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Raspberry Pi Projects for the Evil Genius (2014)- Donald

1. s ii mi Earm So a g rz a ie 7 r TT lt 7 GM tube calibration curve The sloped portion of the curve can be easily represented by a simple equation dose rem c m x 100 15 where c m counts per minute All that needs to be done is to count the number of clicks or triggering events that happen in a given minute and plug that number into the equation Please note that a number of simplifications have gone into formulating this equation and it really is accurate only to 15 to 20 percent That is still sufficient to provide a realistic assessment regarding the presence of harmful radon in the measured space K2645 Geiger Muller Counter A brief discussion of how the GM counter functions will help provide a good basis for understanding how it was interfaced to the RasPi The essence of the GM counter is the detector tube which is the approximately 3 cm tube that may be seen in the upper left hand corner of Fig 14 1 It is a small metal cylinder typically filled with argon gas along with a wire conductor supported lengthwise in the middle of the cylinder The wire has an approximate 600 V DC potential on it When a charged particle or energetic wave enters the tube the gas breaks down or ionizes and forms a brief electrical short circuit between the inner wire and the outer metal cylinder This causes a momentary current flow that is detecte
2. a sep V ASN og687 i arina Li ion charger board This board uses two high capacity Li ion cells rated at 3 7 V DC and 2600 mAh One cell is shown in Fig 12 11 These cells conform to the 18650 form factor which is a bit like an AA battery on steroids Each cell also contains a protection circuit to help prevent overcharging which could lead to a serious situation if the cell was left unprotected Nonetheless these cells should be charged only with an appropriate charger specifically designed for them which is the main reason why I incorporated the complete charger into the car arenae li ion cell OTE The U S Postal Service will no longer ship items that contain lithium batteries to international destinations including APO and FPO addresses The charger board and all the other boards including the RasPi are mounted in a stacked sandwich arrangement Please note that you will need to assemble and disassemble the stack several times as you build the car This is unavoidable because you will have to custom fit the parts to the various mounting boards Figure 12 12 is a Sketchup 3D modeling software once owned by Google but now owned by Trimble representation of the beginning of the stack with the charger board mounted on four 0 25 inch OD nylon spacers Charger board Sketchup mounting diagram Four 1 inch nylon spacers are mounted on top of the board to provide sufficient room between the top
3. SCL t TO EGISTER SE BUS INTERFACE R DS1307 block diagram RTC crystal You should clearly see the frequency in kHz printed on the metal can enclosing the actual piezo electric element These generic type RTC crystals typically will have accuracy within 30 seconds month when properly loaded with a matching 6 picofarad pF crystal and operated at a nominal 23 C ambient temperature The operating temperature is the key parameter that affects clock accuracy assuming the correct capacitance loading is used Figure 15 4 shows the temperature effect as it deviates from the standard 23 C calibration point i G w i00 J a el f g 4 30 A0 W 10 2w G A a M TC TEMPERATURE C Temperature versus RTC frequency deviation The 30 seconds month accuracy will be maintained for a RasPi operating in a home or office However a RasPi that operates in severe environments should expect significant reduction in RTC accuracy Another key feature of the RTC is the ability to maintain the time even if the host processor is turned off This is made possible by using a long life battery to power the oscillator and non volatile NV RAM write mode in the DS1307 chip A lithium coin cell battery is normally used for this purpose after the host is powered off A coin cell will often last for many years before exhausting its energy The current date and time is continually stored in the NV RAM 5
4. 6 pulse Ay scratch G thumbnails Desktop amp gstreamer 0 10 amp python_games idlare Serateh G local D Hello py P File pama Hela py Files of type Python files py pyw Opening a file in the Python shell Selecting the Hello py file will cause a second window to appear on the desktop with the contents of Hello py shown in the window This is very convenient in that you can modify the file contents without affecting any of the content happening in the Python shell To execute the program you must be in the second window that was just opened where you can either open the Run menu tab and select Run or simply press the F5 function key The Hello py program results appear in the Python shell as can be clearly seen in Fig 1 31 I mm py lt Menma ipin ie Fr Fie Edit Format fan pline Windows Help Ci Lhe be Python Shell Lie HE Fal Gee Deen Wei ihip O then 7 7 arce idefault Kay 5 AF 20s L ote 4 6 5 ef limia Pee Pe tr Pee Pe Ps Pe st te E FPEF Hal Lo mar Ld EEE Running a program from the Python shell Summary I have covered a lot of material in this chapter from introducing the RasPi and a bit of its history to explaining the role that its inventors would like it to fulfill I also covered the hardware aspects as you need to understand the design decisions that went into the RasPi and the consequent constraints and attributes th
5. Ain Ce ne Haia Bin A eine rt Feo rennan Baa E ae a a ee el High voltage optoisolator circuit Connect the RasPi GPIO pins to pins 1 and 2 of the optotriac in the same manner as shown in the NTE3041 connections of Figure 4 11 Be sure to include the 220 Q current limiting resistor Information about the suggested parts for the high voltage optoisolator circuit is provided in Table 4 2 Table 4 2 High Voltage Optotriac Parts List Part Model Number Source Optotriac Motorola MOCS010M Mouser SCR STM 511 TY YN408 Mouser 5 6 k v watt Sound and Laser Modules An important part of this project is to have the capability of triggering the camera and flash by using sound and light events This means we need sensors to detect the sound and light as well as the associated circuitry to generate a signal when the preset thresholds are exceeded These requirements raise an issue that often comes up in project planning whether to build or buy In this case I decided to incorporate two inexpensive kits for sound and light detection My decision was based on an estimate of how long it would take to build and test two prototypes versus buying and building two kits and making any appropriate modifications to suit this project Listed here are the kits I used Global Specialties Model GSK 409 Audio Control Switch kit 9 95 Ramsey Electronics Model LTS1 Laser Trip Sensor kit 19 95 It turned out that neither kit required any
6. no Mener Ps ane i ah 191 R28 Cai 57 a Terres eo J rg E EEFE FE e Ei 4 Gigi pa DA B SETIF The Raspberry Pi a small Linux computer A look at a bit of history regarding the Raspberry Pi or RasPi as I will now refer to it and its originally intended market may help you understand the constraints and limitations that subsequently ensued The RasPi concept began around 2006 with Dr Eben Upton and his colleagues at the University of Cambridge s Computer Laboratory in Cambridge England They were concerned about the decline in knowledge and skill levels of incoming computer science students as compared with those of earlier students Dr Upton decided to create an inexpensive computer reasoning that it was likely that parents were not allowing their children to experiment with modern and relatively expensive PCs This idea ultimately led to the development of the very inexpensive RasPi This computer would provide an excellent opportunity for children to learn and experiment with programming while not being a concern to parents if something should go horribly wrong and the board be destroyed Dr Upton teamed with several other individuals to form the Raspberry Pi Foundation a registered United Kingdom charity that promotes computer literacy and enthusiasm especially among young children using the RasPi as their initial platform They seem to be achieving these highly laudable goals since they
7. put your user gmail account here gmail user user gmail com put your gmail password here qmail password password feverything is verbatim from this line on down emtpserver smtplib SMTP smtp gmail com 587 amtpserver ehlo smtpserver starttla smtpserver ehlo smtpserver login qmail user gmail password today datetime date today arg ip route list proc subprocess Popen arg shell True stdout subprocess PIPE data proc communicate split data data 0 eplit local ip split_data split_data index sre 1 public ip os system wget http ipecho net plain 0 g gt test txt echo public ip epen test txt r read msg content Alarm detected Public ip is 8 8081 local ip is ts amp public_ip local ip msg MIMEText msg_content msg Subject Raspberry Pi Alarm on s today msg From gmail user msq To t amtpserver sendmail gmail user to msg as_string amt pserver quit Figure 8 10 shows a slightly altered screenshot of the e mail received after I ran this script the names and public IP are changed to protect my privacy Sia o ejr Raspberry Pi Alarm on Feb 25 2013 Message Plain Text zee Message From yourname gmail com Ta yourname metrocast net Cc Subject Ratpberry Pi Alarm on Feb 25 2013 Alarm detected Public ip is 44 236 239 221 8081 local ip is 197 168 1 71 sees
8. random simulated device server FAKE 0 18520 052405 Hii OWS tease k mountpoint mnt lwire allow_other a http pert 2121 HSS Pees Owe PO Sees sees E Get Help Wri tedut Read File Prev Page cut Text Cur Pos i Exit om Justify gy Where Is gy Next Page gi Uncut Text lj To Spell The owfs conf file changes 4 The last step should be to reboot the RasPi in order to put the configuration changes into effect sudo reboot Viewing the Weather Data The real time data from the modules may be viewed from the owfs server Open a browser on another computer other than the RasPi and go to the local RasPi IP address with port 2121 appended In my case it was 192 168 1 21 2121 Figure 10 18 is a screenshot of the owfs server opening page showing a directory name for each of the modules from Fig 10 16 OWFS on 1 6 us listing directory low highest level directory 28 C1 A25030000 28 C1EA25030000 directory 26 862728010000 26 882728010000 directory 26 827BBC000000 26 827BBC000000 directory Tii sae i stem i inbistics ee P Rul cous lt SOSE The owls web server opening page The first three directory names listed in the owfs server opening page are for the actual sensor modules while the fourth is for the USB dongle The rather odd directory name is how owfs interprets the module ID For example by clicking on the directory named 28 C1EA25030000
9. EI P et Loe DNC MISO ONC 21 ONC SELB atnaepe JOPPSH Td ee DNC 23 ag y 3 DNE E E E E ETEC ETEEEEEGEETN E Pi Cobbler prototype connector Really just a direct extension of or a breakout kit for the GPIO connector it allows all the pins to be connected to a solderless breadboard It is available as a kit from a variety of sources including Adafruit at www adafruit com products 914 A fully assembled Pi Cobbler mounted on a breadboard and connected to a RasPi is shown in Fig 3 2 Pi Cobbler on a solderless breadboard connected to a Raspberry Pi Using the Pi Cobbler along with the breadboard will allow for rapid project construction and easy modifications to the existing project It will help you to have a variety of prestripped wire available to use with the breadboard You can either make your own using 22 gauge solid pickup wire or purchase a package from your favorite electronics components supplier Figure 3 3 shows a package that I bought for the book projects These wires are actually stranded for flexibility and are also terminated with a solid insulated pin connection It is well worth the cost to buy a kit of these wires High quality breadboard interconnect wires Portable Stereo Speaker You will need a way to listen to the MP3 recordings I use the very small and inexpensive stereo speaker device the Veho360 www veho uk com that is shown in Fig 3 4 Veho360 speaker T
10. The RS 232 serial connection can be attached to any computer running a terminal control program with a configuration of 8 data bits 1 stop bit no parity and 115 200 baud The particular sniffer board used in this project is powered via the bus I used an external laptop running the Tera Term program to display the network data The RasPi could have been used however it was simpler and easier just to use another computer for the monitoring and diagnostic functions You will see some sample screenshots in the section describing the operating weather station The sniffer module is an exception to the unique ID protocol because it is not expected to operate as anormal slave device All of the sniffers made by this manufacturer have the same ID of 0x01 which means that only one can be deployed into a given 1 Wire network That s usually not an issue because you would never require more than one sniffer per network The master can issue a limited number of commands to this sniffer including F Puts Sniffer into firmware upgrade mode S Puts Sniffer into the sniffer mode P Pauses the Sniffer H Display help message Set Up the Weather Station Hardware The weather station modules should now be interconnected using Ethernet patch cables and the USB dongle should be plugged into a powered USB hub Plug the cable from the USB dongle into the Power Injector Module All the other modules are daisy chained from the Power Injector Module The
11. EPEAT ETTI Raspberry Pi Projects for the EVIL GENIUS amp satan 2 Evil Genius Series Arduino Android Projects for the Evil Genius Bike Scooter and Chopper Projects for the Evil Genius Bionics for the Evil Genius 25 Build It Yourself Projects Electronic Circuits for the Evil Genius Second Edition 64 Lessons with Projects Electronic Gadgets for the Evil Genius Second Edition Electronic Gadgets for the Evil Genius 28 Build It Yourself Projects Electronic Sensors for the Evil Genius 54 Electrifying Projects 15 Dangerously Mad Projects for the Evil Genius 50 Awesome Auto Projects for the Evil Genius 50 Green Projects for the Evil Genius 50 Model Rocket Projects for the Evil Genius 51 High Tech Practical Jokes for the Evil Genius 46 Science Fair Projects for the Evil Genius Fuel Cell Projects for the Evil Genius Holography Projects for the Evil Genius Mechatronics for the Evil Genius 25 Build It Yourself Projects Mind Performance Projects for the Evil Genius 19 Brain Bending Bio Hacks MORE Electronic Gadgets for the Evil Genius 40 NEW Build It Yourself Projects 101 Outer Space Projects for the Evil Genius 101 Spy Gadgets for the Evil Genius Second Edition 123 PIC Microcontroller Experiments for the Evil Genius 123 Robotics Experiments for the Evil Genius 125 Physics Projects for the Evil Genius PC Mods for the Evil Genius 25 Custom Builds to Turbocharge Your Computer PIC
12. Figure 7 15 is a screenshot of the Scenes web page where one or more devices can be grouped collectively to support a common event happening in the home such as Wake Up TV Kids Sleeping etc Lights Control Control Scenes Scheduler Settings Admin Home Scenes s Manage Manage Scenes overanons List Scenes Displaying 1 5 of 5 results Create Scene ioe a SR is cae ON Drun Wake Up zz pie Lmng Room Lampshade OFE on Ah Bedroom Sleep Kids OFF GEG Ground Floor AJ OFF DH pee Deveinped by Conrad Varmis Pear red by Tifone ak grw k Scenes web page screenshot Figure 7 16 is a screenshot of the Scheduled Events page that works in conjunction with the Scenes page where the actual device times that support a specific scene may be programmed Lights Control Control Scenes Scheduler Settings Admin Hore Sch edulers Manage scheduled Events p List Schedaier D Displaying 1 4 of 4 resus Crealo cheduber i en re Wake Up 05 30 07 00 Mon Tue Wed Thu Fn Wake Up DN ri Feon 17 00 300 un Mon Tug Wied Thu Fr sat prior prs Kids Seep 20 00 21 30 Mon Tue Wed Thu Fn Bedroom Sleep Kids p y ea l Living Room Hash Test 207130297 15 30 15 41 Sun Suse pes Cevreloped by Conrad Vassey Pisngi by Yi racer Scheduled Events web page screenshot My recommendation is to simply experiment with the web app determining the appropriate inputs to the various pages in order to execute the desire
13. The next change concerns localhost operation Localhost refers to the same machine that is hosting the Motion web server No other system can access the webcam if you restrict the service to localhost hence it must be turned off The next two changes are similar to what was discussed above but are concerned with the remote control functions of the webcam I do not enable any remote control functions such as webcam panning or tilting in this project but it is certainly doable I suggest however that you simply keep the port number as assigned and disable the localhost operation Webcam Viewing It is now time to test the remote webcam viewing functionality You will need a separate computer on the same network that the RasPi is connected to You will also need the RasPi IP address It does not matter if the RasPi is connected via an Ethernet cable or by a Wi Fi wireless adapter My suggestion is to login into your network router and click on Attached Devices The local IP address for the RasPi should appear in the appropriate list My Netgear router has separate lists for wired and wireless devices connected to the network Yours might be slightly different but should show something similar to Fig 8 8 Wired Devices EE e __0oDeasoanea lt uniown gt Pa 192 6028 onaezooxer9c_ SSCS Pe teateas19 eonoresaonso anion 5 192 168 1 21 B8 27 E8 BC 74 67 RASPBERRYP sj 19216813 J OO 000048717380 2 a oe 192
14. fee Get Help f WriteOut 7 Read File gj Prev Page cut Text Cur Pos fae Exit Justify y Where Is Next Page gf Uncut Textglj To Spell Screenshot of the ntp conf file OTE The pool servers will be uncommented after the GPS time server functionality has been proven since it is good practice to leave these servers available Next the following series of commands will set up and run the GPS module as a clock source for the RasPi Ensure that no Wi Fi adapter or Ethernet cable is attached because they could provide a clock source if you didn t comment out the pool servers listed in the ntp conf file All the commands should be entered in the sequence shown sudo killall gpsd 4 sudo gpsd dev ttyAMA0 F var run gpsd sock sudo service ntp restart The killall gpsd command stops the gpsd daemon so that a logical socket link may be established by the next command The dev ttyAMAO parameter in the second command specifies that the GPS data will be sourced from the UART The last two parameters F var run gpsd sock set up a control socket for device adds and removals with the full path description to the socket The last command starts the ntp daemon at which point it will attempt to retrieve the clock signal from the source specified in the ntp conf file The GPS module will continue to blink its LED until a solid lock is obtained on four or more satellites A reliable time is not available until the LED stops blinking
15. 0 rel examples 0 re1 examples pn53x sam c 0 rel examples nfc anticol c 0 rel examples nfc emulate tag c 0 rel examples pnsS3x diagnose 1 0 rel examples pn53x tamashell secripts O0 rel examples pn53x tamashell scripts UltraLightRead cmd 0 rel examples pn53x tamashell scripts ReadMobib sh 0 rcl examples pn53x tamashell scripts ReadNavigo sh 0 rel examples pn53x tamashell scripts Makefile in O0 rcel examples pn53x tamashell scripts UltraLightReadWrite cmd 0 rel examples pn53x tamashell scripts Makefile am O rel examples CMakeLists txt O rel examples nfc poll 1 O rel examples nfc dep initiator c 0 rel examples doc O rel examples doc quick start examplel c O0 rcel examples nfc relay c 0 rel examples pn53x sam 1 0 rcel examples nfc emulate uid c 0 rel examples pn53x tamashell c O rel examples pn53x diagnose c 0 rel examples Makefile in 0 rel examples nfc emulate forum tag2 c O0 rcl examples nfc dep target c 0 rel examples nfc relay 1 O0 rcl examples nfc anticol 1 0 rel examples nfc poll c 0 rel examples nfc emulate tag 1 0 rel examples nfc dep target 1 0 rel examples nfc emulate uid 1 0 rel examples Makefile am 0 rel examples nfc dep initiator 1 0 rel examples pn53x tamashell i pi raspberrypi libnfe The libnfc source code extract operation 6 One of the source code files must be slightly modified in order for libnfc to connect to the RasPi through the ttyAMA logical device Type
16. 1 The first step is to simply plug the USB 1 Wire adapter into the powered hub and confirm that the Wheezy OS recognizes the adapter You should also attach the remaining modules at this time Then type the following at the command line prompt lsusb H Figure 11 4 shows what displayed on my setup The USB 1 Wire adapter is shown as Bus 001 Device 005 ID 04fa 2490 Dallas Semiconductor DS1490F 2 in 1 Fob 1 Wire adapter entry Your entry will vary depending on the adapter you use and the unique ID that is associated with every 1 Wire device ee pi raspberypic mm login as pi pPLE192 166 1 21 s password Lingx raspberrypl 3 6 114 371 PREEMPT Thu Feb 7 16 31 35 GMT 2013 armyv l The programs included with the Debian GNU Linux system are free software the exact distribution terms for each program are described in the individual files in fusr share doc copyright Debian GNU Linux comes with ABSOLUTELY NO WARRANTY to the extent permitted by applicable law Last login Fri Mar 6 19 22 13 2013 pifraspberrypi 1s Desktop ocr pl png python games pifraspberrypi lsusb Bus 001 Device O02 ID 0424 9512 Standard Microsystems Corp Bus 001 Device O01 ID 1d6b 0002 Linux Foundation 2 0 root hub Bus O01 Device 003 ID 0424 ec00 Standard Microsystems Corp Bus 001 Device O04 ID 0523 0608 Genesys Logic Inc USB 2 0 4 Port HUB Bus 001 Device O05 ID O4fa 2490 Dallas Semiconductor DS1490F 2 in 1 Fob 1 Wire adapter Bus
17. 15 is a screenshot of the edited ntp conf file aa plaraspberrypl Oo x File Edit Tabs Help GA nano 2 2 6 4 fete ntp conf configuration for ntpd see ntp conf S for help f idriftfile var lib sntp ntp drift iw Enable this if you want statistics to be Logged j statsdir fvar Llog ntpstats istatistics loopstats peerstats clockstats ifilegen loopstats file Loopstats type day enable Ifi legen peerstats file peerstats type day enable jtilegen clockstats file clockstats type day enable iY You do need to talk to an NTP server or two for three server ntp your prov vider ram Le ly pool ntp org maps to about 1000 low stratum NIP servers Your server will i pick a different set every time it starts up Please consider joining the ls pool lt http www pool ntp org join html gt j server ap debian pool ntp org iburst fserver l debian pool ntp org iburst Piserver 2 debian pool ntp org iburst jfserver 3 debian pool ntp org iburst server 127 127 28 0 minpoll 4 fudge 127 127 28 0 time 0 183 refid NMEA Access control configuration see fusr share doc ntp docshtmL accopt html for details The web page lt http support ntp org bin view Support AccessRestric miL gnt also be heli te j Note that restrict applies to both servers and clients so a configuration that might be intended to block re quests from certain clients could also end up blocking replies from your own upstream servers eee ee oe
18. Saving code 28 SCL Serial Clock control line 189 SCR silicon controlled rectifier 48 SD cards class designation on 4 inserting removing with power on 134 preparing using Windows PC 15 16 preprogrammed 3 4 rewriting 16 SD Secure Digital flash memory 3 SDA Serial Data control line 189 seconds argument 28 Secure Digital SD flash memory 3 See also SD cards Secure Shell SSH 95 96 login for home automation project 95 96 for NFC RFID reader project 117 Seismic waves 73 74 Seismic_Monitor py 83 84 Seismology 73 74 data analysis 82 83 sensor design 75 76 See also Earthquake detector project Sensitivity adjustment camera controller 49 Sensors HIH 4021 001 128 for home security controller project 111 113 LDT0 028K 75 76 MPXA4115A 128 for robotic car 173 seismic 75 76 Serial Clock SCL control line 189 Serial Data SDA control line 189 Serial interfaces using uncommitted GPIO pins software 13 Serial Peripheral Interface SPI 9 for earthquake detector project 78 serial protocol 12 Serial protocols 12 13 IPC 12 SPI 12 UART 12 13 Servos robotic car project 156 157 160 163 S5 connector 9 Sharp 6 Sheepwalkelectronics co uk 125 Shell editor 29 Shutter operation camera controller 44 45 Sievert Sv 177 Sigma Designs 92 Silicon controlled rectifier SCR 48 Single ended mode ADC 77 SIS SUC ID Server 92 Sketchup 158 Slave de
19. The second step in the ADC process is to convert the sample voltage to a digital number This can happen in a variety of ways all of which are dependent upon the type of ADC chip that is used I used a Microchip model MCP3008 that is described in the Microchip datasheet as a 10 bit SAR ADC with SPI data output Translated this means that the MCP3008 uses a successive approximation register SAR technique to create a 10 bit digital result that in turn is outputted in a serial data stream using the SPI protocol Figure 6 7 and a short discussion will help clarify this description Functional Block Diagram Dour Note Channels 4 7 are available on MCP3008 Only MCP3008 functional block diagram The analog signal is first selected from one of eight channels that may be connected to the input channel multiplexer Using one channel at a time is called operating in a single ended mode The MCP3008 channels can be paired to operate in a differential mode if desired A single configuration bit named SGL DIFF selects single ended or differential operating modes Single ended is the mode used in this project The selected multiplexer channel is then routed to a sample and hold circuit that is one of the two inputs to a comparator The other input is from a digital to analog converter DAC that receives its input from a 10 bit SAR Basically the SAR starts at 0 and rapidly increments to a maximum of 1023 which is the largest number that can b
20. You will need to determine the RasPi s local IP address in order to connect the Android application to the RasPi web server In my case it was 192 168 1 21 All I needed to do was type that address into the phone as shown in Fig 11 13 mo E E wl ae 10 41 AM DrGPIO Please enter the following information Hostname or IP address 192 168 1 21 Port default 8000 Username default webiopi webiopi Password default raspberry Rasberry PI revision TypeB Rev model have 512MB of RAM If your aspberry only have 256MB please select Rev T Revi L l a pei F Fi arinak Android smartphone setup screen Scroll down to the bottom of the phone screen after you have entered the needed information Tap on the button Save and continue and a pop up dialog box will appear stating DRGPIO is going to try to connect to your Raspberry Pi now Tap the OK button and you should now be shown a screen similar to the one in Fig 11 14 The DrGPIO control screen Figure 11 14 is a graphical representation of the RasPi 26 pin GPIO connector The check boxes shown immediately to the side of each pin box allow you to select whether the pin is to act as an input or output The check mark will be highlighted if it is set as an input We need pins 18 23 and 25 unchecked so that they are functioning as outputs To output a 1 simply tap the pin box The bar in the pin box will fill in and the label will change fr
21. enp Servo B Board CR Servo 12VDC Li ion Charger Board LiPo Battery Block diagram of the robotic car electrical components The RasPi is powered from the Li ion charger board however that board provides only an 8 V DC output The voltage is converted to 5 V DC by a small regulator board that uses an LM7805 three terminal chip with some auxiliary capacitors Figure 13 2 shows the regulator schematic 5 V DC regulator schematic The 5 V output is connected to the Pi Cobbler s 5 V pin 0 Technically this arrangement is known as back feeding because the 5 V 0 pin is normally an output not an input However it makes no difference electrically if you supply or take off power from a parallel connected power bus By following this approach you avoid having to hack up a micro USB connector and cable through which the RasPi is normally powered Shown on the block diagram is another 5 V DC regulator that provides power to the servo motor input on the 16 channel servo control board now simply referred to as the servo board You might wonder why I did this instead of paralleling the output already connected to the RasPi The answer is that I wanted to avoid the situation in which a brief high current demand from the servo motors would cause the regulator voltage output to drop below the minimally acceptable voltage for the RasPi thus Causing it to stop running The logic on the servo board is fed from the Pi Cobbler s 3
22. 1 return result SPICLE 18 SPIMISO 23 SPIMOSI 24 SPICS 25 LED 27 This is pin 21 for rev 1 boards GPIO setup SPIMOSI GPIO OUT GPIO setup SPIMIS0O GPIO IN GPIO setup SPICLE GPIO OUT GPIO setup SPIcs GPIO OUT GPIO setup LED GPIO OUT channel 0 while True ade value adc channel SPICLK SPIMOSI SPIMISO SPICS if jade value gt 720 GPIO output LED GPIO HIGH time sleep 1 The system functioned as expected with the LED being activated by a slight shake applied to the PMS detector Use the nano editor to change the line if ade value gt 720 to any value that you want to set as an appropriate threshold level Summary This chapter began with a brief review of seismology and how earthquakes are generated It was pointed out that quakes produce both P and S waves with the P waves being precursors to the destructive S waves Next I covered the basics of seismic sensor designs The inverted pendulum was selected for this project because it is both sensitive and very inexpensive The analog to digital conversion process was discussed as it is required in order to convert the analog seismic signals to a digital format suitable for processing in the RasPi A thorough discussion of the Serial Peripheral Interface SPI followed This is the interface through which the data flows between the MCP3008 ADC chip and the RasPi Next the ADC chip was set up to function with the RasPi using the Pi C
23. 12 Intrusion detection see Home security controller project Inverted pendulum seismic sensor 75 Ionizing radiation 175 IP Intellectual Property 1 2 IP Internet Protocol address 8 IR light for robotic car 173 IR sensor for robotic car 173 IRNSS system 57 ISM Industrial Scientific and Medical band 87 115 ISO seven layer network model 88 89 K K400r keyboard mouse combination Logitech 166 167 K2645 Geiger Muller counter 175 177 179 L LadyAda 190 Laser module for camera controller 49 50 52 53 Laser trip devices for camera controller project 48 50 for home security controller 104 105 111 LCD liquid crystal display 40 LDT0O 028K sensor 75 76 Learn Adafruit com 79 Least privilege principle 16 Least significant bit LSB 78 LED light emitting diode 8 LED blinker project 23 29 blinking the LED 28 29 preparation for 23 26 turning on the LED 27 28 LG 6 libnfc 116 121 data communication with 116 installing 117 121 Light emitting diode LED 8 See also LED blinker project lightscontrol app 97 99 Lightweight X11 Desktop Environment LXDE 16 17 Li ion charger board 157 158 Linux 1 13 ALSA 31 34 commonly used commands 17 file names in 25 26 fundamentals of 16 17 hardware treatment by 143 initial startup 13 15 preparing SD cards 15 16 on preprogrammed SD card 3 4 user access 16 Liquid crystal display LCD 40 Lithium ion
24. 49 50 optoisolator interfaces 47 48 project requirements 44 shutter operation 44 45 stop action pictures 43 44 time lapse function 55 Camera Serial Interface CSI 2 8 CameraControl py 52 53 Canon 47 Canon 40D DSLR 44 45 Canon 420EX electronic flash 45 46 cat filename Linux command 17 cd Linux command 17 cd Linux command 17 CDMA Collision Detection Multiple Access 89 90 CEC Consumer Electronics Control 6 Celestial almanac 60 Cgps app 69 Chassis robotic car project 156 160 Ci curie 176 Class designations SD cards 4 Clocks atomic in GPS system 60 radio receiver clock source 197 real time 187 193 See also Time keeping project Collision Detection Multiple Access CDMA 89 90 Comments 27 Comparisons equal signs for 37 Compass system 57 Conditional statement 29 Connections 2 Connectors RasPi 4 10 analog composite video 6 7 audio 7 Ethernet and USB 7 8 for future expansion 8 9 GPIO interface 9 10 HDMI 5 6 power 5 Console player apps 36 Consumer Electronics Control CEC 6 Control voltages for electronic flash 47 Controllers camera controller project 43 56 home security controller project 103 113 local and remote logic controller project 139 153 NFC RFID reader project 116 in Z Wave networks 91 92 CSI 2 Camera Serial Interface 8 Curie Ci 176 Current level for optoisolators 47 Current limits 10 11 C
25. B1715 HPR Al 4314 2683 x O7182 7415 U 80 22 18 35 120113 A 40 ee i ec Tt H 8 227 4 0 41 me PGTOP 11 3 6F 7 GPGGA Bizi AAA 4314 2686 H 07102 7416 W1 d 3 7 72 dA 328A p GPGSA A3 27 23 31 25 PE miye P Me 99 981 SGPRAC 821716 apa A 4314 S680 H a712 7416 W6 1818 35 120113 Ami eae 35 1 H 8 18 N 8 33 K A 0B Faedda FMTM SE 5 18 35 128113 Aa4A Tera Term screen capture of GPS data stream The next step in confirming proper GPS operation is to disconnect the USB TTL cable and load the RasPi with a terminal program to confirm that the RasPi can also receive the GPS data stream I used a very nice serial terminal control program that runs in a graphical user interface GUI named CuteCom To install this program type the following into a terminal window sudo apt get install cutecom OTE I had to type sudo apt get update prior to entering the above command because the apt get repository didn t initially find the CuteCom package Next you must edit the file named inittab located in etc directory in order for CuteCom to communicate with the GPS receiver Change the line below into a comment line TO 23 respawn sbin getty L ttyAMAO 115200 VT100 I used the nano editor to place the symbol at the start of this line This action is required to allow Linux to free up the serial console resource You can run the CuteCom program after editing inittab by using File Manager and open
26. BL BANTI100000C 81 BA0731000000 1 BAD731000000 directory bus baso settings C A r AA ASS structure directory iii DLL Ss OS a ee feeen lalarm irecte ectory Screenshot of an owfs initial page overlaid with Tera Term packet data The interpretation of the first line of data follows First data packet RP FO 28 C1 EA 25 03 00 00 C4 RP is short for presence pulse FO is a one byte ROM command This one returned the ROM module ID 28 C1 EA 25 03 00 00 is the ROM ID sent back to the master C4 is a CRC check byte used for error checking The following three lines in the sniffer window performed the same action for the other three modules in the 1 Wire network Notice that they are displayed in precisely the same order as they are listed in the owfs directory web page I then clicked on the Temperature Module directory to see what the sniffer returned Figure 10 24 is the resulting screenshot FC FF FF FC FF FF 4 BE 46 AE 4B dd B0 BE 3E BE 3E 4E 48 jd BA BE 486 BE 40 4E 4B 44 88 BE 3E BR BE 3E BE BE 3E Screenshot after the Temperature Module directory was clicked As one might expect there is obviously a lot more information being created so that owfs can populate the Temperature Module s report page Fig 10 19 You should notice that the module s ROM ID is repeated in each line of the sniffer display This makes it quite easy to identify the spec
27. Figure 2 6 shows the actual connections I simply twisted the cathode lead to a resistor lead and soldered them to ensure a good connection fo SS ee eS Se ee z AE Ai a 2b a Se fe he ee a A ee eel nee o a E i N EEEE EEEE seeccoogdooce9s mi EL ak a a eC One 3 AS Oe Tapa Actual LED connection Project Software The program to turn on the LED is very straightforward You should realize that when the RasPi is first powered on all the GPIO pins are set to be in an input state in other words they will only sense or detect voltage not output a voltage Therefore we must change the state of the pin selected to be an output and then apply a high voltage to the pin This is the fundamental logic behind the program Here is the program to be created using the nano editor Comments are placed above each line to inform you what the following line is doing Comments begin with the symbol All comments are ignored by the Python interpreter import the library that allows us to logically access the GPIO pins refer to the library as GPIO It is like an alias import RPi GPIO as GPIO use the BCM pin numbering scheme as discussed in Chap 1 GPIO setmode GPIO BCM set pin 18 to be in the output mode GPIO setup 1 amp GPIO OUT apply a HIGH voltage to pin 18 GPIO output 18 GPIO HIGH That s it just three lines of code not counting the import statement that is really part of the pro
28. High Performance MPEG 1 0 2 0 2 5 Audio Player for Layers 1 2 and 3 version 1 14 4 written and copyright by Michael Hipp and others free software LGPL GPL without any warranty but with best wishes Decoder ARM Terminal control enabled press h for listing of keys and functions Playing MPEG stream 1 of S classl mo3 G 2 0 Layer III Freq 22050 mode Joint Stereo modext 2 BPF Channels 2 copyright No original Yes CRC No emphasis O Bitrate 64 kbit s Extension value O Title onclassical_deme_demicheli_gemniani_pieces_allegro in f major_small vwe rsion Album Genre Unknown 1046 2369 Time 00 27 16 01 17 95 AVA off Wol 1000160 terminal control keys interrupt restart playback i e un pause next track previous track back to beginning of track loop around current position don t combine with output buffer forward rewind fast forward fast rewind fine forward fine rewind volume up volume down RVA switch verbose switch list current playlist indicating current track there display tag info again print MPEG header info again this help quit or C pitch up small step big step or X pitch down small step big step reset pitch to zero F P zi ofr s g Frame 4008 lj Time 01 44 69 00 00 02 AVA off Vol 114 114 1 44 Decoding of classl mp3 finished Terminal control enabled press h for listing
29. Ultimate GPS Ultimate GPS receiver breakout board This receiver meets the following comprehensive technical specifications that make it ideal for this application Satellites 22 tracking 66 searching Patch antenna size 15 mm x 15mm x 4mm Update rate 1 to 10 hertz Hz Position accuracy 1 8 meters Velocity accuracy 0 1 meter per second m s Warm cold start 34 seconds Acquisition sensitivity 145 dBm Tracking sensitivity 165 dBm Maximum altitude for PA6H tested at 27 000 meters Maximum velocity 515 m s Vn range 3 0 5 5 V MTK3339 operating current 25 mA tracking 20 mA current draw during navigation Output NMEA 0183 9600 baud Bd default DGPS WAAS EGNOS supported FCC E911 compliance and AGPS support Offline mode EPO valid up to 14 days Up to 210 PRN channels Jammer detection and reduction Multipath detection and compensation Capability of an external antenna being attached UART for data communications This last feature will be discussed further in the following section UART Communications I will neither need nor use many of these features but they are listed here to give you an appreciation of the technical complexity and versatility of this particular GPS receiver There are several key specifications that are worth discussing a bit more An acquisition sensitivity of 145 dBm means the receiver is extremely sensitive to picking up weak GPS signals The 165 dBm tracking sensit
30. any code on the RasPi Ensure that you have a good line of sight with the open sky in order to receive the GPS satellite signals I used an external GPS antenna since my test setup was indoors without any reliable satellite reception The antenna was purchased from Adafruit Industries part number 960 and is well worth the modest cost because erratic or unreliable satellite reception will quickly cause this project to fail You will also need an antenna adapter to connect the external antenna s SMA connector to the pFL connector situated on the Ultimate GPS receiver board This adapter was also purchased from Adafruit part number 851 and is shown in Fig 5 15 A word of caution Be very careful when pushing the pFL connector into the board because the inner pin appears to be quite fragile and probably would be damaged if excessive pressure were applied The quickest and easiest approach for a data connection is to temporarily connect the laptop to the GPS receiver with the USB TTL cable using the connections shown in Fig 5 16 You can parallel connect to the existing TXD and GND on the solderless breadboard without a problem Ultimate GPS Receiver USB TTL black cable USB TTL cable connection from GPS to laptop I used the Tera Term program with the baud rate set to 9600 to match the GPS receiver output Figure 5 17 is a screen capture of the GPS data stream showing that the GPS receiver was properly functioning and receiving good sat
31. sys class i2c adapter i2c 1l new device J exit J TOTE 12c 1 is for a rev 2 RasPi Use i2c 0 for a rev 1 RasPi You may now check the time stored in the RTC by typing the following sudo hwclock r The RTC should report back Jan 1 2000 if it has not been previously set Figure 15 8 is a screenshot showing all the previous commands as well as the time Notice that it reported a date different from Jan 1 2000 because I had rebooted the RasPi in the setup a pi raspberrypi File Edit Tabs Help pigraspberrypi sudo izedetect y o m i T 5 T e B 2 u pigraspberrypi sudo modprobe rtc ds1307 pigraspberrypi sudo bash root raspberrypi home pi echo dsl1307 0x65 gt sys class 12c adapter si2c 1 new_device root raspberrypi hom pie exit exit pigraspberrypi sudo hwelock r Mon 06 May 2013 04 36 39 UTC 0 327059 seconds pigraspberrypi Screenshot of the RTC setup You will now need to set the current date and time for the RTC This may be done in two ways The first and probably easiest is to connect the RasPi to an Internet accessible network in order to set the current date and time Simply plug in an Ethernet cable or a Wi Fi adapter and let the RasPi seek out and set its clock using the NTP service After a minute or two the RasPi should have acquired and set its system time to the current date and time The second method of setting the date
32. the video requirements are quite low and the Linux Raspian distribution will automatically detect quite a few types of webcams including many older ones If you already own a webcam my suggestion is to plug it into a USB port and then type the following into a command line lsusb H Figure 8 2 is a screenshot of the command s output Device 008 is the webcam and the other Logitech device listed is a keyboard If in doubt about which device is the right one when multiple devices from the same manufacturer show up simply unplug the device and rerun the command to see which one disappears piaraspberrypi BX File Edit Tabs Help pigraspberrypi lsusb 001 Device 002 ID 0424 9512 Standard Microsystems Corp 00l Device 001 ID 1d b 002 Linux Foundation 2 0 root hub Bus OO1 Device O03 s 001 Device 004 ID 046d 062d Logitech Inc 001 Device 005 ID 0563 0608 Genesys Logic Inc USB 2 0 4 Port HUB OO1 Device 066 ID 7392 7811 Edimax Technology Co Ltd EW 7811Un 802 11n Wi reless Adapter Realtek RITL81eecus Bus 001 Device 007 ID 1241 1177 Belkin F8E842 0L Mouse Bus 001 Device 006 _ID O46d c326 Logitech Inc pigraspberrypi lsusb output screenshot One key point I discovered in creating this project is that the webcam has to be directly plugged into one of the two RasPi USB ports The webcam was not detected by the software when it was connected to a powered hub USB connector I am not sure why this happened bu
33. which could take several minutes depending on the antenna signal strength I used an external antenna and was able to consistently obtain a good lock in about two minutes You may now use the date command to check on the precision time that is obtained from the GPS system The ntp conf file must now be edited if all is well at this stage in the process The following line indicates that the RasPi should be available as a stratum 10 server to other networked computers if desired server 127 127 28 0 stratum 10 Additionally uncomment and edit the following existing line in ntp conf broadcast 192 168 123 255 I changed this line to broadcast 192 168 1 255 This line allows the NTP server to broadcast the time to all computers located on the same subnet as the server Your subnet may be slightly different Type these three commands to ensure that the NTP server is operating sudo killall gpsd J sudo gpsd dev ttyAMAO F var run gpsd sock J sudo service ntp restart J I recommend using a program named ntpdate to confirm that a client computer is connected to and using the NTP server Install the ntpdate program by typing sudo apt get install ntpdate Type the following command on the client computer another RasPi that is intended to use the NTP clock signal to confirm it is being received sudo ntpdate vd 192 168 1 43 J The local IP address for my NTP server is 192 168 1 43 Figure 15 16 is a screenshot of the
