB Now we need to add it to our VM SSH gives Eclipse the ability to connect and transfer files to BeagleBone Black using scp a secure network protocol Install it with the following code sudo apt get install ssh Part II Installing gdbserver on BeagleBone Black We need this package on board the BBB so that we can run gdb from afar or from another box Perform the following steps 1 First download the Debian installation package of gdbserver for armhf the BBB native architecture on your VM as follows wget http http us debian org debian pool main g gdb gdbserver_7 4 1 dfsg 0 1 armhf deb Now use scp to transfer the package to the BBB as shown in the following code scp gdbserver_7 4 1 dfsg 0 1 armhf deb root 192 168 7 2 You should get a password prompt for the root user on BeagleBone Log in and install the package as follows ssh root 192 168 7 2 root arm dpkg i gdbse
243. nager Now open up the new package with this command nmtui A rudimentary interface should open up in the terminal window similar to the following image N 10 NetworkManager TUI Please select an option Edit a connection Activate a connection Set system hostname Quit Select Activate a connection In the next window select your network and you will be prompted for the password Quit the network manager screen after putting in your password Then check to verify that your dongle now has an IP address in the wlanX interface with this command ifconfig a Now power down remove the Ethernet cable and reboot using this command reboot Run the magical ping command to check how we did ping www google com Voila Your BBB should now be connected wirelessly There s more Some users report that the board can interfere with a Wi Fi dongle s USB signal So if you do not get a reliable connection position your powered USB device containing the Wi Fi dongle a few feet away from the BBB See also Take a look at a list of other compatible dongles here at http elinux org Beagleboard BeagleBoneBlack WIFI_ Adapters Package management Installing packages using apt get If you are a newcomer on Linux you will find that managing software on your BBB is a very different experience from the one on your Windows or Mac box Linux distributions have a very different sensibility when it
244. nd consume a small amount of power A servo is really just a motor with an output shaft connected to a sensor The sensor provides feedback of a position to control the motor s motion and final position The shaft is able to turn around 180 degrees In order to run properly the servo requires a fairly robust controller Communication between the servo and the controller can be either digital or analogue On the BBB front the servo requires PWM to send pulsed signals which we discuss later in this section The length of the pulse drives the position of the motor Regardless of the signal type the input signal s purpose is to send data that determines the motor output shaft s position In more sophisticated servos the signal also includes data on the speed However in our recipe we will use a low cost servo that is typically used in RC toys These kinds of devices handle only shaft position Servos are also distinctive for their three wires e Power 5 volts This is often red e Ground This is sometimes black but more often this is brown in cheaper servos e Control This is commonly yellow or white A crash course in pulse width modulation Pulse width modulation PWM is a way to send very fast on off digital signal pulses to a pin These pulses can be modulated in order to smoothly control certain kinds of device like LEDs audio components and motors When coding a PWM driven device or component you are basically setting
245. ndow bin bash Create a variable that will run the Python script ISS sudo python home debian ISS current distance py Create a variable that will grab the current UTC time combine it with the output from the Python script and include the text that we want the TTS engine to speak NOW date Ground Control time is M minutes past l p U T C with current distance to the International Space Station ISS miles echo NOW Run the TTS against the variable we created and then play it back pico2wave w GroundControlTime ISS wav SNOW aplay GroundControlTime ISS wav The comments are pretty self explanatory two variables are created one to run the Python file and the other to do a current timestamp After this combine the variables together into a TT S audio file that is played back Note Be careful not to truncate code that you copy and paste either in or out of a nano window 3 Make the file executable with the following command sudo chmod x timeTTS ISS sh Part V Setting up a cron job We want to automate the use of the bash and python scripts so that we can get continuous readings and feedback without having to manually start them 1 Set up a cron job so that the script will run on a schedule We have not done this for several chapters so here is what we will do sudo crontab e 2 Copy and paste the following line at the bottom of the open window 30 sudo bash home debian timeTTS IS
246. ng Wi Fi to work on the BBB If you were happy using Angstrom only for your projects you were in luck as this distribution was mostly solid given that several USB minidongles on the market worked well However on Debian and Ubuntu unless you did not mind using larger dongles with protruding antennae connections were flaky Alternatively you could invest a chunk of time writing custom drivers So much for out of the box portability Fast forward to the mostly good news With the three different Wi Fi dongles that we tested on the current shipping version of Debian 7 Wheezy for the BBB using 3 8 13 bone71 and on Debian 8 Jessie we largely got positive results The bad news With the exception of using Debian Jessie not all dongles were recognized by the BBB without some configuration However it is fairly easy to set up the hardware and you also may get lucky with the dongle you have in your kit and get immediate connectivity Note If you are using Debian 8 Jessie skip immediately to Method Four Debian Jessie Getting ready The following are the prerequisites for Wi Fi connectivity e DC power to the BBB the board should be powered from a 5V DC 1A minimum supply and not via USB e A connected HDMI monitor e Wired or wireless keyboard and mouse connected to the USB hub e A powered USB hub the Wi Fi dongle draws more power than the BBB can deliver if you only power the board via the USB port on your client box Instea
247. ng design requires two resistors a 1k and a 2k In tandem they serve to step down the voltage from the sensor s Echo pin 5V being sent back to the BBB o Confirm that you have both resistors in place otherwise you may damage your beloved BBB o Power The range sensor needs a 5V supply Anything less will yield unpredictable results BeagleBone fritzin The following table displays the wiring configuration VCC VDD_5V ep fs Or P9_6 Echo peu wien 1k and 2k ohm zes Be sure to double and triple check your work Otherwise you could end up frying your board Log in as root sudo i Clone the files that we will be using from GitHub git clone https github com HudsonWerks Range Sensor PRU git Browse to the new directory cd Range Sensor PRU Take a look inside the directory to get a sense of what kind of files we will be using rangepru dts Device Tree source file from which we will build a Device Tree overlay or driver for our test application rangepru c Contains the application code written in C rangepru p Contains the assembly code which will be run against our C file to build the binary Makefile Builds a binary that we will ultimately use to run our range sensor test with the PRUs We need to add a custom device tree overlay to the mix The overlay serves as a driver for the sensor and maps to the GPIOs we are using In the current directory we will modi
248. ng world that a thicket of third party devices were being cooked up to work with ARM Custom hardware drivers and custom kernels were everywhere This was making the Linux kernel playground increasingly chaotic So Linus roared go back to the kitchen cooks and make a better recipe So they did Or so the story goes Thus was born Device Tree For beginners Device Tree can be a bit difficult to wrap one s head around However in order to use BeagleBone Black in more interesting projects an understanding is often critical Basically Device Tree is a data structure to describe the hardware that you add on to your board With Device Tree the details of a device are available to the board without needing to be hardcoded into the kernel Prior to its existence the kernel image the single binary vmlinuz that we looked at earlier in the chapter contained any description needed for the hardware Beginning with version 3 8 of the Linux kernel for ARM however another binary was loaded at boot along with the kernel Device Tree Blob DTB BeagleBone Black with its 3 8 kernel the shipping version at least is one of the first ARM devices to incorporate the new order of things with Device Tree DT Its benefits for the BBB are many e Upstream dev This provides us with the ability to receive and contribute to all the benefits of upstream kernel development e Kernel build simplification This avoids the hassle of maintaining a
249. nny five io In addition to the BeagleBone Black you will notice that the library supports a host of SOCs and microcontrollers Learn more about the Johnny Five beaglebone io plugin and the specific pin mapping for the board at https github com julianduque beaglebone io beaglebone io Python basic recipes In addition to your JavaScript chops some of you reading this most likely have some Python skills We ll take a look at a similar recipe to activate the onboard LEDs this time however we will do this from a Python perspective Getting ready Let s confirm that you have Python installed and working properly along with its IDE After this perform the following steps 1 Open a terminal window and type the following python 2 Atthe gt gt gt prompt type gt gt gt print This is Ground Control 3 Now you should see this This is Ground Control 4 To quit press Ctrl z Adding libraries The current Debian distribution includes the Adafruit_BBIO and PyBBIO libraries both of which are extremely useful and commonly used on BBB to control the pins of your board with Python We will work with these libraries in the next section If you re using the current Debian 7 Wheezy distribution or Debian 8 Jessie you can skip to the next section However if you have some other version of an OS here are the steps to install the two libraries How to do it Part One Installing Adafruit _BBIO library Perform the fo
250. ns of course And the BBB comes with seven pre assigned analog inputs on our board so it s nearly plug and play Well not quite But at least we don t have to fuss with pin muxing right away Temperature sensors For this recipe we re using the TMP36 a very low cost USD 1 50 analog temperature sensor that you can find at many different electronics stores or suppliers It outputs an analog voltage that is proportional to the ambient temperature We will write a script that takes that proportional value and reads back the temperature into the Cloud9 console Getting ready e Temperature sensor Available at SparkFun http bit ly OCGFDj e 3x jumper wires Easy to connect to the breadboard e Breadboard How to do it 1 Make sure your BBB is powered down first then wire up your breadboard Here s what your wiring should look like BeagleBone Be sure that you Put the GND into the special analog ground GNDA_ADC on the BBB In our diagram that s the black wire into pin P9_34 Put the 3V into the 3V on the BBB In our case that s the red wire into pin P9_3 Note Very Important The analog inputs on the BeagleBone Black accept a maximum of 1 8V Never apply more voltage than 1 8V to the analog pins or you will damage your board For the sensor markings facing you match up the pins as follows Pin 1 left pin Power 3 3V Pin 2 middle pin Analog pin on the BBB which in our r
251. ns of the software as we proceed through the book Note that prior versions of the board were shipped with Angstrom Linux However this book will not run recipes using this distribution Homebrew If you are using a Mac box adding Homebrew to Mac gives you Linux savvy tools on your desktop It includes a basket of Linux utilities so that you don t always have to fire up the board to run a test For a how to on installing Homebrew refer to the developers website at http brew sh Drivers If on Mac install the latest versions of developer Joshua Wise s HORNDIS drivers for USB tethering to BeagleBone Black which you can find at http joshuawise com horndis available versions We will provide more details on this step in Chapter 1 Setting Up for the First Time Who this book is for This is a book primarily for those of you who are new to microcontrollers small board computing and physical computing Although we will get into some relatively advanced examples the vast majority of our book s recipes are for the aspiring maker casual programmer and budding engineer or tinkerer who has wondered how to get started on a full blown microcomputing Linux system You might find some things in here that you could have found in some form on the Web As we are dealing with open source tools and technology this is inevitable However what we found when trying to learn about using BeagleBone Black for the first time was that althou
252. o do it Once ready it s time to begin the recipe Please note that this is split into two parts and you need to complete them in order The objective is to first go through the process of installing a pre compiled version of the software Then based on that outcome see how we can improve the functionality of the tool by compiling it from source files Part I compiling and installing a Linphone binary from the repository To begin this recipe you will firstly need to compile and install the Linphone binary from the repository as follows 1 Installing Linphone This is the easy part you can actually install the Linphone binary via apt get as follows sudo apt get update sudo apt get install linphone With this you ll end up with the latest precompiled binary of Linphone on your BBB So let s check the version that we get using the following command dpkg p linphone Take note of the version from the screen output as we will refer to it later 2 Setting up an SIP account Open up the application under Internet Linphone You will be greeted with a GUI based wizard which includes setting up an SIP telephone number on the application SIP is a signaling protocol that works with Voice Over IP VOIP telecommunications Numerous free SIP servers are available just Google free SIP account Here we will make it easy and use the free one offered by Linphone org the developers of the tool 3 Doing a desktop
253. o execute At the bottom of the Run Configurations screen are two fields Input the following remote absolute file path for C C application root test_project bbb_ground_control commands to execute before application chmod x root test_project bbb_ground_control Note Choose a path on BeagleBone Black where the bbb_ground_control executable file will be placed In our example it is root test_project bbb_ground_control where bbb_ground_control is the name of the binary file that we will compile The purpose of the chmod x command is to give our program permission to execute Click on Apply We are almost there Be patient and hang on tight From the terminal window on the VM we have a couple more things to perform on the BBB itself which is to mirror what we just input in the two fields in Eclipse First log in with the following code sudo ssh 192 168 7 2 Answer yes when prompted are you sure Enter the root password for the BBB root You should now be logged in to the BBB Run the commands to duplicate what we just did in Eclipse which means that we need to create a new directory navigate to it and then run the following command to give the application permission to execute root beaglebone mkdir test_project root beaglebone cd test_project root beaglebone chmod atw Now exit the SSH session on BeagleBone Black with the following code root beaglebone exit Back in the VM Eclipse window click
254. o run These versions would be available at Robert C Nelson s site at http www rcn ee net deb 5 Reboot with your new kernel image and then check that it shows the newer kernel now installed with the following command debian beaglebone uname a Linux beaglebone 3 8 13 bone xx 1 SMP day mo date time UTC year armv71 GNU Linux The xx box should now reflect an updated version running Installing and building a custom kernel This recipe will build the kernel and modules from scratch and copy them to a deploy or temporary directory Getting ready Connect and power up your board via USB to your host computer then open a terminal window How to do it To perform this recipe follow these steps 1 First log in as the root user and then download the kernel file from Robert C Nelson s git repo sudo i git clone https github com RobertCNelson bb kernel git 2 Navigate to the new directory that git created for you on your BBB with this command cd bb kernel 3 Atthis point you have two options for the kernel version you prefer to use either v3 8 x or the latest experimental v3 14 x You ll notice that the git command also generates a tmp directory for the build o For the 3 8 x Wheezy branch this version comes with full cape support use this command bb kernel git checkout origin am33x v3 8 b tmp o For the v3 14 x Jessie branch which comes with better USB and Ethernet support but w