34. you open another page shown in Fig 10 19 that provides data from the Temperature Module 28 C1EA25030000 wo directory address 28C1EA24030000C4 m SEa CHANGE alias ee __ fide family TE fasttemp 2 id C1EA25030000 locator FFFFFFFFFFFFFFFF power YES O O OOOO O r_address C400000325EAC128 r_id 000003 25EACI1 r_locator FFFFFFFFFFFFFFFF temperature 20 125 itemperaturel0 20 75 temperaturel2 20 128 temperature9 2100000 T CHANGE temphigh templow r CHANGE type IDS 1 520 Temperature Module results A lot of information appears but the key data is the temperature itself which is shown at 20 8125 C You need to refer to the owfs user s manual to determine what all the other data means except the temphigh and templow entries which are self explanatory Apparently those readings are shown in degrees Fahrenheit due to the owfs default configuration setup Clicking on the directory named 26 882728010000 opens the Humidity Module page Figure 10 20 shows the data on this page 26 882728010Q00 sic 3 amnas aD RI A S ae ee a a a aE lt lt i TT Jaddress cimmi eo ee Se ed ee a m a date Wed Dec 31 23 16 33 196 disconnect endcharge lendcharge O en IA humidity 16 i es ime ee locator offset r 4400000128278
35. 001 Device 006 ID 1241 1177 Belkin FeSES42 DL Mouse Bus O01 Device 007 ID 046d 326 Logitech Ine pi raspberrypi lsusb display 2 This step is a precautionary one to ensure that the Wheezy distribution is updated and upgraded Type in the following commands sudo apt get update 4 sudo apt get upgrade This can take some time if there are many upgrades needed 3 Next the required build tools need to be installed Type in the following command sudo apt get install autoconf libtool libusb dev libfuse dev J 4 The source code has to be downloaded next Type in the following command sudo wget http sourceforge net projects owfs files owfs 2 8p15 owfs 2 8p15 tar gz el 5 Extract the source code and subdirectory from the archive file by typing sudo tar z2xvf owfs 2 8p15 tar gz J 6 Change from the pi directory to the newly created owfs 2 8p15 directory by typing cd owfs 2 8p15 J 7 The source code must now be configured Type sudo configure This step takes about three minutes to complete 8 The build happens next Type sudo make Be patient this takes over 30 minutes to complete 9 Finish the build process by typing sudo make install It takes about one minute 10 You now need to create a directory where the device files may be accessed Type sudo mkdir mnt lwire J 11 I found the next step useful as a way to ensure that the RasPi was in a
36. 168 1 22 00 27 5A0C A0 E7 HPOCAQE re 1s216a120 onaoasereeca uYBOOKWORID__ _ Router attached devices list The entry RASPBERRYPI has the IP 192 168 1 21 on the wired portion of my home network This is all I need to remotely view the webcam I just have to type 192 168 1 21 8081 into a browser on another networked computer to view the real time webcam video stream Figure 8 9 is a screen capture of the video feed from the RasPi webcam I used the robot car from Chaps 12 and 13 as the subject Lee is mny a r i Faha Bikerie as Piva saes ci Ia Video stream screen capture E Mail Notification The next step in this project is to discuss the software that sends out an e mail when the laser trip system is triggered You will need a working Gmail account in order to have this software function because it uses a Python package named smtplib which in turn uses Google s freely available Gmail smtp server The software is also designed to run in a home network using a router I will show you how to obtain the public facing IP address that is dynamically assigned by your Internet Service Provider ISP The Python code that sends out the e mail notification is shown on page 110 Email Notification Python Code import subprocess import smtplib import socket from email mime text import MIMEText import datetime import os Fput the destination e mail address here to youremail isp com
37. 24 GPIO IN GPIO setup 25 GPIO IH while True fcheck for the focus push button press if GPIO input 18 False trigqger the optoisolator connected to the focus lead GPIO output 4 GPIO HIGH need a little time for the camera to focus time sleep 2 reset the optoisolator GPIO outoutid GPIO LOW Fcheck for the shutter push button press if GPIO input 22 False ftrigger the optoisolator connected to the shutter lead GPIO output 17 GPIO HIGH time sleep 2 GPIO cutput 17 GPIO LOW check for the flash push button press if GPIO input 23 Palse trigger the optoisolator connected to the flash I use pin 27 for rev 2 board GPIO cutput 27 GPIO HIGH time sleep 2 GPIO output 2 7 GPIO LOW I recommend running this program directly from a terminal window as follows sudo python CameraControl py 4 Press each of the push buttons and confirm that the appropriate action occurs When you are finished type c to exit the program You should note that I reset the controlling GPIO pin after making it a HIGH value This ensures that it is in the proper state for the next operation Sound Module Test Program The following program tests the sound module to check that the focus shutter and flash can be triggered when the sound module detects a sound event The first portion of this program is identical to the previous program This program interacts with you through the screen by prompting a number rep
38. 3 ow_eight py 146 owfs 1 Wire File System 125 in local and remote logic controller project 141 143 152 153 in weather station project 133 134 P Packet sniffing 1 Wire weather station project 135 137 Parallax 156 157 Parasitic power supply 131 Password for initial startup 14 PCB printed circuit board 1 Permission Denied error 144 Philips Company 12 pi user 16 Pi Cobbler 31 32 37 connection to GPS receiver 64 in earthquake detector project 79 81 in NFC RFID reader project 121 in remote logic controller project 149 in robotic car project 165 in RTC project 189 Pi Plate see Prototype board PIC24HJ64GA002 microprocessor 76 Pink noise 33 34 Pink noise signal 34 Play Store app 147 PMS Poor Man s Seismograph 75 PN532 NFC breakout board 115 117 121 Pool servers 194 195 Poor Man s Seismograph PMS 75 Portable controllers 91 Portable radiation detector 182 185 Portable stereo speaker 31 34 Positive power supply voltage Vaa 10 Potentiometer 76 Power connector 5 Preprogrammed SD card 3 4 Print function 18 19 Printed circuit board PCB 1 Programming languages color coding of code 19 high and low level 17 interpreted 18 for RasPi see Python programming Programming the Raspberry Pi Simon Monk 17 Prolific 62 Prototype board Pi Plate 23 24 31 32 Pulse width modulation PWM 161 Pulse Width Modulation PWM Servo Driver I C Interfac
39. 3 PIC24HJ64GA002 76 on SoCs 1 in Z Wave devices 91 Microrem mrem 182 Mills David 193 mkdir directory Linux command 17 modprobe app 32 190 Moment magnitude scale 73 Monitors analog 7 choices of 6 Monk Simon 17 MOSFET metal oxide semiconductor field effect transistor 131 132 Most significant bit MSB 78 Motion software package 103 105 109 features of 106 setup of 106 109 Motorola Corporation 187 MP3 files playing 35 37 WAV files vs 34 35 MP3 player project 31 41 ALSA 31 34 audio file formats 34 37 expanding 40 41 hardware switches 37 38 and operational speed of RasPi 38 39 player schematic 40 prototype connector 31 32 requirements 39 41 stereo speaker 31 34 testing 40 writing program 39 40 MP3_Player py 39 40 MP601 operational amplifier 76 mpg 123 35 37 40 mpg 321 35 MPXA4115A sensor 128 MSB most significant bit 78 Multidrop network 12 N NACK Negative Acknowledgment packets 89 90 nano text editor 17 19 20 National Marine Electronics Association NMEA 58 66 See also NMEA 0183 standard Near Field Communications NFC data communications flow 116 defined 115 functioning of 115 hardware 115 116 See also NFC RFID reader project Negative Acknowledgment NACK packets 89 90 Network Time Protocol NTP 187 193 197 Newton Rona 75 NEC see Near Field Communications NEC Shield 115 nfc poll program 121 1
40. 3 time 2013 01 137T1 000Z sept 005 lat J3 238538333 Lon fl 045736667 alt 182 500 S TPV tag RMC device dev ttyAMAO mode 3 time 2013 01 13T1 0 2112 ept 0 005 Lat 43 2385 33333 Lon 71 045738333 alt 182 500 000 track 355 6600 speed 0 139 climb 0 000 arinak A Cgps screenshot cu NNO Ne w tee Ss Eu Gi ai On oo NANO hJ The figure shows the parsed or analyzed GPS data that is streaming in real time from the Ultimate GPS receiver There is a lot of information displayed including the following on the left hand side Date Y YY Y MM DD Time UTC accurate to 1 millisecond Latitude xx xxxxxx Nor S Longitude xxx xxxxxx E or W Altitude Meters above sea level Speed Kilometers hour km h or kph Heading Degrees true not magnetic Climb rate Meters second applicable to aviation Status Usually 3D but maybe 2D or no fix Longitude error Usually several meters Latitude error Usually several meters Altitude error Meters could be 10s of meters Course error Degrees applicable to aviation Speed error Usually a fraction of a km h or kph Time offset Difference between GPS and UTC clocks usually ignored Grid Square The Maidenhead Locator System grid indicator On the right hand side is a real time list of the GPS satellites in view There were six satellites in Fig 5 19 three of which we
41. 4 or higher anything less and you will be disappointed in your RasPi s slow response RasPi Connectors The RasPi has nine connectors power High Definition Multimedia Interface HDMI analog composite video audio ethernet Universal Serial Bus USB two future expansion connectors and the General Purpose Input Output GPIO interface Each connector has specific functions that I will discuss in the following sections except for the expansion connectors which are not yet used although I will tell you what I know about them as of this writing There is no particular order to this discussion although I have left the GPIO connector for last because it is by far the most complex and hence requires the most explanation Power Connector The power connector shown in Fig 1 5 is a micro USB socket that is wired to pass the 5 volt V direct current DC lines from a micro USB plug also shown in the figure Since all voltage in this project is DC I will use just the notation V for V DC No data connections are wired to this socket You can use almost any available smartphone charger that has a micro USB connector or use the power supply that came with the RasPi kit if that s what you purchased a a p Ao Cd Lot AoT am gS ab niem gt in i B y i Py SS ee Oi i pa TELL ch weet ty 3 Jn SU UT apen al a stata eed Micro USB power connector Figure 1 6 shows a RasPi k
42. A 3 15 19 30 13 03 31 21 23 l 39 1 07 0 88 02 SGPRMC 031205 000 A 4314 2616 N 07102 7307 W 0 68 41 33 120113 A 45 SGFYTG 41 33 T H 0 66 N 1 25 KA OD F Clear Hex output r Log to home piicutecom log A reo Ls 32 72 120113 A 7F Input B Send file Plain LF line end Char delay i ms CuteCom GPS data stream Completing the steps just described confirms the proper operation of the Ultimate GPS receiver and the proper functioning of the data connection between the RasPi and the receiver You are almost ready to start using the GPS receiver but first I need to discuss the NMEA protocol and the messages that are being generated from the Ultimate GPS receiver NMEA Protocol NMEA is the acronym for the National Marine Electronics Association but nobody refers to it by its formal name NMEA is the originator and continuing sponsor of the NMEA 0183 standard which defines among other things the electrical and physical standards to be used in GPS receivers This Standard specifies a series of message types that receivers use to create messages that conform to the following rules also known as the Application Layer Protocol Rules The starting character in each message is the dollar sign The next five characters are composed of the talker ID first two characters and the message type last three characters All data fields that follow are delimited by commas Unava
43. Controller Introduction Additional Sensors I a Weather Station Design 14R Introduction Wire External Control Board Wire File S System owfs Installation and Confi 5 UX aoe e uy 8 Channel I O Board uration iene Car pies m Operating the Robotic Car Future Expat adon Detector Introduction Preface This Raspberry Pi project book is not only about building a series of interesting projects but also about providing an education regarding the underlying project technologies I am positive that my over 30 years experience as a college educator forced me to ensure that readers could not only build the projects but also understand why they function as designed Building a successful project is rewarding unto itself but understanding why and how it functions is far more important The reader should expect a manifold increase in experience with the Raspberry Pi if a commitment is made to expend the time and energy to complete most if not all of the projects I learned a lot while completing them sometimes things worked out fine while other times they were not successful But that s the joy of experimenting As Professor Einstein once stated Anyone who has never made a mistake has never tried anything new The joy of learning about and building projects is the core concept within this book I designed and built all of the projects and along the way
44. E ra me e i ra inp 2 eoa amp a s ty s k ty 3 me Le Ata T 4 Po yo Dd Diagram of the GPS satellite constellation Several other GPS systems are also deployed GLONASS tThe Russian GPS Galileo The European GPS Compass The Chinese GPS IRNSS The Indian Regional Navigation Satellite System I will be using the American GPS system as vendors have made many inexpensive receivers available to purchase All receivers function in essentially the same way and conform to the National Marine Electronics Association NMEA standard discussed in the NMEA Protocol section The Basics of How GPS Functions I made up an analogous fictional position location system to help explain how the GPS system functions First imagine a two mile by two mile land area where this system is set up The land terrain contains gently rolling hills each no more than 30 feet in height The subject using a special GPS receiver may be located anywhere within this area Also located in this area are six 100 foot towers each containing a beacon The beacon atop each tower is configured to briefly flash a light and emit a loud sound burst simultaneously Each beacon also emits light and sound pulses once a minute but at a specific time within the minute Beacon one B1 emits at the start of the minute beacon two B2 at 10 seconds past the start of the minute beacon three B3 at 10 seconds later and so on for
45. Fig 1 25 Occidentalis GUI desktop Some Linux Fundamentals As I promised you earlier I am not going to provide a tutorial on Linux in this book However you will still need to have some very basic knowledge of it to understand what is happening with the commands being processed The discussion below is for readers with a very limited knowledge of Linux Feel free to skip this section if you already have a basic to good understanding of Linux The Linux operating system is based upon Unix and it has assigned built in privileges which limit most users to some extent but allow one user unlimited access This unlimited user is named root and essentially is equivalent to an administrator level in a Windows operating system Some commands can be run or executed only by root again for security reasons There is a fundamental computer security principle known as least privilege by which users are granted only as much access or privilege as they need to complete their task It is not considered a good idea to run all tasks or programs as root so most of the time you will be running as the user named pi However as I mentioned earlier some commands can only be run as root The answer to this conundrum is to promote an ordinary user to what is known as a super user The sudo command accomplishes this neat feat I will frequently use the sudo command with other commands and you now know why I will also typically use terminal
46. Figure 13 6 shows the V4 Targus Bluetooth adapter that I used in this project I am sure that similar type adapters will function equally as well but just ensure that you choose a high speed class 4 device Targus Bluetooth adapter Now start the RasPi and check that the Wheezy distribution has recognized the Bluetooth adapter Enter the following at a command line prompt lsusb The listing in Fig 13 7 shows that the adapter has been found and an appropriate driver loaded for it The Targus adapter apparently uses a Broadcom chip from the same fine company that makes the RasPi core processor m pi raspberrypi ireas File Edt Jabs Help pigraspberrypi lsusb Bus 001 Device O02 ID 0424 9512 Standard Microsystems Corp Bus OO1 Device O01 ID 1d6b 0002 Linux Foundation 2 0 root hub Bus 001 Device 003 ID 0424 ec00 Standard Microsystems Corp Bus O61 Device GA ID GaSce 21e8 Broadcom Corp Blurlooth Adapter apes Beco bint Genesys Logic Inc USB 2 0 4 Port HUB Bus 001 Device O06 ID 1241 Belkin FRE842 DL Mouse Bus 001 Device OOF ID O46c Logitech Inc pigraspberrypi lsusb listing You next need to download and install the bluetooth software package Enter the following at a command line prompt sudo apt get update sudo apt get install bluetooth Be patient this takes a while Enter the following to check if the Bluetooth service is running sudo service bluetooth status Figure 13 8 show
47. I used a sheet of Lexan as a support plate to which I mounted all the other components by using nylon spacers and long machine screws and nuts This type of assembly is definitely a cut and fit operation where it is impossible to create a detailed plan because every installation will be slightly different Just take your time as you carefully fit all the boards in place and mark all the drill holes with a Sharpie prior to drilling I must have assembled and disassembled this unit over a dozen times before finishing it Figure 14 14 shows the unit in the box without the top attached and with a portable analog monitor positioned behind the box The Geiger counter installed in a box with the monitor The monitor is powered directly from the LiPo battery through a type N power jack installed in the box Also notice that I drilled a 5 8 inch hole through the box in order to have access to the RasPi s analog video socket There is an on off switch also mounted above the monitor power socket that controls the power to every component in the box If you look carefully at Fig 14 14 you will notice a inch hole drilled through the box just to the left of the GM tube This hole is also capped with a metal plug I drilled this hole so that beta particles could be detected by the Geiger counter if desired Remember from the earlier discussion that beta particles can be shielded by a thin plastic layer so this box would certainly stop them Operatin
48. I will try to use the RasPi pin designations whenever possible however there will be situations where the software will require the use of the BMC2835 pin designations I will try to be as clear as possible regarding the exact pin that is being used and for what purpose Table 1 2 GPIO Pin Descriptions RasPi pin RasPi Description BMC Description RasPi pin RasPi Description BMC Description 3v3 3v3 2 5V0 5vO SDA0 GPIOO i SYO SVO SCLO GPIOT 6 GND GND GPIO_GCLK GPIO4 8 TXDO GPIO14 GND GND 10 RXOO GPIOIS GPIO_GENO SPIO 12 GPIO_GENI1 GPIOW8 GSPIO_GEN2 GPIO Z1 14 GND GND GPIO_GENS GPIO2 16 GPIO_GEN4 GPIO23 aS SVS 18 GPIO_ GENS GPIO24 SPI MOSI GPIOIO 20 GND GND SPI MISO GPIO 22 GPIO_GEN6 GPIO25 SPI_SCLK GPION 24 SPI_CEO_N GPIOS GND GND 26 SPI_CElN GPIO7 Legend aV3 3 5 V os Serial Peripheral Interface BVO 5 0 Y Serial Transmit GND Ground Serial Receive GPIO_ GENn General Purpose Input Output pin n n Can be reconfigured as a GPIO pin The Universal Asynchronous Receiver Transmitter UART Serial Peripheral Interface SPI and Inter Integrated Circuit I C functional pins listed in the table may all be reconfigured as GPIO pins These are shown with an asterisk in Table 1 2 This means that up to 17 GPIO pins 8 existing GPIO 9 reconfigurable are available for hardware interfacing provided that the functions mentioned before are not needed Figure 1 16 shows all the GPIO connector pins with the BCM2835 pi
49. Link Layer 2 that starts with a synchronization preamble followed by a Start of Frame SoF byte Next comes the payload which can be up to 64 data bytes and is terminated by an End of Frame EoF byte The Transport Layer 3 takes the basic packet and adds additional bytes depending upon what is required in the communication process Z Wave is a connection type network similar to Ethernet which has a very robust way of ensuring that packets get where they need to go Layer 3 uses Acknowledgement ACK and Negative Acknowledgement NACK packets to maintain solid connections A receiver node will send back an ACK packet to the sender if it successfully receives a data packet otherwise it sends back a NACK This will continue until the original data packet is successfully sent or a preset number of retries is exceeded Each node also uses Collision Detection Multiple Access CDMA to determine when to transmit on the network signal lines It is akin to the old fashioned telephone party line where a user first listens to determine if anyone is talking and then Starts talking if the line is free In the case where a collision does occur each potential sender backs off a random amount of time tens of milliseconds and then tries again Using ACKs and NACKs depends upon an error checking capability which is why two checksum bytes are included in every data packet These bytes are used by the receiving node in a mathematical algorithm to determine
50. PCA9685 chip that is the logic controller used in the servo board I believe that 0 x 70 is another controller address that is generated during a power on reset In any case 0 x 40 is the only address that will be used in the Python program This address may be changed in hardware by connecting solder bridges located on the board These bridges are easily seen on the upper right hand side of the board as shown in Fig 12 20 Board addresses would have to be changed if multiple servo controllers were used on the I C bus to prevent addressing conflicts pi raspberrypt File Edit Tabs Help pigraspberrypi scrot pig raspberrypi sudo 12cdetect y 1 4567 68 S amp S a bc de f Oo dl RE OW ao ce eee ee Se pigraspberrypi scrotfj Detecting the I C servo controller This chapter does not have a summary section as the project is not yet complete The next chapter shows how to wire the car and program it so that it can be controlled by a Wiimote Robotic Car Part 2 Introduction This is the second of two chapters that will show you how to complete the RasPi controlled robotic car a project that was started in Chap 12 This chapter deals with the electrical wiring and most of the programming required to control the car Robotic Car Block Diagram Figure 13 1 is a block diagram showing all of the robotic car electrical components 1 CR Servo TFT Monitor 16 Channel Cobbler
51. Project Requirements I will start this project by listing the requirements that the controller system should meet These have been simplified to make the controller compatible with a wide variety of cameras and electronic flash units In order to take full advantage of all the system functions you will need a camera that is capable of being remotely triggered The controller system requirements are shown in Table 4 1 Table 4 1 Camera Controller Requirements Mode Trigger Source Delay Range Shutter Operation Camera only Manual 0 10 seconds Focus half press Sound module 1msec Shutter full press Laser module resolution Camera and flash Manual 0 10 seconds Focus half press Sound module 1 msec shutter ull press Laser module resoiuhian Flash only Manual 0 10 seconds M A Sound module 1 msec Laser module resolution Time lapse Manual HA O 8 hours 1 second resolution Shutter full press Figure 4 4 is a high level graphical diagram showing the module interconnections associated with each mode listed in Table 4 1 Mode Setup Trigger source Manual button Audio module Laser module Camera only Controller camera Manual button Audio module Camera and flash Controller Laser module camera delay flash Manual button Flash only Controller Audio module Laser module delay Time lapse Controlle
52. The circuit is extremely simple yet highly reliable two attributes that are important in security systems The relay contacts are normally open which means that the GPIO pin will be in a high state due to the 10 kQ resistor tied to 3 3 V The pin will go to ground or to 0 V when the detector is tripped The software thus has to check periodically for a low state on the selected GPIO pin and then initiate all the desired actions which will be discussed in the software section Motion Software Package I selected a software package named Motion to enable remote viewing of the webcam This is a comprehensive package that contains many features far more than could be covered in this chapter Being able to use this package from among the others available is why the RasPi is so useful Creating similar software for a more traditional board such as one from the Arduino series would be a substantial undertaking if it is even possible Motion also has the capability of detecting changes in the images from frame to frame thus triggering an alarm based solely on real time video analysis I thought about using this feature but eventually decided upon the simpler approach of using an external trip system Detecting an intrusion event based on the video alone requires the RasPi to be almost solely committed to vision processing which could affect the availability of the video for remote viewing This may have been an unwatranted decision but remember tha
53. This is a very handy tool to have available for debugging and for program development Local and Remote Logic Controller Introduction This project consists of two major parts both of which concern logic control or put simply turning IO pins on and off The two project parts are closely related and both involve the control of IO pins One uses an external board that provides eight additional GPIO pins and the other is based on the RasPi itself The external board uses the 1 Wire protocol that was introduced in the Chap 10 project for building a weather station This board may be either controlled through a program running on the RasPi or accessed using the home network as was demonstrated in the Chap 10 weather project The other project part directly controls the RasPi GPIO pins This part may be thought of as an extension of the fundamental concepts that were first discussed in the Chap 2 demonstration of a blinking LED In this part the GPIO pins will be controlled from an Android smartphone client application with the RasPi acting as a web server The RasPi may also be controlled from a browser which will also be demonstrated At the end of the chapter I will discuss how both project parts can be accessed over the Internet The good news regarding this project is that there is very little hardware construction involved The more interesting never bad news is that a fair amount of software installation and configuration is in
54. UART logical connection available to libnfc The default Wheezy image has it connected to a console named ttyAMAQO which prevents it from being used by another process 1 Type the following at a terminal command prompt sudo nano boot cmdline txt Edit the single line of text so that it matches what is shown in Fig 9 5 All references to ttyAMAO are removed GHW nano 2 2 6 File beeot ondling txt awe ot J la enable console ttyl roote dev mechlkope rootistypeeext4 elevator dead ing reestwait The cmdline txt edited content Don t change anything else or you will not be able to reboot the RasPi 2 Type the following at a terminal command prompt sudo nano etc inittab J Add a sign in front of the line below TO 23 respawn sbin getty L ttyAMAO 115200 vtl100 Figure 9 6 shows the edited file k Spawn a getty on Raspberry Pi serial line T0 23 respawn sbin getty L ttyAMA0O 115200 wt100 The inittab edited content 3 Type the following at a terminal command prompt sudo reboot A reboot is needed to proceed with the rest of the installation 4 The source code now needs to be downloaded into a new directory named libnfc Ensure that you are in the pi directory before starting this step Type the following series of commands mkdir libnfc H cd libnfc J sudo wget http libnfc googlecode com files libnfc 1 6 0 rel tar gz 4 Figure 9 7 shows a successful download of the libnf
55. World program I do not like to trifle with tradition and will adhere to this unwritten rule Now it is perfectly possible to execute the print command and see Hello world displayed below as is shown in Fig 1 28 Python Shell Elle Edit Shell Debug Options Windows Help Python 2 7 are2 default May 6 2012 20 02 25 oce 4 6 3 on linux Type copyright credits or License for more information ati Helle World Hallo world Be Python print command As this book is printed in monochrome I will point out the following as you observe the output in the Python shell The word print is reddish orange as it is a reserved word describing a preset function The words Hello world in the parentheses following the print function are shown in green to indicate a string of characters Character strings are enclosed between single quotes Finally the words Hello world displayed below the print function are in blue as they represent a string output This default color coding of program code is fairly standard with various development tools however the exact colors assigned to the different elements will vary From this point on I will now use text only to show the shell prompt commands operations and results to conserve valuable book space You should also carefully observe the Linux shell because there may be information shown that I do not transcribe I will now show you how to create a very simple program that produ
56. are using are the following Baud rate 115 200 Number of data bits 8 Parity None Stop bits 1 You should see a screen similar to the screenshot in Fig 5 12 if you have setup everything correctly including the Prolific driver Wi COM5 115200baud Tera Term VT File Edit Setup Control Window Help hone pi piGraspherrypi ls Pet ee ee ee scrot png class wav Mus ician way 261 2 12 18 874259_1824984_scrot png Desktop python _games COLE LEAMS RSet secret pog drevil way sleep Away mp3 Kalinha mp3 SoundModlest py CaneraControl py LighthodIest py Test_Switch py Ses ee Haid mp3 Time Lapse py lassi wav AP _Plaver py class mp3 APS_Sin py Diraspherrypi 0 Sample screenshot from Tera Term program connected to RasPi Figure 5 13 shows another screenshot using the ZOC terminal control program connected to the RasPi E r e ae dF Ee sein Sf MEE ss j N hie Eie y View Leyi Tren wer Serie Oain Hele i S Oe G8 GCEANN A ee Te ia ison Abai thew Bummer Send ee a Call Heat from Heat Directory a Ran Sampie Sigt Linus sherry fsid rasphberrypi that pasteaed i lagia pi SERLAL OLRECT CONNECTED TO PORT Wi WOGHG CLIS200 8N1 es Sor att logins Sun dan 6 12 24 45 EST 2017 on ttyl eee eila P p i re 250 PREEMPT Thu Oct 1B 19 03 02 EST 2012 ered Tie program fing leded with the Debian Gal Licas gates are free poftware the
57. contents of the current directory Desktop python_games pi raspberrypi S mkdir Python make create a new directory named Python pi raspberrypi ls Desktop Python python games new directory now present pi raspberrypi S cd Python J 20 into this new directory change directory pif raspberrypi pwd J check for the new path home pi Python yes it 1s correct pi raspberrypi S ls J check if anything is in the new directory pi raspberrypi prompt returns without displaying anything directory is empty You should now be in your development directory Python ready to download the GPIO library archive You have several choices on how to download the archive file You can use a browser on the RasPi and just do a direct download or you can use a PC and download it into a thumb drive which you then carry over to the RasPi and transfer it using the File Manager app I choose to do the latter as the PC download process is much faster In days of yore this approach was called the sneakernet The archive must now be uncompressed and the contents extracted Assuming you are still using a terminal window in the Python directory type the following pi raspberrypi tar xzf RPi GPIO 0 4 la tar gz Ensure that you type in the exact name with uppercase and lowercase letters as shown Linux is very picky in this regard and will throw an error message that it cannot find the file if you don t
58. data blocking diode parasitic power Capacitor based parasitic power supply The blocking diode shown in the figure prevents the charged capacitor from interfering with the voltage levels on the data line There are two disadvantages to using this scheme 1 The increased capacitive load on the bus data line decreases the effective physical length of the bus line 2 The capacitor charge can supply only a very small current before being discharged The third way using an active device such as a MOSFET allows for power to be supplied to the data line during idle time It essentially improves the parasitic power supply performance because the master controls the MOSFET to provide a strong pull up during idle time This circuit is shown in Fig 10 14 1 Wire data MOSFET pull up microproce SSO _ resistor V pull up Active pull up power supply The active pull up provides for extended range and a much better current supply at the expense of requiring a dedicated microprocessor GPIO pin as well as additional programming for that GPIO pin 1 Wire Sniffer The 1 Wire Sniffer is a diagnostic module that connects to the 1 Wire network and provides a real time view of the data flow It has an RS 232 serial port that may be seen at the top of the PCB as shown in Fig 10 15 i F i C i Hire Sniffer vi l Me Cera Hob Boor de a a Fug Ci a o pa g 1 Wire Sniffer PCB
59. due to 1945 human experiment Converting radiation activity levels to dose is greatly simplified in this project by the use of a calibration curve supplied by the kit provider Figure 14 2 shows the calibration curve related to the Geiger Muller GM tube used in the K2645 GM counter rE e E b bag gt ee a b E bes CE E E bes i ienn m L i E EE E F E B oo eed E ETEEN DOE eerti T gt ask E u we i a ETI E Ei I J E A L a b ngk 2 a atl forum Bm Spd ao a Bok ee Hate 1a E to p abb a p siti Gi T E u 1 T ee ee a a abb a 1 ir 4 a Li EO n arm a a E pD t tere of e Pee i Peat lR iii d pp 11m m 5 tiha e ehi i a b i aT EL ake THI T of 2 a EFE Pi bett E E F eee ot TETTE E ff erTeere EENT E n b paink E 1 EIS ooo beers fo eb ewes E on Bmaeeer ion ctr fee B r EE EETE EHH Hi rert i kaiii J erii mi E pono r rere ka ai E bibani i abe eris e e e eee tia a E tithe ttt HH His tf Fre oo est i e Pen mat E obter E a m E n De ao E S ro m mmes i badii b pi iiih i i in i miee h ir P PEP CAET EE aes eS tH te eed rst EHER of aan in eren r rama bee ah ee Se i beini ies eee a tis fine eatery ian TE Emm ES EPET 1 bid Bed LS bide ed beeen oes sao ee i haia es eee eee o a Tree r 1a n e c oor a _ ETTI ee a se ee e m e T s EE E E 1 E Lii a
60. enter the name exactly as it appears The tar app will create a new directory named RPi GPIO 0 4 1a where you will find over a dozen files and directories newly created Type the following to transfer into this directory pi raspberrypi cd RPi GPIO 0 4 la Incidentally I will no longer explicitly show these commands as you should now be more comfortable using them I will instead simply say cd into RPi GPIO 0 4 1a and you will instantly know what I mean Let s test this newfound confidence 1s the RPi GPIO 0 4 1a directory You should now be looking at a list of all the files and subdirectories One file should pique your interest it is named INSTALL txt cat this file to read the contents You could also double click on it to open it in a text editor but I am feeling confident that you are starting to get the feel of how to operate quickly and efficiently at the command line level where the pros live Back to the INSTALL txt file It contains important instructions regarding loading another module required to use the GPIO library The key instruction is the following sudo apt get install python RPi gpio ad Please read the following section before you enter the above command apt get Command The acronym apt is short for advanced packaging tool You almost always use the command in the form of apt get for instructing the computer to get a package of software using the Internet The key to making this all work is a list of
61. family latch LCD H PIO 3 PIO BYTE sensed 0 sensed 6 type id latch 5 Emi PIO 4 por sensed 1 sensed 7 latch 0 latch 6 locator PIO power sensed 2 sensed ALL pifraspberrypi mnt lwire 29 Ba2E0s000000 atmes 1 Wire owls mount operation cd mnt lwire J I did an 1s to display the 1wire directory contents that identified the two normal 1 Wire devices on the network the Sniffer Module is non conforming The USB 1 Wire adapter belongs to the family of 1 Wire devices beginning with the string 81 That meant the remaining directory starting with the family designator of 29 must be the 8 Channel I O board I changed into that directory by typing cd 29 B82E08000000 J The directory contents are displayed at the bottom of Fig 11 4 I would like next to clarify an important aspect of how Linux treats hardware before proceeding much further into this part of the project Linux Hardware and FUSE Unix and its descendent Linux treat everything as files according to the old mantra This phrase encompasses all things including hard drive files serial ports thumb drives etc You can read and write to a hardware device if it accommodates such actions in exactly the same way as you can read and write to an ordinary file provided the permissions are properly set The view that everything can be handled as a file certainly simplifies how programs handle data to and from hardware devices There is also a
62. first I would like to demonstrate a simple Z Wave network that uses a portable controller Fig 7 5 along with two nodes one being the duplex outlet Fig 7 4 and the other being an outdoor module shown in Fig 7 8 Notice the black button located on the top of the device in Fig 7 8 The user presses it to join the device to the network when prompted by the controller menu Z Wave outdoor module Notice the black button located on the top of the device in Fig 7 8 The user presses it to join the device to the network when prompted by the controller menu My test network slaves will be made up of the duplex outlet and the outdoor module each controlling a small table lamp The duplex outlet will actually be connected to a power cord plugged into a regular outlet for this temporary test arrangement Figure 7 9 shows the test setup on my dining room table Z Wave test system At first I arbitrarily assigned a device number 4 to the duplex outlet and a device number 8 to the outdoor module I then proceeded to turn the lamps on and off and everything worked just fine I was also able to control both devices simultaneously by selecting the All mode on the remote The next part of the test was a bit harder as I have a smaller home with an open plan layout meaning fewer interior walls than in the average cape style home I was finally able to place the outdoor module device in the basement and the duplex outlet on t
63. gained a lot of knowledge about the Linux OS and how it really shines as an embedded development platform I will not recap the projects here other than to state that the complexity increases from the book s beginning to its end And this is how it should be as experience and confidence in dealing with Linux and the Python language are progressively gained by proceeding through the projects Experienced Linux developers should feel free to jump into any of the projects however there are useful hints and techniques sprinkled throughout the book which might be missed by taking a selective approach to reading it I have also tried to point out the constraints and limitations of the Raspberry Pi as I encountered them when designing and building the projects Just keep in mind a 35 computer simply cannot meet all expectations One disclaimer that I feel is warranted relates to the Python programs These programs while fully functional for the respective projects are probably not in their best form As I tell my beginning programming students there are many ways to develop functional programs Some are better than others not necessarily right or wrong With this perspective I tried to keep the programs simple and to the point and to avoid any unneeded complexity All of the book s projects can be expanded and modified as desired I strongly recommend that readers do so as that is one sure way to understand the concepts and bolster skills
64. good or consistent state Type sudo reboot Login as you would normally and you should be in the pi directory 12 You now need to start the owfs filesystem and identify the mount point Type the following sudo opt owfs bin owfs allow_ other u m mnt lwire J OTE This command should be done only once after the initial boot If you try to remount the 1wire directory from the command line prompt after an initial mount operation it typically results in a Permission Denied error However I did find that remounts were possible if used in a program statement So called nonempty warnings were created by the owfs file system Figure 11 5 is a screenshot showing the results of the mount operation I then changed directories from pi to lwire by typing pifraspberrypi owfs 2 8p15 sudo mkdir mnt lwire pi raspberrypi owfs 2 8p15 sudo opt owfs bin owfs allow_other u m mnt lwi re DEFAULT ow usb msg c 295 Opened USB D59490 bus master at 1 5 DEFAULT ow_usb_cycle c 191 Set DS9490 1 5 unique id to 81 BA 07 31 00 00 00 F4 pifraspberrypi owfs 2 6p15 cd mnt lwire pi raspberrypi mnt lwire 1s PTT alarm settings pifraspberrypi mnt lwire cd 29 BaZE08s000000 pifraspberrypi mnt lwire s 21 c ls latch 7 PIO 0 PIO 6 r address sensed 3 sensed BYTE alias latch 2 latch ALL PIO 1 PIO 7 r_id sensed 4 set alarm erce latch 3 latch BYTE PIO 2 PIO ALL r locator sensed 5 strobe
65. have greatly exceeded the initial estimate of selling 10 000 RasPi s and at the time of this writing the total sales are approaching one million units The foundation s website is www raspberrypi org where you will find all sorts of information about the board current news forums FAQs and so on A key design decision that kept costs low was to incorporate a SoC type chip on the board SoC is short for System on a Chip a technology that physically places the memory microprocessor and graphics processer in a type of silicon sandwich that in turn minimizes the printed circuit board PCB space and the accompanying PCB interconnecting board traces The foundation eventually partnered with Broadcom to use its designs for both the microprocessor and graphics processors in the SoC The SoC and some other key components and connections that you should know about are identified in Fig 1 2 Compote Video Out Fa REA Jack Analog Audio Owi 26 pin GPIO Connector 7 1 8 in Stereo Jack i i Power LED SS E 5 rr ee TPZ ion i k F i l amp amp amp a E LAN Activity LEDS Sifttieettists 1 Future exp PELL A Power ONLY HOM Videw Out Future pane The SoC and other key components Although it is not critical to understand the Broadcom microprocessor in order to use the RasPi it is still helpful to discuss it for a bit so that you will know why the RasPi is slower than
66. if the received data packet was corrupted during transmission There are many good tutorials available on the Internet regarding checksums and error detection if you are interested in digging further into the subject Layer 3 with the help of network Layer 4 further refines the packets by identifying what the packet type is where it is going and where it s been and then sets the data payload There are five packet types used in the Z Wave network which are described in Table 7 3 Table 7 3 Z Wave Packet Types Packet Type Description Payload Length Remarks Multicast Broadcast to all network nodes 64 bytes max Oxif address Singlecast Sent to a specific node 64 bytes max Up to 232 nodes Routed Repeated packet 64 bytes max 4 hops max ACK 0 NACK Negative Acknowledgement Q Layer 4 sets up the routing thereby ensuring that the packets are sent along the correct paths to reach the desired nodes It also ensures that all nodes are repeating as configured The routing configuration is maintained in a table stored in the primary network controller It is possible to have multiple controllers on the network but only one is designated as primary A simple network topology and descriptive routing table is shown in Fig 7 3 A 1 in the routing table indicates a node to node logical connection Node Topology Routing Table Network topology and routing table Every Z Wave network has a four byte ID called the Home ID Each
67. interface modifications for use in the project since both had output relays that could directly connect with the RasPi GPIO pins without the need for optoisolators Audio Module An assembled audio module is shown in Fig 4 13 You will notice that I connected the microphone to the main board with a foot long twisted wire pair so that I would be able to position it for optimal sound pickup The microphone is normally soldered directly to the main board which would have made it awkward to position the board with the 9 V battery attached in order to best detect the trigger sound sensitivity adjust Point 1 Point 2 Model GSK 409 audio control switch This board does feature a flip flop operation where the output relay is latched after a sound event This means that relay contacts will close and remain closed after the first sound event The next sound event will open the relay contacts and they will stay that way until the next event ad infinitum This is really not a limiting feature for the project since you would probably have planned to manually reset the module before any event using sound as a trigger Notice the sensitivity trim pot that I have pointed out in Fig 4 13 I found that I had to adjust the pot almost fully clockwise in order to have a reasonable opportunity to detect low to moderate volume sound events This module is easily connected to the Pi Cobbler prototype board using the schematic shown in Fig 4 14
68. link There are usually two shift registers involved in the data link as shown in the figure These registers may be hardware or software depending upon the devices involved The RasPi implements its shift register in software while the MCP3008 has a hardware shift register In either case the two shift registers form what is known as an inter chip circular buffer arrangement which is the heart of the SPI O rx 3 an 800 d0WN SPI simplified block diagram Data communication is initiated by the master which begins by selecting the required slave The RasPi selects the MCP3008 by bringing the SS line to a LOW state or 0 V During each clock cycle the master sends a bit to the slave that reads it from the MOSI line Concurrently the slave sends a bit to the master which reads it from the MISO line This operation is known as full duplex communication i e Simultaneous reading and writing between master and slave Figure 6 9 shows the Master Slave connection between the RasPi and the MCP3008 SLAVE MCP3008 aeia Lest circuit SPI master slave connections The clock frequency used is dependent primarily upon the slave s response speed The MCP3008 can easily handle bit rates up to 3 6 MHz if powered at 5 V Since we are using 3 3 V the maximum rate is a bit less at approximately 2 MHz This is still very quick and will process the RasPi input without losing any data The first clock pulse received by the MCP3008 with
69. msg_ content msg Subject Raspberry Pi Alarm on s today msg From gmail user mag To to smtpserver sendmail gmail user to msg as_string esmtpserver quit GPIO setmode GPIO BCH GPIO setup 23 GPIO IN use the count variable in with a 10 sec delay to minimize e mails sent count 0 begin the forever loop while True i f GPIO input 23 Palse amp count 0 count count 1 send alarm time sleep 10 count 0 Summary I started this chapter by discussing the selection of the webcam to be used in the surveillance of the security zone It turns out that Raspian Wheezy the RasPi Linux distribution used has drivers for different manufacturers including many older models The laser trip assembly used in the camera controller project was shown in its new role as the primary intrusion sensor I reused the same interface circuit between the RasPi and the camera controller because it was simple and functional for this project The key software package Motion was discussed next I used only a small portion of its capability that being the webcam server The Motion setup for the RasPi was discussed along with a demonstration of an actual webcam stream I introduced a notification program that will send an e mail to a designated recipient that contains both the public and local IP addresses currently associated with the RasPi This program was then incorporated into an overall
70. ntpdate program output clearly showing that the NTP service is being provided by the RasPi NTP server plaraspbernrypl So File Edit Tabs Help ipigraspberrypi sudo ntpdate 1 4 a 113 May 21 58 33 ntpdate 3268 ntpdate 4 2 6p5 01 2349 0 Sat May 12 10 38 22 C 2012 1 itransmit 192 168 1 43 receive 19 gt 158 1 43 itransmit 192 168 1 43 frece1ve 19 gt 168 1 43 itransm2t 192 168 1 43 jreceive 192 168 1 43 transmit 192 168 1 43 ireceive 192 168 1 43 server 192 168 1 43 port 123 stratum 2 precision 20 Leap 00 trust 000 irefid 192 168 1 43 delay 0 02670 dispersion 6 0001 itransmitted 4 in filter 4 jreterence time d53 1895 06e8 193 Mon May 13 2013 21 57 41 026 joriginate timestamp dS3ci ct ddedaSlc Mon May 13 2013 21 58 39 866 itransmit timestamp d5S3cl18cf e40feEebo itilter delay 6 02765 0 02676 0 02670 0 02676 O 00000 0 00000 0 00000 0 00000 filter offset 0 02480 0 02518 0 02507 0 02493 0 000000 0 000000 0 000000 0 000000 idelay 0 02670 dispersion 0 00011 loffset 0 025077 The ntpdate program output Radio Receiver Clock Source Originally there was an additional section to this chapter that dealt with a radio receiver clock source which was fixed tuned to WWVB the U S synchronized time source located in Ft Collins CO WWVB transmits a digital clock signal on 60 kHz 24 hours per day seven days a week There are several low cost r
71. of activity of the ionizing radiation and the absorbing medium which in most cases is human tissue In the United States a commonly applied measure of dose is the roentgen equivalent man or rem It is a complex computed and weighted average of dose representing the stochastic biological effects of ionizing radiation which is one primary risk factor in cancer formation The sievert Sv is the rem s equivalent international SI unit The conversion factor is 100 rem 1 Sv or in more realistic units 100 prem 1 pSv This project s radiation detector measures dose in prem units I have also included the following list in Table 14 2 to help put the whole concept of dose and effect into a reasonable perspective Table 14 2 Dose Examples Dose Effect 0E n5w O25 pSv US limit on effective dose from a single airport security screening 10 wSv One set of dental radiographs 80 usy Average dose to people living within 16 km of Three Mile island accident mv Two view mammogram using weighting factors updated in 2007 Bm Sv Barium fuorascapy 30 mv Single full body CT scan BE mSv Estimated maximum cose to evacuees who lived closest to Pukushima O 67 Sv Highest dose received by a worker responding to the Fukushima emergency 6 Sv Fatal acute doses during Golania accident 2 SY Fatal acute dose to Louis Shotin in 1946 entcalty accident an uncontrolled nuclear accident Ba Sv Honfatal dose to Albert Stevens spread over 21 years
72. of keys and functions Playing MPEG stream 2 of S class mp3 l Title onclassical_demo_latry_bach_fugue_in_d_major_bwv 532_live_cut version Album Genre Unknown ll Time 02 33 68 00 00 02 FWA off Wol 114 114 2 33 Decoding of class mo3 finished mpg123 terminal control key list Table 3 3 is an easy to read list of these terminal control keys with additional explanations Table 3 3 mpg123 Terminal Control Keys Terminal Control Key Action S Pause toggle press once to pause press again to resume f Next track d Previous track b Back to beginning of track D Loop around current position Forward Rewind Fast forward Fast rewind Volume up Volume down r Relative volume adjustment RWA switch uses the MPEG ID3V2 tag to adjust album loudness Verbose switch List current playlist Display tag information Print MPEG header information Help list Quit Small pitch up change Large pitch up change Small pitch down change Large pitch down change Reset pitch to zero i xM CO bee fee See a Incidentally it is very easy to play all the MP3s in a directory by typing the following sudo vC mp3 4 The v in the command line will provide a verbose output and the c puts the app into a full control mode where all the terminal control keys are made operational The in the command line is a wild card commanding the app to play all the MP3s it can find in the current directory When all is said and done thi
73. of the charger board and the bottom of the Lexan mounting board Figure 12 13 shows a portion of the actual mounted charger board so that you will gain an understanding of this arrangement The charger board mounting I used a 2 mm 4 x 4 5 inch Lexan board as a mounting platform to support the RasPi and the servo control board Figure 12 14 shows this board along with the charger board and the nylon spacers The whole stack is held together by four 2 25 inch long 6 32 machine screws that go through the Lexan board hollow spacers and the Li ion charger board I used a 6 32 tap to prethread the four matching holes on the Boe Bot chassis to make the installation a bit easier You can choose to do this or to simply use a 6 32 nut and washer to lock down the screw I believe you will need to slightly enlarge the chassis holes for clearance if you use screws and nuts arina Lexan and charger boards mounting diagram I would also recommend using the charger board as a drill template for the Lexan mounting board Just ensure that the Lexan board is mounted to have the 4 inch dimension between the wheels and the one edge flush with the charger board as shown in Fig 12 14 It is important to ensure that the optional monitor support can be installed without interference Next disassemble the Lexan board to mount the RasPi and servo control board I used two 0 75 inch 4 40 screws and nuts along with two 0 5 inch nylon spacers to mount
74. over short distances to communicate with the RasPi which will be discussed in Chap 13 Chassis and Drive Motors The car uses a simple tripod configuration of two powered wheels and a third one as a free rolling ball to provide stability and a very tight turning radius All the chassis drive and power supply components are listed in Table 12 1 and are available from www parallax com Table 12 1 Chassis Drive and Power Supply Components Quantity Description Boe Bot chassis Continuous rotation servo Futaba Polyethylene Ball Cotter pin 1 2 2 Boe Bot wheels and tires 1 1 Li ion Power Pack Charger 2 Li ion high capacity cell Parallax Part Number fOO 00022 8O0 00008 28109 700 000009 FOO O00023 28986 28987 Price USD each 24 99 12 99 5 90 3 95 0 30 22 96 7 99 A servo control board is also required for this project It is the 16 Channel 12 bit Pulse Width Modulation PWM Servo Driver I C Interface board available from Adafruit Industries part number 815 The Boe Bot chassis is made of 1 5 mm aluminum and is shown in Fig 12 5 aeia pA Car chassis A complete drawing showing all the dimensions is available on the Parallax website for readers who are able and willing to make their own chassis Just use the part number to look it up The continuous rotation servos provide the driving force for the wheels Figure 12 6 shows a servo and Fig 12 7 shows a wheel kit Each wheel is
75. polymer Li Po battery 165 166 183 185 LM 7805 three terminal chip 165 Loadable Kernel Modules LKM 32 190 Local and remote logic controller project 139 153 Android remote control 147 150 FUSE 143 144 hardware 143 and Linux 143 1 Wire external control board 139 141 owfs installation and configuration 141 143 Python test program 146 sniffer monitoring 147 test sequences for 8 Channel I O board 144 146 testing web server with browser 150 153 Login headless 96 SSH 95 96 Logitech C920 webcam 103 Logitech K400r keyboard mouse combination 166 167 Looping 29 Lossless compression 34 35 Lossy compression 34 35 Loughlin Thomas 96 97 99 Low Voltage Differential Signaling LVDS serial display 9 Low level languages 17 1s Linux command 17 LSB least significant bit 78 LVDS Low Voltage Differential Signaling serial display 9 LXDE Lightweight X11 Desktop Environment 16 17 M Magnetic induction 115 Master devices in earthquake detector project 78 in weather station project 129 Maxim 129 Maxim DS18B20 chip 128 130 131 Maxim DS2438A chip 128 130 MC146818 chip 187 MCP3008 ADC 77 connecting testing 79 82 as slave device 78 Measurements Specialties Corp 75 Member of an operator 29 Memory 1 3 4 Metal oxide semiconductor field effect transistor MOSFET 131 132 Micro USB power connector 5 microBuilder eu 115 116 Microchip 76 77 Microprocessors Broadcom 2835 2
76. present a personal shock hazard To check flash voltages for your electronic flash go to the following excellent website www botzilla com photo strobeVolts html I do discuss a possible solution for using an older flash unit in the next section on the optoisolator interfaces However my earnest suggestion would be Do not use an old flash but instead invest in a modern unit Many of these are available at quite reasonable prices Optoisolator Interfaces An optoisolator combines a light source with a photosensitive transistor to create a photonic coupler This type of isolator achieves electrical isolation between two electrical circuits that may have a significant voltage difference present Figure 4 10 shows a physical schematic for the NTE3041 optoisolater that is used in this project It is in a six pin dual in line package DIP form with a gallium arsenide infrared LED as a light source and a silicon NPN phototransistor as the light receiver Anode amp FJ Base Cathode 2 EE Collector N C E Emitter NTE3041 optoisolator Although it might appear that an optoisolator could pass analog or continuous signals it is only Suitable for digital or on off signals That is due to the on off functional nature of the LED used as the light source NTE3041s are used as input and output isolators in this project Figure 4 11 shows a very simple circuit that is used to enable the NTE3041 to isolate one of the RasPi GPIO pins A
77. primary controller has this Home ID that slave nodes acquire when they are joined to the network Every secondary controller also uses this same ID when they are attached to the network Individual slave nodes have a one byte ID that is assigned by the primary controller when that node joins the network Network Devices There are two main device types that make up a Z Wave network controllers and slaves Slaves are also known as end point devices because they can only respond to messages sent by the controllers They typically have built in microprocessors with GPIO pins that control components such as TRIACs which turn AC power on and off Figure 7 4 shows a Z Wave enabled duplex outlet It would be installed in the same way as any ordinary duplex outlet would be installed except that this outlet is also controllable using Z Wave technology The other big difference is that this outlet is much more expensive than a regular duplex outlet however you don t need many of them for most home automation setups Z Wave enabled duplex outlet Notice the white button to the left center of the outlet in Fig 7 4 This is what a user presses to join the device to the network when prompted by the controller menu This operation will be shown in a later section Controllers have two subtypes portable and static Portable controllers are in the form of remote controls one of which is shown in Fig 7 5 These controllers must be able to sel
78. program can be modified to list all the MP3 songs in the directory so that you can select the ones to be played which is the essence of a play list Of course you can connect a battery to power the RasPi that will make it completely portable assuming you are using an LCD type display for user interaction Summary I started this chapter with a discussion of the Pi Cobbler prototyping aide which is an invaluable tool that allows us to experiment with most of the GPIO pins that are available on the RasPi The Linux ALSA system discussion showed you how sound is handled by the RasPi OS You must install ALSA in order to use the mpg123 app that forms the basis for the MP3 player project I also introduced you to the principal audio file formats including the MP3 format that is used to encode the music played in the project There was also a brief detour to discuss the RasPi s audio frequency response using a pink noise stimulus I then showed you how to use push button switches to signal the RasPi using GPIO pins as inputs These switches were also used as part of the MP3 player project We went through a thorough discussion of the mpg123 MP3 app including a detailed list of all the controls available for use with this versatile app I finished with a brief discussion on how to expand the MP3 player so that it might more readily resemble a modern portable player Camera Controller In this chapter I will show you how to build a camera
79. repositories that apt refers to in order to retrieve the requested package The repository list is located at etc apt sources list in the Linux distribution The apt get command also wants to know what you want done with the software package once it has been retrieved That s the purpose of the install portion of the command But apt has other neat features including the ability to update all the packages already installed in the computer Simply type the following sudo apt get update J All available updates for installed packages will now be installed Be patient this will take a while especially if there are many packages involved However that s not all apt is capable of doing on a global scale You can upgrade all your installed packages provided upgrades are available Type the following sudo apt get upgrade Upgrades as the name implies are new versions of installed packages You should always update prior to upgrading in order to lessen the chance that an inappropriate update will be applied to a newer version There is a great deal of information available on apt at www debian org doc user manuals apt howto LED Project I will now show you the LED project that ties together all the information that you have carefully studied so far I will create a program to turn on an LED connected to pin 18 using the Pi Plate as a prototype aid You will need a little information on how to connect the LED and limit the curr
80. shown in Table 1 8 along with some comments regarding why a particular setting was selected Table 1 8 Suggested Configuration Settings raspi config menuitem Setting Comment info m a Info about the raspi config app expand rootfs expand yes or enter The RasPi uses about 2 GB This option will reclaim all root partition te fill SOS card remaining 50 memory for use configure_keyboard change _ pass change_locale change_ timezone memory split overclock select your keyboard rig no Selack your time zone mo ric Leave as default if your keyboard is not listed Leave the default password for now Default is all locales That s sufficient Default of 192 MB for ARM and 64 MB for GPU is OR Far reasons mentioned earlier imn chapter ssh enable or disable secure shel SSH Server Needed to run remote with PC and RasPi boot_behaviour yes or enter Boot into the GUI desktop Performs an update to the Linux distribution This will take several minutes and you must be connected to the Interret update yes or enter After you finish the configuration the monitor prompt will eventually show It is waiting for you to enter the user name which is pi pi raspberrypi pi Next the password prompt shows Password Enter raspberry Password raspberry Please note I am not giving away any secrets as every unmodified RasPi Linux distribution is created with this default password You may have chan
81. take a brief detour from the Z Wave to introduce the SSH login process since I use that in establishing the control software environment SSH Login In this section I will show you how to log into the RasPi by using a network connection as I mentioned in Chap 5 The Wheezy Linux distribution as well as many others includes a great service known as SSH short for Secure Shell It is a network protocol that uses cryptographic means to establish secure data communication between two networked computers connected via a logical secure channel over a physical insecure network SSH uses both server and client programs to accomplish the connection One of the questions you will be asked when first configuring your RasPi is whether or not to start sshd upon bootup I recommend that you answer yes as that automatically starts the SSH daemon each time you start the RasPi The second portion of the connection is the client program which is highly dependent upon what type of computer you are using to connect to the RasPi I recommend using putty exe since most readers will be using a Windows based machine putty is freely available from a variety of Internet sources so I would recommend a Google search to locate a good download mirror You should see the Fig 7 11 screenshot assuming that you answered yes to the sshd question and have downloaded and are running putty on a Windows based computer connected to the same network that co
82. the remaining beacons It is also critical that the GPS receiver have an open line of sight to each beacon and that the position of each beacon be recorded in an embedded database that is also constantly available to the receiver The positions of beacons B1 through B3 are recorded as x and y coordinates in terms of miles from the origin that is shown in the upper left hand corner of Fig 5 2 r Be y BS gps receiver 1 3 7 PULL T 2 miles B1 1 15 1 3 hl B3 arina Deacon test area The actual position determination happens in the following manner At the start of the minute B1 flashes and the receiver starts a timer that stops when the sound pulse is received Since the light flash is essentially instantaneous the time interval is proportional to the distance from the beacon Since sound travels at a nominal 1100 feet per second ft s in air a 5 second delay would represent a 5500 foot distance The receiver must then be located somewhere on a 5500 foot radius sphere that is centered on beacon B1 Figure 5 3 illustrates this abstraction as a graphical representation taken from a Mathworks Matlab application arina One sphere B2 flashes next Suppose that it takes 4 seconds for the B2 sound pulse to reach the GPS receiver This delay represents a 4400 foot sphere centered on B2 The B1 and B2 spheres are shown intersecting in Fig 5 4 The heavily dashed line represents a portion of the circle that is the
83. the RasPi and an attached Z wave dongle Of course the RasPi is programmed to suit the homeowner s needs There is no hardware construction involved in this project the only physical task is to plug ina USB dongle but that does not mean it is easy A lot of software setup and configuration is involved in making the project run successfully Of course that s part of the fun of working with the RasPi and Linux many functions can be done in software versus building hardware peripherals Z Wave Mesh Network Each Z Wave component or node contains a low power radio frequency RF transceiver This radio operates in the Industrial Scientific and Medical ISM band at a frequency of 908 42 MHz in the United States and 860 MHz in Europe These frequencies are far removed from other home wireless devices that typically operate at 2 4 GHz It is thus far less susceptible to causing or being subjected to interference The outdoor range or line of sight is approximately 100 m or 300 ft The indoor range is about 30 m or 90 ft due mainly to attenuation caused by the interior walls Range extension is easily accomplished by simply adding additional nodes into the home Since each node is a transceiver it both receives and transmits digital messages acting as a digital repeater or digipeater Digipeating creates a signal hop There is however one major proviso only four hops are allowed After that the communications protocol automatical
84. the RasPi through the Pi Cobbler i T kog E s a y m x ia 2 T K ig ry 7 1 Ed E F R A r a ire THORP m a l t itt a E ie i 1 Ep IR ns ee r L at Aer ties j 5 I n r eies 9 8S Aa r n koma s ee a gt er p me l e Bk l aie a Saai i i j r mam n Mga iiae i a m T i a i L i PMS connected to MCP3008 Pi Cobbler and RasPi The software also requires a slight modification because we are done with the initial testing and now need to collect some actual data from the seismic sensor The code segment in the code listing titled Test_ADC py Segment modification to allow the collection of seismic data on page 82 replaces all the code starting at the line shown below channel 0 The program with the new code inserted is available on the book s website as Test_File_ADC py This new program writes 1200 adc_values to a file named myData which is located in the pi working directory if you have not changed that location Each value has a new line character appended to enable the data file to be easily imported into Excel for further analysis Python supports two ways to store data in a file by using either string or binary formats The approach taken in this program was to store the data as a sequence of strings since we knew beforehand that the data would be input to an Excel spreadsheet for further analysis Storing data as strings consumes a lot of fi
85. the RasPi to the Lexan board Use the two mounting holes on the RasPi as drill guides for locating the holes in the Lexan board Ensure that the RasPi board edge lines up with the Lexan board edge as shown in Fig 12 15 The servo control board is mounted as shown in the diagram except that there are four mounting holes for that board In addition I used nylon washers to space the servo board from the Lexan board The mounting holes are very tight so you will need four very tiny machine screws and nuts Raspberry Pi 20 Sivo bileriace Board 4x44 heh mmn Lanan Mounting board aeiae RasPi and servo boards mounted Another Lexan mounting board is needed to support the solderless breadboard used for the Pi Cobbler and other items that can be seen in Figs 12 2 and 12 3 This additional Lexan board is 3 5 x 4 inches and is mounted at the back of the car directly to the chassis as shown in Fig 12 16 You will need to notch out the board to provide clearance for two spacers supporting the charger board I drew the cutouts on the board s Lexan protective paper and used a jig saw to make them Also mark three holes to be drilled in the Lexan board using the chassis holes as a guide These three holes are obvious when you fit the board to the chassis I used three 0 5 inch 4 40 machine screws and nuts to hold this board to the chassis 3k 7 mech sgderless r EE breadboard M oia 3524 meh L zan board Lexan board suppor
86. turn up many hits regarding Linux tutorials I will instead use Linux commands and procedures and explain them as I go along ina mentor capacity as if I were standing beside you as you execute the commands Additionally I will be using the Python language to program or code the RasPi and will provide more guidance regarding how Python works and how it is applied with the RasPi as it is the key to success in using the board and in understanding its operation with the underlying project code Initial Startup A suggested RasPi setup that uses the connections discussed in the hardware section is shown in Fig 1 22 This setup will be the basis for your projects once you add some prototyping hardware to the RasPi Right now I will be using the setup to get the RasPi configured in a proper manner to enable project development You should connect all the components as shown in the figure leaving the USB power connection for last The RasPi will attempt to start up when the USB power cord is plugged in and if you have not finished connecting all the other components it is entirely possible that they will not be recognized in the startup sequence and your system will either not start or not operate correctly I will also assume that you are using a prebuilt Linux distribution that is provided with the RasPi Starter kit or purchased separately This 4 GB card should also be plugged into the SD card holder prior to power being applied to the RasP
87. voltage such that only 3 3 V appears on the UART lines thus protecting the RasPi from any overvoltage being applied to the GPIO pins Initial Checkout There is a very useful test program named nfc poll which is provided in the libnfc package and will test the hardware and software for proper operation First ensure that you are in this directory home pi libnfc libnfc 1 6 0 rel Then enter the following at the command line prompt sudo examples nfc poll J Put a tag on or near the reader and you should see something similar to the Fig 9 16 screenshot pi raspbherrypi libntc libnfc 1 6 0 re File Edit Tabs Help ipigraspberrypi Libnfc Libnfc 1 6 0 rcl sudo examples nfc poll ype Libntc 1 6 0 rel examples libs lt nfc poll uses libnfc 1 6 0 re fl irla26 NFC reader pnS32_uart dev ttyAMAG PNSS32 v1 6 0x07 opened INFC device will poll during 30000 ms 20 pollings of 300 ms for 5 modulations ISO IEC 144434 106 eee target AT QA SENS _ RES Od UIO NFCID1 bd Oe bo 23 SAK SEL RES pigraspberrypi Libnfe libnfe 1 6 0 rel The nfc poll test program output Of course your UID tag information will be different from what is shown in the figure but everything else should be the same Successful program execution means that you are now ready for the project program Project Program The project program is designed to check for a predesignated tag ID and then turn on an LED if the tag is dete
88. where the normal primaries act as proxies for the static control This configuration type is known as an SUC ID Server SIS All told there is an incredible amount of flexibility in Z Wave network configurations The Z Wave Chip The original Z Wave chip was designed and manufactured by Zensys now known as Sigma Designs All certified Z Wave component manufacturers must use this authentic Z Wave chip in their devices This ensures that any Z Wave node properly joins the network and communicates with other nodes produced by other manufacturers The Zensys chip design is discussed in this section because it forms the basis for the whole Z Wave concept and is important background to help you comprehend how the RasPi can function as a controller in the network A recent Zensys single module is model ZW3102N containing a ZW0301 chip that uses the venerable 8051 core with a 32 MHz external crystal This is a hybrid module containing a lot of additional components including an RF transceiver operating on either the U S or European ISM frequency There is also a built in digital modem along with a hardware implementation of the network stack operations that were discussed in the previous section The ZW0301 chip has only 32 kB of Flash memory and a meager 2 kB of SRAM It operates on a supply voltage range of 2 1 to 3 6 V and consumes a maximum of 36 mA when transmitting Figure 7 6 is the block diagram of the ZW3102N showing all the component
89. your PC and why the low voltage of 3 3 V is used for interfacing the RasPi to the outside world I will first cover the hardware aspects of the RasPi followed by the software aspect Hardware Broadcom 2835 Microprocessor Graphics Processing Unit The SoC uses the Broadcom BCM2835 as its microprocessor and graphics processing unit or GPU The Broadcom company is what is known as a fabless supplier in that they provide the designs for their product in the form of Intellectual Property IP and other companies actually create the real silicon chips Broadcom specializes in mobile application type processors including the type used in smartphones The BCM2835 portion of the SoC itself is made up of an ARM1176JZF S microprocessor running at 700 MHz and a Broadcom VideoCore IV GPU The BCM2835 is designed for mobile applications and hence it needs to operate with minimal power so as to extend battery life A fairly low microprocessor clock speed helps lower power consumption and this is the reason the BCM2835 operates at 700 MHz which is typically a quarter of the speed of a modern PC Lower clock speed also means the processor can operate at a low voltage thus decreasing the overall heat generated and extending chip life The BCM2835 can be speeded up also known as overclocking to improve performance but this is generally not recommended because the microprocessor can become operationally unstable and its life shortened Be assured that the R
90. 02N module 92 93 Z Wave technology basic server 99 101 basics of operation 88 91 defined 89 device attributes 98 Home ID in 91 lightscontrol app 97 99 mesh network 87 94 network devices 91 92 Open Z Wave software 96 101 packet types 89 90 RasPi and Z Wave interface 94 95 Z Wave chip 92 94
91. 15 V wall wart power supply must also be plugged into the Power Injector Module Figure 10 16 shows the whole setup The 1 Wire weather station 1 Wire File System The software package that drives the whole 1 Wire network is named owfs as mentioned in the introduction It is an open source comprehensive set of applications that works seamlessly with the RasPi Wheezy distribution The following are the instructions on how to set up the RasPi to run owfs 1 Update and upgrade the Wheezy distribution sudo apt get update sudo apt get upgrade this might take some time 2 Next download and install owfs sudo apt get install owfs J 3 Next edit the owfs configuration file sudo nano etc owfs conft J There are two changes to make Refer to Fig 10 17 to see these changes pi raspberrypi 5 x File Edit Tabs Help is is the main OWFS configuration file You should read the s cont S manual page in order to understand the options Listed A A A SOURCES Jn A a A With this setup any client but owserver uses owserver on the local machine server server localhost 4304 and owserver uses the real hardware by default fake devices This part must be changed on real installation server FAKE 5152 052405 OOOO Comment out USE device D59490 server usb all uncomment Serial port 0590607 server device dev ttySl owserver tep address server server 192 168 1 21 313
92. 2048 will be transmitted via the Bluetooth connection to the RasPi Likewise if the button is pressed a value of 16 is sent The values are also cumulative in case of combination button presses For example simultaneously pressing the 1 button and the home button will cause a value of 130 to be sent the sum of the home button value of 128 and the 1 button value of 2 The application becomes a matter of decoding the values received and figuring out what actions to take based upon those values I created a simple test program named Wiimote_Test py that establishes a Bluetooth connection between the car and the Wiimote The four way switch on the Wiimote is then used to send different values depending upon which switch is pressed Enter the following to run this program sudo python Wiimote Test py Figure 13 12 shows the result obtained by first establishing a connection and then pressing all four Switches Wa pi raspberrypr File Edit Tabs Help ipidraspberrypi sudo python Wilmote_Test py Press buttons 1 2 on your Wil Remote Wii Remote connected Press the PLUS button to disconnect Forward button pressed Left button pressed Right button pressed iBack button pressed Closing Bluetooth connection i lt cwlid Wiimote object at Oxb6cbhb44ba gt pigraspberrypi Wiimote_Test py program results The Python code for Wiimote_Test py is available from the book s website www inhprofessional com rasp
93. 22 NFC RFID reader project 115 124 future expansion 122 123 hardware installation 121 initial checkout 121 122 libnfc installation 116 121 NFC data communications flow 116 NEC hardware 115 116 passive and active modes of operation 115 project program 122 Nikon 47 NMEA National Marine Electronics Association 58 66 NMEA 0183 standard 66 69 GPS message types 68 latitude and longitude formats 67 68 parsed GPS messages 68 69 NTE3041 optoisolator 47 48 NTP Network Time Protocol 187 193 197 ntp conf 194 196 ntpdate 196 NXP PN532 microcontroller 116 Nyquist rate 77 O Object oriented programming 29 Occidentalis GUI desktop 16 Occidentalis v 2 161 One third octaves 33 34 1 Wire external control board 139 141 1 Wire File System see owfs 1 Wire Sniffer 132 135 137 140 143 1 Wire weather station project 125 138 design of 125 129 future expansion 138 1 Wire protocol 129 132 1 Wire Sniffer 132 135 137 owls software package 133 134 packet sniffing 135 137 setting up 132 133 viewing weather data 134 135 One wire serial protocol 16 Open Z Wave software 96 101 OpenGL ES 2 0 standard 3 Operational amplifier op amp 76 Operational speed of RasPi 38 39 Operational system for earthquake detector 83 84 Optoisolator interfaces camera controller project 47 48 51 Optotriac 48 Oscillator and divider 187 Output to 5 V logical devices 10 Overclocking
94. 25 GPIO IN ensure that the analog output is selected os 58ystem amixer cset numid 3 1 while True check if the button connected to pin 23 has been pressed if GPIO input 23 False FStart the mpgl23 app with full keyboard control and screen output playing class mp3 os system mpgl23 vC class mp3 check if the button connected to pin 24 has been pressed L E GPIG input 24 False start the mpgl23 app with full keyboard control and verbose output playing classl mp3 a a e 0s System Mpls VU Classl mps eheck if the button connected to pin 25 has been pressed if GPIO input 25 False start the mpgl23 app with full keyboard control and verbose output playing Maid mp3 os system mpgl23 vC Maid mp3 MP3 Player Schematic All the pin and switch connections are shown in Fig 3 9 You can simply add on the two additional push button switches and resistors to the existing circuit that was built according to Fig 3 7 You can also leave the LED connected if you so desire as it will not be incorporated into this circuit 3 3V 3 3V LOK ohms LOK ohms MP3 player circuit Figure 3 10 shows the actual circuit on the breadboard with the RasPi connected via the flat ribbon cable to the Pi Cobbler and the Veho360 connected to the analog output jack The three push buttons that select one of three MP3 songs are placed on the right side of the solderless breadboard ETETE PCT
95. 26 Upton Eben 1 Uranium ore 175 176 U S Department of Defense DoD 57 USB connector 7 8 USB hub 8 User name for initial startup 14 V V voltage 5 Variable resistor 76 Vassallo Conrad 97 99 Vaq positive power supply voltage 10 Veho 360 speaker 31 32 Velleman 175 VGA Video Graphic array 6 Video HDMI for 5 6 for robotic car 173 Video connector 6 7 Video Graphic array VGA 6 Video monitor choices for 6 VideoCore IV GPU Broadcom 3 Viewing video from home security webcam 109 111 weather station project data 134 135 Virtual comm port 63 Volt ohm meter VOM 51 Voltage V 5 Voltage levels digital signal 10 for electronic flash 47 GPIO 10 for optoisolator 48 Voltage output meter VOM 80 W Wall wart power supply 126 Waveform Audio File Format WAV files MP3 files vs 34 35 playing 35 Weather station project see 1 Wire weather station project Web server testing with browser 150 153 Webcam home security controller with Motion 106 selection of 103 104 viewing video from 109 111 WebIOPi 147 149 151 Wheezy 95 96 117 155 161 187 190 while True 29 White noise 33 34 Wi Fi adapter for robotic car 173 Wiimote 155 156 166 169 173 Wiimote_Test py 170 171 win32diskimager exe 15 WWVB 194 197 X X 10 technology 89 92 Z Zensys 92 ZigBee technology 89 ZOC 62 64 Z Stick 94 95 ZW0301 microcontroller chip 92 93 ZW31
96. 2i710 TEYE satie 2r H EN 304 5 a5 ie ie ee ee ee ed FGPGSU 2 1 06 a aa 76457 39 23 53 316 Ti 59 39 DES 40 25 18 046 30 78 7 GPANC A2i7i0 008 4314 2709 HN 87162 7408 U 8 15 18 35 126113 Aa43 GPUTG 18 35 1T 8 8 15 4 8 28 K A80C PGTOP 11 3 6F SGPGGA 621711 608 4914 2708 M 87102 7408 W 1 4 3 74 75 5 4 22 8 4 95D GPGS6 8 3 297 23 31 25 3 87 3 74 8 99 961 GPRAC aiii pa A 4314 2708 H O7182 7408 W 8 13 18 35 1280113 8e45 7GPUTG 18 sek F aH 13 H A 24 K 866 SPGTOP 11 3 Magee ETA 000 4314 2700 M 87102 7411 W 1 4 10 12 74 7 H 32 8 H 6F PGPGSA A 3 27 20 301 25 e2eceeeeeli t6 18 1 oS 79 3B GPRAC 621712 6608 8 4314 2708 H B7162 7411 W 8 18 18 35 1280113 AiD GPUTG 18 35 T H 18 H 8 33 K A808 SPGTOP il GF SGPGGA 621713 608 4314 2698 4 87102 7412 Wed P S GPGS6A A 3 27 23 31 25 4 87 3 74 8 i GPRHG aiia Bea A 4314 2698 H 7102 7412 ms 7GPUTG 16 35 1T 8 8 15 H 0 27 K 063 SPGTOP 11 3 6F GPGGA piid G08 iE a A ra rra k A E E a e ra AA a a N A a E i GPcsa A 3 931 25 ee renee d 87 39 74 0 99 801 GPRAC 62i 714 008 A4314 2686 H A7102 7413 4 8 25 16 35 128113 f 48 SGPUTG 18 35 T H 0 25 H 8 46 K A807 SPGITOP 11 J F SGPGGA 021715 000 4314 2683 H 07102 7415 W1 4 3 7472 9328 M 5C HAE PE P E 3i 25 4 87 3 74 8 EEFT cresu 2 i 5 31 64 049 40 23 59 318 35 29 206 065 40 25 10 046 3077 OPGE pipet 8S a ale w79 Mc
97. 3 3V 10K ohms GPIO pin Point 1 Point 2 RasPi gnd Sound module to Pi Cobbler interface schematic Point 1 shown in Figs 4 13 and 4 14 is connected to the Pi Cobbler ground pin Point 2 also shown in Figs 4 13 and 4 14 is connected to GPIO pin 24 on the Pi Cobbler There is also a 10 kQ pull up resistor tied to the GPIO pin The RasPi control program will be written to detect the high to low transition on the selected GPIO pin Laser Module An assembled laser light module is shown in Fig 4 15 There are two assemblies not counting the 12 V power supply that make up this sensor module The first is the laser pointer that acts as the light source and the second is the light sensor that consists of a phototransistor with some analog signal processing circuitry The laser pointer is a very common low power device that is typically battery powered In this case it is powered by 5 V supplied by the detector board The power is delivered through a pair of small alligator clips one of which is visible in the Fig 4 15 Model LTS1 laser trip sensor The light detector component is a phototransistor that is also pointed out in the figure It looks like anormal LED but is a transistor with only the collector and emitter leads externally connected It will conduct when the laser light strikes the base emitter region however it seems insensitive to normal ambient light I have not tried it in strong di
98. 3 Level 255 MSG F Wave Name set Mode 3 Nane Ouldoow Switch Zone 0 anwes basic server web page All devices that have been added to the Z Wave network and stored in the Z Stick memory will be displayed on this page As you can see the only device displayed is the outdoor power module that was shown in the previous web server demo The light may be turned on and off by clicking on the icon There is no provision for setting Scenes or preprogrammed times as this is just a very functional web test app The essential device attributes are shown as text in the middle of the page I next wanted to test this system to see how a different device type would be accommodated To do this I shut everything down and then added a new device to the network This was a battery operated Z Wave enabled motion sensor as shown in Fig 7 18 Battery operated Z Wave motion sensor I next restarted the basic web service and loaded the appropriate web page Figure 7 19 shows this new page with both the outdoor module and the motion sensor displayed gt gt openzwave local basic E Search Settings CI Imported From lE C Google Kam l Mieje ned k Lasi NSG Hi AA Hoa Lemi Wo ae hami set Hode Hami Undefined Fone t yW Revised basic server web page The motion sensor sends data back to the Z Stick which I confirmed by waving my hand in front of the sensor and observing that the state shown on the sensor wind
99. 33W LOK olina GPO pin 25 Point I Pint 2 Laser light module RaPi gad yen S All of the interface connections The hardest part was to interconnect the modules camera and flash to the breadboards I finally determined that using audio cables terminating with 3 5 mm jacks was the easiest way for me to do it You can use whatever you have available such as a twisted pair because the connections are DC based with practically no speed or bandwidth issues The complete prototype is shown in Fig 4 17 It is a bit of a rat s nest as far as the wiring goes but it is totally functional and allowed me to rapidly progress with the project Gi if BEB inann rid EEA EEI HA another peL dev board n B reat used oa ammar aroen anr rres ssreee id Ss pee r eT A Em BS PEeee Bete jni 72 G9 Peee f anina fe UAU BESEER mm sharing OHH EHHE t xe a in prototype Fa Baaium bmw ae B Pas f noone i Pie f beens fe microphone HEET MEME Es Mee A i ai a ie f s s Oe a M SEE ai mites i A a ee e i a ee A Ern ff annie oo EL P E R a Wee push buttons a E aA FFEA EEFE amp ee Ei ba y En ere a Rtol a 5 beat ante a E is n m Py am TE Bea i focus shutter sound module flash optoisolatars bo c mera shutter i Rta fous shutter flash to flash Complete camera controller prototype Ensure that you use the appropriate ground connections as shown
100. 6 byte memory Figure 15 5 shows the RTC breakout board used in this project It is built from kit number 264 purchased from Adafruit Industries It uses the DS1307 chip along with the crystal shown in Fig 15 3 There are two resistors not installed but are shown as placeholders on the PCB This is because the RasPi already has two pull up resistors attached to the Serial Data Line SDA and Serial Clock SCL control lines negating the need for these components _ DS1307 gy RTC f Breakout tU RTC breakout board The building kit is very easy to put together because there are only five components to install including the coin cell holder Each one has a placeholder noted on the PCB Just be very careful when soldering the crystal to the board because you do not want to overheat it or excessively bend the fragile leads The RTC breakout board is connected to the RasPi by using a solderless breadboard with the Pi Cobbler prototype connector The wiring connections are detailed in Table 15 1 Table 15 1 RTC to RasPi Connections RTC Breakout Board Pi Cobbler Pins 5Y 5VO GND GND SDA SDAQ SCL SCLO The physical configuration is shown in Fig 15 6 without the ribbon cable attached to show all the jumper wires 2 oul TE 8888 saaa a aasa saput HUANA ARRS gt a ae a ail RasPi and RTC setup OTE Even though the RTC is powered by the 5 V RasPi power supply the I7C signal levels ar