255. obal Positioning System Daemon Requires gpsd socket Service ExecStart usr sbin gpsd n N dev tty04 Install Also gpsd socket 5 Then restart the systemd service as follows sudo service gpsd start 6 You should now be able run either of the following services again sudo gpsmon dev tty04 Alternatively you can run the following command sudo cgps s Troubleshooting Part 2 Sometimes the preceding fixes don t fix it Here are several more suggestions for troubleshooting purposes 1 Set up a control socket for GPS with the following command sudo gpsd N D3 F var run gpsd sock Note The explanation of the command line flags or options are as follows o N This tells gpsd to immediately post the GPS data Although this is useful for testing purposes it can also drain power so leave it off if your use case is battery powered o F This creates a control socket for device addition and removal The option requires a valid pathname on your local filesystem which is why our command is appended with var run gpsd sock 2 We may also need to install a package that lets us examine any port conflict that could be occurring as shown in the following command sudo apt get install lsof 3 This installed utility will open and display the system files including disk files named pipes network sockets and devices opened by all the processes There are multiple uses for the tool However we on
256. of the preloaded WEBRADIO stations have outdated or nonfunctioning links leading you to believe that your installation is not working properly However this is not the case you simply need to fix or update the links manually Under the Playback tab you will see a volume control akin to an iPod s click wheel Fiddle with it a bit and you will notice that the volume level of the output doesn t change Frustrating right This means that adjusting sound levels requires another tweak If you connected your system to DAC ignore this step as you will have hardware controls to adjust the volume Otherwise go to MENU SETTINGS click on the dropdown for Volume Control and select Software Following this reboot using a terminal command or via the GUI underneath the MENU SYSTEM tab Once rebooted let s push the recipe a bit further by grabbing a couple of files remotely and loading them into Volumio We will use the familiar wget command wget http hudsonwerks com beaglebone black recipes downloads volumio sample media tar gz Untar the archived files with the following command H tar zxvf volumio sample media tar gz Use this command line to put the files in the correct Volumio directory mv Space Oddity Hadfield CLIP m4a var lib mpd music USB Then run the following mv wbgo_jazzFM_NJ pls var lib mpd music WEBRADIO The media library now needs to be updated to reflect the new additions So via the Volumio web G
257. ommands the command shell How to do it How it works o typical commands Essential GNU Linux commands typical commands Getting ready Google Summer of Code GSOC There s more GPredict o used for satellite tracking Satellite tracking using GPredict and RTL SDR How to do it o about Satellite tracking using GPredict and RTL SDR GPredict manual o URL How to do it GPS o hooking up Location based recipes hooking up GPS How to do it o toolset installing How to do it o URL There s more GPS coordinates o URL How to do it GPSD o troubleshooting URL There s more GPS PCB o URL Getting ready ground station o about Satellite tracking using GPredict and RTL SDR HDMI o troubleshooting URL There s more HDMI LCD o connecting Connecting an HDMI LCD How to do it o URL How to do it header pins o about Header pins and pinmuxing high quality audio platform o creating Volumio used Creating a high quality audio platform with Volumio Getting ready How to do it There s more See also 2C o about Wiring up a mini amp and speakers I2C buses o I2C0 Wiring up a mini amp and speakers o I2C1 Wiring up a mini amp and speakers o 2C2 Wiring up a mini amp and speakers iBeacons Location based recipes Bluetooth LE and Beacons If This Then That IFTTT web service o URL Getting ready o about Getting ready IFTTT S
258. on Run Another pop up window will appear Enter the user and password as root Click on them and agree to the next few prompts from the BBB 40 41 42 43 44 45 46 47 The last few steps are focused on how to set up a remote debug session In your terminal window navigate to the project Debug path with the following code cd bbb eclipse workspace bbb_ground_control Debug Now we will perform a little obscure but necessary step when you run GDB create an invisible file called gdbinit This is an initialization file that resides in the debug directory and automatically loads and parses when you run GDB Typically you would populate this file with any required commands However for our current recipe the file remains empty although it needs to remain present for GDB s proper operation We could use nano to create the file because we used this editor in the earlier chapters However there is another command that actually generates the file on the fly saves it and places it in whatever directory you have entered as shown in the following code touch gdbinit Make sure that the file was created with the following code ls Hmm It isn t there To figure out what is happening this is a case where using different options with a command is vital With the 1s command we want to append the command with the a option So try again using the following code ls a The gdbinit file should now
259. onnected lsusb This captures and lists all USB devices currently connected to the BBB while showing basic information about the device How to do it Use the following command to find out about the USB devices connected debian beaglebone lsusb Bus 001 Device 002 ID Od8c 013c C Media Electronics Inc CM108 Audio Controller Bus 001 Device 001 ID 1d6b 0002 Linux Foundation 2 0 root hub Bus 002 Device 001 ID 1d6b 0002 Linux Foundation 2 0 root hub Note Note that the first device here shows a connected USB audio dongle Device and system insight get information about connected devices cat proc bus input devices Where lusb leaves off this command lists more detailed information about any device connected to the BBB Note the difference in output for the same USB audio device C media shown in our preceding recipe using 1susb How to do it Use the following command to get information about connected devices debian beaglebone cat proc bus input devices Wowrtrenv2Z2yH VWOWWICROUZHA Bus 0000 Vendor 0000 Product 0000 Version 0000 Name tps65217_pwr_but Phys Sysfs devices ocp 3 44e0b000 i2c i2c 0 0 0024 input inputo Uniq Handlers kbd evento PROP 0 EV 3 KEY 100000 0 0 Bus 0003 Vendor 0d8c Product 013c Version 0100 Name C Media Electronics Inc USB PnP Sound Device Phys usb musb hdrc 1 auto 1 input3 Sysfs devices ocp 3 47400000 usb musb hdrc 1 auto usb1 1 1 1 a 3 input
260. or releases at http elinux org Beagleboard BeagleBoneBlack Debian Debian Build Instructions Note Debian testing version You can also alternatively install Debian 8 Jessie using the same steps by substituting the following URL and appending the month day and year accordingly https rcn ee com rootfs bb org testing YEAR MONTHDAY Ixgat 4gb bone debian 8 0 Ixgt 4gb armhf 2015 05 04 4gb img xz 2 Next unpack unzip or unarchive the downloaded file using your favorite archive tool On my Mac I use Unarchive as it s easy to use and flexible After unarchiving there will be an img file available in your chosen folder 3 Now we will flash the img file to the microSD card The easiest method is to use a GUI like tool such as Pi Filler for the Mac or Win32 Disk Imager on your Windows box Wait for a prompt from the imaging software before actually inserting the SD card into the desktop s slot Depending on the speed of your desktop box s environment the flashing writing process will take anywhere from 15 to 30 minutes 4 Remove the SD card from your desktop after the flashing finishes and then remove the microSD card Ensure that your BBB is powered down and then insert the card into the microSD slot on the BBB Either with the USB tether or a 5V power supply power up the BBB 5 In your terminal window we will now SSH into the board with this command ssh debian 192 168 7 2 6 When the login prompts appear use
261. or important notes appear in a box like this Tip Tips and tricks appear like this A few words about nomenclature BBB One thing that gets tiresome to repeat is the darned name of the board BeagleBone Black Too many syllables So instead of spelling it out every time we will often just refer to the board as the BBB or the Black Note There are other versions of the BeagleBone out in the wild including BeagleBone XM BeagleBoard white and the new super charged and much pricier BeagleBoard X15 Desktop Even though your BeagleBone Black has a desktop if you re running it on an external monitor or via an x11 xwindows session we ll use the term desktop to refer to the client PC or Mac or Linux box that you re running as part of the development environment for the BBB Say hello to Major Tom Ubiquitous and nearly inevitable in the world of computer programming is the typical beginner s example code Hello World Although we certainly use simple use cases to get you started we don t use the Hello World rubric Instead because we re space geeks we use Major Tom as a touchstone evoking the astronaut from David Bowie s iconic Ziggy Stardust To that end we round out the book with an assortment of recipes using your BBB for tracking space stuff satellites and the International Space Station specifically Geeks indeed Reader feedback Feedback from our readers is always welcome Let us know what you th
262. ost computer via USB How to do it To run this script you need to follow these steps 1 2 You first need to open up the Cloud9 IDE and create a new script called freeGPIO js If you ran the recipe Device Tree Basic Build earlier in this chapter you will find the file freeGPIO js in the directory that you got from our GitHub repo This was available by running the following command git clone https github com HudsonWerks device tree git Otherwise you can cut and paste the same code below into the IDE window If you run into problems with the cut and paste version here then just grab the same code from the directory file on the GitHub repo usr bin node Lists all gpio pins with MUX UNCLAIMED and GPIO UNCLAIMED in PINMUX Usage freeGPIO js List free GPIOs using P8 or P9 pin number I Approach 1 search PINMUX for all entries with MUX UNCLAIMED GPIO UNCLAIMED 2 An entry looks like pin 8 44e10820 MUX UNCLAIMED GPIO UNCLAIMED 3 Extract the address 44e10820 and subtract 0x44e10800 to ge the offset 4 Format the offset as 0x020 with leading 0 s to give 3 digits 5 Search for the address in the muxRegOffset field in b bone pins 6 Print the matching key var PINMUX sys kernel debug pinctr1 44e10800 pinmux pinmux pins b require bonescript exec require child_process exec exec grep MUX UNCLAIMED GPIO UNCLAIMED PINMUX function error std
263. otypes Wiring up a mini amp and speakers To get some rocking audio going we thought about wiring a BeagleBone Black up to a personal favorite device of ours a C 1960 Gruntal amplifier and radio We then thought better of it and decided to go with something a wee bit smaller for our recipe the TPA2016 PCB which contains a Texas Instruments chipset and is packaged as a final product by Adafruit Class D Stereo O12 Audio Amp a x Vee It doesn t pack quite the volume as an ancient tube based amp but this surface mount PCB amp is a heck of a lot handier and easier to use than our antique beauty Also it delivers nearly 3W of power for our tunes plenty of volume for many situations Additionally its I2C interface allows us to control audio gain via software instead of using jumpers switches or other physical hardware In this recipe you will learn how to set up and test the device on a breadboard with speakers and BeagleBone Black Afterwards in a later recipe we ll use it as part of our kit to set up a listening library on the BBB 12C background and usage I2C pronounced eye squared C or eye two see is a hardware bus intended for motherboards and daughterboards to communicate easily It is frequently leveraged in embedded applications and typically used in accelerometers magnetometers and other sensors as well as other add ons requiring low voltage In our case we will use it to run a very smal
264. our search should have pulled down something like the following into your screen output linux image 3 14 38 ti rt r60 Linux kernel version 3 14 38 ti rt r60 linux image 3 14 39 ti rt r61 Linux kernel version 3 14 39 ti rt r61 linux image 3 14 40 ti rt r62 Linux kernel version 3 14 40 ti rt r62 4 Next from the available list shown from step one install the real time kernel version that matches your currently installed kernel sudo apt get install linux image 3 14 XX ti rtX And you are done RT PREEMPT is now baked into your kernel There s more If you are feeling a bit masochistic and just have to try applying RT PREEMPT onto your Debian Wheezy kernel you can piece it together from the following resources e https github com beagleboard kernel tree 3 8 rt e http www osadl org Realtime Preempt Kernel kernel rt 0 html Modifying the kernel using Xenomai Because it s a magic spell handed down from Gandalf the Grey this recipe will only work by saying it aloud three times fast Xenomai Xenomai Xenomai All right It sounds like an incantation But unfortunately it s only a software layer on top of a kernel The good news however is that adding Xenomai to the kernel mix can magically bring real time ish oomph to our BeagleBone Black So what is it exactly It is a set of patches bringing several useful ingredients e Real time support from the hardware interrupt level to user space applications e A dua
265. out stderr var list Array of unused pins pin pin offset in form 0x020 addr pin address 44e10820 keylist List of all unused header pins P9_12 if error console log error error if stderr console log stderr stderr console log stdout stdout stdout substring 0 stdout length 1 Get rid of extra n list stdout split n console log list for var i in list list i is of form pin 8 44e10820 MUX UNCLAIMED GPIO UNCLAIMED Get the address from the 2nd field and remove the s addr list i split 2 substring 1 9 Find the offset and return as 0x020 that is zero padded to 3 digits pin 0x 000 parseInt addr 16 0x44e10800 toString 16 slice 3 console log pin list i for var j in b bone pins if b bone pins j muxRegOffset pin console log b bone pins j key keylist push b bone pins j key break keylist sort console log keylist join In the Cloud9 IDE click the Run button P8_10 P8_11 P8_12 P8_13 P8_14 P8_15 P8_16 P8_17 P8_18 P8_19 P8_26 P8_7 P8_ 8 P8_9 P9 11 P9_12 P9 13 P9 14 P9_15 P9 16 P9_23 P9_24 P9 26 P9_27 P9_30 P9 41 P9_42 USRO USR1 USR2 USR3 This script gave us a list of pins that are not currently in use by the BBB and can be exploited for other purposes Next we will create and use a second script that we will name findGPIO js a script which wil
266. out the operating system on a MicroSD card is an enormous timesaver In fact you will see us more commonly booting from the MicroSD than the internal drive e Power supply You have more than one option to power up though the recipe will recommend specifically which of these to use o 5V power This is a 5V 2A 2000mA switching power supply o A mini B USB cable A great many of the recipes allow you to power the board with nothing more than the USB cable that should have come with your board when you purchased it The standard USB connector goes into the USB port on your desktop client which becomes the power source for BeagleBone Black e Display There are basically three options to get a display going on your board o An HDMI screen This out of the box approach assumes that you will connect your board to an HDMI monitor Compatible hardware is listed at http elinux org Beagleboard BeagleBoneBlack HDMI If you do use this option you will need a micro HDMI to standard HDMI cable o A mini LCD or cape We will learn how to connect a small LCD to the board s header pins As this is somewhat of a custom solution we do not assume that you will typically use this method except in relevant use cases o A remote session As we will see in an early chapter much of your work on BeagleBone Black can be done via remote sessions using Secure Shell SSH on a client desktop machine such as a Mac or Windows box Note that this will be our
267. out which kernel we are running The command can serve as a first level diagnostic tool when we need to troubleshoot errors or incompatibilities with any software we want to add or compile for our system Getting ready This is a simple setup so all you need to do is connect your board via USB to your host computer and fire it up Then open a terminal window How to do it The steps to do this are simple 1 Firstly log in as the root user using the following command sudo i 2 Now run a command that tells us a few important things about the kernel Let s choose the a option to show all information about the system as follows root beaglebone uname a Linux beaglebone 3 8 13 bone67 1 SMP Wed Sep 24 01 36 09 UTC 2014 armv71 GNU Linux From this command s output we discover several items of interest as follows The kernel version According to our output the installed version of the Linux kernel is 3 8 13 There are other later experimental versions for example 3 14 x that many BeagleBone Black developers are currently using However version 3 8 is the current stable install Kernel ABI Our version is bone67 a flavor specific to our board and one that provides an optimized environment to run a basic BBB system The number 67 is the version number and not significant in itself but it provides context for when we encounter incompatibilities or errors How it works So what is the kerne
268. output P8_15 GPIO HIGH time sleep 1 0 GPIO output P8_15 GPIO LOW time sleep 1 0 3 Now save the script 4 Click Run in the Cloud9 IDE Your LED should begin blinking There s more You can find more support in these tutorials e Sparkfun s multipage tutorial on LEDs provides a top notch further study at https learn sparkfun com tutorials light emitting diodes leds e For a beginner instructables delivers excellent and additional background on LEDs at http www instructables com id LEDs for Beginners Using buttons button press function Buttons come in all shapes and sizes Some are quiet Some are noisy Some are expensive Some cost pennies We ll not only use the cheap and peppy penny variety but also show an example with a more interesting whizzy personality and make it do something more than just turn the switch on and off Pull up pull down and floating Frequently when wiring up circuits you will hear references to pull up pull down and floating configurations When your design is a pull up circuit this means that the resistor holds the positive or supply voltage VCC until you push the button pulling it up to ground This is the most common scenario and one you encounter when you design a circuit with a button press to activate something In the pull down version of a circuit the resistor in the circuit remains at ground unless you push or pull down the button causing the circuit to