101. 826 jr_address JFFFFFFFFFFFFFFFF gt r_ locator SS a a e E bh E ls Sag hi love pos id C ene Humidity Module results bere Again there is plenty of data shown as was the case with the Temperature Module results The humidity reading is near the lower middle of the list and shows a value of 16 5187 I am certain that the sensor is nowhere near that accurate however the owfs software calculates a value based on the raw data sent back to it from the module The last module is the Barometer Module with its results shown by clicking on the directory named 28 827BBCO000000 Figure 10 21 shows the data on this page 26 827 BBC000000 directory B1 R1 A B1 R1 A aeni oer ereere FFFFFFFFFFFFFFF 0 0017087 Barometer Module results However there is a problem here If you look closely at all the data in this figure you will not find any barometric pressure value You must click on the directory entry named B1 R1_A to view another page with the desired data Figure 10 22 shows this page OWFS on localhost 4304 26 827 BBC000000 B1 R1 A meached version Lup directory CHANGE 904 7 CHANGE pressure 1001 87 SSY Barometric pressure value The pressure displayed is 1001 87 millibars The actual pressure measured at a nearby airport wa
102. AXE Microcontroller Projects for the Evil Genius Programming Video Games for the Evil Genius Raspberry Pi Projects for the Evil Genius Recycling Projects for the Evil Genius Solar Energy Projects for the Evil Genius Telephone Projects for the Evil Genius 30 Arduino Projects for the Evil Genius Second Edition tinyAVR Microcontroller Projects for the Evil Genius 22 Radio and Receiver Projects for the Evil Genius 25 Home Automation Projects for the Evil Genius Raspberry Pi Projects for the Evil Genius Donald Norris Mc Graw Education New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto Copyright 2014 by McGraw Hill Education All rights reserved Except as permitted under the United States Copyright Act of 1976 no part of this publication may be reproduced or distributed in any form or by any means or stored in a data base or retrieval system without the prior written permission of the publisher ISBN 978 0 07 181956 5 MHID 0 07 181956 8 The material in this eBook also appears in the print version of this title ISBN 978 0 07 182158 2 MHID 0 07 182158 9 E book conversion by Codemantra Version 2 0 All trademarks are trademarks of their respective owners Rather than put a trademark symbol after every occurrence of a trademarked name we use names in an editorial fashion only and to the benefit of the trademark owner with no int
103. Control Devices Des playing 1 1 of 1 resul pen _ 2 1 2 lt i v 255 3 Cutdoor Switch Binary Power Switch Undefined OFF ON Carved by Conrad yerib Pawnenend bey i Fractnencet lightscontrol server page In my case I had initially set up one device a GE outdoor power module controlling a lamp as I discussed earlier in the chapter Table 7 4 shows the web page attributes for this device Table 7 4 Z Wave Device Attributes Attribute Description state n a A bulb icon that changes from red to gray for ON or OFF respectively Level 255 Node ID 3 Network ID Device Name Outdoor Switch Enumerated from device table Device Type Binary Power Switch Enumerated trom device table Raciti Undetireed Automatically assigned for undefined roam OFF na An action Button that turns device off ON ra An action button that turns device on Clicking on the web page ON and OFF buttons turned the corresponding Z Wave controlled lamp on and off thus confirming that all the software and network connections were properly operating I have included some screenshots of the web app configuration pages to help illustrate how to configure a Z Wave network to support typical home automation tasks There is no professional documentation provided with this open source project which is often the case but I am not complaining and am completely appreciative of the tremendous unpaid effort that goes into such project development done for the general good
104. M 1 O servoLeftFwd time sleep 1 print Closing Bluetooth connection time sleep 1 exit wm drives the car forward when the forward button is pressed You just need to press the back button to stop this motion The same holds true for turning right or left Operating the Robotic Car The car is essentially a peripheral for the RasPi which means that you must start the computer as you would normally do and simply enter the command to run the Robot_Car py program as shown below sudo python Robot Car py 4 You would then simultaneously press the 1 and 2 buttons on the Wiimote to connect to the RasPi via Bluetooth Next you would operate the car by using the four way switch on the Wiimote to control the direction of the car That s it Press the button to disconnect and stop the Bluetooth session Future Expansions The following would be interesting and exciting modifications to this project to expand its usefulness and hopefully the learning experience Add a 5 V DC powered USB hub to the existing two USB ports that are both used Adding a Wi Fi adapter would provide a wireless networking capability and Internet access Add a video camera such as the GoPro Hero3 This unit has Wi Fi connectivity and is capable of being remotely controlled by either its own remote control accessory or an Android smartphone or tablet running the GoPro app The remote control and Android app both have a real time video preview functio
105. PIO setup 27 GPIO IN GPIO setup 4 GPIO OUT while True rdg read counter clear counter mrem rdg 100 15 ave ave Tt Mem mir min j if min 0 Il E ave else max mrem print mreem mrem ti e sleep 40 avemrem ave min pri nt average mrem avemrem time sleep l makmrem max print maximum mrem maxmrem time sleep 10 def read counter bitO GPIO input 17 bitl GPIO input 18 bit2 GPIO input 22 bit3 GPIO input 23 bit4 GPIO input 24 bitS GPIO input 25 bit6 GPIO input 27 temp bitO 2 bitl 4 bit2 8 bit3 16 bitd 32 bit5 64 bite return temp def lear counter GPIO output 4 GPIO HIGH time gleep 5 GPIO output 4 GPIO LOW a pi raspbenypi mr m 193 average mrem maximum mrem min 20 mrem B average mrem maximum mrem min 1 Emrem 100 average mrem maximum mrem average MELEM maximum mrem min 273 mrem 4133 average mrem maximum mrem average Mirem maximum mrem arae Ore sample readings It should be noted that the mrem shown on the screen should be interpreted as microrem not millirem I did not have the u symbol available to output On reflection I probably should have used u in lieu of m a minor change that you should make to your program In any case the dose rate is extremely low about 100 prem or 1 uSv about the same as going thr
106. RasPi should be able to turn your digital flat panel TV on and off as well as control your A V receiver DVD player Blu Ray player etc The RasPi will become the ultimate remote control For more information go to http elinux org CEC_ Consumer_FElectronics_Control _over_HDMI Analog Composite Video Connector The RasPi also produces an analog video output from the RCA socket as shown in Fig 1 9 aran Analog video connector and cable This analog video functionality was deliberately included in the RasPi design to accommodate all those situations where only analog monitors or analog TVs are available especially in developing countries There is however an upside to the composite output To monitor project parameters in real time you can use small analog monitors These monitors are fairly inexpensive and can often be battery powered which is not a realistic option with larger computer monitors I have included the use of a small battery powered analog monitor in one of the book projects This monitor is shown in Fig 1 10 arua S Small analog video monitor Audio Connector The RasPi is also capable of creating an analog audio output in full stereo The output is from a Standard 3 5 mm stereo jack as shown in Fig 1 11 aeua ms Analog audio connector and cable This audio would normally be the analog equivalent of the digital audio outputted from the HDMI connector There is a book project that uses this a
107. SSI 12 See also Serial Peripheral Interface SPI system function 39 System on a Chip SoC technology 1 2 T Target position and velocity TPV 70 Targus Bluetooth adapter 167 169 Tera Term 62 63 65 66 135 137 Terminal windows 16 17 96 Test_ADC py 79 83 Test_File_ADC py 81 82 Test_Switch py 37 38 Text displaying 18 TFT thin film transistor display 155 165 Theory of general relativity 60 Theory of special relativity 60 Thin film transistor TFT display 155 165 Think Python Allen Downey 17 Threads in Motion software 106 TID total ionizing dose 176 Time dilation 60 Time keeping project 187 198 NTP 193 197 RTC 187 193 Time library 29 Time lapse photography 55 TimeLapse py 55 time sleep 5 29 Total ionizing dose TID 176 Townsend Kevin 117 TPV target position and velocity 70 Trimble 158 U UART see Universal Asynchronous Receiver Transmitter Ultimate GPS receiver for GPS project 61 66 for robotic car project 173 Ultrasonic sensor for robotic car 173 Uncompressed audio files 34 35 Universal Asynchronous Receiver Transmitter UART 9 in GPS receiver 01 64 in NFC RFID reader project 117 121 serial protocol 12 13 in time keeping project 195 Universal Powerline Bus UPB technology 89 Universal Serial Bus USB connector 7 8 University of Cambridge Computer Laboratory 1 UPB Universal Powerline Bus technology 89 Updating software
108. Sample e mail notification I wish to mention two items regarding this program First the public IP is determined by using an external website http ipecho net There is no guarantee that this website will be operational for the indefinite future If it becomes unavailable then alternate sites should be used and appropriate changes made to this program to accommodate the new site The second item is that I have not yet included the code for the GPIO trigger This inclusion will consist of restructuring the program as a module that will be called when the laser trip activates the selected GPIO pin Laser Trip Program The laser trip program sends the alarm e mail when a low level on GPIO pin 23 is detected by the RasPi The relay contacts shown as points 1 and 2 in Fig 8 7 will close when the laser beam is interrupted The contact closure puts a low voltage on pin 23 which is connected to the relay via the Pi Cobbler and a long cable as shown in Fig 8 11 Laser trip assembly connected to the RasPi The complete program named alarm py is available on www mbprofessional com raspi and is listed on page 112 Upon receiving the alarm e mail you would open a browser and type in the public IP address with the 8081 port for example http 44 236 239 221 8081 This should take you directly to Motion s webcam server that is streaming the real time video What you do next is up to you as I mentioned earlier I haven t q
109. The ability to experiment has been described as one of the key attributes that modern employers are looking for in twenty first century employees Donald Norris Acknowledgments I thank Karen for putting up with all my experiments and enduring all the discussions about the book s projects I also thank Roger Stewart for his continued support and guidance as the sponsoring editor He is the true champion for this book Thanks to Amy Stonebraker for her support as editorial assistant Thanks also goes out to Nancy Dimitry for her fine work as the project manager Finally I would like to thank all the folks at the Raspberry Pi Foundation for creating the board and getting it to the marketplace Introduction to the Raspberry Pi THIS BOOK WILL INTRODUCE you to the Raspberry Pi and provide 12 projects that will lead you through some simple fundamental operations up to some fairly complex ones The Raspberry Pi despite its small size is a fully functional computer capable of running a full fledged Linux operating system It is also the most inexpensive computer with this level of functionality that is presently available to the public The Raspberry Pi is a small board measuring 56 by 85 mm about the size of a standard credit card Nonetheless it contains some very impressive functionality as you will discover later in this chapter This new board is shown in Fig 1 1 u iz Fa m n ii amp 8 a 3 Ss 8 rs o O I
110. V pin 3 for reasons already stated in Chap 12 The TFT monitor requires 270 mA at 12 V DC to operate This requirement necessitated that an additional lithium ion polymer Li Po battery be added for the sole purpose of powering the monitor The Li Po battery is normally used in a radio controlled aircraft application where it can supply fairly high current for short time bursts However it fits this situation quite well being able to power the monitor for about eight hours given its 2200 mA h rating Figure 13 3 shows this battery Sarr Y The Li Po battery for the TFT monitor The Li Po battery must be recharged only with an approved charger designed for it Under no circumstances should you use an automotive 12 volt charger with this battery Bad things such as a fire will happen You may also have noticed a Velcro strip attached to the underside of the battery I used this strip as a convenient way to mount the battery and to allow it to be quickly removed for a recharge There are two Bluetooth micro USB adapters plugged into the RasPi s USB slots One is for the Wiimote and the other is for the wireless keyboard and mouse unit that I use with the car Figure 13 4 shows this Logitech model K400r keyboard and mouse combination I have found it to be extremely reliable and very moderately priced Logitech K400r wireless keyboard mouse The servo motors connect to the servo board by means of the three lead cables alre
111. ZIG Zulu UTC time and time to go to destination ZDA Date and tirme Latitude and Longitude Formats The two digits immediately to the left of the decimal point are whole minutes to the right are decimals of minutes The remaining digits to the left of the whole minutes are whole degrees Examples 4224 50 is 42 degrees and 24 50 minutes or 24 minutes 30 seconds 50 of a minute is exactly 30 seconds 7045 80 is 70 degrees and 45 80 minutes or 45 minutes 48 seconds 80 of a minute is exactly 48 seconds Parsed GPS Message The following is an example of a parsed GPGLL message that illustrates how to analyze an actual data message SGPGLL 5133 80 N 14240 25 W 75 2 3 4 5 6 7 1 GP GPS NMEA designator 2 GLL Lat Lon message type 3 5133 80 Current latitude 51 degrees 33 minutes 48 seconds 4 N North South 5 14240 25 Current longitude 142 degrees 40 minutes 15 seconds 6 W East West 7 75 Checksum All GPS applications use some type of parser application to analyze data messages and extract the required information to meet system requirements This will be discussed in the next section The gpsd Apps It is time to install and run the RasPi GPS application now that the GPS receiver and serial data connection have been proved to work correctly I will actually be using a suite of GPS tools or apps contained in a package named gpsd Enter the following command in a Linux terminal window to download and install t
112. ady attached to the motors Each cable plugs directly into one of the 16 three pin connectors I used connector numbers 0 and 1 for the right and left hand motors respectively It doesn t matter which servo connectors are used as long as the software is appropriately modified to reflect the actual connectors There is a more or less standard color code used for servo cables as follows red power white signal black ground I have one last item to mention regarding the wiring the Li ion charger board s power socket should be accessible so that it can be recharged Figure 13 5 shows such an arrangement on the prototype robot car The wall wart power cord plugged into the Li ion charger board Notice also that I had to remove the RasPi 5 V regulator board from the breadboard in order to provide clearance for the power cord I soldered two pins to the regulator so that the board plugs directly into the 5 V and GND strips that are the outermost strips on the breadboard It makes it very convenient to have a pluggable regulator for use with a breadboard I7C Software The servo board communicates with the RasPi using the I C protocol The I C RasPi setup which has already been discussed in Chap 12 must be completed before proceeding with the remaining software installations Bluetooth Software The first step in setting up the car to use Bluetooth is to plug in the Bluetooth adapter Just make sure the RasPi is not running
113. ake effect sudo reboot Enter the following commands after booting the RasPi sudo apt get update sudo apt get upgrade J Be patient this could take a while These commands ensure that the Wheezy distribution is current with all the latest changes Next enter sudo apt get install python smbus J sudo apt get install i2c tools J These commands load some useful applications that among other things allow you to check the address of attached IC modules The i2c tools package contains the i2cdetect application that will display all the I C devices connected on the bus Using it will confirm that the servo controller is being recognized by the RasPi The python smbus package contains all the software needed to access I C devices from Python This library installation is critical to ensure that the robot control program works The next step may not be required It depends upon the Wheezy distribution that you are running Check if there is a file name etc modprobe d raspi_blacklist conf installed You do nothing if it doesn t exist otherwise comment out these lines blacklist spi bem2708 blacklist 12c bem2708 Enter the command below to edit the file and put a symbol in front of the lines shown above sudo nano etc modprobe d raspi_ blacklist cong I7C Initial Test I would defer testing the I C bus if you have only one RasPi and it is already installed in the car However if you are using a second RasP
114. al for E details The web paga chetp support ntp org bin view Supports AccessResleicrions gt i might alsa be helpfal i i Bete that restrict applies to beth Servers and clients 6 a configuration that might be intended to block requests from certain clients could also end I up Blocking replies from Your pun USL reas servers E By default exchange time with everybody but don t allow configuration Featriet 4 default kod notrap nomadiiy Mope nequery Get Help D Writeour Road File Prev Page Cot Text re Exit om Justify Bhere Is Mext Page Mbut Text ee To Spell Screenshot of the ntp conf file There are four NTP servers listed starting with 0 debian pool ntp org through 3 debian pool ntp org The RasPi will typically connect to one or more of these servers each time it is booted I am unsure whether the lead number 0 to 3 represents a stratum level however it is irrelevant as the NTP software will automatically select the best clock signal and use it The RasPi NTP software is run as a daemon and requires no manual intervention for normal operation The software is formally named ntpd with the d indicating a daemon application Building a RasPi NTP Server I will show you how to build an NTP server that can provide accurate clock signals without the need to connect to one of the pool servers described above Sometimes it is necessary to provide an independent NTP network server that does not rely on an Internet co
115. al for seismic wave detection The piezoelectric film sensor does need some amplification to detect weak seismic signals Figure 6 6 shows a portion of the PMS circuit the electronic amplifier amp that increases the signal to useful levels The IC1 shown in Fig 6 6 is a Microchip model MP601 operational amplifier op amp that operates from a single power supply of 3 V and is configured as a noninverting amplifier The 11X gain is fixed by resistors R1 with a resistance R of 100 kQ and R2 with a resistance R of 10 kQ and is calculated using the following equation Re 18K Seismic detctor Output aoe lI M i lt R3 3VDC eee i 1 meg R4 Offset arwa OCISMiIc amplifier circuit Gain R R5 R Plugging in the values we get 11 100 KQ 10 kQ 10 kQ The potentiometer or variable resistor R4 in combination with resistor R3 sets an adjustable DC voltage offset so that the full range of the amplitude swing from the seismic sensor is input to the op amp without clipping or distortion The op amp output from pin 6 goes to both the RasPi processing circuit and the PMS microprocessor The original PMS uses a Microchip PIC24HJ64GA002 microprocessor to convert and store detected seismic waves onto an SD card which is later processed on a PC to display the waves My project uses the RasPi to process the seismic waves in real time thus making the information immediately available Unfortunately the RasPi doe
116. ality of the uncompressed WAV versus the lossy compressed MP3 Playing an MP3 File There are many Linux compatible apps available to play MP3 files I have selected a file named mpg123 as it is very stable and is easily controlled from a command line which is what we need for our RasPi MP3 player Use apt get to load this app as follows sudo apt get install mpg123 OTE There is a clone of mpg123 available on the web named mpg321 I am sure that it works just fine however I prefer to stay with the original Now type this to play the MP3 file that you downloaded sudo mpg123 class mp3 4 The MP3 will play for precisely the same amount of time as the WAV version and can be stopped at any time by pressing c as was the case for the aplay app I could not detect any appreciable difference between the two formats but you may and it might also be fun to invite friends and family to see if they can detect differences between the audio file formats mpg123 is also known as a console player app since you interact with it by using the keyboard and observing the app output on a terminal window This is exactly what we need to create a RasPi controlled MP3 player It is important to see what terminal controls are available and what their respective functions are This is easily accomplished by pressing the h key while the app is running Figure 3 6 shows the result of pressing this key while an MP3 was playing Pi File Eat Jabs Help
117. am using a rev 2 board so I will use pin 27 in lieu of pin 21 GPIO setup 27 GPIO OUT GPIO setup 1 amp GPIO IH GPIO setup 22 GPIO IN GPIO setup 23 GPIO IN GPIO setup 24 GPIO IN GPIO setup 25 GPIO IN select input Enter 1 shutter only 2 flash only 3 shutter and flash 0 exit J while select gt 0 shutter only if select 1 while True 1f GPIO input 24 False GPIO output 17 GPIO HIGH time sleep 2 GPIO output 17 GPIO LOW break flash only if select 2 while True 1f GPIO input 24 False GPIO output 27 GPIO HIGH time sleep 2 GPIO output 27 GPIO LOW break shutter and flash if select 3 while True if GPIO input 2z4 False GPIO output 17 GPIO HIGH GPIO output 2 GPIO HIGH time sleep 2 GPIO cutput 17 GPIO LOW GPIO ocutput 27 GPIO LOW break select input Enter 1 shutter only 2 flash only 3 shutter and flash 0 exityj 4 print All done To test this module you will need to aim the laser at the phototransistor which should turn off the LED on the detector board Next block the laser light beam with an opaque item which should trigger the light module and initiate the requested function There is no need to reset the light module since it is not latched Time Lapse Function The last camera controller function to test is time lapse photography This is where you set a maximum time to take photos at a pre
118. and time is simply to enter it at a terminal prompt using the following sample as guidance sudo date set 12 MAY 2013 22 15 49 J The RTC will automatically reset its internal memory based upon your manual input You should always check on the system time after setting it by entering sudo date You may also force the RTC clock to synchronize to the system date and time by entering the following sudo hwclock w H Next check the time reported back by the sudo hwceclock r RTC by typing in the following Figure 15 9 is a screenshot showing the set time command as well as the time reported back by the RTC p File Edit Tabs Help pigraspberrypi 5123 3 4 j iraspbel mpi Bii 4 sudo 1 cdetect y m m amp r 8 2 Bee ce ss sa ss ns sa ye wa ri pigraspberrypl sudo bash root raspberrypi home pi exit exit ipigraspberrypi sudo hwelock Mon 06 May 2013 84 38 39 ure pigraspberrypi sudo hwelock pigraspberrypi sudo hwelock Wn la May 2013 U i 0 Ll UG pigraspberrypi r l pi raspberrypi sudo modprobe rte g5 1307 fsys class i2c adapter i2c 1 new_device 0 327059 seconds seconds Screenshot of setting and checking the RTC date and time The next portion of this procedure concerns how to permanently configure the RasPi to use the RTC board The rtc ds1307 module must first be added to the LKM list that is stored in the etc modules fi
119. application and then used as an input in another part The major difference between the RasPi and the I O board is that a physical switch must be set on the I O board while a GPIO pin may be reset by a program statement with the RasPi It is just a bit more limiting to use the I O board as compared to the pure programming situation allowed with the RasPi However having eight channels available provides a good deal of flexibility The relay contacts are rated for a maximum of 250 mA at 250 V AC which equates to an approximate 60 watt load Do not attempt to switch more than a 60 watt load using these light duty relays and under NO circumstances should you try to control a line voltage AC motor If you want to control a heavy AC inductive load use the relay to control a motor controller that is rated for the AC load This is a safe practice and one that should be adhered to at all times ow_eight py import time import os w id o 6 system sudo opt owfs bin owfs allow other u m mnt lwire file object statement modify the device directory to match your own board ID file os path join mnt lwire 29 B827E08000000 PIO BYTE while True file obj open file r file obj write 10 line print time file line time file file obj read iline sleep 5 obj write 0 file obj read sleep 5 obj close Sniffer Monitoring I was in
120. appropriate internal motor control signals that move the servo to the commanded position or angular velocity Table 12 2 shows some of the specifications for the Parallax servos used in this robot car Table 12 2 Servo Specifications Specification Value Servo manufacturer Futaba RPM range O to 50 Operating voltage 4 to 6 vV DC range Max torque 38 oz in 6 V DC Weight 1 5 oz 42 5 g Mounting Four mounting screws I7C and the Servo Controller A servo controller board is required for this project because the RasPi only has one channel that can output PWM signals and the car needs two one for each motor I used the 16 channel 12 bit PWM Servo Driver I C Interface Board available from Adafruit Industries It is a bit of overkill for this application but it is flawless in operation and very easy to set up I C is another one of the serial protocols that was first introduced in Chap 1 The servo control board uses I C to communicate with the RasPi However the RasPi must first be configured to operate with the I C protocol which is not built into the Wheezy distribution as of the date of this writing It is part of the Occidentalis v 2 if you choose to use that version and is not very hard to setup Wheezy with the I C protocol At the command line prompt enter the following sudo nano etc modules Add the next two lines to the end of the file 12c bem 2708 12c dev Reboot the RasPi for the changes to t
121. ar I would remove it from the car and program it as you would normally and then reinstall it when everything is all set up Obviously if you have a second RasPi you can use that one to do all the programming and then put the programmed SD card into the RasPi that is already mounted in the car The next sections are brief discussions on the servos and associated drive components Servos Two analog continuous rotation servos drive the robot car A servo differs from an ordinary motor in that it requires a specific digital pulse train to operate Regular or non continuous servos are designed to rotate a shaft a certain number of degrees based upon the pulse width modulation PWM of the control signal Continuous rotation servos are designed to maintain a certain angular velocity based upon the PWM control signal In either case the standard PWM signal frequency is set at a nominal 50Hz and operates at a nominal 5 V DC for a high level and 0 V DC for a low level Figure 12 19 shows a typical PWM signal Period 10 to 22 mis Neutral Pulse Width 1500 ps Minimum _ Maximum Typical PWM signal The neutral position where neither a position nor a velocity is being commanded is set to be a 1500 ps pulse width The servo controller will increase or decrease the pulse width up to 500 ps depending upon the new desired position or velocity The servo motor contains an electronic circuit that converts the PWM pulse train to the
122. ard is designated rev 2 while the earlier version is designated rev 1 The additional pins are plated PCB holes as shown in Fig 1 17 and are located next to the GPIO connector Additional GPIO pins available for expansion Table 1 5 shows all the additional pins with their RasPi and BMC designations Pin 1 is the square plated hole located in the upper left corner of P5 You will need to install a 12 pin connector to access the pins The connector is supposed to be installed on the board s underside per Note 3 on the rev 2 0 board s schematic which is available at http www raspberrypi org wp content uploads 2012 10 Raspberry Pi R2 0 Schematics Issue2 2_027 pdf A suggested connector is shown in Fig 1 18 You will not need any of these additional pins from P5 to build any of the projects in this book Table 1 5 Additional GPIO Expansion Pins RasPi pin RasPi Description BMC Description RasPi pin RasPi Description BMC Description 5V0 5VO 33 aV3 GPIO_GEN GPIO2S GPIO_GENS GPIO29 GPIO_GENS GPIO30 GPIO_GENIO GPIOSI GND GND GND GND Legend 3V3 43W GND Ground BVO 50 V GPIO_GENn General Purpose Input Output pin n Sp a a Ri Rfi i TTT TTETeTrereiT Made in China ma p iek aria eka GPIO pin expansion connector Interrupts Each GPIO pin can also accommodate what are known as interrupts An interrupt is an event that stops or interrupts the normal programming flow and directs t
123. as all modules are interconnected via the RJ45 cables It just allows for additional flexibility The Humidity Module will be described next I am not showing an external case picture because it is identical to that of the Temperature Module except for the Humidity designation on the case front The internal PCB however is considerably different as you may see from Fig 10 8 Humidity Module PCB The humidity sensor designated as U3 not visible in Fig 10 8 is located at the top of the board It is a Honeywell model HIH 4021 001 sensor that produces an analog output based on the humidity it senses in the ambient air These analog sensor readings are sent to chip U1 which is a Maxim DS2438A This chip is also incorporated into the Barometer Module and will be discussed in a following section The external terminal connection strip is also present and can be seen on the right hand side of the board This strip is not used here as I mentioned in the Temperature Module discussion The Barometer Module is the last sensor to be discussed Again no external case picture is needed but the PCB board is shown in Fig 10 9 a eee g oO a Li E i Barometer Module PCB The pressure sensor designated as U2 is located on the left side at the top of the board It is a Freescale Semiconductor model MPXA4115A sensor which produces an analog output based on the ambient air pressure within the range of 28 to 32 inches of merc
124. as measured using an uncalibrated voltage output meter VOM This is quite close to the computed value of 1 612 The difference was primarily due to a slightly higher supply voltage measured at 3 32 V that when factored into the computation yields a 1 621 V or only a 008 V difference This is equivalent to about 3 counts or 0 3 which is quite normal for this type of ADC pia raspbernryplh File Edit Tabs Help Ln es OF LA Gn in idan tt tt oa u er rl j Ern i m i E E mi Ai a H 7 i a a E i oy c if af 1 i W om H Test_ADC py program output The sharp eyed reader may have noticed that the program does not rely on the built in SPI functionality but instead implements a bit banged interface that was discussed in Chap 1 page 13 This approach was taken because the Linux version used in this project did not directly implement the SPI protocol It makes no functional difference which approach is taken other than that four GPIO pins are dedicated in the bit banged version and are not otherwise available for other uses Connecting the Seismic Detector It is very simple to connect the PMS detector to the MCP3008 circuit First disconnect and remove the test circuit that was used in the above section Then connect the PMS op amp output and ground to the MCP3008 channel 0 and ground respectively Figure 6 13 shows the PMS connected to the MCP3008 circuit that in turn is connected to
125. asPi is sufficiently fast for all the projects in this book Broadcom has also graciously provided software drivers to allow the BCM2835 input and output pins to be connected to external peripherals This software is in the form of a Python library that I will discuss later The Broadcom VideoCore IV GPU handles all the video and audio processing for the SoC This GPU directly supports the OpenGL ES 2 0 standard that is essentially an Application Program Interface API capable of running on embedded hardware which in this case is the Broadcom 2835 Loosely translated this means the 2835 can easily display three dimensional 3D graphics using all the requisite shaders and texture filters normally required for modern games and high definition HD video This chip implements in hardware a 1080p 30 frames sec H 264 codec required for HD That is an impressive performance For readers fascinated with performance statistics it is interesting to note that the Broadcom Videocore IV GPU has the following processing capabilities 1 gigapixel sec that s one billion pixels processed per second 1 5 gigatexels sec that s one and a half billion texture elements per second 24 gigaflops that s 24 billion floating point operations per second All of this capability translates to the equivalent performance of a first generation Xbox not bad for a small embedded chip in a SoC sandwich I will not pursue this discussion any further other than t
126. ased your RasPi as part of a starter kit you will have received a 4 GB SD card with a Linux OS distribution already installed on the card A picture of this preprogrammed SD card is shown in Fig 1 4 element includes Raspian Operating System ideal tor Raspberry PI G cs Preprogrammed SD card I will explain later on in this chapter how to create your own memory card so you do not have to purchase a preprogrammed SD card Note that most SD cards also have a class designation on the label The one shown in Fig 1 3 does not as it has had a customized label attached The class designation relates to the minimum data transfer speed the SD card can handle Remember the SD card is taking the place of a hard drive so the faster the better Class 4 is very typical of the consumer grade SD cards that are available in most office supply stores Class designations and their associated minimum transfer speeds are shown in Table 1 1 Table 1 1 SD Card Class Designations Class Minimum Performance Class 2 2 MB sec Class 4 4 MB sec Class 6 6 MB sec Class 10 10 MB sec What you should take away from this SD class discussion is that the higher the class number of the SD card used in the RasPi the better it will perform The only downside is that SD cards with high class numbers are more expensive than ones with lower numbers sometimes more than twice the cost for the same storage capacity My only suggestion is to purchase a class
127. at you must consider when incorporating this board into a real world project A brief Linux introduction was covered to get you started in using this great operating system Most people find that once they become proficient in using Linux especially at the command line level they look at MS Windows with a newfound disdain I am not pooh poohing Windows I am simply saying that Linux gives you much greater control of your programming environment than you could achieve by using Windows Next I discussed Python and demonstrated how simple it is to start programming the RasPi with the traditional Hello World program Using the Python shell named IDLE just makes the whole effort very easy and I hope enjoyable LED Blinker Project Now we start creating projects using the RasPi However I still have some preparatory steps to discuss and information to provide about the prototype board that will be used in this and other projects I will also present a detailed discussion of the GPIO library which is critical to making all of the projects work The first project will consist of turning on an LED connected to a GPIO pin and then causing that LED to blink Prototype Board Let s focus on a piece of hardware that I will use to demonstrate how to blink an LED using the RasPi and some Python code This section is entitled Prototype Board and that is exactly what I will be using The board is called the Pi Plate and is available from Adafrui
128. ativity objects located close to massive objects such as the Earth will have their clocks moving slower as compared to objects that are further away from the massive objects This effect is due to the curvature of the space time continuum and has been predicted and experimentally verified by the general relativity theory Now back to the GPS satellites that are orbiting at 14 000 kilometers per hour km h while the earth is rotating at a placid 1 666 km h The relativistic time dilation due to the speed differences is approximately 7 microseconds per day us day while the difference due to space time is 45 ps day for a net satellite clock gain of 38 ps day While this error is nearly infinitesimal on a short term basis it would be very noticeable over a 24 hour time period The total daily accumulated error would amount to a position error of 10 km or 6 2 miles mi essentially making GPS useless That s why the earth ground stations constantly update and synchronize the GPS satellite atomic clocks OTE The atomic clocks within the GPS satellites are deliberately slowed prior to launch in order to counteract the relativistic effects described earlier Ground updates are still needed to ensure that the clocks are synchronized to the desired one nanosecond accuracy The Ultimate GPS Receiver I will be using the Ultimate GPS receiver breakout board available for about 40 from Adafruit Industries This receiver is shown in Fig 5 7
129. attached to the drive servo with a 0 25 inch screw that is also provided with each servo PARALLAX www parallax com amaA Continuous rotation servo Wheel kit The polyethylene ball is shown in Fig 12 8 and it is held in place with the cotter pin specified in the parts list Polyethylene ball Figure 12 9 illustrates the bottom side of all the assembled chassis parts The servos are mounted through the cutouts in the aluminum chassis with 0 5 inch 4 40 machine screws and nuts This generic hardware should be readily available at local hardware or home supply stores E A E z a O n m T Bottom view of the assembled car chassis You can also see a hole conveniently placed in the middle of the chassis top that is used to thread the servo control wires to the servo control board The chassis assembly should be a very quick and easy procedure if you have all the kit parts available Parallax has Boe Bot assembly instructions available on its website if you find that you need additional guidance Mounting the power source is the next step in the assembly process I chose to use a Parallax Li ion power charger board because it has ample capability to power a robot car and it just happens that its form factor precisely matches the Boe Bot chassis including the mounting holes Figure 12 10 shows the Li ion charger board Li ion Power BORE ee Cel Feta CEL Al AAI Mb DE In USA OHoriig
130. ave created Then type the following echo 255 gt PIO BYTE You should be rewarded by hearing all eight relays click and seeing all eight LEDs light up This command simply sends a byte of all 1 s into the file named PIO BYTE that controls all eight relays simultaneously Tired of seeing all the LEDs lit Type the following echo 0 gt PIO BYTE HJ All the LEDs should be off now and all the relays deactivated Of course specific relays may be activated by sending the appropriate bit pattern encoded into the equivalent decimal number to the PIO BYTE file For instance if you wanted to turn on relays 1 3 5 and 7 you would need to send 85 to PIO BYTE The number 85 was calculated by using the binary weights listed in Table 11 2 Table 11 2 Relay Binary Weights Relay l 2 3 4 5 6 7 8 Binary weight 1 2 4 8 16 32 64 128 To turn on relays 1 3 5 and 7 all that is needed is to sum the binary weights associated with each relay Relay Number Weight 1 z 5 16 i 64 Sum 85 Type the command echo 85 gt PIO BYTE J Relays 1 3 5 and 7 should now be activated and their LEDs on You now know how to turn them off Individual relays may also be controlled by using specific files dedicated to each relay For example to turn on relay 4 type the following echo 1 gt PI0O 3 JH Relay 4 turns on The individual relay file names start at 0 not 1 This is not true for the board re
131. be output at motion detection Recommended range 0 to 5 default 0 Do not use large values Large values will cause Motion to skip video frames and cause unsmooth mpegs To smooth mpegs use larger values of post_capture instead CHANGED pre_capture 10 E Humber of frames to capture after motion is no longer detected default 0 Ih hk w TH H CHANGED An event is defined as a series of motion images taken within a short timeframe Recommended value is 60 seconds Default The value 0 is allowed and disables events causing all Motion to be written to one single mpeg file and no pre_capture CHANGED gap 5 Maximum length in seconds of an mpeg movie When value is exceeded a new mpeg file is created Default 0 infinite max mpeg time Always save images even if there was no motion default off output all off Change the no to yes then save the nano buffer and exit the editor Next comes Motion s configuration file Motion has no GUI it is totally configured by making changes to its configuration file etc motion motion conf This is a very big text file well over 600 lines although much of file s contents are comments inserted to help the user Fortunately only a few changes are necessary for this project In Table 8 1 I provide the changes to be made to the configuration file section but I do not give you step by step instructions because it should be fairly obvious by now how the edi
132. be used as a disk image file The Raspberry Pi Foundation currently appears to be updating the Wheezy Raspian Linux distribution almost every month This is subject to change so take advantage of it while it lasts It is now a simple matter to create your own SD card once you have the image and the disk writer program Insert a blank SD card into the PC run the app and then browse to the location where the image is stored Then click on Write and you will get a warning about destroying existing data on the card Click OK and wait It takes several minutes to create the image You now have your own Linux distribution on an SD card Also remember that you can rewrite an SD card as often as you want so feel free to experiment with different distributions I now need you to create a new SD card both to ensure that you understand this process and that you have a specific distribution available that will also support the Chap 10 book project which requires what is known as the 1 Wire serial protocol This distribution is named Occidentalis V0 2 and is available at http learn adafruit com adafruit raspberry pi educational linux distro occidentalis vO dot 2 This distribution was created by the kind folks at Adafruit where I purchase most of my RasPi goodies The unusual name derives from the Latin name Rubus Occidentalis for the black raspberry which is apparent from the GUI desktop that appears when this distribution is running as shown in
133. bles to interconnect all the 1 Wire modules for this project Be sure that you do not inadvertently use an Ethernet crossover cable because that will break the 1 Wire connection scheme It will not harm the modules but the data connection will not work The next element shown in the system diagram is the Power Injector Module which is shown in Fig 10 4 W Power Injector Module A 15 V wall wart power supply a box shaped device that plugs into the AC electrical wall outlet and provides DC power to various electronic devices plugs into a socket mounted on the case top There are also two RJ45 connectors mounted on the sides of the case that are not visible The cable from the USB dongle connects to the left socket while the patch cord that goes to the next module connects to the right socket The 15 V are sent out through the Ethernet cable and are also down regulated to 5 V for local use by a 78M05 regulator mounted on the internal PCB that is shown in Fig 10 5 Power Injector PCB It turns out that some 1 Wire modules do not require a separate power supply This is discussed in the section describing various ways to power a 1 Wire network In this weather station project the barometer humidity and packet sniffer modules do require the use of a power injector because their power consumption exceeds the 1 Wire standards for parasitic power supply operation which will be discussed shortly The weather modules foll
134. book projects to help avoid confusion on your part MP3 Project Requirements The first step in any project is to specify the requirements that must be met to satisfy the project user In this case the project requirements are rather simple They are listed below Use the mpg123 app as the MP3 player Play selected MP3 files tracks stored in a preset directory Use the computer monitor to display file track data Use the 3 5 mm analog audio jack for output Use the keyboard to enter commands to control the mpg123 app while it is playing a song Use one of three push buttons to play a preselected song It is a straightforward process to build this project as most of the component parts and software have already been discussed Writing the Program The key issue is to start the mpg123 app from a Python program with all the needed arguments Fortunately Python provides a function named system that allows us to do this quite easily And it is part of the OS package The following Python program I created is named MP3_ Player py and it is available for download from the book s website MP3_Player py import the os package as it contains the system function call import os Fimport the GPIO library to access the pins import Rp1 GPIO as GPIO fuse the BCM pin numbers GPIO setmode GPIO BCM set pin 273 as an input GPIO setup 23 GPIO IN Set pin 24 as an input GPIO setup 24 GPIO IN set pin 25 as an input GPIO setup
135. both simultaneously Internet access will be done in exactly the same way as discussed above except the forwarding port is 2121 Summary The 1 Wire 8 Channel I O board was first examined with a detailed review of the board s key specifications This board provides an expanded number of GPIO pins beyond the RasPi s seven Next a 12 step build and configuration process that created an owfs development environment supporting the I O board was carefully explained I then took a brief digression to explore Linux FUSE and owfs This explanation should help you understand how owfs functions Testing the I O board inputs and outputs came next I used only commands entered at the terminal prompt to exercise the board functions A short Python program ow_eight py that controlled the I O board through a series of output commands was demonstrated A brief view of the Sniffer Module output was also shown The ow_eight py program should serve as an example of how to create more complex programs suited to unique applications I next showed you how to control the RasPi s GPIO pins by using an Android smartphone application named DrGPIO along with the WebIOPi web server installed on the RasPi I also demonstrated how you could operate the same functions with the same WebIOPi web server by using a regular browser The chapter concluded with a demonstration on how to control the I O board using the HTTP owfs web server from a browser Roboti
136. c Car Part 1 Introduction This chapter is one of two that will show you how to build a RasPi controlled robotic car I ve spread the project over two chapters because of the build complexity and the software involved The elements covered here in Part 1 include the mechanical construction and the hardware and software that control the drive system Developing the robotic car has been a very enjoyable experience and the project has attracted a lot of interest among folks who are curious about what the Raspberry Pi is and how it can be used There is nothing like a robotic car to stir up interest in this great little board Now on to building the car Overview I thought it would be a good idea to show you some pictures of the car all built and ready to run Figures 12 1 to 12 3 show the final project with the optional thin film transistor TFT display mounted Raspberry Pi robotic car front view Raspberry Pi robotic car right side view And yes that is the Wheezy Linux desktop being displayed in Fig 12 1 I use a wireless keyboard and mouse to interact with the RasPi just as I would normally when sitting at my desk This is truly a portable computer on wheels The car however will not be controlled by keyboard or mouse commands but will instead be handled by a Wii remote control device Wiimote as shown in Fig 12 4 Senap Wiimote a k The Wiimote uses Bluetooth a wireless technology for data transfer
137. c sensor design 75 76 seismology basics 73 74 Serial Peripheral Interface for 78 8 Channel I O board for logic controller project 139 140 144 146 remote access to 151 153 test sequences for 144 146 Einstein Albert 60 Electrical buffers 23 Electronic amplifier amp circuit 76 Electronic flash 45 47 52 E mail notification home security system project 109 111 NFC RFID reader project 123 End of Frame EoF byte 89 Ephemeris 60 Ethernet connector 7 8 in local and remote logic controller project 140 and 1 Wire connection 126 Expansion connectors 8 9 extract_data py 122 123 F Fabless suppliers 2 Filesystem in Userspace FUSE 143 144 Flash electronic 45 47 52 Flip flop operation 49 Floating inputs 150 4 wire serial bus 12 See also Serial Peripheral Interface SPI Freescale Semiconductor 128 Frequency response of analog audio 33 34 Full duplex communication 78 FUSE Filesystem in Userspace 143 144 Future expansion connectors 8 9 G Galileo system 57 Gamma rays radiation 175 Garden gate seismic sensor 75 Gas tight connections 24 Geiger counter K2645 Geiger Muller counter 175 177 179 portable 183 185 geiger py 180 181 General Purpose Input Output GPIO connector 9 10 accessing pins 23 20 current limits 10 11 GPIO library 25 26 input state for pins at power on 27 interrupts 11 12 isolating pins 47 48 making pins p
138. c source code pifraspberrypi ed libnifc pifraspberrypi fe sudo wget http libnfc googlecode com files libnfc 1 6 0 rel1 t ar gz 2013 03 ego 52 Connecting to Llibnfc googlecode com libnfc googlecode com 173 194 69 82 80 connecte d HTTF request sent awaiting response 200 OK Length 571772 550K application x gzip Saving to Libnfc 1 6 0 rel tar gz i 1004 ssssss3s55555555555555555555555555555555555555E gt 71 772 l1 31M3 in 0 43 1013 03 07 13 04 06 1 41 MB s libnfe 1 6 0 rel tar gz 1 saved S71772 571772 m pifraspberrypi The libnfc source code download 5 The downloaded source needs to be unzipped A new subdirectory named libnfc 1 6 0 re1 will automatically be created in the libnfc directory after this action is completed Type the following at a terminal command prompt sudo tar xvzf libnfc 1 6 0 rel tar gz J Figure 9 8 shows the end portion of the display after this extract operation has finished libnfc 1 libnfe 1 libnfc 1 libnfc 1 libnic 1 libnfe 1 libnfc 1 libnfic 1 libnfc 1 libnfc 1 libnfc 1 libnfc 1 libnfe 1 libnic 1 libnfe 1 libnfc 1 libnfc 1 libnfc 1 libnfc 1 libnfc 1 libnfc 1 libnfe 1 libntc 1 libnfc 1 libnfc 1 libnfc 1 libnfc 1 libnfic 1 libnfc 1 libnfc 1 libnfe 1 libnfc 1 libnfe 1 libnfc 1 6 6 6 y 6 6 6 6 z 6 6 6 6 6 6 6 6 6 6 E 6 6 6 6 6 6 6 6 Li 6
139. ces the same result as discussed above I will use the nano editor to write the program and save it I will then recall the saved program and run it from the Linux shell Open an LXDE terminal window and type nano Next type print Hello World Press the key combination Ctrl and the letter o I will show this as o from now on O This action will bring up a prompt at the bottom of the editor requesting the name of the file in which to save the buffer s contents Type Hello py The py is a standard Python program extension Fig 1 29 shows the nano editor at this point in time File or Jabs Help CMU Anand 2 2 6 File Name to Write Hello py Catt H Lin et E wee aie eN nano editor Type to exit nano There will now be a Python program named Hello py in your home pi directory A Python shell must now be opened to allow the file that I just created to be opened and run Opening the file is done by clicking on the File menu tab and then clicking on Open from the drop down menu A file browser dialog box will be opened that shows the contents of the pi directory Select the Hello py file as shown in Fig 1 30 E Python Shell File Edt shal Debug Options Windows Help P eython 2 7 are2 default May 6 2012 20 62 25 cee 4 6 3 on linua Type copyright eredita or Licenge for more information m Directory homem
140. ch has been available for many years first appeared with the advent of the PC in the early 1980s There were timing systems available before that period but they were fairly complex and expensive devices and suitable mainly for mainframe computers The RTC introduced with the first PC was based upon an integrated chip named the MC146818 which was manufactured at that time by the Motorola Corporation A modern version of that chip is used in this project It is the DS1307 pictured in Fig 15 1 which is manufactured by the Dallas Semiconductor company previously mentioned in Chaps 10 and 11 DS1307 DIP The DS1307 is an I C controlled device as may be readily seen by the block diagram shown in Fig 15 2 It is a fairly simple peripheral that uses a quartz crystal controlled oscillator in conjunction with a binary counter that is labeled as an oscillator and divider in the diagram The crystal is rated at a nominal 32 768 Hz frequency equivalently 32 768 kHz which is exactly the value of 2 raised to the fifteenth power Therefore a 15 bit binary counter will overflow or reset once every second if a 32 768 kHz signal is input to the first stage of the counter Theoretically this setup will produce a once per second clock tick Notice I used the word theoretically as the reality is that the clock crystals typically used with the DS1307 do not produce a perfect 32 768 kHz waveform Figure 15 3 shows the actual crystal used in this project
141. commands but also the interchange of ACKs and NACKs This is similar to the TCP protocol in that it ensures error free data communication Figure 9 4 is a graphical representation of the same data interchange Host Controller PN532 puewwog Sd ection E r ACK PN532 s RX Graphical representation of the data interchange between the RasPi and the PN532 controller The libnfc software package controls all the data communication between the PN532 reader and the RasPi The reader s firmware will push data to the RasPi when it detects the presence of a tag Installing libnfc This libnfc installation is based upon an excellent tutorial created by Kevin Townsend from Adafruit Industries I have performed this installation using both the Wheezy 2_2013 and Occidentalis v2 0 distributions The project Python test code uses the Wheezy distribution The PN532 breakout board provides hardware support for UART SPI or I C communication protocols This project uses the UART protocol because the Wheezy distribution supports it without any modifications as of the time of this writing What follows is a step by step process that is complemented by many screenshots to help you navigate through this somewhat complex process I also found it easier to use a SSH connection to accomplish this installation I refer you to an earlier discussion in Chap 7 on how to run a SSH session The initial steps are to make the Wheezy
142. connect the wires going between the GPIO pins and the module interfaces for these tests The sound module connection will be either on or off depending upon the State of the latched relay Using the VOM check to see that pin 24 switches between 3 3 V on and 0 V off This is a valid test for the sound module because it operates in the same manner as the push button interface The laser light module is checked in a similar fashion at pin 25 However as mentioned above the module relay contacts are closed when light is not striking the phototransistor This means that pin 25 should have 0 V when no light is on the sensor and 3 3 V when light strikes the sensor If you have any problems recheck all the wiring since it is very easy to misplace a jumper wire on the solderless breadboards Also ensure that you have all the appropriate grounds connected as shown in the figures Initial Test Program The following program tests the camera focus and shutter controls as well as the electronic flash by using the push buttons It is named CameraControl py and may be downloaded from the book s website www mbprofessional com raspi CameraControl py LAE T LIR import RPi GPIO as GPIO GPIO setmode GPIO BCH GPIO setup 4 GPIO OUT GPIO setup 17 GPIO OUT WT am using a rey 2 Board so I will use pin 27 in lieu of pin 21 GPIO setup 27 GPIO OUT GPIO setup 18 GPIO IN GPIO setup 22 GPIO IN GPIO setup 23 GPIO IH GPIO setup
143. controller by using the RasPi with several auxiliary modules that will act as trigger sources The controller will allow you to trigger a digital camera and or an electronic flash if they are inherently capable of being remotely controlled It will also enable you to take some very interesting pictures including stop action photos The following three figures illustrate one simple experiment that demonstrates the controller s stop action effect I made a flag object out of black and white duct tape onto which I printed the numbers 1 and 2 I attached this flag to a nail that I inserted into a portable drill chuck Figure 1 shows the drill chuck with the flag at rest Flag at rest Next I started the drill and had it rotating at approximately 500 revolutions per minute r min Figure 4 2 is a normal photograph taken with my usual studio lights and without an electronic flash This figure mimics what the human eye perceives in that both numbers are visible because I used a Slow shutter speed Flag rotating at 500 r min Figure 4 3 is a picture taken with the electronic flash and a slow shutter speed in a darkened room You can clearly see the number 2 visible and not blurred even though it was rotating at 500 r min or almost 10 times per second Flag captured in a stop action photo The controller will assist you in making similar stop action pictures as well as many other effects that you may want to accomplish
144. cted by the reader This program provides the basic functionality of the NFC design and serves as a template to expand the application for additional uses which will be described later The Python code listing is shown on page 123 This program named extract_data py uses the nfc poll program to capture the tag information and writes it to a text file named nfc_data txt This file is then read and parsed to extract the tag ID data This ID data is then compared to a hard coded tag ID to check if it matches A match will turn on the LED for 10 seconds as well as display the word match on the console screen If the tag doesn t match the phrase no match appears on the console Run the program from the pi directory by entering the following at the command prompt sudo python extract data py 4 The console display cursor will jump to a new line and wait for a tag to be placed near the reader Once this is done the display will show match or no match and the LED will light for 10 seconds only on a match condition This program is quite constrained in that it must have the desired tag ID hard coded before it is run But as previously stated it is only a starter or template that you can use to greatly increase the flexibility and utility of the project Suggested modifications and improvements are discussed in the next section Future Expansion The obvious expansion would be to have the RasPi signal an electronically con
145. ction I will show you how to control the RasPi GPIO pins by using an application running on an Android smartphone The smartphone application is named DrGPIO and is available as donationware from the Google s Play Store app Donationware as the name implies means that you may donate to the author if you use it and find it useful You must also download the web server portion named WebIOPi Follow this procedure to download and install the server 1 Type the following at a command line prompt sudo wget http webiopi googlecode com files WebIOP1i 0 5 3 8aE gZ l 2 Next extract the source code sudo tar xvzf WebIOP1 0 5 3 tar gz H 3 Change directories to the newly created one cd WebIOPi 0 5 3 J 4 Install and set up the software using a preset script sudo setup sh J OTE I had the initial setup fail on me I did the following to resolve the issue sudo apt get update sudo apt get python3 2 dev J Repeat step 4 above Figure 11 10 shows the end result of the setup command C Pi raspherypi AVeblOPi 0 5 3 File Edit Tabs Help byte compiling buildsbdist linux armv6l egg _webiop1 GPIO py to GPIO cpython 32 5 pyc epee compiling build bdist linux armv6 l fegg _webilopi _ init__ py to _imit__ cpy thon 32 pyc creating build bdist linux armv6L eqg EGG INFO copying WebIOP1 egg into PKG INFO gt bur ldybdist linux armv l egg EGG INFO copying WebIOP1 egg info SOURCES txt gt build bdist Linux ar
146. d and results in the click from the counter These clicks are counted for the dose level measurement Figure 14 3 is the schematic for the K2645 GM counter y EFL i lia hi oH ee iS Ts It a iwi T TAA A i Teje oi 9 CH ake ake Ail AG j IT ais i ell a7 Mie E TE ET gn a a VELLEMAN K2645 GEIGER MULLER COUNTER K2645 GM counter schematic There are four functional areas in the schematic 1 A square wave oscillator that is connected to the transformer TRAF 01 primary 2 A voltage multiplier array that uses diodes and capacitors and is connected to the TRAF 01 secondary winding This array creates the 600 V DC 3 The GM tube 4 A monostable oscillator that detects the momentary current pulses due to the radiation and activates a piezo electric buzzer for the audio click The output from the board IC labeled N6 is used as an input to the RasPi interface which is discussed next GM Counter RasPi Interface The interface has two requirements 1 To transform the click signals to pulses that may be counted 2 To count the pulses for preset intervals and output the resulting digital count to the RasPi The block diagram schematic for the interface is shown in Fig 14 4 GM Counter RasPi interface block diagram schematic Table 14 3 is a parts list for the interface circuit Table 14 3 GM Counter RasPi Interface Parts List Item Distributer Model Number Description Ripp
147. d automation sequences Figuring out the web page inputs should not be a very hard task for you given that you already have reached this stage in building a RasPi home automation system and have successfully loaded and run all the support software Mr Vassallo has stated in his blog that the software is still evolving so don t be surprised if a better perhaps somewhat easier version is developed and put in the public domain basic Server The second approach mentioned above is to use the basic server that Mr Loughlin created to test the Z Wave network functions In order to do this you must first kill the lightscontrol server that is currently running since there cannot be two Z Wave servers running concurrently You can also close the browser at this time it will need to be reopened however once the next service is started Kill the current web service by typing killozw J at the SSH command line This is the reason why I did not want you to stop running putty To start the basic server simply enter the following at the command line basic Once that is done minimize putty and open the browser going to this website http openzwave local basic This should take you to the basic server page as shown in Fig 7 17 e gt D openrwavelocal basic EJ Search Settings C Imported From IE 5 Google Name Outdoor Switch Type Binary Power Switc Group g Haus On Last MSG MSG ave Nodes
148. d be exactly 1200 values in a single column Each value represents the digitized value of a sample from the PMS detector The samples were taken at an interval of 1 second hence the entire record spans two minutes During this time the PMS was subjected to some shaking which provided the data for analysis My Excel file is available on the book s companion website as Seismic xlsx Figure 6 14 is a graph of an interesting portion of the data set I selected it by visually scanning a graph of the entire record This portion covers the first 200 samples I next wanted to zoom in on and examine in finer detail a portion of this graph that covered X axis numbers 139 to 168 Figure 6 15 shows this detail 1200 4 l 1000 Bod i i O erii Gal ieee 200 o 4 SRRATASRGRSE SNES EERE ES anaes 200 samples 1700 1000 4 ae Piot Area O Series lgsiF TT BET BiB Sil B 30 samples Test_ADC py Segment modification to allow collection of actual data file open myData w for i in range 1200 adc value ade channel SPICLK SPIMOSI SPIMISO SPICS str converts the numeric ade _value into a string The n is the newline char adcstr strjade value n file write adestr 1f DEBUG print value adc value sample 10 times per second time sleep 1 file close print All done Fou
149. d categories for audio file formats 1 Uncompressed An uncompressed storage uses the most storage of any format 2 Lossless compression Skips silent portions stores audio content 3 Lossy compression Compresses everything introduces a little distortion Table 3 2 lists some representative formats from each of these categories Table 3 2 Audio File Formats Compression Type Compression Ratio Remarks Also called PLM VAW Uncompressed 1 1 AIFF Uncompressed 11 1 1 Al Uncompressed FLAC Lossless compression 1 WMA Lossless Lossless compression 2 Windows Media Audio Were Lossless compression 2 Apple lossless format MPS Lossy compression 1 1 t 20 1 Vorbis Lossy compression IO to 20 1 ACC Lossy compression 10 1 to 20 1 WA Lossy Lossy compression 10 1 te 20 1 WAV versus MP3 Formats I will further discuss these formats since the project uses the MP3 format However I have also included a simple demonstration of the RasPi playing a Waveform Audio File Format WAV file The WAV format provides the truest reproduction of the original audio content as is possible using digital technology The source content is sampled at a high rate using a sufficiently large number to precisely record the amplitude of the digital sample High sample rates and large data storage numbers mean very large storage requirements For instance a three minute symphonic musical score might take 30 MBs of storage In comparison an MP3 forma
150. d versus buy decision regarding the sound and light modules I was very pleased to find that I had made the right decision as I had no trouble incorporating these kits into the project You will find that your time is very valuable and finding ways to shorten a project such as incorporating prebuilt components and or kits can be a valuable tool for maximizing your productivity I next went through a step by step testing procedure to ensure that the interface circuits were working as designed There was no need to run any programs on the RasPi at this stage It is always a prudent idea to carefully check and test all interface circuits before running any programs Testing in this fashion allows you to determine that any later functional problems are probably due to program glitches not the interface circuits I then introduced a series of four test programs to methodically check that all planned project requirements were met and that all the components functioned as desired These four programs will serve as good templates to allow you to create your own custom programs You can design them to best suit your needs or you can simply use them as they are GPS Introduction In this chapter I will first discuss what constitutes the Global Positioning System GPS a satellite based navigation system and the advantages and limitations that are involved with using it I will next explain how a serial communication link may be set up and run between
151. der to provide power to the Pi Cobbler and breadboards First check each of the push buttons There should be 3 3 V present on pins 18 22 and 23 The voltage should drop to 0 V when one of the buttons connected to the pin under test is pushed Next check the camera optoisolators First ensure that the wires going from pins 4 17 and 21 are temporarily disconnected Then plug the shutter control cable into the camera and then turn on the camera Using a jumper wire connect the 3 3 V power supply on the breadboard to the 220 Q resistor that connects to pin 1 of the optoisolator Do not touch pin 1 on the optoisolator with the 3 3 V jumper wire You must go through the current limiting resistor or else the LED in the optoisolator could burn out from excessive current You should observe either the camera auto focusing or the shutter operating depending upon which optoisolator you are testing The electronic flash should be tested next Plug the remote hot shoe into the flash and ensure that it is also connected to its controlling optoisolator Turn on the flash and then touch the 3 3 V jumper wire to the 220 Q current limiting resistor that is connected to the optoisolator The flash should operate Remember to reconnect all the wires between the optoisolators and their respective GPIO pins as shown in Fig 4 16 The sound and light modules are tested last Connect the modules to the breadboard and power them on You do not have to dis
152. do fetc init d weblop1 start Look in home pi WebIOP1 0 5 3 examples for Python Library usage examples pidraspberrypi WebIOPi 0 5 3 Setup command end result 5 The HTTP web server is started using Python as follows sudo python m webiopi 8000 The 8000 is optional because it is the default I like to include it since it is a reminder of the actual port number Figure 11 11 shows the console display for the web server starting pigraspberryp1 WebIOP1 0 5 3 sudo python m weblopi 8000 ebIOP1 Python2 0 5 3 Access protected using etc weblopi1 passwd ebI0P1 Python2 6 5 3 HTTP Server started at http 192 168 1 21 8000 webiop1 Starting the WebIOPi HTTP web server The user name is webiopi and password is raspberry if you are asked for them by the application The service may be stopped by either a keyboard interrupt C or closing the terminal window in which it was started You may also start and stop the web server as a service using these commands sudo etc init d webiopi1 start J sudo etc init d webiopi stop The web server can even be started during the boot process by entering the following command sudo update rce d webiopi1 defaults 4 Testing the Web server with the Android App I set up the RasPi with a Pi Cobbler prototype tool to drive three LEDs as shown in the Fig 11 12 diagram ribbon cable LED RasPi 270 ohm Test setup diagram
153. does nothing Print the IP addres P lhostname I if IP then printt My IP address is s n _IP f1 echo ds1307 Ox68 gt sys class i c adapter i c 1 mew device sudo hweleck 8 exit Z Get Help fm wWriteQut iE Read File i Prev Page i Cut Text T Cur Pos a Exit am Justify Mo Where Is Next Page Uncut Text W To Spell x The edited rc local file screenshot I shut down the RasPi after completing the previous configuration steps and waited until the next day to restart the system in order to check the RTC function Figure 15 12 shows that the date function worked perfectly indicating that the RTC was performing as expected and accurately tracking the passage of time pi raspberrypi a File Edit Tabs Help pi raspberrypi date Sun May 12 23 02 41 UTC 2013 pigraspberrypi 0 Screenshot of the date function Introduction to the Network Time Protocol NTP NTP is probably the most common way time is set and maintained in today s modern networks including the Internet The protocol itself was created by Dr David Mills at the University of Delaware in 1985 Currently Dr Mills is an emeritus professor at the University of Delaware where he was a full professor from 1986 to 2008 He along with a team of volunteers is still involved with the development and maintenance of NTP In reality the NTP is implemented by a layered hierarchical network of computers each one of which is set u
154. e still at an acceptable 3 3 V level RTC Software The procedure discussed in this section is based upon a fine tutorial developed by LadyAda on the Adafruit website The RTC chip uses the I C protocol for communication with the RasPi which means that the basic I C software must be installed in the Wheezy Raspian distribution The detailed I C installation procedure shown in Chap 12 should be accomplished before you proceed with the following software instructions Enter the following command in a terminal window to confirm that the RTC is detected by the I C bus sudo i2cdetect y 1 J 1OTE Note Replace the 1 with a 0 if a rev 1 RasPi is being used Figure 15 7 is a screenshot showing that the RTC board was detected at address 0 x 68 EE pi raspberrypi 0 File Edit Tabs Help pigraspberrypi sudo izcdetect y 1 sn ee 7 8 abecede f 2 6 7 B E E a E E a s m Detecting the RTC board on the I C bus The next step is to load the RTC module software which is done by entering this command sudo modprobe rtc ds1307 J The modprobe application loads what is known as a loadable kernel module LKM which in this case is named rtc ds1307 You may have to run the following two commands if the LKM is not found sudo apt get update sudo apt get upgrade The next step is to instantiate the RTC object which you must do at the root level using the following commands sudo bash J echo ds1307 0x68 gt
155. e board 156 161 163 Putty exe 95 96 PV Electronics 197 P waves 73 74 pwd Linux command 17 PWM pulse width modulation 161 PWM Servo Driver I C Interface board 156 161 163 py extension 19 Python programming 13 17 20 comments in 27 data storage in 81 82 looping in 29 modifying program 28 29 nano text editor for 17 19 20 Saving code 28 shell versions 18 19 website for 17 writing program in 19 20 Python Programming for the Absolute Beginner 3e Michael Dawson 17 Python programs xi Python shell opening 20 opening running program in 28 versions 2 and 3 18 R rad 176 Radio Frequency Identification RFID 115 See also NFC RFID reader project Radio frequency RF signals 60 Radio frequency RF transceiver 87 Radio receiver clock source 197 Radioactivity 175 178 See also Radon detector project Radon detector project 175 185 initial test configuration 179 182 K2645 Geiger Muller counter 178 179 modifications and expansions 185 portable detector 182 185 radioactivity and radon gas 175 178 Radon gas 175 176 Ramsey Electronics 48 Raspberry Pi RasPi 1 21 Broadcom 2835 microprocessor on 2 3 connectors on 4 10 current limits with 10 11 digital signal voltage level 10 graphics processing unit of 2 3 hardware for 2 13 history of 1 IDLE application for 18 20 initial startup 13 15 interrupts 11 12 key components connections on 1 2 Linux
156. e differences noise and line distances It is somewhat ciificult ta canhigure and is subject to erratic performance UPS is short for Universal Powerline Sus and was created to overcome many of the AlO problems it is also not compatible with the X l0 technology thus requiring 4 controller that can talk to both UFE and X 10 if you are using components from tach system INSTEON The first home automation technology to use both powerline and wireless communication it is fairly simple to configure and run Z Wave A totally wireless technology that is very simple to configure and run Individual nodes also extend the total network range by the use of a digital repeater mode It is alsa standards based ZigBee This recent addition to home automation uses wireless It is also used in low power control area networks It 5 somewhat complicated to canhigure and runs inte problems when components from different manufacturers are being used I selected the Z Wave technology to use in this project because it is wireless very robust based on standards and has components that are easily purchased and available from reliable manufacturers including GE Black amp Decker Schlage ADT and Draper Anyone can purchase a Z wave remote control and several nodes and have an automation system functioning in a matter of minutes the simplicity of setting up an automation system is what attracted me to this technology This project replaces the remote with
157. e dynamic nature of the RasPi project Fig 1 14 is a close photo of one of the connectors labeled S2 This connector is a 15 way flat flex connector designated for use with the Camera Serial Interface CSI 2 A prototype digital serial camera was just introduced at an international electronics show at the time of this writing The other flat flex connector labeled S5 and located just behind the Ethernet RJ45 connector is designated as a Display Serial Interface DSI that will eventually drive a Sony Low Voltage Differential Signaling LVDS serial display You should check the RasPi website for the latest news regarding the RasPi Ti l piae ii E di l i Cit EN ee i gt i A e J F 7 Be ace a OF 8 ji isk TE i Fm a re r mi p aee a amp ih io 0 d A x F am fie Ba Par pA ad LP A vo Ba 7 ot Pe ls m aT IEB yrna me Expansion connectors GPIO Pin Interface Connector The General Purpose Input Output GPIO connector has 26 pins positioned in two rows of 13 pins each Fig 1 15 shows this connector with pins 0 1 25 and 26 pointed out Pin 26 Pin25 Fe Ans or The wo mre th d 1 2 oh ee GPIO connector Table 1 2 details pin assignments with both the RasPi pin designations and the BMC2835 pin designations Using two different sets of pin designations is confusing but unfortunately that is the situation with this board
158. e is a stack of two USB connectors shown on the right hand side of the figure These are normal USB connectors in the sense that USB peripherals will be recognized when plugged into the sockets The only issue with these is that the RasPi cannot supply the standard amount of current according to the USB specification which is 500 mA per socket Remember that I mentioned earlier in Fig 1 6 that the power supply in the RasPi kit provides up to 1000 mA If peripherals plugged into these sockets took 500 mA each there would be none left for the poor RasPi Obviously this situation should not be allowed to happen and there is a good and relatively cheap solution I use a powered USB hub as shown in Fig 1 13 that can easily provide all the current that typical unpDowered USB peripherals require Self powered USB hub There is one USB cable that connects between the hub and the RasPi That leaves one available USB socket on the RasPi for a low power peripheral such as a thumb drive The number of USB ports provided by the hub varies with the manufacturer however four or five ports are fairly common The power supply shown in the figure is rated for 2100 mA which precisely matches the USB specification for four ports and a little left over for the hub internal electronics Future Expansion Connectors Two connectors prominently populated on the RasPi are not currently used Referred to as future expansion connectors they reflect th
159. e level high enough to forestall false alerts yet low enough to accurately capture real seismic events Examining the data set again reveals that a level of 720 would probably suffice It is sufficiently high to avoid random vibrations that may be caused by heavy trucks rolling nearby yet it is low enough to capture real activity In any case the value can easily be reprogrammed if needed Operational System The primary requirement for an operational system is to create a warning if the detected seismic activity exceeds a preset or threshold level I determined that a 720 level would be a good starting point The following program Seismic_Monitor py will light an LED if a level of 720 or more is detected The LED will remain on until reset by restarting the program Seismic_Monitor py is available on the book s website Seismic_Monitor py import time import os import RPi GPIO as GPIO GPIO setmode GPIO BECH def adc chan clock mosl miso cs ifi chan lt 0 or chan gt 7 return GPIO output s True GPIO output clock False GPIO outputi cs False cmd chan emd 0x18 cmd lt lt 3 for 1 in range 5 if cmd amp 0x80 GPIO output mosi True else GPIO output mosi False cmd lt lt GPIO output clock True GPIO output clock False result for i in range 12 GPIO output clock True GPIO output clock False result lt lt 1 if GPIO input mise rie b fine result gt gt
160. e open source library libnfc which will be discussed in this chapter s software section A full board schematic may be downloaded from the microBuilder website http www microbuilder eu Projects PN532 There are other interesting links at this website including a detailed discussion on how the board antenna was designed and optimized for this NFC application The board uses an NXP PN532 microcontroller hence its name The controller is a hybrid type in that it processes both analog RF and digital signals In Chap 7 I introduced another hybrid chip the ZW0301 which processed Z Wave signals This chip is similar in operation to the NXP PN532 microcontroller and uses a somewhat familiar ISO layer network communications model that I discussed in previous chapters NEC Data Communications Flow The information in this section is based upon the discussions and figures contained in the PN532 User s Manual that is available from the Adafruit Industries website Figure 9 3 shows the format of a sample data interchange between the host computer which would be the RasPi and the PN532 controller RX Information COMMAND frame Information RESPONSE frame RX ACK frame In case of communication from host to PN532 TX ACK frame In case of communication from PN532 to host ee a Sample data interchange between the RasPi and the PN532 controller You should notice that the data interchange involves not only sending and receiving
161. e pin 18 is set to GPIO LOW Run the program and observe that each time you press the switch the LED light turns on and continues to stay lit as long as the switch is pressed Figure 3 8 shows the actual circuit on the breadboard with the RasPi connected with the flat ribbon cable to the Pi Cobbler Actual switch test setup Thinking in RasPi Time You must always think about the operational speed of the RasPi when creating a new program The while loop in this program repeats over a million times a second meaning that all the commands in the loop are constantly being repeated That s the reason why I used an if else conditional test Statement to repeatedly set the pin value HIGH so that it matches the duration of the key press If I had neglected to add the else portion the first time the button was pressed it would have lit the LED but it would have remained on Try deleting the else portion to confirm this behavior But why does it stay on The answer is simple without the else portion there is no command to turn it off The pin becomes latched so that it remains in the last state it was commanded to be in That s what I mean by thinking in RasPi time I have found that it is possible for new and sometimes not so new microprocessor programmers to become very confused regarding this real time aspect of programming Controlling actual hardware can be a challenge I will attempt to point out these challenging program areas in the
162. e represented with 10 bits Each increment increases the voltage appearing at the DAC s comparator input The comparator will trigger when the DAC s voltage precisely equals the sampled voltage and this will stop the SAR from incrementing The digital number that exists on the SAR at the moment the comparator trips is the ADC value This number is then outputted one bit at a time through the SPI circuit discussed below All this takes place between Sample intervals The actual voltage represented by the ADC value is a function of the reference voltage Vprr connected to the MCP3008 In our case Vppp is 3 3 V therefore each bit represents 3 3 1024 or approximately 3 223 millivolts For example an ADC value of 500 would represent an actual voltage of 1 612 V which was computed by multiplying 003223 by 500 Serial Peripheral Interface The Serial Peripheral Interface SPI was introduced in Chap 1 as a synchronous serial SS data link that uses one master device and one or more slave devices There are a minimum of four data lines used with the SPI and Table 6 2 shows the names associated with the master RasPi and the slave MCP3008 devices Table 6 2 SPI Data Line Descriptions Master Device RasP Slave Device MCP3008 Remarks SOLE CLK Clock HOSI D Master Out Slave In MISO D Master In Slawe Out CS SHON Ss Slave Select Figure 6 8 is a simplified block diagram showing the principal components used in an SPI data
163. eceiver kits available that can receive WWVB throughout the lower 48 states I used a 15 kit that is available from PV Electronics which is actually situated in the UK I stated all of the above because even though the receiver functioned properly the RasPi itself generated so much radio frequency interference RFI that it literally swamped out the WWVB signal The RasPi is FCC certified to be compliant with class B low power consumer devices however it is not required to be tested for signal emission interference EMI at levels lower than 450 kHz Obviously 60 kHz is much lower than the minimum EMI requirement and thus it acts as an inadvertent interference while being perfectly compliant with all FCC regulations for this device type The conclusion is not to use the RasPi as a WWVB controller unless you are willing to experiment with various shielding techniques to mitigate the inadvertent interference which I did without a lot of success Summary The first part of the chapter covered how to set up a hardware clock to be used with the RasPi because it does not incorporate one and would lack a time capability if not connected to the Internet The hardware clock was based on the DS1307 chip and used the I C bus to communicate with the RasPi The clock board also incorporated a lithium coin cell battery that maintained the time even if the RasPi was turned off Next I presented a brief background about the origin and function of the Netwo
164. ed on the 8 Channel I O Board directory named 29 B82E08000000 which revealed the web page shown in Fig 11 19 I apologize for the fine print here as the figure has been resized to make it fit on a page in this book It is definitely readable in a browser window FS en localhost 4304 29 B82E08000000 r id DOOOOOOSZEBS rlocator_ FFFFFFFFFFFFFFFF 7 sensed BYTE Si semsed YES 1 lsemsed 6 YES 1 zet alarm 0 CHANGE p CHANGE type DS 2408 Directory 29 B82E08000000 web page One neat feature is that now you can enter relay control numbers directly into the box labeled PIO BYTE and click on the Change button I entered 255 clicked on the Change button and instantly heard eight relays click and saw all eight LEDs light up You should also review Fig 11 5 to understand why this web page is so big All the files listed in the device directory are also displayed on this web page All the data operations discussed in the section entitled Testing the Inputs are available through this web page Figure 11 20 shows the result of entering 255 in the PlIO BYTE box OWFS on localhost 4304 29 B82E08000000 Testing the PlIO BYTE data entry I did notice that starting the owfs web server stopped the owfs file system application and unmounted the files in the 1wire directory I do not believe this should be a real problem because you will likely be using either one or the other but not
165. ee ee ee ee eee ee Ue UWM E auus sares senem hii P T s 7 Tai a a oe Janas anana ee i 7 ai amp eee a af on E Ee Ea oo eee ewes ee Li mz Actual MP3 player Testing the Project Load the MP3_Player py program into the pi directory Then open a terminal window and type sudo python MP3 Player py I found that trying to use a Python IDLE shell to run this program might cause unreliable operation because the mpg123 app requires a direct keyboard input that the shell may interrupt All the keyboard commands shown in Table 3 3 are available for use once the program is started You should experiment with the various commands to gain an appreciation of the depth of functionality that the mpg123 app possesses Figure 3 11 is a screenshot showing an MP3 player in operation Its Moving Picture Experts Group MPEG header tag information and the runtime data are shown on the last line in the figure plgraspberryp1 sudo pyt on MPS Player py num d 3 1f ace MI XER name PCM H Playback Route type INTEGER atcesserw Values 1 Mn ao haxk 2 stTep 0 values 1 High Performance MPEG 1 0 2 0 2 5 Audio Player for Layers 1 2 and 3 version 1 14 4 written and copyright by Michael Hipp and others free software LGPL GPL without any warranty but with best wishes Decoder ARM Terminal control enabled press h for listing of keys and functions Playing MPEG stream 1 of 1 cla
166. ellite signals a COM5 9600baud Tera Term VT File Edit Setup Control Window Help SGPGGA 021705 000 4314 2670 H 07102 7413 Hdd a 7d 7A d eee ee GPGSA A 3 27 23 i E me g E P MA EEE Ti GPGSU2 1 85 31 64 047 39 23 29 J10 35 29 27 065 46 25 16 6046 3078 GPGSU 2 85 35 78 GPRAC 021705 000 A 4314 2670 H O7102 7413 U 8 17 18 35 120113 A14 GPUTG 18 35 1T 4 8 17 N 8 31 K A O6 SPGTOP 11 36F EGPGGA B2i706 O68 4314 26390 4 87182 3 oa eaaa 74 743 2 H 32 8 A 58 SGPGSA A 3 29 23 31 25 eo 86 3 74 808 99 908 CPRMC 21 706 Ane A 4314 2680 M 87102 7413 U 80 14 18 35 120113 A 4F SGPUTG 18 35 T H 8 14 H 26 K AHAJ POTOP i11 3 6F GPGGA 821787 68 4314 2687 4 87102 7412 4 1 4 3 74 74 8 4 32 8 0 53 SGPGSA A 3 29 23 31 25 3 87 3 74 8 99 901 SGPRAC 21707 6000 8 43914 2687 N 807102 7412 U 8 271 18 35 1270113 Aa4E GFPUTG 18 35 1 H 8 21 H 8 38 K A 0A yPGTOP 11 36F GPGGA D21708 PaA 4314 2697 H EA PrE k Pe e ri ee ee F A a T SGPGSA LA 3 29 23 jJi 255 CP ee eee CPRMC 021708 000 A 4314 2697 H aria 7411 U 8 36 18 35 120113 A415 SGPUTG 18 35 1T 4 8 36 N 0 66 K a807 SPGTOP ii GF gt GPGGA 21789 HBA 4314 27604 4 871802 74897 W 1 4 18 608 75 4 0 32 8 H 61 SGPGSA A 3 27 22 31 25 11 72 18 ae Mi a PEET SGPRHC 621709 80 0 4314 2784 N 87102 748097 U 8 25 18 35 120113 Aa44 GFUTG 18 35 1T 48 0 25 H 08 47 K a 06 POTOP 11 GF Jaroa 0