269. ow Restart a music track on your media player that in our case is an iPod You should be able to hear the track playing through the speakers Now click on the Run button on the Cloud9 IDE to test the script Audio levels should shift up and down as you input the or sign at the command prompt Success we hope Give yourself a high five for getting dirtier with your board and adding some PCB add ons to the mix Creating a high quality audio platform with Volumio Volumio is a wonderful open source alternative to the Tunes straightjacket For audiophile geeks who happen to be microcomputer or electronic geeks you know who you are and RPi enthusiasts in particular Volumio is well known for its fastidiousness at serving up high quality audio be it web based radio or high resolution audio files The system has now been ported to the BBB from its earlier incarnation as RaspyFi Essentially Volumio leverages a Linux music server called Music Player Daemon MPD MPD provides a client environment with a web centric GUI sans plugins and a robust networking architecture to serve your audio files One of the many appealing aspects of Volumio is that it is nearly file agnostic so you can play virtually any audio file type within the environment For now this includes FLAC WAV MP3 AAC ALAC MAA and playlist PLS files Each new version of Volumio seems to leap forward in stability and ease of use However it does come wit
270. owing Users username ssh known_hosts updated Original contents retained as Users username ssh known_hosts old username hrh Next type the following username devicename ssh debian lt your_ip address gt Now you will see the following on screen The authenticity of host lt your_ip_address gt lt your_ip_address gt can t be established RSA key fingerprint is 97 b4 04 f5 24 f3 75 f9 90 3c cc ff 78 36 f3 d9 Are you sure you want to continue connecting yes no Type yes no quotes all lowercase You will then see the following with a new prompt Warning Permanently added lt your_ip_address gt RSA to the list of known hosts debian lt your_ip_address gt s password Type the password of your BBB login the default is temppwa If you typed in your password correctly you will end up back here debian beaglebone Congratulations You ve now gained control over your BBB using the command line from another box Using VNC to control your BBB So are you still not entirely comfortable with the command line and want access to some of the GUI based tools Or do you need to test and control using an actual GUI Or perhaps is your app not running properly from only the command line Then it s time for VNC Virtual Network Computing VNC allows remote access to a device that s running an X session or windows GUI based system from a remote device or client machine With the current Debia
271. p machine There you can choose Devices CD DVD devices IDE IDE Primary Master Choose a Virtual CD DVD disk file Browse to where you put the vBoxGuestAdditions iso file and select it The iso file should now appear in the CD DVD drive options Click on OK and restart the VM With the terminal window open in your Debian VM run the following two commands apt get update apt get upgrade Now confirm that you have the make and GNU C compiler installed which should already be on the distribution that you installed Check it with the following code gcc version If you don t get an output that shows the version but a command not found error you will need to install it as follows apt get install make gcc Reboot your Virtual Box machine 10 11 12 13 14 Determine the exact version of your kernel with the following code uname a Install the correct version of the linux headers package Replace the following version numbers with the version number shown in the prior step apt get install linux headers 2 6 26 2 68 This may take some time just wait for the installation to finish and return to your terminal prompt Restart your VM with the following code reboot From the screen options select Machine options General and then click on the Advanced tab In the Shared Clipboard dropdown select the Bidirectional option The cut and paste functionality b
272. p the headers on the PCB amp as you can see on the left hand side in this picture We used lead free solder so when finished the joints will look dull instead of the typically shiny cast from a well poured leaded joint Solder the speaker terminal blocks to the PCB amp Verify that your connections are solid You may notice that the blocks don t sit neatly parallel to one another This appears to be due to a slight design imperfection in the PCB amp but there s nothing to pia about functionally 3 Snip off the white connector that comes already attached to the ends of the speaker wires Following this with a wire stripper cut away the wire ends as you can see in the following image 4 Next attach the finished PCB amp to a breadboard Then insert the speaker wires into the speaker terminal blocks The black wires go into the ground connectors and the white wires into the power connectors Use a small Philips head screwdriver to first release tension in the block Finish by tightening it after the wires are inserted The end result is shown in this image 5 Since we plan to use sound in this recipe which is what an audio amplifier is good for we need to also add some means for sound input You can use either the breadboard ready headphone jack which you will see in the next picture or the pigtail cable as described at the beginning of this recipe 6 Hook up your audio player to the othe
273. pace Channel o URL How to do it initial state o URL See also Integrated Interchip Sound 125 bus Wiring up a mini amp and speakers International Space Station ISS How to do it Grabbing the International Space Station flyover data and visualizing it Internet of Things IoT o about Introduction ISSs flyover data o grabbing Grabbing the International Space Station flyover data and visualizing it How to do it o URL How to do it o RTL SDR used for tracking Tracking using RTL SDR ISS tracking o URL There s more o about Adding other interfaces ISS tracking and text to speech How to do it o TTS installing How to do it o bash script creating How to do it o cron job setting up How to do it ITP soldering lesson o URL How to do it J e Jasper project o URL There s more e Java o to Node js URL There s more e Johnny Five o Node js using with Using Node js with Johnny Five How to do it There s more o URL There s more K e kernel o building basics Kernel building basics See also o application binary interface Kernel application binary interface How it works o interactions with Interactions with the kernel sysfs entries and controlling the GPIOs How to do it o modifying RT PREEMPT used Modifying the kernel using RI PREEMPT How to do it Modifying the kernel using Xenomai e kernel image o latest kernel image in
274. pe y for yes Error What a bummer that we couldn t save our work This is because we didn t first execute nano with the right user privileges So try again by closing the file by pressing Ctrl x when prompted type n for no We lost our work but it was only one line of text We would now have popped back into the command line and we will have another go this time we need a few more steps 1 Let s make a custom directory run this command mkdir bbb_recipe_ book 2 Go into this new directory and make a subdirectory then make a subdirectory of this one This may sound overly complicated but we re just trying to set up some files and directories by organizing principles early Use the following commands for this cd bbb_recipe_book mkdir projects cd projects 3 Check your work to ensure that you ve set up the directory structure properly Use the following command pwd 4 Now let s type sudo nano major_tom txt This time we appended the filename with a text file type If you don t do this nano and Linux won t know with which application type to associate the file 5 In the nano window again type I love my Beaglebone Black so much I want to send it into orbit with Major Tom as shown in this image debian beaglebone File Edit Tabs Help GNU nano 2 2 6 File major_tom Modified I love my Beaglebone Black so much I want to send it into orbit with Major Tom 6 Then press Ctrl x when prom
275. pes in this chapter The basic shell script Epoch Time shell script Compile and install Compile and install Git from source Debugging Debug a simple C code application from the command line using GDB Debug an application remotely from Eclipse and GDB server systemd services Basic commands for systemd services Optimize boot time Create a systemd service to run at boot time Introduction In our last chapter we jumped right into how to make our hardware dance or at least blink for us This time you will learn more about how to bend the software to your will We ll build on some foundational principles first and then head towards greater complexity of scripts including how to compile an open source software package install it on your system and troubleshoot it when things go out of whack Lastly we ll examine some core system level software called systemd a framework that has become an essential ingredient in modern Linux distributions The basic shell script Shell scripts A shell script has a myriad of purposes on a Linux box You can have them run at bootup so that they initiate commands or processes without you having to manually start them They can be used to run a sequence of events They can manipulate files execute a program print text and walk your dog Well the last part is true if your dog is a robot However we re getting ahead of ourselves It s time for our friend Major Tom We ve missed him but
276. pheral Interface SPI o URL Using videos and displays in projects e servo motors o about Servo motors How to do it e shell scripts o about The basic shell script How to do it e Ship iot o URL See also e SIP account o setting up How to do it e Software Defined Radio SDR Tracking using RTL SDR e soldering o URL How to do it e Sparkfun o URL Getting ready Getting ready e speakers o wiring up Wiring up a mini amp and speakers Getting ready How to do it e SPIdev pins o URL There s more e SSH o used for controlling BBB Using SSH to control your BBB How to do it SSH Remote access o about SSH Remote access systemd commands o quick reference cheat sheet URL There s more systemd service o creating to run at boot time Create a systemd service to run at boot time How to do it systemd services o about systemd services There s more system images o about System images System navigational command o directory changing System navigational command change your directory cd There s more o current directory showing System navigational command show your current directory pwd o file finding System navigational command find a file find How to do it test tool o about Installing a test tool How to do it text file o editing from command shell Edit a text file from the command shell How to do it See also
277. physical hard drive check whether you prefer the VM to have a fixed drive space allocation which can be faster once built or a dynamic storage capacity which will only expand as needed I kept mine at dynamically allocated Click on Continue For the file location and size click on Create This closes the setup window and returns you to the main dashboard 11 At the dashboard you should now see the VM we just created Debian Wheezy Before running the VM we need to configure it some more So click on Settings Follow these settings 1 General Advanced Shared Clipboard Choose bidirectional because you will want to share the clipboard data in both the directions between the client box in our case Mac OS X and the Debian VM You will still need to follow additional steps to get this function working Navigate to the following System Storage Controller IDE Click on the sign Add CD DVD device to open a browse directory window Click on Choose Disk Navigate to the folder where you downloaded the iso file of your preferred Linux distro The filename will be something similar to debian x y z i386 netinst iso or some variant on the architecture that you chose Then click on Open Your OS should now be loaded But now we need to have the OS actually installed in its normal fashion on the virtual drive that you set up Perform the following steps 1 2 On the dashboard while making sure that your new D
278. press com 2014 09 22 installing jasper on the beaglebone black Blogger and technologist Steve Hickson has also made great strides in getting voice recognition on board the RPi at http stevenhickson blogspot com Other space related Projects A variety of other projects using the BeagleBone Black for space related purposes are underway Here are a few e NASA s ice rovers and the BeagleBone Black NASA s Jet Propulsion Lab is using the BBB in an early prototype for a rover that could be used on Jupiter s icy moon Europa Being tested in icy conditions in Alaska the rover actually crawls on the under side of the ice as if it s on the ground https youtu be s YSWQG3 3mo Here is a close up of BeagleBone Black inside the ice rover Credit NASA JPL Here you can see an ice rover about to descend underneath the ice TOR uss Credit NASA JPL Here is the BBB powered rover crawling under the ice Credit NASA JPL e BeagleSat This is an excellent Google Summer of Code GSOC project developed by Niko Visnjic The objective of this work in progress is to send a BBB driven sensor payload into space aboard a CubeSat the small form factor satellite payload specification http nvisnjic com beaglesat Code for the project is also available on Github at https github com nvisnjic BeagleSat e NASA s CubeQuest challenge For more information refer to http www nasa gov cubequest detail
279. project gpredict Gpredict 1 3 gpredict 1 3 tar gz tar zxvf gpredict x y z tar gz Navigate to the new directory created with this command cd gpredict 1 x Run the usual steps to compile and install as follows sudo autogen sh sudo configure sudo make amp amp sudo make install Note We recommend downloading the GPredict manual at http sourceforge net projects gpredict files Gpredict 1 3 gpredict user manual 1 3 pdf download Once you ve got GPredict installed you will want to use its graphical interface as it enjoys a robust GUI and is easier to operate than the command line If you don t have an external monitor connected to your BBB power down and then attach it Alternatively just continue headless and run GPredict via vncserver vncserver Open up GPredict Then update the two line element TLE files TLE is a format originated by NASA to display Keplerian elements Commonly called Keps these are sets of numbers allowing satellite tracking programs to calculate a satellite s position in space while giving us specific information about its orbit at a specific moment Keps must be updated however which is easy to do in the Update menu Note Here is an example of a Keplerian element for the International Space Station 6 May 2004 ISS 1 25544U 98067A 04127 92349537 00017095 00000 0 14786 3 0 7232 2 25544 51 6276 176 0525 0011067 106 0444 249 6038 15 69246258311835 7 GPre
280. prompt from your BeagleBone Black Just do the same drill user root and password root If all went as planned and the gremlins stay home you should see the following output on your Eclipse console screen Last login DAY MO DATE TIME YEAR from 192 168 7 1 echo PWD gt chmod x root test_project bbb_ground_control gdbserver 2345 root test_project bbb_ground_control exit root beaglebone echo PWD gt root gt root beaglebone chmod x root test_project bbb_ground_control gdbserver 2345 root test_project bbb_ground_control exit Process root test_project bbb_ground_control created pid 2910 Listening on port 2345 Remote debugging from host 192 168 7 1 Since the ultimate goal of all this effort was to actually perform some debugging on a program now you can really get to work Make sure your bbb_ground_control c window is selected Then at the top choose Run From the drop down list you will see the basket of debug commands now ready for your able debug twitchy fingers If you made it to this point this recipe has one last set of command ingredients Go to actual cabinet on actual shelf Take out bottle of single malt scotch Pour dram perhaps two Lean back head and drink Congratulate Major Tom on a good test flight There s more A thorough review of how to debug is beyond the scope of this book Fortunately there are ample resources to learn more Here are a few e RMS s gdb d
281. pted type y for yes 7 Now you will see that the bottom menu has a new prompt which reads as follows File name to write major_tom txt 8 Hit return Enter on your keyboard The file is saved to the new directory we re working in home debian bbb_recipe_book and closed simultaneously You ve now made a very exciting txt file that you can go back and read whenever you want Okay that wasn t terribly challenging But don t worry we will be adding more complexity as we proceed in upcoming chapters See also For those who find nano a bit Spartan in functionality and prefer a more powerful editor vim is a popular choice Although challenging to learn at first you may find it to be a more rewarding and flexible choice as a tool Learn how to use it at http www openvim com tutorial html Connectivity We will show you the two principal recipes to get your BeagleBone Black connected e Ethernet e Wi Fi Beware that there is a third way to get the BBB online which is by tethering your board to your desktop machine and piggybacking on its network connection This is a highly useful but occasionally tricky option Connectivity Ethernet If you have direct access to your network s router using the Ethernet connection is pretty much Plug and Play on the BBB Getting ready Here s what you need for this recipe e 5V DC power supply e An Ethernet cable e A BBB connected to an HDMI monitor For ease of use