167. els are not significant SPEESOLITE 420 x m 44 278 35 SO 70 105 E ry a OFF FON Canon model 420EX electronic flash The 420EX is designed to mount into the camera s hot shoe connection that provides the shutter activation as well as a series of data interconnections The data flow between the flash and the camera is not relevant to the project as the flash will not be mounted on the hot shoe However it is important to point out the control connections that will be used to trigger the flash These are detailed in Fig 4 8 Ground Q Shutter control 4 5 tO Flash hot shoe connections The flash will fire when the shutter control pin is connected to the ground pin OTE I used the descriptor shutter control to emphasize that the flash is fired only when the camera shutter operates This pin obviously triggers the flash itself The ground pin in actuality consists of two spring loaded cam shaped pins located on either side of the inner slides for the hot shoe These make contact with the camera s metal hot shoe There are five spring loaded pins shown on the bottom of the hot shoe As mentioned earlier we are only concerned with the center pin The other four pins visible to the left of the center pin are data connections that are not used in this project I also used an inexpensive commercially available hot shoe adapter to bring out both the shutter control and the ground con
168. en the pivots so that seismic vibration tracings can be recorded in a horizontal direction as shown in Fig 6 3 arina Garden gate seismic sensor Figure 6 4 is a basic diagram illustrating the classic design for the inverted pendulum seismic sensor A vertical mass is suspended from a horizontal hinge assembly and tracings are recorded in a vertical direction as shown in the figure arina Inverted pendulum seismic sensor Both designs are very capable of creating mechanical paper tracings that you may have recognized from TV news reports or even disaster movies The modified inverted pendulum design used in this project is very responsive to low frequency seismic vibrations and is fairly inexpensive to construct The sensor is a modification of a seismograph project the Poor Man s Seismograph PMS which was described in the May 2012 edition of the Nuts and Volts magazine Ron Newton created the sensor that I found very appealing because it was an extremely simple design yet highly capable of detecting low frequency seismic waves The sensor produces an analog voltage representation of the seismic wave in lieu of a mechanical tracing as is the case in the classical design Figure 6 5 shows the actual sensor assembly that consists of a thin brass strip bolted to a thin film piezoelectric sensor that in turn is attached to a circuit board The brass strip is 1 4 inch wide by 1 32 inch thick and 9 inches long There
169. ent flowing through the device Figure 2 5 is a diagram showing the LED connections as well some physical descriptions that should be helpful to you in understanding the circuit AA Cathode short lead LED ES ag red light et long lead 570 ohm GND Pin 18 Pi Plate Diagram illustrating LED connection to the Pi Plate The LED anode has a longer lead that is connected to the pin 18 screw terminal The LED s shorter lead is the cathode and it is connected to one lead of the 570 ohm Q resistor The other resistor lead is connected to the ground screw terminal The resistor s value was calculated as follows Current range that a RasPi pin can handle is 2 mA to 16 mA So 5 mA was selected as a low to mid range value with just enough current to operate the LED with a dim red light No sense in overstressing the RasPi The high output voltage from pin 18 is 3 3 V The LED has a nominal drop of 0 7 V Therefore 3 3 0 7 or 2 6 V must be dropped with a 5 mA current Ohm s law R E I where R stands for the resistance of a conductor in ohms E stands for the potential difference across a conductor in volts and J stands for the current through a conductor in amperes Plugging in the values for E and I we get 2 6 V 5 mA 1000 520 Q resistance Note that the 5 mA had to be converted to amperes by dividing by 1000 570 Q is the nearest standard value resistor to 520 Q
170. ention of infringement of the trademark Where such designations appear in this book they have been printed with initial caps McGraw Hill Education books are available at special quantity discounts to use as premiums and sales promotions or for use in corporate training programs To contact a representative please visit the Contact Us page at www mbhprofessional com McGraw Hill Education the McGraw Hill Education logo TAB Evil Genius and related trade dress are trademarks or registered trademarks of McGraw Hill Education and or its affiliates in the United States and other countries and may not be used without written permission All other trademarks are the property of their respective owners McGraw Hill Education is not associated with any product or vendor mentioned in this book Raspberry Pi is a trademark of the Raspberry Pi Foundation Information contained in this work has been obtained by McGraw Hill Education from sources believed to be reliable However neither McGraw Hill Education nor its authors guarantee the accuracy or completeness of any information published herein and neither McGraw Hill Education nor its authors shall be responsible for any errors omissions or damages arising out of use of this information This work is published with the understanding that McGraw Hill Education and its authors are supplying information but are not attempting to render engineering or other professional services If such services are req
171. erminal control program in lieu of using a direct serial cable But for now you have the background and familiarity to set up a serial link with a GPS receiver GPS Receiver UART Communication The Ultimate GPS receiver uses a 9600 Bd UART to communicate with the controlling microprocessor in order to both receive and transmit data back and forth The UART interface pins available on the Ultimate GPS receiver are shown in Fig 5 14 There are only three pins that we need to use for data communication as was discussed in the previous section transmit receive ground Ultimate GPS data communication interface pins There is no need for a separate clock signal line since the UART protocol is designed to be self clocking Next you need to make the connections between the Pi Cobbler UART pins and the GPS receiver pins as shown in Fig 5 15 Pi Cobbler to GPS receiver connections Ensure that the TX connector from the GPS receiver connects to the Pi Cobbler RX pin and likewise that the RX connector from the GPS receiver connects to the Pi Cobbler TX pin Do not connect RX to RX or TX to TX even though that may seem like the logical action to take You will not damage anything but the data communications between the GPS receiver and the RasPi cannot be established if you make those connections Initial GPS Receiver Test It would be wise to check that the Ultimate GPS receiver is functioning as expected prior to running
172. espond as appropriate I will now return to the Z Wave control software discussion now that you are a bit familiar with SSH Open Z Wave Software I took a very easy approach to implementing the control software between the RasPi and the Z Wave network I used a prebuilt Wheezy Raspian image kindly made freely available by Thomas Loughlin at http thomasloughlin com new open zwave image for raspberry pi Simply download the image and create a new SD card using the procedures discussed in Chap 1 While Thomas has carefully detailed the steps required to get the RasPi working with a Z Wave network I will paraphrase and use some figures to help clarify the somewhat involved process I used a headless approach meaning I logged into the RasPi using putty Headless is a bit of network jargon meaning you don t need a local monitor or keyboard for the RasPi because you will login remotely using the RasPi as a server The step by step procedure for starting the Z Wave RasPi network is 1 First add one or two devices to the network as described above This establishes a beginning configuration that enables you to see and control some devices 2 Plug the Z Stick into a powered hub connected to an unpowered RasPi that has the downloaded Open Z Wave image 3 Power on the RasPi and wait a minute or so Remember we are running headless and are not looking at a monitor screen connected to the RasPi 4 In the opening putty screen enter
173. ess In Fig 8 6 you can see the emitted laser beam and a dot of reflected light in the mirror however you cannot see the projected laser beam This of course conflicts with what you see in the movies when the hero or bad guy attempts to get past the laser beams protecting the secret vault or whatever I would actually have to put smoke or dust in the beam s path to see it which would have caused much consternation in my household An elapsed time photo of the laser trip assembly in operation The extra red light seen on the detector side is the returned beam reflecting off of the nearby white trim board You could place some black cloth behind the detector if a more stealthy installation is desired The trip system functioned very well never missing my exiting or returning Another trip assembly could be stationed at four feet above the floor if you are worried about intruders simply stepping over the invisible beam My philosophy regarding such matters is that criminals will simply go to easier targets if they suspect or detect that a relatively sophisticated intrusion system is in place and operational RasPi Interface to the Laser Trip Assembly I have used the same relay switched circuit that was used in the camera control project The schematic is shown in Fig 8 7 3 3V F 10K ohms GPIO pin 25 Point Laser light module RasPi gnad Schematic of relay switched interface for the laser trip assembly
174. essional software developer using C C C Python and Java as well as 5 years as a certified IT security consultant Mr Norris started a consultancy Norris Embedded Software Solutions dba NESS LLC that specializes in developing application solutions using microprocessors and microcontrollers He likes to think of himself as a perpetual hobbyist and geek and is always trying out new approaches and out of the box experiments He is a licensed private pilot photography buff amateur radio operator avid runner and last but very important new grandfather here s to you Hudson Contents Preface Acknowledgments 1 Introduction to the Raspberry Pi Hardware Software Summary 2 LED Blinker Project Prototype Board Soldering Accessing the GPIO Pins apt get Command LED Project Summary 3 MP3 Player Project Prototype Connector Portable Stereo Speaker Audio File Formats Hardware Switch Inputs Thinking in RasPi Time MP3 Project Requirements Summary 4 Camera Controller Project Requirements Camera Shutter Operation Electronic Flash Optoisolator Interfaces Sound and Laser Modules Interface Connections Time Lapse Function Summary 5 GPS Introduction The Basics of How GPS Functions The Ultimate GPS Receiver The e psd A Ap 6 Earthquake Detector Introduction iaai Digit al l Co nversi on Serial Peripheral Interface anec ctin and T ea the MCP3008 with the RasPi 8 Home Security
175. exact distribution tires for each program are described in the jiredivideal files ia iarsshare dees foo Pee beirinn GA Linus comes with ABSOLUTELY M D WARRANTY to the extent HEITE applicable liw ihraspherrypi starta Server 1l 12 4 Release Cate 2012 08 27 ree werd ie ji Bedaien Build Seoratin Sys tems Linux 3 2 0 2 00 ary Fl De Purrent Gperat na 3 Tyrian Lisa Pepher pt 2 2 A are PREOMPT Tho Get 18 19 03 09 BST 2017 areal biel paak dia daachanista F545 AHi fe Paidthalais harria fh Lae id ginsi beers beardreveticl boat ih seria latnad TG pma macaddren fh 3 TER Bor rae tihei bo 8 emm e lock reg IODO we EE EN mee bat eto ee annA 2O00 dec otg lpeenable 0 console thea LSA kpi brst iyiMat ILS200 consoleet tyl rotepar mabik p rootfatypreecst4 elewatoredead line rootwait Build Gate 20 oeteber FoF l i porg server Zil 12 4 1 Julien Cristau cjcristamtdebl an orge Current wersion of piemin 0 2 Before reporting ert eee check htt pamik 5 arg to make g sure that you have the latest Were Markers i pF 5 fron config file i default Fencing ier Tise C10 notice TI LARR marniag EE error NIJ mt inplenented ae i f Log File var laira i Tire Jaa FOS POL Using system config directory just fehereMLLfaorg conf Le a Sample screenshot from the ZOC program connected to the RasPi In a later chapter I will show you how to connect to the RasPi over a network by using another type of t
176. f discover their location within the network topology because they would not be typically placed in a fixed location Such self discovery is made possible by having the portable controller ping nearby nodes that are within RF range The controller can thus join the network based upon the ping results Portable controllers are battery powered for portability reasons and are usually used as primary controllers in Z Wave networks Portable Z Wave controller The static controller is another subtype and it so named because its logical location is fixed at the time of the initial network configuration It is usually powered from the AC mains and constantly listens for network traffic A static controller can serve as a secondary controller in an advanced network configuration The current network configuration may be stored in it and if so it is known as a Static Update Controller SUC More often the role a static controller plays is to serve as a bridge between non Z Wave components such as X 10 devices In that configuration the static controller serves as a virtual node between the X 10 device and the Z Wave network The network can have up to 125 virtual nodes that help incorporate older technologies into the modern Z Wave system Static controllers may also serve as TCP IP gateways thus allowing the network to connect to the Internet if so desired Finally static controllers can serve as primary controllers in the configuration
177. fundamentals 16 17 memory used in 3 4 Model B 11 PGIO pin expansion 11 preparing SD card 15 16 Python programming for 17 20 serial protocols 12 13 SoC chip on 1 2 software for 13 20 See also individual projects Raspberry Pi Foundation 1 11 16 rc local 191 Reagan Ronald 57 Real time clock RTC 187 193 Relativity theories of 60 rem roentgen equivalent man 177 Remote control for HDMI CEC compliant devices 6 home automation system controllers 91 92 local and remote logic controller project 147 150 of security webcam 109 See also Robotic car project Representational State Transfer REST 151 RF radio frequency signals 60 RF radio frequency transceiver 87 RFID Radio Frequency Identification 115 See also NFC RFID reader project Richter magnitude scale 73 74 Richter numbers 73 74 rm directory Linux command 17 rm filename Linux command 17 Robot_Car py 171 172 Robotic car project 155 163 165 173 block diagram 165 167 Bluetooth software 167 171 chassis and drive motors 156 160 future expansions 173 I C software 167 operating the car 172 173 overview of 155 156 program for 171 172 servos 156 157 160 163 Roentgen equivalent man rem 177 root user 16 28 Root terminal 16 17 RTC real time clock 187 193 S Sample and hold circuit 77 Sample rate 77 Samsung 6 SAR successive approximation register 77 Satellites GPS 57
178. g 00 271 80 9A 01 34 Nintendo RVL CNT O1 F CE 46 0D A9 4B Photosmart Prem Web C309n s semak Wiimote discovered Notice that all Bluetooth enabled devices in the immediate vicinity are discovered In Fig 13 10 both the Wiimote Nintendo RVL CNT 01 and an HP wireless printer were discovered Don t be concerned with conflicting Bluetooth devices because the protocol is quite capable of keeping track of which device needs to be addressed by an application Another software package is needed to enable a Python program to interface to a Bluetooth device This package is named cwiid and is downloaded and installed by entering sudo apt get install python cwiid This package contains all the necessary applications that allow the Wiimote to interface with a user created Python program I would also like to extend my thanks to Brian Hensley www brianhensley net for his fine tutorial on using the Wiimote with the RasPi It was invaluable in helping me to create the following programs However before discussing an actual program I need to show you how the Wiimote buttons are set with regard to state values which are those numbers sent to the RasPi indicating their corresponding buttons have been pushed Figure 13 11 is a Wiimote with all the corresponding state values superimposed on the image seaks Wiimote with state values For instance if the forward button of the four way switch is pressed a value of
179. g comments that should help you explore some of the additional features of this software package A portion of the configuration file dealing with motion detection is listed on page 107 to illustrate what I mean Motion Setup You must of course install the Motion package before using it I would strongly suggest that you update and upgrade your distribution before installing Motion Simply type the following at a command line prompt to update and upgrade the Linux distribution in use sudo apt get update J sudo apt get upgrade Be patient since the updates and upgrades can take a bit of time if there are many to install Next install Motion by typing sudo apt get install motion J Again be a bit patient as this package is over 50 MB in size and has many component parts Motion will be run in the background as a daemon which means that it will be a constantly available service To enable the daemon you must edit the etc default motion file Type the following sudo nano etc default motion You will see in the nano editor the line start motion daemon no Motion Detection Settings Threshold for number of changed pixels in an image that triggers motion detection default 1500 threshold 1500 CHANGED threshold 4000 Automatically tune the threshold down if possible default off threshold tune off Noise threshold for the motion detection default 32 noise level 32 Automatically tune the noise
180. g the Portable Geiger Counter I installed the WiPi adapter in one of the RasPi s USB ports and put a Bluetooth adapter in the other one for the wireless keyboard and mouse unit that we also used in the robot car project After you do this connect the analog monitor through the side hole for the video Don t forget to plug in the power jack It is then a simple task of turning on the power and doing a normal boot operation The command to start the program is sudo python geiger py That should be it you should now be seeing the radiation readings displayed on the monitor I also connected to the Geiger counter remotely to capture a screenshot of the unit in action Figure 14 15 shows a screenshot of the Geiger counter registering normal background readings EP p raspbenypi Tere login as pi pi 192 166 1 42 s password Linux raspberrypi 3 6 11 371 PREEMPT Tho Feb 7 16 31 35 GMT 2013 ammyv l The programs included with the Debian GNU Linux system are free software ithe exact distribution terms for each program are described in the individual files in usr share doc copyright Debian GNU Linux comes with ABSOLUTELY NO WARRANTY to the extent permitted by applicable law Last login Sat Mar 30 20 30 07 2013 pi raspberrypi sudo python geiger py ISe Sk Portable Geiger counter in operation Finally you can connect to the Internet if you want which makes this unit quite unique not many network enabled Geiger counte
181. ge due to combination button presses which is something to keep in mind when you start to create your Own programs Robot Car Program The program requirements for controlling the car were deliberately made very simple The car was to go forward when the forward button on the four way Wiimote switch was pressed It was to turn right when the right button was pressed and turn left when the left button was pressed It was to stop when the back button was pressed Obviously much more sophisticated control commands could be devised but this simple set was deemed adequate to prove out the basic car functionality The program follows the same state variable detection and corresponding action as was demonstrated in the test program only this time the commands are being sent to the servo control board which in turn controls the servo motors This program would not function except for the brilliant PWM servo library provided by Adafruit Industries This library enables PWM commands in Python that directly control the servo board and indirectly control the servo motors The only tricky part in developing this program was determining the PWM parameters that set the servo motors rotating at the correct angular velocity and direction These are shown in the code as constants servoRightFwd 300 servoLeftFwd 2400 You will have to experiment with different values if you desire to have the robot go a bit faster I know that these values make the robot t
182. ged it in the configuration menu if so enter that password Next type startx and press Enter startx J This will create the GUI desktop as shown in Fig 1 24 fide Ech io ilp coe T Raspberry Pi GUI desktop Congratulations it is now about 15 pages into the book and you now have the first indication that you have a working and useful Linux computer Fear not progress will be much faster from now on To partially accomplish this goal I will minimize the number of screenshots and simply use text to show you what to enter and how the computer responds Preparing your own SD card using a Windows PC You will need two items other than the card itself First you will need to download and install a program named win32diskimager exe This program is available at http sourceforge net projects win32diskimager The file is in a compressed Zip format from which you have to extract the program before running it Note that in spite of the win32 in the name this app works without a problem on my Win7 64 bit laptop The second item you will need is the image file for the RasPi Linux distribution that you desire to install The current version at the time of this writing may be downloaded from the main Raspberry Pi website http downloads raspberrypi org images raspbian 2012 10 28 wheezy raspbian 2012 10 28 wheezy raspbian zip It is a very large Zip file 647 MB from which the Linux distribution must be extracted before it can
183. grade because of two relativistic effects The best way to describe the first effect is to retell the paradox of the space travelling twin Imagine a set of twins male female it doesn t matter one of whom is slated to take a trip ona fast starship to our closest neighboring star Alpha Centauri This round trip will take about ten years traveling nearly at the speed of light The remaining twin will stay on earth awaiting the return of his her sibling The twin in the starship will accelerate very close to light speed and will patiently wait the ten years it will take to make the round trip according to the clock in the ship Now according to Albert Einstein if the traveling twin could view a clock on earth he she would observe time going by at a much quicker rate then it was in the starship This effect is part of the theory of special relativity and more specifically is called time dilation If the twin on Earth could see the clock in the starship he she would notice it was turning much more slowly than the earthbound clock Imagine what happens when the traveling twin returns and finds that he she is only ten years older but the earthbound twin is 50 years older because of time dilation The space traveling twin will have time traveled a net 40 years into Earth s future by taking the ten year space trip The second effect is more complex than time dilation and I will simply state what it is According to Einstein s theory of general rel
184. gram initialization You should create the code in the nano editor and save it with a name that makes sense I saved mine as Pin18_Test py Remember to use the py suffix since IDLE checks it to ensure that it is a valid Python program You need to open and run this program in the Python shell However there is an important action that you need to take or Python will complain and not run the program You must run IDLE at the root level not at a normal user level This is needed I believe because the GPIO library is accessing Linux functions or resources that can only be accessed as root Do the following to run the IDLE Linux shell as root Open a terminal window and type sudo idle That is all that s needed and you will be at the exact place where you can open and run your program as discussed in a previous section Running the program will turn on the LED not very exciting so far as our journey begins with small steps The next section shows you how to blink the LED Blinking the LED A variety of approaches can be taken to blink the LED The approach I took was simple and direct The logic was to turn on the LED wait a set amount of time turn off the LED wait a set amount of time and then continually repeat this process forever Waiting a set amount of time may be accomplished in several ways The way I selected was to use a function named sleep seconds that is part of the time library All you need do is provide the a
185. haring There is a long running anecdotal observation that 90 percent of all electrical electronic malfunctions are related to connection malfunctions This makes a lot of a sense when you think about it We live in an oxygen rich atmosphere and oxygen is a great reduction agent it wants to oxidize every element it can possibly chemically combine with Metal oxides are reasonably good insulators because some of their free electrons have been taken up by oxygen molecules This leads to higher and higher resistance being built up in a connection that will eventually cause a failure Of course current flowing through a resistance produces heat which in turn can cause a fire if the current is sufficiently high So what is the solution One expensive solution is to gold plate electrical contact surfaces Gold does not oxidize and is not subject to this type of failure It is of course very expensive and not practical for large scale connectors Another solution that the power industry employs is what is known as gastight connections which require the use of special components and specialized training to produce For the type of projects that I work on I can only ensure that the solder joints are sound from both a mechanical and an electrical perspective I also inspect electrical connections for oxidation and foreign matter and take appropriate action to replace the compromised connection or component Accessing the GPIO Pins The GPIO pins have
186. he code is based upon the sample code available from the Learn Adafruit com website in their discussion of the MCP3008 Test_ADC py import time Import og import RPi GPIO as GPIO GPIO setmode GPIO BCH DEBUG 1 define a function to read the MCP3008 ADC value def adec chan clock mosi miso cs if chan lt 0 or chan gt 7 return 1 GPIO output cs True GPIO output clock False GPIO output cs False cid chan cmd 0x18 emd lt lt 3 for i in range 5 if cemd amp OxB80 GPIO output imosi True else GPIO ocutput mosi False cmd lt lt 1 GPIO cutput clock True GPIO output clock False result 0 for i in range 12 GPIO cutput clock True GPIO output clock False result lt lt 1 LE GPIO input miso result 0x1 GPIO output cs True result gt gt 1 return result These pin definitions are set to work with the test circuit SPICLE 18 SPIMISO 23 SPIMOST 24 SPICS 25 GPIO s tup SPIMOSI GPIO OUT GPIO setup SPIMIsSo GPIO IH GPIO setup SPICLK GPIO OUT GPIO setup SPIcs GPIO OUT channel 0 while True F read an ADC value ade value ade channel SPICLEK SPIMOSI SPIMISO SPICS if DEBUG print value adc value walt a second and repeat time gsleep 1 Figure 6 12 presents a screenshot of a portion of the program output with the analog voltage adjusted to a 500 value or count as it is sometimes called An actual voltage of 1 629 V w
187. he first floor and then operated the controller in a second floor bedroom I was not able to turn on the basement module without having the first floor module plugged in This proved that the first floor module was digipeating and forwarding the control packets to the module located in the basement The controller showed Failure on its LCD screen with the first floor module unplugged which indicated that no ACKs were being received Obviously no NACKs could be sent since the first floor module was unpowered and the basement module was out of range 3 Setting up the test arrangement was an extremely simple process which shows how well the high tech Z Wave network functions in the background while also providing the homeowner with a very easy and useful interface But that s not what we are after I want to demonstrate how the RasPi interfaces with a Z Wave network and what neat experiments can be accomplished RasPi and Z Wave Interface Connecting a RasPi to a Z Wave network requires the use of a Z Wave USB dongle One such device made by Aeon Labs called the Z Stick is shown in Fig 7 10 Aeon Labs Z Stick The Z Stick incorporates a Zensys module and a USB interface chip along with some additional firmware to make the two components work together It also has an internal rechargeable battery that enables the storage of firmware updates and configuration data The Z Stick has three operating modes that you shou
188. he microprocessor to execute some special handler program or code for the interrupt source Interrupts may be triggered in several ways HIGH level detected LOW level detected HIGH to LOW transition detected LOW to HIGH transition detected Using interrupts will certainly improve performance but at the expense of adding a certain level of complexity to the software Serial Protocols There are several serial protocols shown in the pin descriptions that I wish to discuss briefly SPI Serial Protocol The first is the Serial Peripheral Interface SPI which is shown in the Fig 1 19 block diagram SPI Slave SPI block diagram The SPI interface pronounced spy or ess pee eye is a synchronous serial data link A clock signal is needed because it is synchronous It is also a full duplex protocol which means that data can be simultaneously sent and received from the host and slave SPI is also referred to as a Synchronous Serial Interface SSI or a 4 wire serial bus The four interconnecting signal lines between the SPI host and SPI slave shown in Fig 1 19 are explained in Table 1 6 Table 1 6 SPI Signal Lines Signal Name Description RasPi Name SCLK Clock SPI SCLK MOSI Master Out Slave In SPI_MOSI MISO Master In Slave Out SPI MISO Ss Slave Select SPI CEn There are two pin connections on the RasPi named SPI CEO and SPI CEI These connections allow two separate SPI slave devices to be ind
189. he x y and z coordinates to latitude longitude and altitude and you have the basics of the real GPS system The satellites transmit digital microwave radio frequency RF signals that contain both identification ID and timing components that a real GPS receiver will use to calculate its position and altitude The counterpart to the embedded database mentioned in my fictional example is called an ephemeris or celestial almanac and it contains all the data necessary for the receiver to calculate a particular satellite s orbital position As mentioned in the history section earlier all GPS satellites are in high earth orbits and are constantly changing position Because of this situation the receiver must use a dynamic means for determining its position fix which in turn is provided by the ephemeris This is one reason why it may take a while for a real GPS receiver to establish a lock as it must go through a large amount of data calculations to determine the actual satellite positions within its field of view In my fictional example the radii of the location spheres are determined by the receiver using extremely precise timing signals that are contained in the satellite transmissions Each satellite contains an atomic clock to generate these clock signals All satellite clocks are constantly synchronized and updated from earth based ground stations These constant updates are needed to maintain GPS accuracy which would naturally de
190. hips make 2 Entering directory home pi libntc libnfc 1 6 0 rccl libnfc chips mm Ef 1i15s libs test z libnfcchips la om f libnfechips la rma f s0 location 5 mm i 6 rm f lo make 2 Leaving directory home pi libafe libnfe 1 6 0 rel libnafc chips Making clean in make 2 Entering directory home pi libnic libnfe 1 6 0 r e1 libnic test z libnfc la mm libnfc la mm E s0_locations rm rf libs 1ib m f o rm E 16 make Z Leaving directory home pi libnfc libnfc 1 6 0 rcl libntc make 1 Leaving directory home pi libnfc libnfc 1 6 0 rel1 libnfc Making clear in make 1 Entering directory home pi libnfic libnfc 1 6 0 rc1 test 2 Doxygen log coverage info libnafe pe oa f Doxygen l g coverage info libate pe a r libs libs 1 Ef doc m Ei coverage m i 1lo make 1 Leaving directory homespislibafeslibnfe 1 6 0 re1 pi raspbercypi libnic libnfc 1 6 0 rel The end of the build prep 9 The actual build happens in this stage I have included two screenshots showing the start and end of the process This build will take about 30 minutes so be patient Type the following at a terminal command prompt sudo make install all J Figure 9 12 shows the start of the build pifraspberrypi libnfc libnfc 1 6 0 rel sudo make install all Making install in libnfc make 1j Entering directory home pi libnfc libnfc 1 6 0 re1 libnfc Maki
191. his device has a 3 5 mm jack that you can plug into the RasPi audio out connector It also has a rechargeable battery that can be recharged by plugging it into any standard USB socket However I would not recommend using the RasPi USB sockets due to the current limitations that I discussed in Chap 1 The volume control on the speaker will allow you to adjust the volume in only two steps All in all this powered speaker is fairly decent in reproducing audio however I would not get rid of my home theater system for it ALSA Advanced Linux Sound Architecture ALSA is the principal sound driver that is used in most of the RasPi Linux distributions It is very stable software that has been widely adopted for use in various Linux distributions It is totally open source and is strongly supported at www alsa project org The eight packages that currently make up ALSA and a brief descriptions of each are listed in Table 3 1 Table 3 1 ALSA Packages Package Name Description alsa driver Low level drivers connecting hardware with the Linux kernel alsa lib A C language API for the drivers alsa utils A collection of very useful utilities alsa tools An advanced toolkit used with certain sound cards not the RasPi alsa firmware Firmware to be installed on certain sound cards not the RasPi alsa plugins Used with audio libraries and sound servers i s 3 l alsa 0S5 Open Sound System an older version provided for compatibility purposes pyalsa A
192. his suite sudo apt get install gpsd gpsd clients python gps H gpsd is known as a daemon pronounced daymon and essentially is a program that runs in the Linux OS background The nice thing about daemons is that they go about their business without needing any attention once started To start gpsd type the following in a Linux terminal window gpsd dev ttyAMAO J All that s happening here is that you are telling the daemon which serial connection is being used in this case ttyAMAO Display GPS Data The cgps app displays the GPS information such as speed position altitude etc To see this information type cgps in a Linux terminal window after starting the gpsd daemon cgps You should see the screenshot shown in Fig 5 19 appear on the RasPi screen pi raspberrypk Edit Tabs Help Time 2013 ak IST 18 27i 20 211Z uM Elev Zim SNR Ls Latitude 43 238538 N 85 5 31 Longitude 71 045738 W 2 52 30 22 Altitude 82 5 m 5 Sl 052 Al Speed 5 kph 32 0 00 Heading 55 7 deg true 2 25 3 20 Climb 2 0 m min 13 136 00 Status 3D FIX 146 secs Longitude Err n a Latitude Err DE Altitude Err 2 Course Err n a Speed Err nja Time offset 0 510 Grid Square Faal f n ass TPV tag RMC device dev ttyAMAO mode 3 time 2013 01 137T1 0002 ept 0 005 Lat 43 238538333 Lon 71 045735000 alt 182 500 s TPV tag RMC device dev ttyAMAO mode
193. i R Pi usa Hub Mouse Ethernet et Patch Cable HOM te YGA p supply Converter m Switch oF Router Power Supply HORA in I inl VGA in Monitor A suggested RasPi configuration Inserting or removing an SD card while the RasPi is powered on is never a good idea Bad things can happen including data corruption or worse Also now would be a good time to skip down to the section that discusses how to load your own Linux distribution on an SD card if you did not purchase a starter kit or a prebuilt SD card You should see the initial configuration screen shown in Fig 1 23 on the monitor after you connect the USB power to the RasPi Please be patient it takes a while You will at first see a massive amount of text scrolling by on the screen which will make absolutely no sense to you if you are not familiar with Linux pi raspberrypi O X File Edt Tabs Help Information about this tool xpand_rootts Expand root partition to fill SO card overscan Change overscan configure keyboard Set keyboard Layout change_pass Change password for pi user change_Locale Set locale change_timezone Set timezone rene a gh Change memory split overclock Configure overclocking ssh Enable or disable ssh server boot behaviour Start desktop on boot update Try to upgrade raspi config lt Select gt lt Finish gt Raspberry Pi configuration screenshot Suggested configuration settings are
194. i and is also listed below Wimote_Test py i f usr bin eny python import time import cwlid print Press buttons 1 2 on your Wii Remote time sleep 3 wm cwlid Wlimote print Wil Remote connected print nPress the PLUS button to disconnect time sleep 1 wm rpt mode cwlid RPT BTN while wm state buttons lt 4096 if wm state buttons 20468 print Forward button pressed time sleep 1 if wm state buttons lO24 print Back button pressed time sleep 1 LE wm state buttons 212 print Right button pressed time sleepi lj 1f wm Bta atef buttons j 256 print Left button pressed time gleep 1 print Closing Bluetooth connection time sleep 1 exit wm The expression wm cwiid Wiimote is all that it takes to instantiate an object that logically represents the Wiimote The object is then placed in the proper state to report its state value by the program line wm rpt_mode cwiid RPT_BTN From then on all that needs to be done to retrieve the state value is to use the expression wm state buttons The Wiimote disconnects and the program stops when the button is pushed The expression while wm state buttons lt 4096 establishes a loop and waits for the state value to exceed 4096 to stop the looping Using a high value for this state change precludes any unintended program stoppa
195. i for development you might want to do the following test using the temporary setup shown in Fig 12 20 I C test diagram IGNO Pi ISCL Cobbler isnao 4 aal TT i Raspberry Pi Sie of eee ja be f v Dak i alo elele Sleleleleloic Temporary C test diagram Connect the servo controller board to the Pi Cobbler with four wires as shown in the figure I used the Cobbler s 3 3 V power supply to power the servo controller board to ensure that 3 3 V was the maximum voltage that could appear on the I C bus lines However I do believe that the controller itself limits the voltage to 3 3 V even if it is powered by a 5 V source but I could not confirm it from any data sheet Better safe than sorry as the old adage goes The servo control board has a two screw terminal strip that routes power directly to the servos This power source takes up to 6 V DC and is separate and distinct from the Vcc supply that powers the board logic Do not connect the servo supply to the Vcc supply or you will destroy the servo control board Enter the following at a terminal control prompt sudo i2c detect y 1 OTE If you are using an early 256 MB RasPi model B change the 1 to a 0 in the above command Figure 12 21 shows the result of this command In the figure you will see that two I C addresses were detected one at 0 x 40 and the other at 0 x 70 The 0 x 40 is the default slave address preset into the
196. ic amplifier circuit 76 Analog audio output 7 ALSA 31 34 frequency response 33 34 testing 33 Analog composite video connector 6 7 Analog to digital conversion ADC for earthquake detector project 76 77 on PIC microprocessor 76 in weather station project 130 Android remote logic control with 147 150 aplay app 35 Application Layer Protocol Rules 67 See also NMEA 0183 standard apt advanced packaging tool 26 apt get command 26 Arduino series 13 Atomic clocks in GPS system 60 Audio analog 7 31 34 camera controller project 48 49 52 54 file formats for 34 37 HDMI for 5 6 MP3 player project 31 41 Audio connector 7 B Back feeding 165 Battery power 41 158 165 189 BCM2835 microprocessor Broadcom 2 3 20 Becquerel Bq 176 Beta particles radiation 175 Binary data storage 81 82 Bit banging 13 80 Blinking LEDs see LED blinker project Bluetooth defined 156 robotic car project 167 171 Boe Bot chassis 156 157 Bq becquerel 176 Broadcom 1 2 Broadcom BCM2835 microprocessor 2 3 20 Broadcom VideoCore IV GPU 3 Browser testing HTTP web server with 150 153 Bus network 12 Buy vs build decision for camera controller project 48 C Camera digital serial 8 9 webcam for home security 103 104 106 109 111 Camera controller project 43 56 audio module 48 49 electronic flash 45 47 interface connections 50 55 laser module
197. ice and Medical ISM unlicensed band While Fig 9 1 shows a maximum range of 20 cm a more realistic range is 4 cm or about 1 6 inches The standard data rates are 106 212 or 424 kbits s which are quite suitable for reader applications and low to moderate volume data transfers There are two primary modes of operation using NFC RFID 1 Passive The Target becomes energized when placed within the Initiator RF field Only then will it respond with its preprogrammed data 2 Active Both the Initiator and Target have self energized RF fields and can establish and maintain communication when in range of each other Until recently the passive mode has been the most popular however the use of active mode NFC among smartphone user has become widespread Smartphone manufacturers are aggressively marketing this new feature to enhance the data sharing capabilities of their products NEC Hardware I will be using the PN532 NFC breakout board manufactured by microBuilder eu and distributed in the United States by Adafruit Industries part number 364 Adafruit also sells a similar board the NFC Shield part number 789 but this is designed to work with the Arduino microcontroller board and is not the board that will be used in this project Figure 9 2 shows the breakout board PHS Breakout Board fe microGuilder eu amp Adadrint Industries PN532 NEC breakout board The PN532 NFC breakout board has been designed to work with th
198. ich programmers must contend with bits bytes and memory locations The concept of abstractions and abstract data types will become clearer as we start developing Python programs The Python language design encourages the creation and use of modules that can be reused New functions modules and classes can easily be added Software reuse is a key goal that all programmers should try to adopt It makes no sense to keep reinventing the wheel when proven solutions have already been developed and are available for reuse We will see this reuse in action in the very first project program Python is also an interpreted language which means that the code is executed line by line by the Python engine as it is encountered Programs using interpreted languages typically run slower than programs that have been compiled and linked This performance hit will not be an issue with any of the programs within this book The advantage of interpreted programs is that they are considerably easier to modify and rerun as compared to compiled programs All you have to do is make any needed changes in an editor save the code and then rerun the program in the Python shell This significantly reduces program development time and at the same time increases your productivity and efficiency One other detail should be mentioned before I show you how to start developing your first Python program The language is not named after the reptile but instead takes its name fr
199. ific module that is transmitting data over the 1 Wire network I refer you to the owfs user s manual if you desire to learn more about commands and returned data Future Expansion Adding modules is very simple and the owfs software will easily handle most existing 1 Wire weather modules You are really limited by your own resources if you desire to add additional modules to the 1 Wire network A useful module to add would be an anemometer to measure wind speed and a compass encoder to get wind direction The only other module that could be added to fully populate this weather station is a rain gauge Summary The chapter began with a review of the weather station design that is based upon using a series of separate interconnected sensor modules all using the 1 Wire network Next the components and functions of each module used in the project were discussed The 1 Wire protocol was then examined along with an integral controller chip the DS2438A Various ways the 1 Wire network could be powered were also reviewed and the pros and cons of each approach were pointed out Instructions on how to set up both the hardware and software were provided The software package owfs was also configured to provide Web based weather reports These reports were accessed both locally over the home network and remotely over the Internet Finally the Sniffer Module was discussed as a means of checking real time data flowing over the 1 Wire network