282. putfile1 and inputfile2 with the files and or directories that you want to combine You can use any name in the place of file tar you should keep the tar extension though There s more You may occasionally run into errors while opening tarballs or other gzip files If so one troubleshooting tip is to ensure that the file is actually a zipped archive with the following command file filename This will show the file type and size if it s not an archive you can t run the tar command on it Modify content data commands clean up files autoclean This command removes partial packages from the system How to do it Use the following command to clean up files sudo apt get autoclean Modify content data commands purge a package apt get purge apt get remove purge These commands completely get rid of packages and dependencies How to do it Use the following command to get rid of packages and dependencies sudo apt get purge packagename Alternatively you can use the following command sudo apt get remove purge packagename Modify content data commands shutdown the system options It is a bad idea to pull the plug on your board to turn it off Doing so can often lead to a corrupted SD card or mangled files Instead here s how you power down your board gracefully How to do it If you want to shut down the BBB and reboot it the following command will be us
283. quencies for example from 50 to 2500 MHz without actually requiring specialized hardware Using various software modules SDR also performs different radio protocols The result is that this software in conjunction with an RTL dongle now replaces what used to be a wide variety of specialized radio components For radio enthusiasts including old school ham radio operators and hackers alike the flexibility of SDR is compelling you can now transmit and monitor anything across a vast radio spectrum from cordless phones to Bluetooth devices microwave ovens car alarms video devices ZigBee airplanes and even satellites The RTL SDR dongle See also SDR is a large topic and we will only explore a handful of recipes using it You can learn more about its applications at the principal source for all things related to RTL SDR at http www rtl sdr com about rtl sdr Because of its many uses certain applications of SDR and similar radio scanners may be illegal in some countries Before proceeding with any of the following recipes ensure that you will not encounter any restrictions on usage at https en wikipedia org wiki Scanner _ 28radio 29 Legislation Airplane tracking with RTL SDR Before diving into some of the more challenging and arcane upper atmosphere options to use RTL SDR we will do a recipe that s a little easier and more down to Earth namely tracking planes This recipe is derived from a variety of
284. quite a different animal from nearly all the other recipes in this book It doesn t help that current documentation though extensive is scattered sometimes useful but more often poorly written The good news though is that Beagleboard org and the open source community have made considerable progress in simplifying the tasks ahead of us Note Although you could cross compile the following recipes on another client machine we will develop them natively on the BBB Now let s prep and enable the PRUs Earlier methods of interacting with the PRUs were a truckload of hurt The process required many steps including creating and compiling a device tree just to run a sample application However cooking with PRUs has been simplified considerably with the recipe below And happily you can use everything for both Debian Wheezy and Jessie versions Getting ready The usual minimal setup is all you need a BBB powered over mini USB with Internet connectivity enabled How to do it 1 Log in as the root user sudo i 2 Install driver Library and PRU toolset apt get install am335x pru package amp amp ti pru cgt installer Note The installation includes a number of items required to operate the PRUs from user space o PASM assembler Being rather unique in nature the PRUs don t speak BoneScript or JavaScript or Python or C Instead they communicate using Assembly and require the PASM assembler to compile and ru
285. r Anything from 700 7008 to 1k is fine We will use a 700 version here violet black brown gold bands e 2x jumper wires These are easy to connect to the breadboard e Breadboard How to do it Now let s begin with the following steps 1 From our fritzing tool here s the diagram we made for our wiring BeagleBone nn 2 2 2 2 1 42 1 1001000000000U0 00 0 010000 E E E a O o a a a a a a a E a a ee eee eneneeeeeeeee e E 2 2 2 8 a a ra E a a a a a a a a E a a a a a oe LEE SE 2 5 E 5 a E a ee eee eee sekee e ee eene khie ee e ee ee ee e oe LOREODODOO11U0 600600000000000000000000000 2 Now wire up your breadboard using the following steps 1 First put the Ground wire into GND P8_2 on the BBB 2 Then insert the other wire to the P8_15 pin on the BBB 3 On the breadboard put the LED s shorter end the cathode pin into the GND rail and the longer end the anode pin into the sixth slot of the breadboard 4 Now insert your resistor and make sure that the top end is aligned in the slot with the GPIO wire and the bottom end is aligned with the LED s anode 3 Open up Cloud9 IDE at http 192 168 7 2 3000 and create a new file called blink_LED js 4 Then copy and paste the following code into the open IDE window Setup var b require bonescript Call library var LED P8_15 Pin choice var state 0 LED state b pinMode LED out
286. r BBB is powered down and then insert the card into the microSD slot on the BBB 5 Press and hold the Boot switch which is the small button on the BBB above the microSD card slot Take a look at the the following image to confirm that you are pressing the Boot switch and not one of the other switches 10 11 While holding this button down insert the 5V supply into the power jack As the board boots up the array of LEDs next to the Ethernet jack at the other end of the board will begin flashing in a sweeping pattern When the boot completes all four LEDs should be lit and not blinking Remove the power cable and then remove the microSD card from the BBB Now plug the 5V supply back into the board again The BBB will boot directly from the eMMC In your terminal window we will now SSH into the board with the following command ssh debian 192 168 7 2 When the login prompts appear use the following credentials username Debian password temppwd You should now be ready for action with the default graphical desktop showing the BeagleBone Black logo in the lower right corner of the screen This means that you are almost ready to go There s more Good practice to manage your system OS and files includes having enough room to add more packages being able to clone your eMMC and backing up your code image Expand your partition Unless you use an SD card larger than 8 GB you re likely to run
287. r end of the audio cable In our case we used an old iPod that we had in a drawer If you refer closely to the following image it shows how all the parts should fit together before you have hooked it up to your BBB 7 Choose an audio track on your player and press Play Now that we know we have solid audio output with all hardware soldered snipped breadboarded and wired properly we will run an audio test using Python 8 Now we want to wire the amp up to our BeagleBone Black following the Fritzing diagram Although it looks like a thicket of mini jumper wires the scheme is really simple In fact you will notice that on the BBB s GPIO pins there are only two pins in use other than power and ground In case there is any uncertainty from the diagram here is a table clarifying how to wire it up o MA L on 3 5mm headphone jack R on 3 5mm headphone jack 10 11 12 13 14 Audio e o ER O to R w F on 3 smm Let s get programming To start open up the BoneScript IDE and create a new py file called audio amp test1 py Download the Python script from our Github repo with following command git clone https github com HudsonWerks audio amplifier git Browser to the audio amplifier directory created and open up the python script in a nano window cd audio amplifier sudo nano audio amp test1 py Now copy and paste the code into the Cloud9 IDE wind
288. ragment So let us set up our environment to load the fragment on boot nano etc default capemgr In the open edit window you should see the following Default settings for capemgr This file is sourced by bin sh from etc init d capemgr sh Options to pass to capemgr CAPE Append it to the following Default settings for capemgr This file is sourced by bin sh from etc init d capemgr sh Options to pass to capemgr CAPE BB BONE PRU 01 Reboot your BBB log in as root user and check that the fragment loaded ff P O L Bone LT eMMC 2G 00A0 Texas Instrument BB BONE EMMC 2G Ff P O L Bone Black HDMI 00A0 Texas Instrument BB BONELT HDMI ff P O L Override Board Name 00A0 Override Manuf BB UART4 8 ff P O L Override Board Name 00A0 Override Manuf BB BONE PRU 01 cat sys devices bone_capemgr 9 slots 0 54 PF 1 55 PF 2 56 PF 3 57 PF 4 5 7 All right now we can move on to an actual test of the PRU A simple PRU test with an assembler Although there are many complex and far more sophisticated tests for the PRUs our intention is to create a very minimal test recipe that you can observe from user space To do this we will use a C program that runs directly on our BBB s ARM processor From Linux user space it will give a big hug to the PRU upload an assembler code binary run it then pass and fetch information between the ARM and the PRU The basic steps a
289. rated material We appreciate your help in protecting our authors and our ability to bring you valuable content Questions If you have a problem with any aspect of this book you can contact us at lt questions packtpub com gt and we will do our best to address the problem Chapter 1 Setting Up for the First Time In this chapter we will focus on the following topics First boot up Power requirements basic guidelines Display Essential GNU Linux commands the command shell Essential GNU Linux commands typical commands Edit a text file from the command shell Connectivity Package management Installing packages using apt get SSH Remote access System images Introduction Getting off to a running start with your BeagleBone Black requires diving into a number of fundamental recipes first After all you have to learn to chop and dice before making a proper soup As you probably already know creating the right development environment saves time reduces errors and creates a good workflow To this end after we get our display hardware hooked up it s critical to learn a bit about the Linux commands that power our projects Then we will move on to getting your board both connected online and controlled remotely over a network Next we will learn the basics of installing and managing applications packages Finally we will explore how to get an OS onto your board whether it s with the internal solid state
290. rd and the PWR button should be securely squeezed in place 6 Power up your board Most distributions including the Debian firmware of course have compatible drivers for the display so you should boot right into your desktop within a few moments There s more For more information on the following topics refer to the respective websites e HDMI Troubleshooting http elinux org Beagleboard BeagleBoneBlack HDMI e Other LCD cape options http elinux org Beagleboard BeagleBone_Capesux driver Essential GNU Linux commands the command shell Fancy GUIs are nice but on BeagleBone Black you will be mainly working with the command shell and its accompanying command line tools to provide access to the operating system First let s take a look at some terminology command shell command line shell command line or simply shell will all be used somewhat interchangeably as they all basically refer to the same thing a means to provide access to the operating system with the command line and without a GUI Bash is the default shell on Linux Terminal is yet another typical way to refer to the shell The term is derived from its preceding technologies where any interaction with a computer required using a text based terminal interface Often intimidating to new users command shell is the starting point for any serious embedded system project The Debian distribution for BeagleBone Black comes preloaded with two command line too
291. re 1 Create a program in assembly language for the dedicated hardware the PRU Note The PRU only speaks assembly 2 Create a program in C for the main CPU BBB s ARM Note This program reaches over and handshakes the assembler code on the other PRU 3 Run a PRU test with the combined compiled magic of the first two steps Getting ready The usual minimal setup is all you need a BBB powered over mini USB with Internet connectivity You will also need to have executed the preceding recipe on prepping and enabling the PRUs Note Be sure that you are properly connected online so that the BBB time clock accurately reflects the current time Otherwise you may run into errors in compiling the binary file How to do it 1 We begin by logging in as root and cloning a repository on Github containing the files sudo i git clone https github com HudsonWerks bbb pru git Note The example files in the repo are based on code from developer Douglas G Henke http mythopoeic org bbb pru minimal 2 Browse to the sample files directory cd bbb pru simple tests Note You should see three files major tom pru c major tom pru p Makefile and a README 3 The Makefile will run the PRU assembler application and generate a binary from the combination of the p file and the c make The output should look as follows pasm b major tom pru p PRU Assembler Version 0 86 Copyright C 2005 2013 by Texas Instruments
292. reliable connections and power fluctuations We were successful in powering some USB dongles directly via the BBB s USB port whereas some devices such as USB webcams were not reliably powered e If you connect USB devices it is best to power them from a powered USB hub and then supply power to the BBB via a 5 VDC power supply of at least 1A e 5V DC power most users of the board will invariably recommend that you always power your board using a 5V DC supply e You can also use a 5V wall charger power adapter with a USB port on it as long as it can deliver 1A Tip Downloading the example code You can download the example code files from your account at http www packtpub com for all the Packt Publishing books you have purchased If you purchased this book elsewhere you can visit http www packtpub com support and register to have the files e mailed directly to you In many cases you will also be downloading code from the author s github site at https github com HudsonWerks Display The BBB s on board micro HDMI port provides a relatively easy way to attach a display device With the new Debian distribution compatibility and ease of installation the process is greatly simplified We will take a look at two types of devices you may be using an HDMI monitor and a small form factor LCD without HDMI Note Using a display is not a requirement to operate the board and is merely optional You will learn how to control t
293. ronment not desktop centric as RPi is As such an add on similar to this mini display cape addresses the needs of typical use cases for an embedded device These are situations that commonly require extremely low power and minimal display if any e The need for fast prototyping durability and testing drive the design of a cape such as this results in an overall form factor much larger than the screen itself Looking more closely at the cape we discover a number of exciting things o Open source design The cape design and its components are all open sourced with the core element the display itself referenced and clearly sourced so that you can make your own mods once you ve got your prototype device ready to fly or amble Here are the design files and schematic http elinux org CircuitCo MiniDisplay_ Cape and the component vendor s URL for the display https www crystalfontz com product CFAF128128B0145T o Low cost At the preceding referenced source you will see that in a high quantity purchase of the display not the finished cape the price dramatically drops per unit So you can model a low cost scenario for multiple final production units of your device without incurring the finishing and design costs of a third party supplier such as CircuitCo Getting ready In this recipe we will cook a bit more professionally so that our environment looks more like a true embedded device Thus our kit is minimal e A mini
294. rver_7 4 1 dfsg 0 1_armhf deb When finished log out by exiting the SSH session as shown in the following code root arm exit Part III Installing and setting up the toolchain This part and the next one are the hairiest bits of the process many online tutorials on this subject purport to deliver a working toolchain lashed to an IDE though few of them actually deliver Fortunately for us engineer and blogger Aaron Clarke s very clear steps at http bit ly 1x7TGUY provide superb guidelines for a successful toolchain and the Eclipse IDE setup The vast majority of the credit for the next two parts of the recipe go to Mr Clarke Note We chose not to include screenshots of the process because doing so would have made the recipe considerably longer However you can find a more graphical version of this recipe online at Aaron Clarke s blog which includes a version for Debian Jessie at http blog embeddedcoding com 2015 05 beaglebone black development part 6 html Here we go Perform the following steps 1 At the terminal prompt on your Debian VM if you are not already logged in as root do so now with the following command sudo i 2 Create a new directory where you will download the toolchain and then navigate to that directory as shown in the following code root debian home user mkdir bbb tools root debian home user cd bbb tools 3 Using wget download the toolchain from the following link to the direc
295. rw rw T 1 root spi 153 Mar 1 20 46 dev spidev1 1 Next we need to install a number of Python libraries and their dependencies Some of them may already be available on your system but run the following commands just to be certain apt get update apt get install build essential python dev python pip python imaging python smbus python dateutil pip install spidev pip install pil pip install Adafruit_BBIO Note You could run all the pip install commands off one line however for clarity s sake we will show each individual package install Next we want to actually do something with the display and all these libraries So download a GitHub repo with sample code git clone https github com HudsonWerks OLED SSD1306 git Browse to a subdirectory of example in the directory of code we just downloaded and take a look at what is inside 10 11 12 13 OLED SSD1306 samples ls Before looking at what is inside the code let s run the main example to see if all of the hardware wiring is correct python oled test1 py If all went well you will see text cycling on the screen with messages from ground control We want to take a brief look at the Python code so we will now run the following command nano oled test1 py Finally open up the Cloud9 IDE http 192 168 7 2 3000 ide html create a new py file called oled test1 py and then copy and paste the code from your nano win
296. ry debian beaglebone ls Desktop At the moment the only thing you will see is the Desktop directory As we continue adding content in subsequent chapters there will be more that would be seen upon using 1s Adding the lah option at the end of the command gives more detailed information on the files as follows debian beaglebone 1s lah total 112K drwxr xr x debian debian 4 0K Mar drwxr xr x 24 debian debian 4 0K Mar drwx 3 debian debian 4 0K Mar 2015 fontconfig 2015 gimp 2 8 2015 local drwxr xr x 19 debian debian 4 0K May 4 23 37 drwxr xr x 3 root root 4 0K May 5 00 05 FW 1 debian debian 55 May 4 23 37 Xauthority FW 1 debian debian 2 4K May 5 01 41 bash_history rw r r 1 debian debian 220 Jan 1 2015 bash_logout rw r r 1 debian debian 3 4K Jan 1 2015 bashrc drwxr xr x 6 debian debian 4 0K Mar 8 2015 cache drwxr xr x 9 debian debian 4 0K Mar 4 23 51 config drwx 3 debian debian 4 0K Mar 4 23 37 dbus rw r r 1 debian debian 35 Mar 4 23 37 dmrc 2 8 8 8 The options in the command now reveal a variety of things about the file their permission status column 1 owner and group columns 3 and 4 file sizes column 5 and modification date column 6 The 1 option outputs in the list form adding the a forces the command to show any hidden files and the h option turns it all into a human readable format Device and system insight find out what USB devices are c
297. ry using ls Desktop bin jdk 8u6 linux arm vfp hflt tar gz jdk1 8 0_XX packages Next we set up PATH and JAVA_HOME so that the compiled Linphone binary will know where to find the working directory for Java We will do this by adding PATH information to the bashrc file sudo nano bashrc In the open nano window and at the end of the file paste the following export PATH home debian jdk1 8 0_07 bin SPATH export JAVA_HOME home debian jdk1 8 0_07 Note Reminder Here debian is the username and may be different in your case based on any earlier changes you may have made the JDK version shown here should be replaced with the version that you downloaded and unarchived earlier 10 11 12 13 14 15 You should then save and close the file by pressing Ctrl X when prompted type Y for yes and then press the return key Enter Following this reboot your BBB In the terminal confirm that the version of the SDK you just installed is now being referenced properly through the following command java version Cross your fingers and you will see an output similar to this Java version x y z_00 Java TM SE Runtime Environment build x y z_00 xyx Java HotSpot TM Client VM build 00 0 xyz mixed mode If so hurray We can move on If not you need to repeat the preceding steps to install the JDK Next we need to install the belle sip and linphone dependencies as follows sudo apti
298. s Index A Adafruit I O o URL See also airplane tracking o RTL SDR used Airplane tracking with RTL SDR How to do it alternative script o writing Python used Writing an alternative script with Python AMSAT o URL There s more Antenna o URL Getting ready antenna o URL Getting ready application o debugging remotely from Eclipse Debug an application remotely from Eclipse and GDB server o debugging remotely from GDB server Debug an application remotely from Eclipse and GDB server apt get o used for installing packages Package management Installing packages using apt get See also autotools arcana o URL See also autotools toolset o URL See also BBB o URL See also Beacon o URL There s more Beacons Location based recipes Bluetooth LE and Beacons o smartphone setting up How to do it o simple IoT test environment setting up How to do it o BBB setting up How to do it BeagleBone Black o audio bringing on Introduction Beaglebone Black BBB o about First boot up How to do it boot up First boot up How to do it How to do it prerequisites Getting ready power requisites Power requirements basic guidelines display Display controlling SSH used Using SSH to control your BBB How to do it controlling Virtual Network Computing VNC used Using VNC to control your BBB How to do it There s more BeagleBone Black Sys
299. s HDMI Audio disabled cape_disable capemgr disable_partno BB BONELT HDMI cape_enable capemgr enable_partno BB BONE AUDI 02 Once opened we want to uncomment remove from the section labeled Disable HDMI and the following command comes in handy optargs capemgr disable_partno BB BONELT HDMI Note Take note of two things while modifying the uEnv txt file for this step o You only need to disable BB BONELT HDMI BB BONELT HDMI as it will not conflict with the audio cape o You may however run into a different overlay conflict if you ran other recipes or DT experiments If so be sure to also comment out any new lines you might have added for other recipes as these may prevent the AUDI 02 overlay from loading Finally you need to close and save the uEnv txt file Now run the export command export SLOTS sys devices bone_capemgr slots After this go to the following directory cd sys devices bone_capemgr Then run the echo command echo BB BONE AUDI 02 gt slots This command takes the output of echo BB BONE AUDI 02 and writes it in the slots file which in turn enables the drivers and device for AUDI 02 using the Device Tree overlay Now reboot the BBB as follows reboot Confirm that the DT overlay loaded properly by going to the designated directory and running the following command cd sys devices bone_capemgr 9 cat slots 0 54 PF 1 55 PF 2 56 PF 3 57 PF
300. s an input however in our case we had an LED which needed to be in the output mode Note also b which is used in the notation This was used to tell the code interpreter Node js that the subsequent function will be found in the BoneScript library For this we used the following code b pinMode ledPin b OUTPUT With the pin initialized we declared whether the pin began in a state of being on HIGH or off Low At this point we also needed to tell the interpreter that we would actually be writing to the pin as opposed to collecting data from it or reading it with the following script var state b LOW b digitalwrite ledPin state Our task moved on to telling the interpreter how often we will be doing a particular thing In our case we toggled the light on and off in 1000 millisecond intervals by executing the following script setInterval toggle 1000 It was great that we knew the frequency of our toggle event but as we did not yet tell the interpreter what the toggle term actually does we had to explain its meaning We described it as a function that alternates between the states of HIGH and LOW which was applied to the pin that we declared at the beginning of our script with the following lines of code function toggle if state b LOW state b HIGH else state b LOW b digitalwrite ledPin state Okay For the moment that s enough of a script breakdown If you have not already jumped
301. s artificial neural networks automated programming software improvement and optimization for power consumption In his free time Nathan enjoys tinkering with embedded systems and electronics ranging from full systems such as Raspberry Pi and BeagleBone Black to simple microcontrollers such as Arduino adding circuitry to communicate using 433MHz RF and infrared He blogs about his projects and topics such as website development Android and dancing at http www nburles co uk Anuj Deshpande is a fan of BeagleBone Black and all things embedded He dabbles in embedded Linux and loves to prototype ideas and build interactive installations Some of the projects that Anuj has been a part of are Userspace Arduino and Tah He completed his bachelor s degree in computer science from PICT Pune Anuj currently runs his own development and consulting firm called Makerville Solutions http makerville io Deepak Karki is a software developer and open source Evangelist based in Bangalore India He enjoys working with like minded hackers and is often a participant in hackathons in and around the city During the day Deepak works on challenging hyperconvergence problems with Nutanix and in the night he keeps busy pushing code onto GitHub He was a Google Summer of Code GSoC student for beagleboard org in 2014 and consequently a mentor for the same organization during GSoC 2015 Deepak s main areas of interest include SaaS applicat
302. s do a quick and easy recipe with BoneScript one that turns on and off the on board LEDs also known as USR LEDs We will tackle more complex recipes with BoneScript in the next chapter How to do it In order to do this perform the following steps 1 2 3 vonoau Remove all cables and power from your BBB Power up your board via the mini USB using your desktop USB port On the BEAGLEBONE_BLACK device that appears on your desktop browse to and open the START htm file some versions of the OS may have a slightly different file name such as BASIC_START htm Note Note that on Debian 8 Jessie your board will be labelled BEAGLEBONE on the desktop and not BEAGLEBONE_BLACK Scroll down the page to BoneScript interactive guide where you ll see an embedded script that you can run to interact with BBB Click on Run Allthe LEDs should stay on for two seconds Let them return to blinking Now change USRO from b HIGH to b LOW Change the timing from 2000 to 12000 You should now see two differences from the default script that you just ran Firstly the LEDs now stay on for longer 12 seconds and the USRO LED the LED closest to the Reset button now remains off Voila You re talking to the hardware using JavaScript and BoneScript See also If you run into any errors while running your BoneScript recipes such as Cannot find module bonescript you may need to do two things 1 Check t
303. s on an alternative user interface However a good exercise would be to combine the two pieces of code into one so that you can exploit both TTS and a graphical rendering of the ISS location in the same script The code is heavily commented and pared down to only output the current distance from the latitude and longitude coordinates you set and stop once the task is completed In fact before moving on you must input your home latitude and longitude coordinates in the designated code blocks in order for the script to run home_lat HOME_LATITUDE home_long HOME_LONGITUDE 3 After inputting your coordinates save the modified code then run it sudo python ISS current_distance py You should see a multidecimal number showing the current kilometer distance from your coordinates your number will vary naturally 3631 37279398 The output is a little underwhelming isn t it However this is by design it does not keep updating the number as we run the script according to specified intervals and we want the TTS engine to capture a snapshot in real time of the ISS s location relative to where you are Part IV Creating a bash script To create a more interesting experience we will have a bash script run the Python code stamp the time and tell us all about it via the TT S engine 1 Open up a nano editor window and create a new file as follows sudo nano timeTTS ISS sh 2 Copy and paste the following bash code in the open wi
304. s on various machine learning techniques and computer graphics Agrima is a voracious reader and a trained Indian Classical dancer who enjoys participating in public speaking events A complete list of her work is available at http agrimaseth github io and the latest happenings can be read at https agrimaseth wordpress com I would like to thank my parents and my HoD Dr Sangeeta Jadhav for constantly encouraging me to pursue my dreams and work towards achieving excellence www PacktPub com Support files eBooks discount offers and more For support files and downloads related to your book please visit www PacktPub com Did you know that Packt offers eBook versions of every book published with PDF and ePub files available You can upgrade to the eBook version at www PacktPub com and as a print book customer you are entitled to a discount on the eBook copy Get in touch with us at lt service packtpub com gt for more details At www PacktPub com you can also read a collection of free technical articles sign up for a range of free newsletters and receive exclusive discounts and offers on Packt books and eBooks A PACKTLi2 https www2 packtpub com books subscription packtlib Do you need instant solutions to your IT questions PacktLib is Packt s online digital book library Here you can search access and read Packt s entire library of books Why Subscribe e Fully searchable across every book published by
305. sage There are 45 slides providing a deeper discussion on Device Tree at http free electrons com pub conferences 2013 elce petazzoni device tree dummies petazzoni device tree dummies pdf Take advantage of this great find of a site that helps you easily generate device tree overlays which provide easy pin muxing http kilobaser com blog 2014 07 28 beaglebone black devicetreeoverlay generator Linus Torvalds original rant about the ARM device mess that led to the emergence of Device Tree is at the following site It doesn t get more geeky than this http article gmane org gmane linux ports arm omap 55060 Universal cape overlay Developer Charles Steinkuehler developed an enormously useful addition to the BeagleBone Black and DT world with his universal cape overlay Now included by default on the current 3 7 and 3 8 kernels the code greatly simplifies pin and cape management via simple command line calls The toolset can in some cases obviate the need to use many types of sysfs calls some of which you learned earlier in the chapter Getting ready A BBB hooked up and powered via USB How to do it Perform the following steps 1 Begin by logging in as the root user and then loading the cape overlay using the following commands sudo i echo cape universaln gt sys devices bone_capemgr slots This command loads all devices and exports gpio The pins currently default to gpio inputs However with the nex
306. sed a Gmail account as the server and user credentials although you can use any service you prefer Just replace the Gmail details with your preferred provider 00 nu Navigate to the systemd directory with the following code cd lib systemd system Now create a new service file as follows nano email ip service Copy and paste the following code to the nano window Let s take a look at the systemd code in its entirety first Then we ll break down its meaning as follows Unit Description Email current IP Address Service WorkingDirectory home debian ExecStart usr bin python email ip bbb py SyslogIdentifier emailip Restart on failure RestartSec 5 Install WantedBy multi user target What does this all mean First let s begin with inputting a human readable name for the systemd service which describes the properties of the process you d like to run as shown in the following code Unit Description Email current IP Address Next we will describe where the file is that will be run on bootup with the following code Service WorkingDirectory home debian Then we will tell the service about the command or script to be executed for the file ExecStart usr bin python email ip py Now the system logs should capture the run data so we have to give the service a unique name for that purpose as follows SyslogIdentifier emailip We have to prepare for the application exiting
307. sensor git 2 Browse to the directory with the Python script and run it cd light_sensor sudo python light_sensor py Your output should be very similar to what you saw in the BoneScript example Using motors Whether it s a robot an RC toy a CNC a 3D printer or a high end industrial machine motion control is one of the most popular subjects in physical computing In our examples we 1l be using BoneScript to run our devices beginning with a DC motor and then following with a servomotor However first you should learn a little about the type of pins that we will use in the following recipes DC motors They re fun They re cheap They re everywhere The little motors that have been driving toys for decades still remain a mainstay for projects where locomotion is part of the picture Understanding how to drive a DC motor requires more complex and powerful mechanisms such as robotics Getting ready You will need several items for this recipe e DC motor This is a standard issue 2 lead motor prevalent in toys and cheaper RC devices e H Bridge IC motor driver This Texas instrument component SN 754410 is available at Sparkfun https www sparkfun com products 315 and other similar sources for approximately 2 50 USD It is also commonly used in the L293D version This little circuit is an important piece of the puzzle because it is the mechanism used to send the voltage that drives the motor s direction and re
308. sorted by their boot times systemd analyze blame From this output you can immediately pinpoint some of the culprits We will assume that you re running the current Debian distro so you ll see things similar to the following command wicd service 7205ms apache2 service 3430ms wpa_supplicant service 1938ms Some of these may be expendable startup services and worth disabling Experiment by disabling the different services and see how it affects your boot times Here is an example systemd systemctl disable wicd service Create a systemd service to run at boot time Remember those ancient days of Chapter 2 Basic Programming Recipes when you were just learning how to send an e mail with Node js No You skipped that recipe Well you may want to do that one before you dive into this one In this recipe we ll perform something similar and have the script run at boot up Instead of having Node js perform the job it ll be Python and systemd The scenario is that you need to control your BBB remotely via SSH or VNC but the board is offsite or running headless As you have learned previously in order to control the BBB remotely we have to know the board s IP address If you re in front of the board it s easy enough to check the IP at the bottom of your screen via the GUI popup However our board is 100 miles away and isn t attached to a display Systemd with a healthy dash of Python comes to the rescue Let s t