200. ight i e the number of protons and neutrons located in the nucleus An associated key measure that will be mentioned in this discussion is half life or the length of time it takes for a specific radioactive element to lose half of its activity level For U the half life is 4 5 billion years Most other radioactive materials have a much shorter half life including radon which has a half life of 3 8 days Radon is a colorless odorless gas that is one of the many products of U radioactive decay Radon s elemental symbol with atomic weight is Rn It is also one of the densest gases known The real problem that radon poses is that it also decays and transmutes into what are known as daughters solid particles that stick to surfaces such as lung tissue Radon gas can and often does accumulate in confined spaces such as basements and attics It also occurs naturally in springs both hot and cold High levels of radon when inhaled over a period of time can lead to the formation of lung cancer According to the U S EPA radon is the number one cause of lung cancer in non smokers Radon being in the U natural decay chain is found wherever natural uranium ore is found Often U is found in granite and shale deposits I guess I am a bit unfortunate as I happen to live in New Hampshire otherwise known as the Granite State However I have measured my home basement for radon and have not detected any activity Nonetheless there i
201. ilable but it has served me well The key to quality soldering work is to have good soldering technique keep the soldering iron tip clean and use the highest quality solder available Figure 2 3 shows the essence of good soldering technique It is vital that the solder joint be hot enough for the solder to flow easily It takes practice to apply just the right amount of solder too little may result in a cold solder joint and too much could lead to a short between closely spaced components Feed sokler on opposite side Soldering iron positkemed from saldering iran so that He S0 thal tip lowches both the pad the solder ls meted inte a onthe PC board and the component the joint wa lead coming through tha hote Sit MM aae ataei a e AARE Good soldering technique Another issue regarding a good solder joint is the use of lead free solder Now don t get down on me I am all about maintaining a healthful environment but the elimination of lead from solder often produces poor solder joints unless some extra precautions are taken The simplest and probably the best approach is to apply a high quality acid free solder flux to the joint prior to heating the joint with the iron This will allow the lead free solder to flow more freely and produce a better soldered connection Again it takes practice to perfect soldering techniques One final thought that relates to solder joints as well as to other types of electrical connections is worth s
202. ilable data is designated by only the delimiting comma The asterisk character immediately follows the last data field but only if a checksum is applied The checksum is a two digit hexadecimal number that is calculated using a bitwise exclusive OR algorithm on all the data between the starting character and the ending character but including those characters There are a large variety of messages available in the NMEA standard however the following subset is applicable to the GPS environment and is shown in Table 5 2 All GPS messages start with GP Table 5 2 NMEA GPS Message Types Message Type Prefix Meaning AAM Waypoint arrival alarm ALM Almanac data APA Ate pilot A Senhence APE Auto pilot sentence BOD Bearing origin to destination BWE Bearing using great circle route DTM Datum baing used GAA Fix inhtormation SLL Lat Lon data GRS GPS range residuals GSA Overall satellite data GST GPS psuedorange Moise statistics GSV Detailed satellite data MSE Send control for a beacon receiver MSS Beacon receiver status information RMA Recommended Loran data HME Recommended navigation data for GPS RME Recommended minimum data for GPS RTE Route message TRF Transit fix data STN Multiple data ID WEW Dual groundwater speed VTG Vector track a speed over the ground WC Waypoint closure velocity velocity made good WPL Waypoint location information x Tt Cross track error XTE Measured cross track error
203. in Fig 4 16 For instance the camera ground is separate and distinct from the RasPi ground No harm would result if you inadvertently connected the optoisolator grounds to the breadboard ground but the isolators would simply not function properly Table 4 3 lists all the GPIO pins used in the interface with the associated functions tied to those pins Table 4 3 GPIO Pin Function Interface List Pin number Input Output Function A Output Focus optoisolator 17 Output shutter optoisolator 18 Input Focus push button 21 revision 1 Output Flash optoisolator 22 Input Shutter push button 23 input Flash push button 24 Input Sound module input 29 input Laser light module input 27 revision 2 Output Flash optoisolator OTE Starting with revision 2 for Models A and B pin 21 has been redesignated pin 27 It remains pin 21 for revision 1 models A and B The Pi Cobbler Pi Plate and likely other prototype tools have pin 21 shown I would suggest putting a piece of tape over the 21 and relabeling it 27 if you are using revision 2 models The GPIO library recognizes pin 27 without any issues Testing the Interface Connections You should test all the connections to ensure that everything is wired correctly The only item you will need is a standard volt ohm meter VOM to run through all the tests You will not require any software to be running on the RasPi for these tests although the RasPi must be turned on in or
204. including a sudden displacement or shift in the ground often located well below the surface level This energy is measured in a localized area by the Richter magnitude scale and globally by the moment magnitude scale The Richter scale is considered open ended but generally ranges between 2 and 9 with level 2 quakes not being felt and level 9 quakes creating catastrophic destruction Figure 6 1 diagrams the Richter scale plotted with quake severity designations 1L00E 10 1006 09 F F an L OOE 08 F4 major 1 00E 07 IIM i Pa strong Microns 1L00E 06 Er 5 moderate max ampl 1 00E 05 Fo 7 Sima 1 00E 04 i minor LOOE 03 ri LOOE 02 i not felt 1 00E 01 Pt 2 P4 2 4 6 g 10 12 iboe i log microns max amplitude 1 00E 02 Richter scale Richter scale and quake severity The X axis shows the actual Richter numbers which are the base 10 logarithms of values on the Y axis The Y axis shows the maximum ground displacement values measured in microns or millionths of an inch Therefore each increment of the Richter number represents a 10 time increase in quake severity For example going from a 5 to a 6 level means shifting from a moderate to a strong quake The most common type of quake is created by faults deep within the Earth s crust that suddenly release energy due to an almost unimaginable force build up This release or ground displacement generates two types of energy waves that rapidly tra
205. ing its icon located in the other folder in the Applications folder You must enter the appropriate configuration data in the CuteCom GUI as follows Device ttyAMAO Baud Rate 9600 Data Bits 8 Stop Bits 1 Parity none Figure 5 18 is a screenshot taken from the RasPi display showing the CuteCom program with the GPS data stream Cutecom Open device Device idewttyAMAO Parity None Close device Baud rate ps y Handshake M Software Hardware About Data bits fe Openfor Reading F Writing Stop bits ae IY Apply settings when opening OT d F pip op Lb 23 ou Lbr Gr dde a PRALA SGPRMC 031202 00 A 4314 2916 N 07102 7304 W 0 SGPFVTG 232 72 T H 0 12 4 0 23 K A 39 SPOTOF 11 3 6F SGPGGA 041203 000 4314 2616 H O7102 7386 W 1 8 1 07 73 7 P 32 4 E H a 52 SGPGSA A 3 15 19 30 13 03 31 21l 23 7 1 36 1 07 0 88703 SGPRMC 031203 000 A 4314 2616 HN 07102 7306 W 0 29 232 T2 120113 A T4 SGPVTG 232 72 T H 0 29 4 0 54 K A 31 SPOTOF 11 3 6F SGPGGA 031204 000 4314 2616 N 07102 7306 W 1 1 07 73 7 P 32 4 E H a 55 SGPGSA A 3 165 17 30 13 03 31 21 23 l 30 1 07 0 Ep03 SGPRMC 041204 000 A 4314 2516 N 07102 7366 W 0 45 232 T2 120113 A T9 SGPVTG 232 72 T H 0 45 4 0 63 K A 3 SPOTOF 11 3 6F SGPRGA 041205 000 4314 2616 N 07102 7367 W 1 6 1 07 T3 7 P 32 6 H a 55 SGPGSA
206. input that is less than 0 7 V will be detected as a logical zero or LOW However the input voltage can never exceed 3 3 V or it will destroy the GPIO pin circuit Table 1 3 Digital Signal Voltage Levels Logic Voltage Range lor HIGH 2 7 tO 5 3 O or LOW 0 0 to 0 7 It turns out that standard 5 V logic accepts 3 3 V as a logical one or HIGH and anything less than 0 7 V as a logical zero or LOW This is exactly the reason that a RasPi can output to a 5 V logical device The difficulty happens if a 5 V device inputs into a GPIO pin The 5 V logical device has the logic HIGH voltage range of approximately 4 4 to 5 V that will immediately burn out the GPIO pin input circuitry Current Limits There are also some current draw limitations for both the 3 3 V and 5 V power pins The limitations are dependent upon the RasPi model as shown in Table 1 4 Table 1 4 Raspberry Pi Current Consumption vs Model Raspberry Pi Model 3 3 V 5V A 50 ma 1000 500 500 ma B 50 ma 1000 700 300 ma Every GPIO pin can sink or source a limited amount of current ranging from 2 mA up to 16 mA This means that you must be very careful about the current demands put on the RasPi as well as how much current it will accept without causing problems GPIO Pin Expansion Recently the Raspberry Pi Foundation made a revision to the Model B that added access to some additional GPIO pins that were not available in the earlier production run This latest bo
207. intersection of these two spheres The receiver must lie somewhere on this circle which appears to be a straight line when observed in a planar or perpendicular view However there is some uncertainty about where the receiver is located on the circle Thus another beacon is still needed to resolve the uncertainty arinaa WO Spheres B3 flashes next Suppose that it takes 3 seconds for the B3 sound pulse to reach the GPS receiver This delay represents a 3300 foot sphere centered on B3 The B1 B2 and B3 spheres are shown intersecting in Fig 5 5 The receiver must be located at the star shown in the figure In reality it could be at either a high or low point since the third sphere intersects the two other spheres at two points The receiver position has now been fixed with regard to x and y coordinates but not the third or z coordinate Guess what You now need a fourth beacon to resolve whether the receiver is at the high or low point I am not going to go through the whole process again because I think you have figured it out by now arinaa ree Spheres Figure 5 5 shows a plane view of all three spheres with the GPS receiver position shown You can think of it as a horizontal slice taken at z 0 in Fig 5 6 your position 2D Btn Plane view In summary it takes a minimum of three beacons to determine the x and y coordinates and a fourth beacon to fix the z coordinate Now translate the beacons to satellites and t
208. ion nor its licensors shall be liable to you or anyone else for any inaccuracy error or omission regardless of cause in the work or for any damages resulting therefrom McGraw Hill Education has no responsibility for the content of any information accessed through the work Under no circumstances shall McGraw Hill Education and or its licensors be liable for any indirect incidental special punitive consequential or similar damages that result from the use of or inability to use the work even if any of them has been advised of the possibility of such damages This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract tort or otherwise To Karen my lovely soul mate and most ardent supporter Her faith in me never wavers and is my core strength About the Author Donald Norris has a degree in electrical engineering and an MBA specializing in production management He is currently teaching undergrad and grad courses in the IT subject area at Southern New Hampshire University He has also created and taught several robotics courses there He has over 30 years of teaching experience as an adjunct professor at a variety of colleges and universities Mr Norris retired from civilian government service with the U S Navy where he specialized in acoustics related to nuclear submarines and associated advanced digital signal processing Since then he has spent more than 17 years as a prof
209. ion of the chapter concerned the gpsd suite of applications including cgps xgps and gpsmon These apps provide an excellent set of tools to display and analyze the continuing stream of GPS data produced by the Ultimate GPS receiver Earthquake Detector Introduction I will show you how to build a sensitive earthquake detection system using the RasPi as a controller that both processes and displays the signals generated by the detector Let us begin with a discussion of seismology and earthquakes focusing on their makeup and how they are measured Seismology is the term used to describe the study of earthquakes This background section will help you understand the key concepts behind the detection system design and what you should realistically expect from this fairly simple system I have also included a section on the analog to digital conversion that is needed to allow the RasPi to link to the earthquake or more generally termed seismic detector Some sample plots are also shown to help you understand the system outputs and to show you how you might use this system to detect imminent quakes thereby providing you and your family with a bit more warning time in order to allow you to avoid or minimize a bad situation Seismology and Earthquakes An earthquake or more simply a quake or tremor generally refers to any large release of energy from within the Earth s crust There are a variety of sources that can cause this energy release
210. ion that holds the various boards that make up the car A discussion followed regarding the servo drive motors and the associated PWM control signals Then we looked at the procedure for setting up the RasPi to run the I C protocol that is necessary to communicate with the 16 channel servo control board Some preliminary testing was next shown that proved the I C interface functioned as expected A complete block diagram was shown to assist in connecting all the component boards and modules that make up the car After that step came a detailed procedure for setting up Bluetooth to run on the RasPi A companion software package named cwiid was downloaded and installed to enable a Python program to control a Wii remote control Wiimote A simple Python program was shown that allowed a user to control the car using a Wiimote The car can go forward turn right or left and stop The project finished with many suggestions for future car expansions and modifications Radon Detector Introduction This project could save your life How s that for an attention grabber Radon as most people know is a radioactive gas that can be present in homes and that often goes undetected This project couples a Geiger counter with the RasPi to measure and display the level of radioactivity in the monitored space I will present plenty of background information so that you may learn precisely what radon is how it is created at what levels it is acceptable a
211. is a 1 16 inch diameter hole drilled 1 8 inch on center from one end The brass strip is bolted to the sensor using a fine threaded 80 nut and bolt set You should also use a drop of adhesive such as blue Loctite on the nut to ensure that it does not loosen arina Seismic Sensor assembly The thin film piezoelectric sensor is a model LDTO 028K manufactured by Measurements Specialties Corp It consists of a 28 um thick piezoelectric PVDF polymer film with screen printed silver ink electrodes all laminated to a 0 125 mm polyester substrate Two crimped contacts provide for external electrical connections The bending forces on the piezoelectric polymer film create a very high strain that in turn causes high voltages to appear across the electrodes The 9 inch brass strip attached to the sensor adds additional mass that lowers response frequency when combined with the damping effect of the sensor The pendulum response period t is determined by the following equation IL t 21Va where L the pendulum length and g the standard gravity constant which is 9 8 m sec In this case L 9 8 inches the 9 inch brass strip plus the 0 8 inch long piezoelectric sensor or 249 m Plugging in the values we get 249 m__ t 20V 9 8 m sec which yields a response period of 1 second t 2 x 3 14 x 16 1s or a frequency f of 1 Hz Recall that the frequency is the inverse of the response period or wave period This value is ide
212. it power supply that is rated to supply 5 V at 1000 milliamperes mA or 1 ampere A The regulatory compliance document supplied with this RasPi states the following External power supply This product shall only be connected to an external power supply rated at 5 V anda minimum current of 500 700 mA for model A and 700 1200 mA for model B I will have a bit more to say regarding current consumption when I discuss the USB connector HDMI Connector The RasPi provides video and audio using a fully compliant HDMI which is modern by most standards The board socket and sample cable plug are shown in Fig 1 7 HDMI connector and cable I have previously discussed the Broadcom GPU chip that controls the HDMI output To keep things simple the book projects will use only the standard type of audio video output and will not take advantage of the true potential of the RasPi s multimedia capabilities Trust a fellow Evil Genius that you will be working hard to complete the book projects without getting involved with HDMI development tasks One real problem that you will likely encounter is the lack of an HDMI input port for your computer monitor This leaves you with three choices for observing the RasPi video 1 Use the composite video output with a compatible analog monitor 2 Use an adapter to convert from HDMI to Video Graphic Array VGA or Digital Video Interface DVI 3 Take over the family s flat panel digita
213. its CS pin held LOW and D pin HIGH constitutes the start bit The SGL DIFF bit follows next and then three bits that represent the selected channel s After these five bits have been received the MCP3008 will sample the analog voltage during the next clock cycle The MCP3008 then outputs what is known as a low null bit that is disregarded by the RasPi The following 10 bits each sent on a clock cycle are the ADC value with the most significant bit MSB sent first down to the least significant bit LSB which is sent last The RasPi will then put the MCP3008 CS pin HIGH ending the ADC process Connecting and Testing the MCP3008 with the RasPi The MCP3008 is connected to the RasPi using the Pi Cobbler prototype tool along with a solderless breadboard Figure 6 10 is the schematic for this circuit The physical setup is shown in Fig 6 11 Pi Cobbler MCPs3O08 CLK 13 Dout 12 Din 11 cs 10 RasPi and MCP3008 test setup There is a temporary test setup on the left side of the breadboard consisting of a potentiometer connected between 3 3 V and ground The ADC channel is connected to the tap allowing a variable voltage that can be used in the test The test software that produces a continuous stream of ADC values is shown below It is also available on the book s companion website www mhprofessional com raspi as Test_ADC py The code follows the ADC configuration and the SPI protocols as discussed above T
214. ividually selected or enabled In fact the CE in the RasPi name is short for Chio Enable r C Serial Protocol The next serial protocol that I will discuss is the Inter Integrated Circuit interface or I C pronounced eye two cee or eye squared cee which is also a synchronous serial data link Fig 1 20 is a block diagram of the I C interface showing one master and one slave This configuration is also known as a multidrop or bus network SDA SCL Master Slave I C block diagram IC supports more than one master as well as multiple slaves This protocol was created by the Philips Company in 1982 and is a very mature technology meaning it is extremely reliable Only two lines are used SCLK for serial clock and SDA for serial data Table 1 7 shows the RasPi names for both the clock and data lines Table 1 7 IC Signal Lines Signal Name Description RasPi Name SCL Clock SCLO SDA Data SDAO UART Serial Protocol The last serial protocol shown in Table 1 2 is the standard Universal Asynchronous Receiver Transmitter UART that uses two pins in the RasPi and is shown in the block diagram in Fig 1 21 UART block diagram The UART protocol needs no clock signal just as it is described by the asynchronous adjective in its name The RasPi transmits data on the pin named TXDO and receives on the pin named RXDO There is also no concept of a master or slave in this protocol since it is used
215. ivity means the signal once acquired can lose up to 90 percent of its original strength yet remain locked in by the receiver Having an output operating at 9600 Bd and compliant with the National Marine Electronics Association NMEA 0183 standard means the receiver generates standard GPS messages at a rate twice as fast as that of comparable receivers The V range of 3 to 5 5 V matches very nicely with the RasPi 3 3 V operating voltage thus eliminating the need for any buffer circuitry The 34 second start up time is excellent and probably due in part to the extreme receiver Sensitivity UART Communications The Universal Asynchronous Receiver Transmitter UART was introduced in Chap 1 as one of the several serial data protocols sub systems that the RasPi incorporates into its design In this section I will explore how to set up a terminal control session also known as a console control session by using the built in serial UART protocol A minimum of three GPIO pins are necessary to establish a console control session As shown in Fig 5 8 these pins are part of the 26 pin GPIO header and have the function of transmit TXD receive RXD and ground or common GND TAD Ground Ld ai iz i Cam y STi Pi ore i te UART pins A simple serial communications link between a laptop computer and the RasPi will demonstrate how this type of communication functions A terminal program running
216. l TV The first option is really not a very good choice since the quality is diminished as compared to what is displayed by a high quality computer monitor The second option is the preferred method as it yields the best results using your existing computer resources Choosing the third and final option will likely result in family discord and upheaval for which I will take no responsibility The choice of an HDMI to VGA or HDMI to DVI adapter will of course depend upon what type of monitor input you have Most monitors have a VGA input and an adapter for that type of input is shown in Fig 1 8 The HDMI to DVI adapter is similar and the cost for each is also similar HDMI to VGA adapter The HDMI connection also contains a very interesting surprise The RasPi can act as a very sophisticated remote control for HDMI CEC compliant devices The CEC suffix is short for Consumer Electronics Control which is a one wire bidirectional serial bus link protocol used for the control of audio and video devices HDMI CEC has been implemented by many A V manufacturers including Sony with its Bravialink LG with its Simplink Sharp with its Aquos Link Samsung with its Anynet and so on The bad news is that there is currently no RasPi software support available for HDMI CEC remote control functions The good news is to simply wait for a short time because new software apps are constantly being created free of charge By the time you are reading this the
217. lays which are numbered 1 through 8 This difference is a small detail that can nonetheless cause some confusion Testing the Inputs Sensing inputs is very similar to setting outputs except for one major difference A 1 is used to indicate that no input is present or detected All the relays must also be disabled by turning all the Switches on the Relay Control DIP switch to the off down position This configuration is required because an IO line cannot be both an input and an output at the same time Next ensure that nothing is connected to any input and then type the following cat sensed BYTE H You should see the value 255 displayed just before the command line prompt just like the circled number in Fig 11 8 pi raspberrypi mnt ilwire 29 B82E08000000 cat sensed BYTE 55pi raspberrypi mnt 1wire 29 B82E08000000 M Se Value returned by typing cat sensed BYTE Result for the sensed BYTE command The value 255 is the decimal equivalent of all 1 s for 8 bits or 1 byte To test this concept out a bit further connect a jumper wire between the screw terminals marked 5v and on input terminal 8 What would you expect to see displayed after you type in cat sensed BYTE A moment s thought might help you realize that the binary value of the bit for the number 8 input relay binary weight of 128 would be 0 hence the value should be 255 128 or 127 Go ahead and type the command cat sen
218. ld know 1 Inclusion This mode adds or includes Z wave devices into the network To add a device a Unplug the Z Stick from the USB connector b Press the large button on the Z Stick The Z Stick LED will start to blink slowly c Go to the device that you wish to add while continuing to press the large Z Stick button and press and release the device s button d The Z Stick LED will blink rapidly for several seconds then glow steadily for three seconds and finally return to a slow blinking state The device has been added to the network Removal This mode will remove or exclude Z wave devices from the network To remove a device a Unplug the Z Stick from the USB connector b Press and hold the large button on the Z Stick for about three seconds The Z Stick LED will start to blink slowly and then transition to a fast blink c Go to the device that you wish to remove while continuing to press the large Z Stick button and press and release the device s button d The Z Stick LED will then glow steadily for three seconds and finally return to a fast blinking state The device has been removed from the network Serial API This is the mode where the Z Stick acts as the portal between the RasPi and the Z Wave network Simply plug it into a powered hub USB connector The RasPi probably does not have sufficient power for the Z Stick The RasPi software will now take control of the Z Wave network I now have to
219. le To do this edit the modules file by adding a line rtc ds1307 at the end of the list Figure 15 10 shows this edit using the nano editor HE pl File Edit Jabs Help ie GNU nano 2 6 Pile f E i le i at boot time one per line Lines i Parameters can be specified after isnd bom2oess i 2c bem2708 ji 2c dev irte aslso7 fee Get Help ae Exit Read ay Where oe Wri teQut am Justify LKM module screenshot fete modules araspberrypi etc modules kernel modules to Load at boot time This file contains the names of kernel modules that should be Loaded beginning with are ignored the module name Read 10 lanes T 4 Cut Text ra Cur Pos Uncut Text g To Spell Pile Is i Frev Page oe aet Page The last remaining step is to edit a file named rc local that is located in the etc directory This file contains scripts that are run at the end of the boot process which is how the RTC object will be created once the following script lines are entered into the rc local file sudo nano etc re local J echo ds1307 0x68 gt sys class i2c adapter i2c 1 new device J sudo hwclock s IOTE 12c 1 is for a rev 2 RasPi Use i2c 0 for a rev 1 RasPi Figure 15 11 shows this edit using the nano editor m pi raspberrypi Zas File Edit Tabs Help OM nano 27 2 6 File fete re local Modified l By default this script
220. le counter Digikey 296 2048 5 ND CD4040BE CMOS 12 bit ripple counter 16 pins DIP Level shifter Adafruit Industries 395 amp channel level shifter breakout board Mini proto board Adafruit Industries 1171 Perma Prototype board The voltage output from the GM counter is reduced by 50 percent and connected to the input of the CD4040 chip Counter output bits 0 to 6 are in turn connected to an 8 channel level shifter chip that converts the 5 V DC counter voltages to the 3 3 V DC level which is compatible with the RasPi GPIO input signal lines A single GPIO output from the RasPi is connected through the level shifter chip to the counter reset line thus allowing the ripple counter to be reset for the start of a new count period Figure 14 5 shows the bottom side of the GM counter with a white wire connected to the N6 output and a green wire connected to a ground point ae PEUGOLS IELAI anaE Output wire connections on the GM counter Initial Test Configuration The interface circuit was first set up on a solderless breadboard with the GM counter connected as shown in Fig 14 6 Sample of Uranium 8 channel level mini prote shifter board Initial test configuration I also purchased a sample of uranium ore that was used to test the project The ore sample is rather innocuous although it was certified to have a 6000 cpm vwith most of that activity due to alpha radiation The certification paper is shown i
221. le space as compared to storing the data in a binary format The following code line shows how to store the data in a binary format file write adc value wb where wb is short for write binary Of course you would need to read in the data using the complementary rb short for read binary Not only that but you need to restructure the program to keep track of the number of bytes read to ensure that you don t mix up the byte sequence and start reading garbage You also will not need the line adcStr str adc value n because the binary data is written in a contiguous byte stream that you as the programmer must decipher This is another reason to use strings it is much easier to debug the file contents This program takes two minutes to run as the time between samples has been reset to 1 second Recall that this sample frequency is 10 Hz which was discussed earlier as an optimal value for this application Also note that DEBUG is set or you will get 1200 values displayed on your screen You should run Test_File_ADC py while moderately shaking the PMS to create pseudoseismic activity Do not be so vigorous as to have the brass pendulum strike the PVC pipe wall The sensor is quite sensitive so only gentle force is needed We will be ready for some data analysis once the file is generated Seismic Data Analysis Copy and paste the contents of the myData file into an Excel spreadsheet There shoul
222. ll that is needed is a current limiting resistor in series with the GPIO pin The resistor value was set at 220Q to provide a 10 mA drive current to the LED in the optoisolator This current level is suitable for both the RasPi and the optoisolator There is also a 3 V Zener diode connected in series with the photo transistor s collector which affords a bit of protection in case of excessive voltages that might be present in the output circuit INS 2236 RasPi to optoisolator circuit The NTE3041 is rated for a maximum of 30 V collector to emitter voltage VCEO Any voltage that exceeds that maximum rating will likely damage the optoisolator however the RasPi will still be protected I have used the NTE3041 optoisolators to connect the RasPi GPIO pins to the shutter full press focus half press and electronic flash control pins The sound and light modules do not require isolation as they already use isolated relay contacts High Voltage Optoisolator Circuit Figure 4 12 shows a circuit that can be used if you need to control an electronic flash that has high voltage present on the control pins This circuit uses an optotriac triode for alternating current isolator in lieu of the NTE3041 optoisolator The optotriac in turn turns on a silicon controlled rectifier SCR that fires the flash unit The SCR recommended is rated up to 400 V I strongly recommend you do not use a flash unit with more than that voltage
223. ly terminates the signal in a process known as hop kill This is done presumably to limit range and probably to remain in legal compliance with governmental regulations regarding low power unlicensed operations Basics of Z Wave Network Operation The Z Wave network from its very beginning was designed to be compliant with the ISO seven layer network model As such its inherent design is based upon proven computer network concepts that are robust efficient and well understood by most system designers Figure 7 1 shows the Z Wave logical network stack with the corresponding ISO layer number All subsequent network software developed for the Z Wave network follows this model ISO Level Application layer main loop Z Wave Application specific specific commands commands Network routing Frame routing topology scan routing table update PHY MAC Layer Media access 908 MHz 860MHz Z Wave and ISO network layers Data sent through the Z Wave network is in packets similar to the Ethernet format Figure 7 2 shows how these packets are initially constituted at Layer 2 and subsequently modified at higher layers as needed to suit the real time network communication need Application Packets Layer 7 Various Network packets Poso ner ce e ead Transport packet Layer 3 Data Link packet j Layer 2 Z Wave network packets versus model layers A basic packet is created at the Data
224. mount of time in seconds that you want the RasPi to do nothing essentially spinning its wheels The seconds argument the value put in the parenthesis is a real number i e one with a decimal point I used 5 second for my initial program The modified program with comments is shown below import the library that allows us to logically access the GPIO pins refer to the library as GPIO It is like an alias import RPi GPIO as GPIO import the time library to access the sleep function use the BCM pin numbering scheme as discussed earlier in the chapter GPIO setmode GPIO BCM set pin 18 to be in the output mode GPIO setup 18 GPIO OUT loop forever while True apply a HIGH voltage to pin 18 GPIO output 18 GPIO HIGH sleep for 5 seconds time sleep 5 apply a LOW voltage to pin 18 GPIO output 18 GPIO LOW sleep for 5 seconds time sleep 5 While you can make the modifications to the original program using the nano editor I found it more convenient to use the shell editor which displays the program when you first open it This editor will allow you to save the program with the original or a new name There are a few items in the program that should be explained The time library is accessed by using the import statement the same way the GPIO library was accessed The looping behavior is imposed by two things First I used what is known as a conditional statement while True The while portion of this sta
225. mv6l7ag EGG INFO copying ETA sont ante dependeney Linke ext gt build bdist Linux armv 6l egq EG G INFO copying WebIOP1l egg info top Llevel txt gt build bdist Linux armv6l egg EGG INFO writing build bdist Linux armv6l egg EGG INFO native_lLibs txt zip_sate flag not set analyzing archive contents webiopi pycache GeTo Adobe 32 module references file creating dist Webl0Pi 0 5 3 py3 2 linux armv6l egq and adding buildsbdist lin UX armv l egg to it removing build bdist linux armv6l egg and everything under it Processing WebIOP1 0 5 3 py3 2 Linux armv6l egg removing usr Llocal lib python3 2 dist packages WebIOP1 0 5 3 py3 2 linux armv6 l egg and everything ander it creating usr local slib python3 2 dist packages webIOP1 0 5 3 py3 2 Linux armv6l e99 Ex tracting WebIOP1 6 5 3 py3 2 linux armv6l egg to usr local lib python3 2 dist packages febIOP1 0 5 3 15 already the active version in easy install pth Installed f usr localslib python3 2 dist packages webIOP1 0 5 3 py3 2 Linux armv6 L egg Processing dependencies for WebIOPi 0 5 3 Finished processing dependencies for WeblOPi nd 5 ebIOPi installed for Python 3 2 3 Copying resources WebIOP1 successfully installed To start WebIOPi with python sudo python m webiopi To start WebIOP1 with python3 sudo python3 m weblopi To start WebIOP1 at boot Sudo update rc d weblop1 defaults To start WebIOPl service su
226. n Add an ultrasonic sensor that is capable of detecting objects in the forward path of the car The Python program can easily be modified to handle sensor inputs and modify the path accordingly Add an IR sensor to detect IR beams to redirect the car basically creating an invisible fence or barrier Add a GPS sensor to map the path of the car assuming it travels more than a few meters The Ultimate GPS receiver discussed in an earlier chapter would be an ideal unit to install on the car The path taken could be recorded in the RasPi SD card and later sent to Google Earth for display in that application Add swarm or hive behavior if you happen to have an additional car or know someone with one The RasPi can easily handle the computing challenge that it takes to enable this type of collective behavior The cars should be able to talk with one another using their installed adapters Add an IR light and an IR sensitive camera to allow the car to maneuver in total darkness This would be a very interesting and informative task since rescue robots need to have this capability As you might imagine many more items could be added to this list It really is only limited by your imagination The robot car built in this project is only a start to bigger and much better projects Summary This project commenced with an overview of the car s final form Next came specific build instructions for the chassis as well as for the sandwich construct
227. n ALSA Python mocule used with a Video editing system Although the ALSA drivers should be preinstalled with the distribution you should execute the following command in a terminal window to ensure that the drivers are in place sudo modprobe snd bem2s835 J The app modprobe loads Loadable Kernel Modules LKM which in this case is the ALSA compliant sound driver snd bcm2835 You should also check a file named modules located in the etc directory for the presence of a snd bcm2835 item This file is checked at boot time for all the LKMs that are to be loaded You also need to install the alsa utils package as that contains several apps that are important to get our project working The installation uses the aptget command that was discussed in Chap 1 Type the following command in a terminal window sudo apt get install alsa utils J One more step is required to ensure that sound is produced at the analog audio jack Type the following in a terminal window sudo amixer cset numid 3 1 J The app amixer is part of the alsa utils package that allows us to select the desired audio output connector The HDMI is the default audio output device when the RasPi is first booted The audio output is redirected using the above command The number at the end of the above command line represents the following O auto 1 analog 2 HDMI Testing the Analog Audio Now it is time to test the audio from the RasPi Connect a powered speake
228. n Fig 14 7 in case anyone is interested in purchasing a sample It is also perfectly legal to ship this type of ore sample because its activity levels fall well below any regulations governing radioactive material transport United Nuclear Certificate of Measured Radiation Uranium Ore ea feu poe ee ee ee ee Eh pee Pee eee ee Wt Mq samp ee ee ae ee ee bran ri bran fey psec ATEI MIE a th ee ee FAL he a Bes auld eee 20 ee ee F Piada A eg P at bas Pit ay bee PA irr gee ea eg ed Epi ey oe ja mp p p ri ir bhaniiag pl am Tein p ee ppa h aeae Uranium ore sample certification All eight of the RasPi GPIO pins were used in the interface Seven were set up as inputs to read the count from the 12 bit ripple counter and the eighth was set as an output to reset the counter Below you will find the Python code available on the book s website www mhprofessional com raspi from a program named geiger py that was used to test the initial configuration Figure 14 8 is a screenshot of the program output captured from my laptop that was on an SSH connection to the RasPi The ore sample was put in essentially direct contact with the GM tube in an effort to obtain the highest readings possible geiger py import time import RPi GPIO as GPIO GPIO setmode GPIO BCM GPIO setup 17 GPIO IN GPIO setup 18 GPIO IN GPIO s etup 22 GPIO IN GPIO setup 23 GPIO IN GPIO setup 24 GPIO IN GPIO setup 25 GPIO IN G
229. n a lower level stratum with a higher stratum number provide a higher quality clock signal than a server on a stratum closer to the primary clock sources Don t worry if all this sounds a bit confusing I provide it only as background to promote your awareness of the underlying NTP structure A series of public NTP servers connected to the Internet are known as pool servers The URLs for these servers are stored in the ntp conf file located in the etc directory Figure 15 14 is a screenshot of this file GH nan 2 2 6 File mtp cont a Tete ntp coni Confhiquration for nipd see ntp contis for help driftfile vwar lib sntp ntp drift f Enable this af you want statistics to Ee leaped PSsEatadir var flegintpstatss statistics LOSPSEATA PROEELATS Clockscats filegen loopstats file loopstats type day enable Filegen peeratata Fille peeratatesa type day amable Filegen lockstats file lockstats type day enable You do need to talk to an HTP server or two for three PSGEVRE BEE Yr provi axanple E pool ntp org maps to about 1000 low stratum NTP servers Your server will f pick a different et every time it starts up Please consider joining the i pool lt http www pool ntp ong join html gt Server 0 cdabian pool ntp org ibarst server lodebian pool ntp ong ibarst server 2 deblan pool ntp org ibarst server Jidebian pal ntp org ibareset Access control configuration see fusr share doc ntp doc html accopt ht
230. n designations You should always crosscheck your connections with this figure anytime that you are directly wiring to this connector left bottom top P1 01 Pi1 02 3V3 Power SV Power GPIO 0 SDA SV Power 0 e Ground PID 4 am ELi conmo Ground Q GPIO 15 RXD mor O Ri GPIO 21 PCM_DOUT Q Meson GPIO 23 3V3 Power GPIO 24 GPIO 10 MOSI o Ground GPIO 9 MISO GPIO 25 GPIO 11 CKL GPIO 6 CEO crus crore GPIO 1 SCL GPIO 22 Pl 25 P1 26 bottom top right GPIO connector pins with the BCM2835 pin designations All GPIO voltage levels are 3 3 V not 5 V tolerant There is no overvoltage protection incorporated on the RasPi and if you inadvertently subject a GPIO pin to 5 V you will wreck your RasPi I will not take any responsibility for such foolish actions as you have been warned I have incorporated hardware buffers into projects where 5 V sensors interface to the RasPi thus avoiding any chance of damaging the RasPi due to an input voltage overload You must always pay careful attention to how the projects are wired because it is easy to damage the RasPi through an inadvertent construction mistake Digital Signal Voltage Level The RasPi operates at a positive power supply voltage Vdd of 3 3 V with the digital logic levels shown in Table 1 3 This means that any GPIO input voltage greater than 2 7 V will be detected as a logical one or HIGH Any voltage
231. nalog output to play MP3 songs You will need an audio amplifier to hear the music as the RasPi does not generate a powerful enough signal to drive an unamplified speaker However a good quality set of headphones will work Ethernet and USB Connectors Both the Ethernet and USB connectors are shown in Fig 1 12 I will discuss the Ethernet connector first followed by the USB connectors Ethernet and USB connectors with cables The Ethernet connector shown on the left in the figure is a standard RJ45 connector You would simply plug your standard Ethernet patch cable into the socket and connect the other end to either your router or switch if that is the way you have setup your home network The RasPi will then automatically negotiate with your router to gain an Internet Protocol IP address in a process known as Dynamic Host Configuration Protocol DHCP There are five light emitting diodes LEDs to the left side of this socket as you look at it head on The LED furthest away from the socket is labeled 100 If it is shining with a yellow light this means that a 100 megabits per second Mb s connection was made The next two LEDs just to the right of the 100 LED are labeled LNK and FDX These LEDs shine with green lights to indicate that the Ethernet is alive and operating Checking these LEDs is a quick way to determine if your Ethernet connection is working or if something somewhere has gone down Ther
232. nd lIn the last phase the master and selected slave engage in half duplex communication in which the master issues commands and the slave responds as designed Maxim DS2438A Chip The Maxim DS2438A chip is used in both the Barometer and Humidity Modules It deserves a Separate discussion because it serves as a specialized controller between a module sensor and the 1 Wire bus This chip is formally designated as a Smart Battery Monitor however it is used in another role for the aforementioned modules Figure 10 11 is a block diagram illustrating the many functions implemented by this small chip which is only an eight lead small outline integrated circuit SOIC DS2438 BLOCK DIAGRAM BATTERYVAGENERAL VOLTAGE REGISTER DS2438A block diagram The chip contains an analog to digital converter ADC that converts the sensor s analog signals into equivalent digital signals that can be passed over the 1 Wire network The module s unique 64 bit ID is also stored in a ROM contained in this chip The ROM contains all the programming code needed to respond to the master s reset command as well as to the other commands unique to the module The parasitic capacitor and blocking diode discussed below are also shown in Fig 10 11 Maxim DS18B20 Chip This chip is called a Programmable Resolution 1 Wire Digital Thermometer by the manufacturer Some key specifications are listed below Configurable from 9 to 12 bits Meas