309. stalling Installing the latest kernel image How to do it L e LCD cape options o URL There s more e LEDs o controlling Python script running for How to do it There s more o references There s more e Linphone o used for creating video chat client prototype Making a video chat client prototype using Linphone Part I compiling and installing a Linphone binary from the repository o binary compiling from repository Part 1 compiling and installing a Linphone binary from the repository o binary installing from repository Part I compiling and installing a Linphone binary from the repository o compiling from source Part II compiling and installing Linphone from source How to do it o installing from source Part II compiling and installing Linphone from source How to do it e Linux o URL See also e location based recipes o about Location based recipes hooking up GPS o GPS hooking up Location based recipes hooking up GPS o Bluetooth LE Location based recipes Bluetooth LE and Beacons o beacons Location based recipes Bluetooth LE and Beacons e low Earth orbit LEO o about Satellite tracking using GPredict and RTL SDR Satellite tracking using GPredict and RTL SDR e LXQt OS image flashing internal drive boot MAA file support o URL See also Make use of o URL See also micro USB dongle models Getting ready Mini Amp o wiring
310. t 2947 of your BBB and efficiently parses the NMEA text that pours out of the GPS receiver as shown in the following command sudo apt get install gpsd gpsd clients python gps For the preceding code gpsd clients installs some test clients and python gps installs the required Python library to communicate with gpsd via Python scripts Note After the installation you may find it useful to run man gpsd and review the package s well written and informative manual It not only provides the details around what you just installed but it also provides the general GPS related content If the planets or communication satellites are aligned you can run this command from the newly installed toolset and begin to display the GPS data sudo gpsmon dev tty04 You should see a terminal GUI that looks similar to the following screenshot me a a mmm m Y 800 GS charleshamilton debian beaglebone ssh 80x24 dev tty04 9600 8N1 Generic NMEA gt Time 2014 12 02T17 19 04 000Z Lat 40 43 47 796 N Lon 74 00 17 160 W Cooked PVT GPVTG GPGGA GPGSA GPRMC GPGSV Sentences 171904 000 Time 171904 000 4043 7966 N Latitude 4043 7966 Longitude 07400 2860 W Longitude 07400 2860 Speed Altitude 52 8 Course Quality Sats 4 Status DOP H 2 45 V 0 95 P 2 63 GSA 39 GPVTG 181 94 T M 1 49 N 2 77 K A 36 x0d x0a a To quit press Ctrl C or enter q and then return Enter key Now we will test
311. t set of commands we can easily change their state 2 Let s consider the example of the P8_12 pin and run a command to find out its state config pin q P8 12 P8_12 Mode gpio Direction out Value 0 You will recall from earlier recipes that the O value means that the pin is set at low or off 3 Then we can easily change its state with the following commands config pin P8 12 hi config pin q P8 12 P8 12 Mode gpio Direction out Value 1 Now the value will change from 0 low to 1 high Indeed this is a much snappier method to manipulate pins than the sysfs approach we discussed earlier 4 The toolset has additional functionality and options that you can further explore with the following command config pin h There s more e The developer s site https github com cdsteinkuehler beaglebone universal io has extended examples and usage for the overlay Rumning a script to check D T usage on GPIO pins When modifying or working with Device Tree files we frequently need to check pin usage so that we do not inadvertently try to write to claimed or unsuitable pins The following recipe employs two scripts that you can run with Node js and helps us locate which pins are free The scripts exist thanks to the coding work of Professor Mark Yoder at Rose Hulman Institute of Technology Getting ready You do not need anything more than your basic BBB kit for this recipe which is a board connected to your h
312. t the year Here are two excellent Python courses offered o University of MICHIGAN offers Python in their Programming for Everybody series You can find it at https www coursera org specializations python o Rice Unversity s 8 week course is another excellent introductory dive to be found at https class coursera org interactivepython1 003 e Python org is an excellent place to get started with its tons of links on the beginners page at the link https wiki python org moin BeginnersGuide Programmers Chapter 3 Physical Computing Recipes Using JavaScript the BoneScript Library and Python Now that you re armed to the er fingertips with your Linux commands and can happily control your BeagleBone Black remotely like a pro it s time to get physical with the board So to begin with our exercises in physical computing we re whipping up some essential recipes on the following topics Controlling external LEDs Using buttons button press function Using analog sensors Variable resistance sensor photocell Using motors Our programming language of choice will principally be JavaScript in tandem with BoneScript which is a Node js and browser side library We will also include or reference a few Python script analogues to broaden our skills with the hardware Introduction The basics of physical computing typically require understanding and shaping input and output on your hardware We will begin with taking a
313. tance expressed in ohms and commonly seen as Q As long as we know any two of the three variables we will use Ohm s law to calculate the third and remaining number Typically you will need to use Ohm s law to determine the right resistor to use when you wire up a circuit There are numerous and exhaustive free examples available online that show you how to use Ohm s law for your projects Here are a few excellent ones e Sparkfun s tutorial on Voltage Current Resistance and Ohm s Law is one of the best for beginners and is available at https learn sparkfun com tutorials voltage current resistance and ohms law e Collin Cunningham formerly of Make magazine and now an Adafruiter gives us the video version skinny at https www youtube com watch v mHLvtGjum4 e A very handy online Ohm s law calculator tool is available at http www onlineconversion com ohms_law htm Note If you take nothing else from this section at least heed this one warning be very careful how you power your BeagleBone Black otherwise you may damage it Header pins and pinmuxing The magical thing about microcomputers is that they give you the ability to interact with the physical world This interaction is essentially possible via the GPIOs and other pins These pins are intended to generate different voltage levels and pulses This is the essential purpose of programming a GPIO you will tell the board to generate a specific level of voltage or
314. tandard tool in the Linux arsenal thus sudo apt get update sudo apt get upgrade sudo apt get install gdb Once you ve installed the pretty package on your BBB it s useful and often interesting to take a peek inside So another apt get variant gives you some interesting insight sudo apt cache show package name In our case this would be as follows sudo apt cache show gdb Package gdb Version 7 4 1 dfsg 0 1 Installed Size 5192 Maintainer Hector Oron lt zumbi debian org gt Architecture armhf Depends libc6 gt 2 13 28 libexpat1 gt 2 0 1 libgcc1 gt 1 4 4 0 libncurses5 gt 5 5 5 libpython2 7 gt 2 7 libreadline6 gt 6 0 libtinfo5 zlibig gt 1 1 2 0 gdbserver Suggests gdb doc Description en The GNU Debugger GDB is a source level debugger capable of breaking programs at any specific line displaying variable values and determining where errors occurred Currently gdb supports C C D Objective C Fortran Java OpenCL C Pascal assembly Modula 2 and Ada A must have for any serious programmer Homepage http www gnu org s gdb Description md5 8132571fab028a898d029eecd88e571e See also To list all installed packages enter dpkg list Alternatively you can use this command dpkg list less You can also run the following command dpkg list grep i http Note the grep option as part of the command string One of the most popular commands on Lin
315. tem Reference Manual o URL Header pins and pinmuxing BeagleSat o URL There s more Bluetooth Classic o versus BTLE discussion URL There s more o installation troubleshooting URL There s more bluetooth dongles o URL Getting ready Bluetooth Low Energy BLE o about Location based recipes Bluetooth LE and Beacons o classic Bluetooth Location based recipes Bluetooth LE and Beacons o key elements Location based recipes Bluetooth LE and Beacons BoneScript o about Introduction to BoneScript o URL See also BoneScript Library o URL Introduction boot time o optimizing Optimize boot time BTLE documentation o URL There s more Bubble app O O O 0 90 0 o URL There s more e button press o about Pull up pull down and floating How to do it e buttons o using Using buttons button press function C code application o debugging from command line GDB used Debug a simple C code application from the command line using GDB How to do it See also capes o about Connecting anon HDMI LCD or cape Cloud9 IDE o using Using the Cloud9 IDE How to do it command line interface CLI Getting ready o pointers Getting ready command memento o URL See also commands o URL See also o for systemd services Basic commands for systemd services How to do it command shell o text file editing from Edit a text file from the command shell How to do it See also
316. tep in making sure that your devices are hooked up because it will show the raw NMEA data coming out of the GPS cat dev tty04 Note NMEA The National Marine Electronics Associations GPS language protocol standard 9 Verify that your wiring is correct and that the module is generating data properly irrespective of a satellite fix as follows sudo screen dev tty04 9600 The output should immediately begin and look something similar to this GPGGA 163356 000 4044 0318 N 07400 1854 W 1 5 2 65 4 0 M 34 2 M 67 GPGSA A 3 13 06 10 26 02 2 82 2 65 0 95 04 GPRMC 163356 000 A 4044 0318 N 07400 1854 W 2 05 68 70 031214 A 46 GPVTG 68 70 T M 2 05 N 3 81 K A 09 GPGGA 163357 000 4044 0322 N 07400 1853 W 1 5 2 65 3 7 M 34 2 M 68 GPGSA A 3 13 06 10 26 02 gt 10 Now quit the program using one of the the following methods Ctrl a enter or copy and paste quit with the colon to the highlighted box at the bottom or press Ctrl a k y Installing the GPS toolset 1 The next set of ingredients in the recipe consists of installing and testing a common toolset to parse GPS on Linux As always before installing something new it is good practice to update your repos with the following command sudo apt get update 2 Install the tools including gpsd a service daemon to monitor your GPS receiver The package exposes all the data on location course and velocity on the TCP por
317. ter 1 Setting Up for the First Time you learned the magical apt get install routine to get a package that you want on your BeagleBone Black However you ve already encountered situations where you wanted a package typically abbreviated as pkg and the repository came up with nada E Unable to locate package xyz This often implies that there is no precompiled binary for you to install which means that we now have to put on our big girl and big boy boots and compile from source files Building software from original source files is one of the prerequisites when you work with SOCs such as BeagleBone Black This is true in part because the BBB is a Linux environment Many software applications have to be compiled in order to use them However it s also a fact that you will often want a version of a tool that doesn t come with a packaged binary to suit your use case or the prototype that you ll build Native packages in our case the armh packages are almost always a better fit than prebuilt binaries if you have the time and fortitude to build them Therefore mastering creating and building from source files gives you tremendous power over how you customize and optimize the software that you use on the board Autotools aka the GNU build system is a toolset to build native packages The tool chain is familiar to Unix users for its holy triad of commands configure make and install Like almost anything related to Linux there is a un
318. text to speech TTS o about Adding other interfaces ISS tracking and text to speech How to do it There s more audio Setup and testing How to do it Python code used for tracking International Space Station How to do it bash script creating How to do it cron job setting up How to do it o URL There s more 0 0 O 0 ThingSpeak o sensors using with Using sensors and data with ThingSpeak How to do it See also o data using with Using sensors and data with ThingSpeak How to do it See also o URL How to do it Toggle LED o about Toggle LED See also two line element TLE files How to do it o URL There s more Ubidots o about See also o URL See also ultrasonic range sensor o running with PRUs Running an ultrasonic range sensor with the PRUs How to do it Universal asynchronous receiver transmitter UART Location based recipes hooking up GPS universal cape overlay o about Universal cape overlay How to do it Universal Unique Identified UUID Location based recipes Bluetooth LE and Beacons 5V power o URL Getting ready video chat client prototype o creating Linphone used Making a video chat client prototype using Linphone Part 1 compiling and installing a Linphone binary from the repository How to do it Virtual Network Computing VNC o used for controlling BBB Using VNC to control your BBB Ho
319. the Home directory using the following command debian beaglebone Desktop cd debian beaglebone 4 Go back to the previous directory you were in by typing in the following commands debian beaglebone cd home debian Desktop debian beaglebone Desktop There s more In addition to the preceding commands you should be familiar with the four special directory symbols The current directory The parent directory The root directory The home directory System navigational command show your current directory pwd This stands for print working directory a means to show the user where in the system they are currently working or the absolute path relative to the current directory How to do it Use the following command to show your current directory debian beaglebone pwd home Debian System navigational command find a file find Looking for a file One way to search for it is with the find function Just be sure to add the name option so that the output shows the directory location Add sudo as well so that you do not get directory access errors How to do it Use the following command to find a file sudo find name lt filename gt Device and system insight shows what s inside a directory Is The 1s command lists the contents of your current directory How to do it Use the following command to see the list of contents in the current directo
320. the International Space Station We will discuss how to use the very low cost but powerful and exciting Software Define Radio chip RTL SDR What you need for this book Describing every permutation and combination to set up BeagleBone Black is beyond the scope of this book Although every recipe starts by describing your hardware requirements we will suggest a baseline setup here that can be assumed for nearly all chapters There will be a number of recipes scattered throughout the book that require additional hardware such as sensors jumper wires resistors breadboards and so on Never fear The vast majority of these parts is very low cost and typically already a part of your physical computing and electronic kits There are a few examples however where you might need to spend a little more money on daughterboards called capes and some other peripherals such as powered USB hubs The hardware requirements are as follows e BeagleBone Black Revision C Typically referred to as Rev C the version of the board we will use is the most current one available on the market at the time of writing Earlier versions should work with the vast majority of the recipes in this book however we cannot guarantee their reliability in all cases e MicroSD card minimum 8 GB Even though the board has an internal solid state drive MMC to run the OS we often need to test recipes and different flavors of the kernel So being able to quickly swap
321. the code let s look at how the script breaks down First as always evoke the BoneScript library with the following code Setup var b require bonescript Read library o Now choose the pin number where your LED is wired You can change this option easily just be sure to choose from an available pin see the pin layout reference diagram at the end of this section for more background on the GPIOs var LED P8_11 Pin where LED is connected o Then we will set the pin number for the button as follows var BUTTON P9_15 o Now we will tell the previously specified pins to function in an OUTPUT mode for the LED and in an INPUT mode for the button as shown in the following code b pinMode LED b OUTPUT b pinMode BUTTON b INPUT You can also write it this way b pinMode LED out b pinMode BUTTON in o Now we need to check the status of the button at specific intervals in this case every 10 minutes as shown in the following code setInterval readBUTTON 10 o Then we need to define another function as shown in the following code this time one that triggers an event based on when the button is pressed function readBUTTON b digitalRead BUTTON writeLED o Finally we will define a function for the LED when the button is pressed with the following code function writeLED x b digitalWrite LED x value 4 Finally we run the script by clicking the Run button Your
322. the command line Run this command to stop the service systemctl stop systemd timedated service Now disable the service using the following code systemctl disable systemd timedated service Then do the opposite and enable it as follows Systemctl enable systemd timedated service Although your service may be enabled you need to actually start it so that the system has access to its routine as shown in the following code systemctl start systemd timedated service Finally check whether the service is running correctly with the following code systemctl status systemd timedated service There s more A handy list of systemd commands is available as a downloadable PDF or an online reference at http www cheatography com tme520 cheat sheets systemd Optimize boot time You can use systemd to speed up your startup time This recipe is not a definitive recommendation for which services may be expendable Instead it provides the overall method to test the impact of different services on your boot time How to do it Perform the following steps 1 Navigate to the systemd directory root user as follows cd 1ib systemd system Next determine how long your overall system is taking to get going with the following code systemd analyze You can quickly figure out the pokier services Just point the finger at them with the following command that reveals all the systemd services that are
323. the following credentials username debian password temppwd Updating your current OS kernel Sometimes you want to stick with what you have already installed as it runs fine and does the job But more often than not you want the latest and greatest kernel including updating to Debian 8 0 aka Debian Jessie The following steps show you how 1 Ensure that you are logged in as the root user with the following command sudo i root beaglebone Check the version of the kernel that you have currently installed uname r 3 8 13 bonexx Navigate to the directory with the update kernel script cd opt scripts tools Run a command on the kernel you currently have installed that pulls down to your local drive information regarding any changes git pull Note We will explore the git command in a later chapter Now we will run the script that takes advantage of the information we just pulled down and updates our OS update_kernel sh Time to reboot Run the following command reboot When the login prompts appear use the following credentials username debian password temppwd Finally verify that the script did what we expected through the following command uname r 3 8 13 bonexx Compare the preceding screen output with the version you wrote down in Step 2 of this recipe You should hopefully see the new version kernel goodness See also If you know a specific vers
324. this is that we can make use of another set of pins available on BeagleBone Black the Serial Peripheral Interface or SPI pins The BBB packs two SPI ports and we will use one of these Some of the advantages of this interface include higher throughout and lower power consumption than I2C which we used in an earlier recipe in this chapter Tip To be clear this recipe will not result in an alternative desktop display Instead it is the basis for building a more robust albeit considerably smaller low powered display option for your customized prototyping requirements and tests To demo the screen we will run Python scripts as they are an easier entr e into the hardware Getting ready You ll need the following items e OLED PCB We will use the SSD1306 driver chip version which is available mostly preassembled at Adafruit https www adafruit com product 938 The board requires only a minor soldering job to attach the pins and costs around USD 25 00 e The BBB both powered and remote SSH called via the USB cable Let s go headless no cheating There s also a practical reason to eschew an external monitor in this recipe we will be disabling the HDMI port so you would lose the signal anyway e 6x jumper wires e A breadboard Adafruit s OLED comes with its own tutorial and Python example scripts Although we will rely on the Adafruit Python BBIO library we will actually use an additional Python library developed b
325. thods of adding playlists to Volumio e The drag and drop method With any pls files you may have simply drag and drop the file into your WEBRADIO folder e Manual method You may have already found that some of the default web radio stations listed don t work There is a good chance that the problem is not your in hardware it s more likely that the station s URL has changed which is one of the vagaries of web radio So you will need to tweak the address in the playlist file Here s what we do 1 Open up a pls file in a text editor You can do this on your BBB or locally on your media library drive The drive is connected to the server as a shared drive so you should see it appear on your client box desktop Here is what you should see when you open the file playlist Filei http xxx yyy zzz port Titlei station name Length1 1 Numberofentries 1 Version 2 2 We will typically modify two items in this file First we will use the following command to modify the web radio address Filei http xxx yyy zzz port In this line insert the URL of the stream you are adding the port setting is optional Here s an example Filei http http xstream1 somafm com 8000 Then we want the name of the station to appear in the Volumio player while the audio is streaming Titlel station name For example if we wanted to call our station Space Station Soma we would run the following line Titlel Space Station Soma S
326. ting ahead of ourselves Commands are for the next section How it works Let s take a quick look at the various parts of what LX Terminal shows us Firstly we know that Linux likes to keep the current user name at the front and center in this case debian This way you always have a quick reference point to know whether you are a root user which gives you total control over the system or just another user with limited privileges Then comes the address of the device you re working on beaglebone You can actually customize the name but we will save that for the appendix Lastly consider the sign which denotes that you re logged in as a regular user If you were a root user the symbol would be the sign You will learn more about users and root users in a later section debian beaglebone n you hear me Major Tom address name means regular user not superuser Essential GNU Linux commands typical commands The command line is your friend For advanced users this is an obvious statement for the beginner not so friendly Where do you start with that darn blinking cursor How many Linux commands are there A whole bunch Thousands Tens of thousands depending on dependencies and packages But don t worry you don t have to learn them all Saying or writing something original about Linux commands is a bit difficult far smarter folks than I have written about compiled and battle tested the multiple combinat
327. to remove any Wi Fi dongles you may have inserted into the USB hub E We need to create a conf file for wpa_supplicant a tool that comes preloaded on the current Debian distribution The following command line will be useful for this sudo nano etc wpa_supplicant wpa_supplicant conf Paste in the open file the following information ctrl_interface DIR var run wpa_supplicant GROUP netdev update_config 1 network ssid my ssid scan_ssid 1 psk my psk proto RSN key_mgmt WPA PSK pairwise CCMP auth_alg 0PEN Two things need to be modified just as in Method Two my ssid which you will replace with your network s name and my psk which will be your network s password We now need to figure out the Wi Fi dongle s interface name To do this we will first examine which interfaces are present using the following command ifconfig a This command outputs the currently active interfaces which may include ethe 1o and usbo Reboot your board Plug in your dongle and run the same command again ifconfig a The output should now show the new device s interface name which could be rao wlan or so on Open the file in the directory specified in the following path sudo nano etc network interfaces At the top of the file paste the following code replacing interfacename with the name that appeared in Step 6 allow hotplug ra0 iface interfacename inet manual wpa roam etc
328. tory that we just created wget c https launchpad net linaro toolchain binaries trunk 2013 10 download gcc linaro arm linux gnueabihf 4 8 2013 10 _linux tar xz 4 Then untar the file with the following code tar xf gcc linaro arm linux gnueabihf 4 8 2013 10_linux tar xz 5 Now run the echo command to create the bbb vars file this will be used to test that our environment is set up properly as shown in the following code echo export CC pwd gcc linaro arm 1linux gnueabihf 4 8 2013 10_linux bin arm linux gnueabihf gt bbb vars 6 Verify that the command worked The bbb vars file should appear in the directory as follows root debian home user bbb tools ls bbb vars 7 Set up the environment for a remote test by sourcing the bbb vars file Take a look at the command preceding the is the file location root debian home user bbb tools bbb vars Now verify that the toolchain version we installed is correct using the following code root debian CC gcc version arm linux gnueabihf gcc crosstool NG linaro 1 13 1 4 8 2013 10 Linaro GCC 2013 10 4 8 2 20131014 prerelease Copyright C 2013 Free Software Foundation Inc This is free software see the source for copying conditions There is NOwarranty not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE Part IV Installing and setting up the Eclipse IDE Perform the following steps 1 Se Oe AO Ol e a m oO 11
329. tude install libswscale dev libavcodec dev libv4l dev libglew1 6 dev libxml12 dev libgsm1 dev libsqlite3 dev libupnp dev libsdl1 2 dev This next step is not difficult but it will slow down the recipe as we need to both get another library libvpx and compile it from source files This library which we get from Google installs a neon optimized version of libvpx an HTTP and web file management library Use the following command for this git clone https chromium googlesource com webm libvpx b v1 3 0 You can then change the directory via cd libvpx Following this run configure with the following options CC cc AR ar AS as LD gcc CXX g configure enable vp8 target armv7 linux gcc disable examples disable docs enable error concealment enable realtime only enable spatial resampling enable multithread disable vp9 enable pic Now run make with the following option and then run install These two commands will take several minutes to complete make j2 sudo make install Now we will go after an audio codec known to efficiently deliver high quality audio Called speex We will compile it with NEON optimizations enabled Go to your packages directory and then run git clone as follows cd packages git clone git git linphone org speex Change the directory and begin the compile process by running the following 16 17 18 19 20 command cd speex amp amp autogen sh Yo
330. u then need to run configure with the following options configure enable armv7neon asm with pic enable fixed point disable oggtest CFLAGS mfpu neon disable ogg Now go ahead with the following option and run make install You will note that you can combine these two commands with the double ampersand amp amp make j2 amp amp sudo make install Next compile and install belle sip as follows cd packages belle sip autogen sh configure make amp amp sudo make install Then compile and install 1inphone using the following command autogen sh configure disable x11 enable gtk_ui no disable xv enable sdl make V 1 CFLAGS Wno error amp amp sudo make install Note We used the wno error flag here because the mediastreamer dependency would otherwise keep alerting us about unused functions We need to relink with export LD_LIBRARY_PATH usr local lib You can verify that linphone passes the tests via cd tester amp amp liblinphone_tester We are nearly finished We will now set up the video output by forcing the video display to use a Simple Direct Media Layer SDL output which will optimize video playback We will do this by launching a command line tool that comes with Linphone called linphonec linphonec At the prompt type the following gt quit Simply executing this command transparently generates a file called linphonerc which we now need to e
331. ually consists of a detailed explanation of what happened in the previous section There s more This section consists of additional information about the recipe in order to make the reader more knowledgeable about the recipe See also This section provides helpful links to other useful information for the recipe Conventions In this book you will find a number of text styles that distinguish between different kinds of information Here are some examples of these styles and an explanation of their meaning Code words in text database table names folder names filenames file extensions pathnames dummy URLs user input and Twitter handles are shown as follows There is no reason to recapitulate all the material covered in the START htm presentation A block of code is set as follows function updateDuty compute and adjust duty_cycle based on desired position in range 0 1 var duty_cycle position 0 115 duty_min b analogwrite SERVO duty_cycle 60 scheduleNextUpdate console log Duty Cycle parseFloat duty_cycle 100 toFixed 1 Any command line input or output is written as follows sudo apt get update sudo apt get upgrade sudo apt get install gdb New terms and important words are shown in bold Words that you see on the screen for example in menus or dialog boxes appear in the text like this From your BBB s desktop open up LX Terminal Note Warnings
332. uff breaks especially with software And when your software is broken it makes it really hard to get things done with your hardware So the truth of the matter is you already know this if you re an experienced programmer that most of your time when you create some shiny new software thing a considerable amount of time is spent on fixing and debugging your code In Linux Land GDB GNU project debugger rules the roost as the standard debug tool It is the go to app that provides a window to what is happening in the guts of another program and allows you to saunter through the source code line by line when the program runs Conveniently it comes preloaded on the Debian distribution for your BBB GDB provides four key things needed for fast and efficient debugging 1 2 3 Starts your program and illuminates anything that may affect the program s behavior Stops your program on the specified conditions Investigates an error or anomaly and tells you what was happening at the time a program crashed Tweaks code in your program allowing you to quickly stomp one bug and go on to get another See also Check these links for more guidance on debugging http www dirac org linux gdb 01 Introduction php http www unknownroad com rtfm gdbtut gdbtoc html http elinux org EBC_Exercise 28 Remote gdb and more http elinux org EBC Exercise 14 gdb Debugging Debug a simple C code application from the command line using GDB GDB is fr
333. umns in front of the photocell with one end of the resistor aligned with the bottom wire of the sensor Voltage wire Plug the red wire into the P9_32 slot on the BBB This is one of the board s specially designated pins labeled VDD_ADC for 1 8V reference voltage a low power source for analog sensors like this The other end of the wire should be inserted into the breadboard aligning with the phototcell s top wire Ground wire The blue wire is for ground GND and for this we will also use a special ground pin at P9_34 for 1 8V GNDA_ADC Note VERY IMPORTANT The analog inputs on the BeagleBone Black accept a maximum 1 8V Never apply more voltage than 1 8V to the analog pins or you will damage your board Sensor pin Plug one end of the yellow wire into P9_37 on the BBB and the other end into a breadboard slot in front of the resistor It should align with the bottom wire of the light sensor Open up Cloud9 IDE at http 192 168 7 2 3000 Create a new file called 1ight_sensor js and paste the following BoneScript code into the window var b require bonescript function lightSensor b analogRead P9_37 lightValue function lightValue reading var millivolts reading value 1800 console log Light output in millivolts millivolts n setInterval lightSensor 1000 Press the Run button to begin capturing light intensity readings Your console output should look something like th
334. up Wiring up a mini amp and speakers Getting ready How to do it mini LCD cape o testing Testing a mini LCD cape How to do it module o new module adding to Node js Adding a new module to Node js How to do it See also motors o using Using motors Music Player Daemon MPD Creating a high quality audio platform with Volumio NASA s CubeQuest challenge o URL There s more NMap security scanner o URL There s more Node js o recipes Node js basic recipes o URL There s more o using with Johnny Five Using Node js with Johnny Five How to do it There s more nodemailer o URL See also node modules o URL There s more Nodered js o URL See also non HDMI LCD o connecting Connecting a non HDMI LCD or cape How to do it O e Ohm s law calculator tool o URL The essentials of electronics e OLED PCB o URL Getting ready e OS image flashing partition expanding Expand your partition code image backing up to file Backing up a code image to a file SD card boot OS image flashing the SD card boot How to do it 0 0 0 0 internal drive boot OS image flashing internal drive boot How to do it package management o about Package management Installing packages using apt get packages o o o installing apt get used Package management Installing packages using apt get How to do it See also updating
335. ur real time requirement but not so good holistically since it often results in an overall system slow down This is not to say that RI PREEMPT is a duffer Much outstanding work has gone into this code to optimize it and make it as useful as possible for many scenarios In fact RT PREEMPT is often considered a software standard precisely because it fulfills the majority of real time requirements for devices and systems The last thing we will say before moving on to the recipe is that we are only going to give you the method for applying RI PREEMPT onto Debian Jessie and intentionally ignore Debian Wheezy Why Because much hair pulling has been occurring over the years to get RI PREEMPT onto the 3 7 3 8 kernel And for budding Linux and BBB users the process could make you go bald The great news though is once you are committed to using the Jessie kernel 3 14 x it s an easy few steps to get up and running Getting ready All you need is the usual minimal setup a BBB powered over the USB tether with Internet connectivity enabled How to do it 1 Log in as root user sudo i 2 Check the version of Jessie that you are running uname r 3 14 39 ti r61 Note Your version may vary and will follow the convention 3 14 XX ti rxx 3 Run a command that will do a custom search for available real time Jessie kernels sudo apt cache search linux image grep ti rt Although the version numbers may vary somewhat y
336. ux grep is a powerful search mechanism to find a particular file a directory a pattern or chunk of code SSH Remote access Local control of your BBB should always be supplemented with the ability to control it remotely There are a variety of reasons you may want to do this For example you may want to operate the device from one location while you are in another location The primary and most typical reason for remote access however is to run the board headlessly This means running it without a display keyboard or mouse Headless control is in fact the way I operate the board about 99 percent of the time I rarely even use an external monitor with the BBB since it requires fewer pieces of hardware and reduces headache There are two basic recipe types for remote usage 1 Command line via SSH 2 GUI centric via VNC Using SSH to control your BBB Using SSH secure shell on a desktop PC or other client will give you control over your BBB across a network Here is the recipe How to do it On your BBB 1 2 Open LXTerminal Now enter the following command sudo ifconfig In the onscreen text get the IP address of your BBB Under ethos look for inet addr XXX XXX XXX XXX On your PC Mac Linux box go Open your preferred terminal app On the Mac it s just called Terminal At the command prompt type the following ssh keygen R lt your_ip_address gt You should then get the foll
337. vice that can be enclosed protected and positioned in a location optimized for better satellite tracking is a better long term strategy than leaving your laptop on the roof of a building e Custom alerts and signals A device that can deliver a custom signal indicating when the satellites are approaching opens up numerous possibilities for physical computing IoT enablement and a more indelible user experience Getting ready The following are the materials needed e An RTL SDR dongle e An antenna For the recommended low cost antenna that we are using see the Diamond antenna in the prior recipe on plane tracking http www aesham com glass magnet diamond antenna mr 75s Attach the antenna to the RTL SDR dongle via the uSML adapter e An antenna adapter If you use an antenna other than the small one that often comes with the dongle such as the one mentioned before you will need to buy a separate adapter Don t worry They re cheap too and ours was only about USD 6 00 http amzn to 1WoB7La e Powered USB e Ethernet or Wi Fi connectivity How to do it Here are the steps that you need to perform 1 Install package dependencies through the following commands sudo apt get install automake build essential make sudo apt get install intltool libgoocanvas dev sudo apt get install libgtk2 0 dev libcurl14 openssl dev Grab the source file and untar it as follows wget http downloads sourceforge net
338. view of the chmod command Finally it s time for the magic This tells bash to run the script and tells bash where the file is located as shown in the following code bin major_tom_bash_script This is how your output should look debian beaglebone bin major_tom_bash_script Commencing countdown engines on This is a very small blast off but still a beginning Epoch Time shell script Shell scripts A shell script has a myriad of purposes on a Linux box You can have them run at bootup so that they initiate commands or processes without you having to manually start them They can be used to run a sequence of events They can manipulate files execute a program print text and walk your dog Well the last part is true if your dog is a robot However we re getting ahead of ourselves Epoch time more commonly known as UNIX time also POSIX time is widely used in Linux UNIX systems as a way to describe instants in time Specifically it measures the number of seconds that have elapsed since January 1 1970 and is used as a timestamp reference point With this shell script we can quickly compare the Epoch time on our machine with the UTC that we are more accustomed to using How to do it Perform the following steps Unix time can be checked on most Unix systems by typing date s on the command line Perform the following steps 1 First create the following script in nano sudo nano epoch t
339. w paste the following text into the end of the file Choose the option based on the version of Debian you are using Wheezy deb arch armhf http repos rcn ee com debian wheezy main deb src arch armhf http repos rcn ee com debian wheezy main Jessie deb arch armhf http repos rcn ee com debian jessie main deb src arch armhf http repos rcn ee com debian jessie main 2 Save and close the edit window then update your repositories sudo apt get update With Debian Wheezy you may encounter an error of the following ilk W GPG error http repos rcn ee com wheezy Release The following Signatures couldn t be verified because the public key is not available NO_PUBKEY D284E608A4C46402 3 So run this command to fix it sudo apt get install rcn ee archive keyring 4 Update your repositories again and the error should be gone sudo apt get update 5 Check the version of your installed kernel uname r 6 Next we will run a search command to find the version of Xenomai that is suitable for our kernel Make sure you run the command appropriate to Wheezy or Jessie Wheezy sudo apt cache search linux image grep 3 8 xx xenomai Jessie sudo apt cache search linux image grep xenomai At the time of writing this chapter your Debian output will look like the following Jessie will vary slightly according to your installed version 10 11 12 linux image 3 8 13 xenomai r67 Linux kernel vers
340. w to do it There s more o Viewer URL Getting ready voice recognition There s more Volumio o used for creating high quality audio platform Creating a high quality audio platform with Volumio How to do it There s more See also o URL Creating a rem audio leas with valamin Getting ready See also o running prerequisites Getting ready W e wireless digital picture frame o building Making things smarter building a wireless digital picture frame How to do it If This Then That IFTTT web service using Getting ready smartphone setting up How to do it Dropbox script setting up on BBB How to do it Dropbox script testing on BBB How to do it desktop client How to do it BBB How to do it script testing How to do it script running How to do it O O O O O O O 0
341. wered o USR2 Two down from the Ethernet jack this LED flutters subtly during CPU access Power indicator LED Heartbeat Note Unless otherwise noted all images are copyright Charles A Hamilton 3 Within a few moments on your client machine the BEAGLE_BONE drive should appear as a visible volume on your desktop Browse the folder and open up the START htm file 4 Once opened you will find a clear set of quick start steps including how to install drivers if needed 5 Browse your board BeagleBone Black s boot system includes a handy web server that allows immediate connectivity Clicking on the link will take you to the local IP address of the board at 192 168 7 2 Once there you will find a very helpful presentation on the board There is no reason to recapitulate all the material covered in the START htm presentation Instead review it as a good jumping off point for the upcoming recipes in this chapter Getting ready Power down Before proceeding remove all cables and power USB Ethernet DC cord HDMI and so on How to do it Perform the following steps 1 Connect the USB cable With a USB 2 0 A to Mini B cable connect the BBB to a USB port on your desktop PC Look for status lights After plugging in the USB cable you will see the board s first LED light up followed subsequently by the three other LEDs If all goes well the BEAGLE_BONE device will appear on your desktop
342. with an error tell it not to despair and 12 13 14 15 try again with the following code Restart on failure Now not only should the service try again but keep trying to relaunch in this case every 5 seconds as shown in the following code RestartSec 5 Once the service is enabled we want to give it a run level target in our case tell it to launch as part of a group of processes the multi user processes that trigger near the end of the boot cycle as follows Install WantedBy multi user target Save the file and then enable the service you just created root beaglebone lib systemd system systemctl enable email ip service Now reboot If everything went as planned you should get an e mail in your inbox that tells you the IP address of your BeagleBone Black Pretty handy Chapter 5 Basic Programming Recipes with the Linux Kernel In this chapter we will cover the following recipes Kernel application binary interface Installing the latest kernel image Installing and building a custom kernel Interactions with the kernel sysfs entries and controlling the GPIOs Device Tree and its roots Device Tree basic build Device Tree advanced adding DT overlay to run a custom cape Universal cape overlay Running a script to check DT usage on GPIO pins Introduction We will now learn something about the real guts of our platform the Linux kernel Of course understanding all the bits about the
343. work with both these sizes AdaFruit and Sparkfun have vetted collections although you can certainly get them cheaper on Amazon e Resistor 10 000 10kQ version with brown black orange gold bands e 6x jumper wires e Breadboard How to do it 1 Make sure your BBB is powered down first then wire up your breadboard according to the following fritzing diagram BeagleBone 2 Here are the details for the wiring if the diagram isn t clear o Connect your 10k resistor to row 5 of your breadboard with the ends spanning the bridge In this recipe the resistor is not vital but it is good practice to keep the voltage under control and protect the board if the servo is malfunctioning o For the servo cable attach three jumper wires and match them as follows The brown servo lead GND This is the black jumper wire The red servo lead PWR This indicates the red jumper wire The orange looks almost yellow servo lead This denotes the yellow jumper wire o Now attach the second set of jumper wires to the BBB as follows Connect one end of the GND black wire to the P9_1 pin on the BBB and the other end to the breadboard following the diagram s position Connect one end of the 3V red wire to the P9_3 pin on the BBB and the other end to the breadboard following the diagram s position o Now we ll hook up the yellow jumper wire which we ll connect to our PWM output on the BBB Connect one end to the 9_
344. wpa_supplicant wpa_supplicant conf iface default inet dhcp 10 11 12 13 14 Close the file by pressing Ctrl x when prompted type y for yes then press the return Enter key Assuming your dongle is still plugged in run a command that brings up the interface ifup interfacename Power down the BBB by running this sudo poweroff Make sure your Wi Fi dongle is plugged into a powered USB hub with the hub s USB cable inserted into the BBB s USB port Restart the board this time plug into the DC power supply You will now get a solid Wi Fi connection Test it via the command shell using the following command ping www google com If all went well you should see a steady screen output from the ping Note Sometimes you may need to power off unplug the 5V input and then plug in again as the dongle isn t always recognized through the S1 Reset or the S3 Power buttons Method Four Debian Jessie Using Jessie is the easiest and fastest route to a reliable Wi Fi connection Here is how to do this 1 2 3 Plug an Ethernet cable connected to your router into the BBB s Ethernet port Boot up and log in to your BBB connected to a monitor Open a terminal window and log in as root with the following command sudo i Install the package network manager Before installing a new package always begin by updating your repositories as follows apt get update apt get install network ma
345. wpix service Finally run the following command that enables the service to start at bootup systemctl enable nowpix service Now reboot your BBB If all is well you should now have pictures cycling on your screen updated from your new photos on your smartphone See also Crontabs is a bigger subject to learn and useful in many scenarios where you want to time events on your BBB For more information refer to e https help ubuntu com community CronHowto e http www unixgeeks org security newbie unix cron 1 html Chapter 9 The Black in Outer Space In this chapter we will cover the following recipes Grabbing the International Space Station flyover data and visualizing it Tracking using RTL SDR Airplane tracking with RTL SDR Satellite tracking using GPredict and RTL SDR Satellite tracking using the SatNogs Network client ground station and RTL SDR Adding other interfaces ISS tracking and text to speech Introduction There are thousands of satellite birds up there Buzzing around at all hours of the day and night whether commercial military or educational these satellites send and receive data from professional and amateur ground stations around the globe And as satellites get cheaper the number of them has proliferated leading to an increasing problem for potential catastrophic collisions in space Tracking all that activity is a challenge So why not employ your own BBB in this endeavor Amateur
346. y approximately 1x per second We will come back to check the integrity of the module s satellite connection in a later step In order to gain access to the UART pins on the BBB we have to enable them using a Device Tree overlay Until recently this was a multistep process However now that the BeagleBone Universal I O package comes preloaded on the current versions of the firmware enabling the pins in the case UART4 in a snap Let s begin by logging in as root with the following command sudo i Then run the relevant Universal I O command and check whether it went to the right place as shown in the following code config pin overlay BB UART4 cat sys devices bone_capemgr slots Now reboot your BBB and check whether the device is present in the device list by using the following command ls 1 dev ttyo crw rw 1 root tty 247 O Mar 1 20 46 dev tty00 crw rw T 1 root dialout 247 4 Jul 13 02 12 dev tty04 Finally check whether it is loading properly with the following command dmesg This is how the output should look 188 335168 bone capemgr bone_capemgr 9 part_number BB UART4 version N A 188 335235 bone capemgr bone_capemgr 9 slot 7 generic override 188 335250 bone capemgr bone_capemgr 9 bone Using override eeprom data at slot 7 188 335266 bone capemgr bone_capemgr 9 slot 7 Override Board Name 00A0 Override Manuf BB UART4 188 335355 bone capemgr bone_capem
347. y Guy Carpenter and modified by Ethan Zonca along with our own custom example code How to do it Now that you re ready let s get started 1 Wire up your board and breadboard in the following manner 2 2 e eee a a E 8 E 1 1 E a na 8 2 2 2 ees LEE E 2 2 o e LEE E 2 LO A LEE 2 2 2 2 oe LEE 2 2 2 9 E DE 2 Mal a Oreesessse Q a4 e BeagleBone fritzina To be clear here is the hookup in table form I S G VIN VDD_3V3 P9_3 Power GPIO P9_24 Reset display In order to use SPI pins we need to enable a Device Tree overlay which is easy to do as it is already compiled on the system and most efficient to load at bootup So first call SSH into your BBB open a terminal window and then browse to the following directory cd boot Now open the file uEnv txt sudo nano uEnv txt Then add the following lines at the very end of the document This line added to enable device tree overlay for SPIDEV optargs capemgr enable_partno BB SPIDEV1 Save and close the file and then reboot your BBB as follows reboot Log back in as the root user and confirm that the dev spidev1 0 and dev spidev1 1 files are visible indicating that the SPI drivers are available for access sudo i 1s 1 dev spidev You should get an output similar to this crw rw T 1 root spi 153 1 Mar 1 20 46 dev spidev1 0 c
348. y sensor audio platform requires a high level of machine responsiveness to fulfill a performer s expectations and performance techniques thus the need for predictable timing from the board o Project overview http www eecs gmul ac uk andrewm hackable html o Open source code https code soundsoftware ac uk projects beaglert e PRU speak An implementation of the BotSpeak robotics language for the PRU This project enables dynamic control of the BeagleBone Black s PRU from the Linux user space on ARM o http botspeak org supported platforms beaglebone o https github com deepakkarki pruspeak e PRUCAPE Texas Instruments designed a low cost cape to facilitate usage of the PRUs o Good verbiage on its purpose and usage http linuxgizmos com beaglebone cape eases access to the sitara socs pru o You can purchase it here http www ti com tool PRUCAPE buy Chapter 7 Applied Recipes Sound Picture and Video In this chapter we will cover the following recipes e Wiring up a mini amp and speakers e Creating a high quality audio platform with Volumio e Using videos and displays in projects e Testing a mini LCD cape e Making a video chat client prototype using Linphone Introduction We need to get a little dirtier So far we played it safe with physical computing recipes But how far can you go by just plugging in some wires into a breadboard To make the BBB a really useful tool we have to heat up the iron

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