233. nd at what levels you should take some action The Geiger counter used in this project was built from the Velleman kit number K2645 and is shown in Fig 14 1 This popular Geiger counter kit has been previously incorporated into other microcontroller projects including ones using the Arduino or the Parallax Basic Stamp Velleman K2645 Geiger Muller counter Radioactivity and Radon Radioactivity is the process in which an unstable atom loses energy by emitting particles or rays of ionizing radiation These particles and rays consist of Alpha particles Helium nucleus Beta particles High energy high speed electrons or positrons with a neutrino Gamma rays Highly energetic rays The term ionizing radiation relates to the upset or damage a radioactive decay particle or ray can do to a living cell The alpha particle does the least damage because the epidermal skin layer stops it A beta particle is a bit more penetrating but it can be stopped by various items including a layer of cardboard a sheet of polyethylene plastic aluminum foil moderate to heavy clothing etc The most damaging is the gamma ray which can penetrate deep into the human body Gamma sources are normally shielded with lead steel concrete etc The source of most natural radioactivity is uranium ore It is the most abundant naturally occurring radioactive element found in nature The prime element found in uranium ore is U where the 238 is the atomic we
234. nections This adapter is shown in Fig 4 9 Hot shoe adapter The adapter brings out the connections to a 3 5 mm plug that can be inserted into a standard mono jack The adapter also incorporates a standard tripod mount as shown in the figure inset This makes it simple to mount the flash in any position as needed Electronic Flash Control Voltages You may have noticed that I put the 4 5 V control voltage in the Fig 4 8 pin description This is a typical voltage found on Canon electronic flash units and it is quite compatible with this project s interface circuits However older electronic flash units may have significantly higher voltages present on the control pin These may range up to several hundred volts Connecting an electronic flash with more than 24 V on the trigger contact to the project interface circuit will destroy the interface and may cause further damage to the RasPi Modern electronic flash units are expected to conform to ISO Standard 10330 2002 entitled Photography Synchronizers ignition circuits and connectors for cameras and photoflash units Electrical characteristics and test methods One portion of the standard requires that trigger voltages not exceed 24 V max Canon has designed their units to operate at less than 6 V and Nikon at less than 12 V Older units were not designed to the standard and could conceivably have hundreds of volts exposed that would not only destroy the interface but also
235. ng install in chips make 2 Entering directory home pi libnfc libnfec 1 6 0 rel libnfc chips EC libnfechips la pn53x lo E The Build start Figure 9 13 shows the end of the build There will now be a complete libnfc installation on the RasPi after this screen appears Entering directory home pi libnfc libnfc 1 6 0 rcl test Nothing to be done for all 2 Leaving directory home pi libnfc libnfc 1 6 0 rcl1 test Entering directory home pi libnfc libnfc 1 6 0 rel Leaving directory home pi libnfc libnfc 1 6 0 rec1 Leaving directory home pi libnfc libnfc 1 6 0 rcl1 pi raspberrypi libnfc libnfc 1 6 0 rcl The build end Hardware Installation The interface between the RasPi and the PN532 breakout board requires only four wires as shown in the block diagram in Fig 9 14 The Pi Cobbler prototype tool is also used to ease this installation pi Cobbler PNS32 Breakout ribbon cable A LED 2 270 ohm The RasPi and the PN532 interface I also connected an LED to pin 23 with a series current limiting resistor The LED will provide a visual indication when a tag is detected using the Python program Figure 9 15 is a picture of the physical layout of the hardware Project hardware layout Do not be concerned with the fact that 5 V is being connected to the PN532 board while there are direct connections to the UART lines TXD and RXD The PN532 shifts the
236. nnection and can serve as a central clock source for all networked computers There are commercial NTP servers available but they typically cost anywhere from 1500 to 2000 Using a RasPi with a GPS will drop the cost to less than 100 and will provide the desired functionality The GPS used in this stage of the project is the same model previously discussed in Chap 5 I will not repeat all the background and setup information provided in that chapter and will simply assume that you will follow those instructions in establishing the GPS to RasPi UART communications link Refer to Fig 5 15 in Chapter 5 to see the essential wiring required to connect the GPS module and the RasPi You should ensure that the gpsd package is installed on the RasPi as you will need it to process the GPS clock data I recommend that you also install the CuteCom terminal control program Using that program will enable you to easily confirm that both the UART link and the GPS module are functioning properly Again simply follow the procedures detailed in Chap 5 to set up the GPS module and the RasPi to use the UART communications device ttyAMAO The ntp conf file located in the etc directory must be edited to force the ntpd application to use the GPS instead of one of the pool servers I commented out all the pool servers and added the following two lines to that section of the file server 127 127 28 0 minpoll 4 fudge 127 127 28 0 timel 0 183 refid NMEA Figure 15
237. nnects to the RasPi Don t be concerned with the host name that appears in the screenshot I will get to that shortly ise PuTTY Configuration _ amp Session Basic options for your PuTTY session reer Specify the destination you want to connect to if L Keyboard Host Name or IP address Port Bell pi openzwave local 22 I Featu I Win 8 ii Connecton type a Raw O Iene Riogin SSH Segal Appearance Behaviour H Translation Load save or delete a stored session Selection Saved Sessions Colours TERN Default Settings Load L Proxy Sae e i Telnet L Rlogin es L Senal Close window on exit Always Never Only on clean exi aew putty screenshot When you click on the Open button at the bottom of the putty screen you will see in Fig 7 12 a screenshot of a RasPi terminal window asking in this case for a login password ee openzwave local Pull a aT Using username pi ppifopenzwave local s password J Raspberry Pi terminal window At this point you are in a RasPi terminal window session It is absolutely no different from looking at a monitor connected directly to the RasPi and using a locally connected keyboard and mouse This transparency is what makes SSH so great it allows you to login remotely to the RasPi without being concerned with any minutia about the connection You may type in any normal command and have the RasPi r
238. nother particular file category that doesn t appear until the OS is running In this category are virtual files that are dynamically created upon demand and are often times stored in the sys directory The Filesystem in Userspace FUSE application supports the owfs application by creating and storing these virtual files in FUSE registered directories The mnt 1wire directory is the designated site in which to store all the virtual files created for the 1 Wire network currently operating You can prove to yourself that the virtual files exist Simply reboot and do a 1s on the mnt 1wire directory Nothing will show Next type in the mount command from step 12 and redo the 1s command Then you should see a directory data display like the one shown in Fig 11 4 for the lwire directory owfs applications and FUSE are integral to each other the system wouldn t work without either of them Another very useful feature is that the 1wire directory will automatically be updated as modules are removed from and or added to the 1 Wire network Figure 11 6 shows what happened before and after I plugged a Temperature Module family 28 into the 1 Wire network Note that I did not have to type any commands the addition was automatically detected pi raspberrypi amp ed ent aspberrypi mnt lwire 1 EPECROOOONO Fj a E a etl a hae tar tat hae Autodetection of 1 Wire Modules You will see that a new directory entr
239. nsverse through the Earth The initial energy wave is termed a P wave also known as a primary or pressure wave and it has a velocity of approximately 1000 meters second P waves while energetic carry far less energy than the S wave also known as a secondary or shear wave The S wave travels at 250 meters second slower than the P wave but containing much greater ground displacements than the P wave The larger amplitude S waves cause the majority of damage to surface structures The seismic detector is sensitive to both P and S waves The P waves will be detected first since they travel faster than S waves The difference between the time of arrival TOA of the two waves will depend upon the distance from the quake epicenter to the location of the detector A distance of a few kilometers will result in only a few seconds between the waves while that of several hundred kilometers can amount to 20 minutes or more The RasPi can be set to generate an alarm if an initial wave greater than a threshold amount is detected This should provide some time to take shelter in a secure and strong location provided that the epicenter is not too close The velocities of the P and S waves are very much dependent upon what makes up the ground through which the waves travel Table 6 1 shows some typical velocities for these waves as they travel through a variety of ground types Table 6 1 P and S Wave Velocities versus Ground Type Ground type P wave m
240. nts 3 3V 570 ohms LOK ohms ii Switch A pin 18 pin23 Pi Cobbler Test circuit for switch input Here is the Python code that will run this little circuit This program is available on the book s website as Test_Switch py OTE There are two equal signs required to do a comparison i e GPIO input 23 False If you make a mistake and put only one it will become an assignment statement which may or may not be evaluated to a logical state An erroneous statement GPIO input 23 False would likely evaluate to False since you cannot programmatically set an input In any case the program will run but not operate as expected This is called a logical error and is a common occurrence with beginning programming students Test_Switch py Fimport the GPIO library to access the pins import RPi GPIO as GPIO use the BCM pin numbers GPIO setmode GPIO BCM set pin 18 as an output GPIO setup 18 GPIO OUT set pin 23 as an input GPIO setup 23 GPIO IH start a forever loop while True check if the switch has been pressed if GPIO input 23 False set the pin to a HIGH output GPIO cutput 18 GPIO HIGH Hot pressed then set pin to a LOW output else GPIO cutput 18 GPIO LOW I have used an if else conditional statement in this program that checks if pin 23 is LOW or False and if so will set pin 18 to GPIO HIGH Otherwise the conditional statement will go directly to the else portion wher
241. o state that the BCM2835 is more than adequate to display all the graphics and output all the audio streams required for all the projects in this book Memory There are two memory types used in the RasPi dynamic random access memory DRAM and Secure Digital SD flash The original version model A of the RasPi had 256 MB of RAM installed while the latest Model B has 512 MB The 512 MB chip is easily seen on the board as the top layer of the SoC sandwich The SoC chip shown in Fig 1 2 has top DRAM marked as supplied by Samsung with a part number K4P4G324EB ACC1 which translates to a lowpower 4 Gbit 512 MB DRAM designed for mobile applications This means that it too uses low voltage while maintaining reasonable clock speed Having 512 MB of DRAM means the operating system will function very efficiently and programs should also run smoothly provided they are properly created The SD flash memory is used to store the operating system all programs and all other data that need persistence In other words nothing will be destroyed when the power is shut off The RasPi uses SD flash memory in the same manner that a PC uses a hard drive to permanently store data and programs You have a choice in selecting the memory size of a SD memory card that simply slides into a holder that is located on the underside of the RasPi as shown in Fig 1 3 tHthbphhbhbn bb em amp amp oe ie ee ee ee Back side of the Raspberry Pi If you purch
242. oard The only additions I made to the board are the 5 V DC voltage regulator that is located on the left side of the board and the two screw terminal connectors A 12 V DC LiPo battery is connected to the leftmost terminal while the Geiger counter is powered from the terminal connector just to the right I must confess to a slight cheat that I made in powering the Geiger counter It is normally powered by a 9 volt battery All I did was put in a Series resistor that dropped the LiPo s 12 V to between 9 and 9 5 V I used a 470 Q resistor since the current was only a nominal 6 mA The black and white twisted pair of wires to the right connect to the ripple counter input and sround Also the mini proto board makes the RasPi connection extremely easy just use the ribbon cable as you did in previous projects with the Pi Cobbler Probably the most difficult part of the project was assembling all the pieces so that they fit into a project box I selected a box that I thought was large enough to accommodate all the parts It did but it was a Struggle My box is 6 25 x 4 68 x 2 25 in 15 5 x 11 5 x 6 cm which is simply too small I would recommend a box no smaller than 8 x 6 x 2 75 inches in order to have everything fit comfortably inside Figures 14 11 to 14 13 are photos of the assembled portable Geiger counter not yet installed in the box Right side view of the portable Geiger counter Left side view of the portable Geiger counter
243. obbler prototyping tool Also shown was a test program using bit banging to control the ADC chip and implement the SPI protocol A seismic detector based on a kit called the Poor Man s Seismograph PMS was connected and tested with a program that collected data samples and stored them in a file on the RasPi file system This data file was then analyzed by using MS Excel to determine a realistic alarm level Finally the project concluded with the demonstration of an operational system that lit an LED when the seismic level went above the trip level Home Automation Introduction In this chapter I will cover how to effectively use the RasPi in a home automation system But how do you define a home automation system The answer is after you examine the needs and requirements of the homeowners you design an automated system that best meets those needs Hence one size or type of automated system does not serve all instead you start with a flexible base system that can be easily tailored to fit a specific situation The real purpose of a home automation system is to simplify a homeowner s life It accomplishes this goal by removing repetitive and tedious tasks and relegating them to a hardware and software system that never forgets and accurately and consistently carries out the programmed tasks Some of the tasks that a home automation system could handle are shown in Table 7 1 Table 7 1 Home Automation Tasks Category De
244. of Fig 5 19 In a similar fashion the data shown on the bottom of Fig 5 20 is nearly identical to the left hand side data shown in Fig 5 19 One difference is that the error data is abbreviated as EPX EPY EPV etc in Fig 5 20 while it is spelled out in Fig 5 19 GPS Packet Monitor The gpsmon app allows you to monitor the GPS data stream while providing a simplified view of the packets flowing from the receiver to the RasPi Figure 5 21 shows a screenshot of gpsmon in operation pi raspberrypi 0 X File Edit Tabs Help Generic NMEA gt O07 Lat 43 14 16 632 WN Lon Cooked PVT GT OP GPGSV Sentences Time 214235 000 Time 214235 000 Latitude 4314 2772 N Latitude 4314 2772 Longitude 07102 7464 W Longitude 07102 7464 Speed 0 06 Altitude 49 8 Course 107 03 Quality 2 Sats 6 Status 5 FAA D HDOP 1 38 EA 32 8 RM 6cA a 3 lUTC RMS MAJ MIN ORT LAT ALT GST A e D G O syt Abune GT W okhoMe i RK _ arina A gpsmon screenshot When you compare Fig 5 21 to the previous two figures you won t see a whole lot of new information but the latitude and longitude have been converted to an easy to read format of degrees minutes and seconds There are also some other lesser used data shown including DOP H Horizontal dilution of precision DOP V Vertical dilution of precision DOP P Total or 3D dilu
245. om off to on The pin will now be outputting a 1 or high level 3 3 V DC Figure 11 15 is a picture of the test setup with the three LEDs turned on Functioning output test setup Testing the inputs is very easy Just select the pins that you want to be used for inputs by ensuring that the check marks are highlighted and then connect those pins to the 3 3 V DC power supply Figure 11 16 shows the phone screen with pin 18 set as an input and also connected to the 3 3 V DC supply Pins 23 and 24 were left as outputs A phone input test screen Sharp eyed readers may have spotted two additional pins that are set up as inputs and appear as if they are on yet are not connected to the 3 3 V DC These two pins are called floating inputs meaning they are unconnected and can receive stray voltage that can trigger a false reading of a high input I deliberately left this condition in the figure to show you that you can unwittingly create a short circuit to ground by resetting a floating input GPIO pin to output without removing the ground wire Testing the Web Server with a Browser The HTTP web server may also be run from any local computer s browser Simply type in the RasPi s local IP address with port 8000 as a suffix In my case this was http 192 168 1 21 8000 Figure 11 17 is a display of the resulting web page All the configurable GPIO pins were set as outputs for this screenshot All the functionality disc
246. om the famous BBC show Monty Python s Flying Circus Apparently the Python creators were great fans of the show and they currently encourage authors or bloggers now to incorporate related humour when writing about Python IDLE IDLE is the name of an application that creates and runs the shell environment that I will use to develop and test your Python programs Fig 1 26 shows a portion of the desktop with two IDLE icons appearing Python V3 Python V2 Python Games IDLE desktop icons The top icon opens a Python version 3 shell while the icon directly underneath opens a Python version 2 shell I will be using the version 2 shell as that Python version is compatible with the software libraries that are needed to run the hardware used in the projects User interaction using the Python shell is intuitive results are instantly displayed after an Operation is performed and the Enter key is pressed Adding 7 5 with the sum displayed below the input numbers is shown in Fig 1 27 m Python Shall File Edit Shell Debug Options Windews Help Python 2 7 3rc2 default May 6 2012 20 02 25 oct 4 6 3 on linux Typ copyright credits or license for more information aoe 7 5 fe 2i A simple Python operation Displaying text in the Linux shell is also easy to accomplish simply use the print function Traditionally the first program to be run in most programming books is the so called Hello
247. on the laptop will handle that side of the link while the built in serial protocol software will handle the RasPi side An interconnecting cable will also be needed along with a very useful software driver The link is set up using a USB to serial TTL cable that is connected to the GPIO header as shown in Fig 5 9 USB to Serial TTL link cable The cable has four pin connectors that are color coded and attached to the GPIO header as detailed in Table 5 1 This cable is available from Adafruit Industries as part number 954 Table 5 1 GPIO Header to USB TTL Cable Connections GPIO header Color pin number Function Black 6 Ground White G TAD Green 10 RAD Red 2 5 V Caution See warning below DO NOT CONNECT the red lead to the GPIO header if you are using the regular micro USB power supply This red lead is provided to allow you to power the RasPi from the host computer s USB port however you cannot simultaneously power the RasPi from the micro USB power supply and the USB port power supply only one or the other My recommendation is Do not use this 5 V power supply just continue to use the regular power supply There are many terminal programs available that will provide the laptop side communications very nicely Two recommendations are Tera Term the Tera Term Project http ttssh2 sourceforge jp index html en ZOC http www emtec com zoc terminal emulator html You will need one more vital software
248. onfig status creating config status creating config status creating config status creating config status creating config status creating config status creating config status creating config status creating config status creating config status creating config status creating config status creating config status creating config status config h config status config status Selected drivers BCEIZ2 4 avails BCEUZ23 P E a ss sssrsss pnS3e usb no no no no pn532_uart eer yes config status Doxyfile Makefile cmake Make file cnake modules Makefile contrib Makefile contrib devd Makefile contrib udev Makefile contrib win32 Makefile contrib win32 sys Makefile examples Makefile examples pn53x tamashell scripts Makefile include Makefile include nfc Makefile libnfc pc libnfc Makefile libnfc buses Makefile libnfc chips Makefile libnfc drivers Makefile test Makefile utils Makefile config h is unchanged executing depfiles commands executing libtool commands pi raspberrypi libnfc libnfc 1 6 0 End of the configure operation 8 The preparation for the actual build of the source code starts next Type the following at a terminal command prompt sudo make clean This preps all the source code libraries etc for the actual build Figure 9 11 shows the end of the prep stage make 2 Leaving directory fhome pi libnfc libnfc 1 6 0 rel libnfc buses Making clean in c
249. or 6 Headless login 96 Hello World program 18 19 Hensley Brian 169 High Definition Multimedia Interface HDMI connector 5 6 High definition HD video 3 High level languages 17 High voltage optoisolator circuit 48 HIH 4021 001 sensor 128 Hive behavior for robotic car 173 Hobby Boards 125 139 140 Home automation project 87 101 Open Z Wave software 96 101 RasPi and Z Wave interface 94 95 SSH login 95 96 Z Wave mesh network for 87 94 Home automation system defining 87 popular technologies for 89 tasks handled by 88 Home ID Z Wave 91 Home security controller project 103 113 additional sensors 111 113 laser trip assembly 104 105 laser trip program 111 Motion software package 105 109 protected security zone in 104 webcam selection 103 104 webcam viewing 109 111 Honeywell 128 Hop kill 88 I I C see Inter Integrated Circuit IDLE 18 20 desktop icons 18 running as roots 28 if else conditional test 38 Image file 15 16 import 29 Industrial Scientific and Medical ISM band 87 115 Initial startup 13 15 Inputs 5 V device 10 floating 150 switch 37 38 INSTALL txt file 26 INSTEON technology 89 Intellectual Property IP 1 2 Inter Integrated Circuit I7C 9 initial test 162 163 robotic car project 161 163 167 serial protocol 12 and servo controller 161 162 Internet Protocol IP address 8 Interpreted languages 18 Interrupts 11
250. orated into this project program The e mail would be automatically created and sent when a tag is detected I could envision a situation in which a child or perhaps a disabled person might need to send a non urgent e mail for help or assistance Obviously calling 911 or the international equivalent should be used in an emergency All the person need do is to swipe the tag near the reader and the e mail will be sent An LED should also light to confirm that the e mail was sent Other applications that might use tag initiated activities include home tasks such as starting an irrigation system pool cleaning garage door opening closing home spa operations and so on Summary This chapter began with an explanation of what NFC is and how it works The two primary operational modes were shown The PN532 breakout board was discussed next along with the rationale as to why it was selected for this project This was followed by a brief overview of the NFC communication interchange which illustrated that it was a robust TCP like data flow between the RasPi and the PN532 A comprehensive nine step procedure was detailed showing how to install the open source libnfc software package This package is installed in the Wheezy Linux distribution run on the RasPi A relatively easy hardware install was covered along with a quick test program to prove that the PN532 could detect a tag The project program was discussed next and then executed cau
251. ough TSA screening four times as shown in the dose examples listing in Table 14 2 I also tested the area for background radiation by removing the ore sample and letting the detector simply operate for a while Figure 14 9 shows the screenshot for background radiation a pi raspberrypi 2c average mrem maximum mrem 20 average mrem maximum mrem 13 fmin 12 mrem 26 average mrem anae Background radiation readings The average reading was approximately 11 prem or in the banana equivalent dose range a non issue regarding exposure I should also mention that the readings were taken in my basement thus reconfirming that absolutely no radon was present or at least detectable Building a Portable Radiation Detector While the Geiger counter breadboard version worked fine it is not a very practical solution to detecting radiation in various spaces I thus wanted to build a portable battery powered version to use in the field The first step was to assemble a prototype board for the interface circuit that was successfully tested as described above I used a strip line protoboard that I purchased from a local electronics supply store and wired it in exactly the same configuration as the one used for the original solderless breadboard Figure 14 10 shows this wired board Sits E E ee ogee fff a h a a a E p EEEF CE E i i i Teter rt oe PaaS aeS Wired interface b
252. ow changed from off to on Note I did have to reload the page to observe this change Also the essential device attributes shown on the page reflect the selected device Summary I started this chapter with a definition of home automation and provided a list of representative tasks that would fall under the broad umbrella that comprises home automation Next followed a discussion of the underlying base technologies that support home automation implementations I provided a rationale for selecting the Z Wave protocol it is a modern highly flexible system that is very easy to configure and lends itself quite well to a simple RasPi interface connection Two representative Z Wave devices were next described along with a working small scale Z Wave network Then we conducted a network demonstration by using a commercial remote control device The core Z Wave chip was discussed to provide you with a better understanding of how the overall network functions and how devices are highly dependent upon the chip functions which can be added seamlessly to the network The Z Stick that enables the actual RasPi to Z Wave interface was shown along with the driver software However before discussing the software I showed you the highly useful SSH remote login procedure The open Z Wave software package was shown with two variations for the web application side 1 lightscontrol and 2 basic Some simple tasks such as turning a lamp on and off
253. owing the Power Injector Module do not have to be inserted in any particular order I will show you the Temperature Module next Figure 10 6 shows the external case Humicdity Temp waa we Fee Be Be pe diet ae ot thee ee atin cies Temperature Module case The external case is the same size as the Power Injector Module except that there are two RJ45 sockets at the top but no separate power socket The RJ45 sockets are wired in parallel so there are no specific in or out connections to worry about The bottom case panel has six holes in it to allow for airflow so that the sensor can measure the ambient air temperature not just the air contained in the case Figure 10 7 shows the PCB inside the Temperature Module Temperature Module PCB The temperature sensor marked U1 may be clearly seen mounted near the top centerline of the board It appears as if it is an ordinary TO92 a three lead plastic encased transistor but it is remarkably far more than that It actually houses a microprocessor with a temperature sensing element which is only made possible due to the nature of the 1 Wire protocol U1 is a Maxim DS18B20 chip which will be further described later You should also notice that a three terminal strip located at the midpoint of the right side allows for a separate power supply to be attached and for the module s digital output to be accessed via the terminal marked DQ We do not use this terminal strip
254. p as a time server running the NTP protocol Figure 15 13 is a representative block diagram of this hierarchy Clock Sources stratum 1 o S e B srama m Stratum 3 aena kk NTP server hierarchy The layers in the NTP hierarchy are referred to as strata starting with 0 and progressing to as high as 256 In reality layers 16 or higher are considered unsynchronized and are probably not implemented The highest layer shown in the figure is stratum 0 which consists of clock sources from which the actual time is referenced There are a variety of primary clock sources available in the public NTP network including sophisticated atomic clocks GPS clocks and the National Institute of Standards and Technology NIST time signal radio station WWVB to name a few Stratum 1 connects directly to the clock sources and usually is a high quality clock server source but this is not always the case NTP does not inherently guarantee that a server situated in the lowest numbered stratum will provide the highest quality or most reliable clock signal The reason for this is that the servers are networked and are constantly crosschecking the clock signals from other servers both in their same stratum as well as in the strata situated logically above them Poor quality clock signals will be rejected from adjoining servers and only quality signals will be passed on to other servers Thus it is entirely possible to have a server o
255. pi openzwave local as a host name Fig 7 11 5 The password is the regular one raspberry 6 A terminal window Fig 7 12 will appear 7 You are now ready to take one of two approaches to monitor and control the Z Wave network lightscontrol Server One of two server applications may be run at this point The first is a web app named lightscontrol that was created by Conrad Vassallo and can be downloaded from the website http conradvassallo com category open zwave controller This will be the one that I use The second approach is a bare bones server app that Thomas created to test the Z Wave network I will discuss that server after demonstrating the lightscontrol server All you need to do to start this service is type the following at the command line prompt lightscontrol This starts the lightscontrol server Figure 7 13 shows the lengthy preamble to the lightscontrol server web app EP pi opennmave Using usernane a pifopenzwave local a password Linus openzvave J 2 274 250 PREEMPT Thu Get 18 19 03 02 BST 2012 The programs included with jan GEU Linuxs syst th xact distribution tams ch progran are de imdividual files in usr shar copyraght em are free software i ro ribed in the Debian GNU Linux comes with ABSOLUTELY NO WARRANTY permitted by applicable law ITITITILL lr Hostnas ptnivave local Starting open Ivave Servers a default server ele fopeniwave You m
256. piece to complete the communications link This would be a USB driver that provides the logical connection between the RasPi UART TTL pins and the laptop s USB port connection The driver is available from the Prolific website at http www prolific com tw US ShowProduct aspx p_id 225 amp pcid 41 which takes you to the PL2303 Windows driver download page The driver file name is PL2303_Prolific_DriverInstaller_v1 7 0 zip This driver creates what is known as a virtual comm port that allows a USB port to emulate a standard RS 232 serial port The comm port created in my case was comm5 however yours may vary depending upon your laptop s configuration In any case use the new comm port in configuring the serial link as I have shown in Fig 5 10 In this screenshot I was using the Tera Term program Tera Term New connection Host fC 1 serial port History service Telnet TCP port 22 SSH SSH version SSH2 Other Protocol UNSPEC Serial Port COMS Prolific USB to Serial Comm Por ahs Terminal program port selection The port configuration settings are shown in Fig 5 11 You click on Setup then Serial Port to get to this screen when using the Tera Term program Tera Term Serial port setup Ti Baud rate 115200 Flow control none Transmit delay 0 msecichar 0 mseciine Serial port configuration settings The key parameters to set independent of the terminal program that you
257. primarily for data communications instead of for control which is the focus of both the SPI and I C interfaces All three serial protocols described in this section are implemented in hardware meaning that there is actual silicon dedicated to performing the protocol functions This is the most efficient and fastest way to provide these serial interfaces but it is not the only way You can implement these Same serial interfaces by using uncommitted GPIO pins and software Although this would provide nearly the same functionality as the hardware implementation it would not be as fast The term bit banging is often used to describe this approach Sometimes you must use bit banging when the hardware is not available I will now jump into the heady software arena I m sure you already sense that hardware and software are closely linked in the RasPi Software The RasPi was designed to be run with a Linux operating system This design decision stands in stark contrast to many other similar microprocessor boards including the popular Arduino series that do not operate in this fashion This is not to imply that an Arduino board is inferior to the RasPi but simply to show that using the RasPi brings additional flexibility and capability to projects because of the Linux environment I will not start this discussion with a Linux tutorial since there are many good Linux resources available on the web Google or your favorite search engine will
258. program that sent the e mail when the RasPi detected an intrusion signal Finally I concluded with a brief discussion about future modifications and the ease with which additional sensors could be added to expand the system NFC RFID Reader Introduction Near Field Communications NFC is a contactless communication technology based upon the ISO 14443 standard Being standards based NFC devices can easily interoperate with other contactless protocols including the highly popular Radio Frequency Identification RFID protocol RFID tags are often used for building access and asset inventory In this chapter I will show you how to interface an NFC RFID reader with the RasPi The reader will detect the nearby presence of a tag device and then light an LED The reader will be controlled by a software package named libnfc and a Python program running on the RasPi Be forewarned a fairly involved development process is required to install the libnfc software How NEC Works Magnetic induction is the fundamental physics principle involved with NFC RFID Figure 9 1 shows a simplified diagram where the reader or more formally Initiator emits a radio frequency electromagnetic field that is received by the tag or Target close range up to 20 cm 07 an effective air core transformer Initiator NFC RFID block diagram The RF field frequency is set at 13 56 MHz which is in the low frequency low power Industrial Serv
259. r Manual button La camera C High level camera controller diagram Camera Shutter Operation A brief discussion on how a Digital Single Lens Reflex DSLR shutter operates will help you understand the interface between the RasPi and the camera Modern DSLRs such as the Canon 40D that I am using in this project have a multifunction shutter control The camera will autofocus when the shutter button is depressed halfway and operate the shutter with a full press Figure 4 5 shows the interface connector that has both the focus and shutter control pins along with the common or ground pin There is 3 3 V present on both the focus and control pins and connecting either pin to ground completes the circuit and causes its corresponding action focus or control to be actuated Canon 40D shutter control connector A special plug has to be used with this connector I cannibalized a commercial inexpensive remote shutter control in order to have a plug for this project Figure 4 6 shows this plug with a molded cable Canon shutter control plug and cable You can go to the website www doc diy net photo remote_pinout to look up your camera s shutter control pin layout and matching connector Some of the newest DSLRs are using a standard 3 5 mm stereo jack that will make the interface connection much easier Do not despair if you do not have a camera capable of being remotely controlled Simply use the sound or light activated func
260. r peaks located at X axis numbers 8 11 14 and 18 in Fig 6 15 are clearly visible These peaks are separated in time by 3 3 and 4 second as each X axis number represents a 1 second interval The average of the peak separation is 33 second or equivalently 3 Hz This frequency is the apparent resonant frequency of this PMS detector It falls well within the acceptable frequency span discussed earlier and is very suitable for seismic detection purposes The other analysis aspect that must be considered is the seismic magnitude or Y axis The highest value recorded within the two minute data record was slightly over 1000 Recall that the 10 bit MCP3008 can measure up to 1023 using a 3 3 V reference Again the maximum is OK but we do have to be aware of the minimum value or else the detector range will bottom out Examining the graphs indicates that the equilibrium level is around 500 counts This is ideal in that an equal range both high and low is available to capture the sampled data You may have to adjust your PMS if the equilibrium is not at this ideal level That adjustment is easily done by turning the PMS offset potentiometer R4 until the displayed level is approximately 500 Refer to Fig 6 6 to identify this control Also you can run the Test_ADC py program to make this adjustment The final step in the analysis is to determine a valid warning or threshold level This is somewhat subjective in that you need to set th
261. r to the 3 5 mm jack and type the following in a terminal window sudo speaker test You should now be hearing a rushing noise from the speaker This is a pink noise signal being created by the speaker test app that is part of the ALSA package For a more detailed explanation of pink noise see the following section on Analog Audio Frequency Response If you do not hear this noise review the commands listed above and ensure that they were entered as shown The speaker test app has many more options than just producing a noise output Go to http manpages ubuntu com manpages natty man1 speaker test 1 html for more information Analog Audio Frequency Response Having a pink noise output provides an unexpected opportunity to measure the frequency response of the RasPi analog audio system I have had many years of experience as an acoustical engineer and to me this seemed a natural opportunity to assess the acoustic performance with this particular subsystem First let us delve into a bit of background information regarding pink noise and why it is so useful in determining a system s frequency response Noise by its intrinsic nature is random with energy spread uniformly across the observed frequency spectrum or bandwidth This type of noise is also called white noise to point out the uniformity of the energy Frequency analysis for acoustical systems typically uses a set of filters known as one third octaves that simulate to some extent
262. ravel in a straight line when so commanded The program is named Robot_Car py and is available from the book s website The program listing along with some amplifying comments can be found on page 172 The program line pwm PWM x40 debug True sets up a PWM object that is at I C address 0 x 40 This is how multiple I C devices can be configured when they all are attached on the same bus lines The program segment if wm state buttons 2048 pwm setPWM 0 0 servoRightFwd pwm setPWM 1l 0 servoLeftFwd Robot_Car py i usr bin eny python from Adafruit PWM Servo Driver import PWM import time import ewlid pwm PWM 0x40 debug True servoRightFwd 300 servoLeftFwd 2400 servoRightRey 0 servoLeftRevy pwm SetPWMFreq 60 print Press buttons 1 2 on your Wii Remote time sleep 1 wh cwiid Wiimote print Wil Remote connected print nPress the PLUS button to disconnect time sleep 1 wn rpt mode cwiid RPT BTH while wm state buttons lt 4096 Lf wm state buttons 2048 pwm 3etPWM 0 O servoRightFwd pem S tPWH 1 0 servoLeftFwd ti e sleepi 1 1f wi St tel butt ns 1024 pwm Set PWM 0 0 servoRightRev pwm S tPWM 1 0 servoLeftRev time sleep 1 if wm state buttons 512 pem SetPWM 0 O servoRightFwd pwm S EPWHM 1 O 0 time sleepi 1 if wm state buttons 256 pwm SetPWM O O pem SGEPW
263. re I will demonstrate this dual action in a later section of this chapter A block diagram of the 1 Wire network used in this project is shown in Fig 11 3 The USB to 1 Wire adapter and 1 Wire Sniffer Module used in the Chap 10 project are also being used in this project The 8 Channel I O board is also configured to supply power to the entire 1 Wire network Ras bern ey j USE ta IL Wire ji Chanel T A ire Lair e akarki ii Admter O Board Babee lig Liss Levine Lire Block diagram of the 1 Wire network All the modules are interconnected using Ethernet patch cables except for the special RJ12 RJ45 cable that connects the USB 1 Wire adapter and the I O board 1 Wire File System owfs Installation and Configuration The software required to control the 8 Channel I O board needs to be built from the owfs source code in a procedure similar to that followed in Chap 9 for the libnfc software This time I will not include the many screenshots shown in Chap 9 since you should now be somewhat familiar with the build process I do caution you to carefully follow all the steps because it is quite easy to miss something and consequently to be unsuccessful in creating the operational software The prerequisite conditions for the build are to have an Internet connected RasPi running the latest Wheezy distribution with a powered USB hub attached You can also choose to login remotely by using an SSH connection but that is not a requirement
264. re a knowledge of HTML and Javascript to accomplish this which is well beyond this book s scope I refer you to the WebIOPi documentation located at https code google com p webiopi There is a lot of information at this site including a discussion of Representational State Transfer REST which is the underlying technology that powers the web server It is well worth your time to look at the content and gain an appreciation of what is happening behind the curtains Remote Access to the 8 Channel I O Board The first step is to ensure that the owfs HTTP server is running Type this at the command line prompt sudo etc init d owhttpd start Next open a browser on a computer that is part of the local network and go to the RasPi s local IP address with port 2121 appended In my case this was http 192 168 1 21 2121 Figure 11 18 is a screenshot of the opening web page This should look somewhat familiar as I described a similar operation in Chap 10 when opening a web page to access the weather station data OWFS on localhost 4304 directory E op lhighest level directory 81 BA0731000000 81 BA0731000000 directory 29 B82E08000000 29 B82E08000000 directory stru structure directory alarm Initial web page for 8 Channel I O board I then click
265. re used in computing the location fix In all likelihood the satellites not used had insufficient signal strength as indicated by a low signal to noise ratio SNR The bottom of Fig 5 19 shows a portion of the raw GPS data stream that gpsd uses to parse data for the cgps application The TPV tag seen repeatedly in the data stream stands for target position and velocity and is probably the most common tag in a GPS data stream There is also a graphical GPS display that can be run by typing xgps in a Linux terminal window Figure 5 20 is a RasPi screenshot showing this graphical display xgps K File wiew Units Step of gid Satellite List Skyview PRN Elev Azim SNR Used S 32 64 339 Y 15 86 135 35 i241 35 299 19 26 48 si a e 2 a x 9 34 137 6 6 O 18 32 284 0 29 22 17 16 324 O0 0 0 Se eee ee class TPV tag RMC device dewttyAMAO mode 3 time 2013 01 13T18 33 11 000 GPS data Time 2013 01 13T18 33 11 000Z2 Status 30 FIX 61 secs Latitude 43 237938 N EPX 21 396 m Longitude 71 045140 W EPY 21 963 m Altitude 145 700 m EPV 22 310 m Speed 0 259 kph EPS 43 930 m Climb 0 000 kph EPC n a Track 94 810000 EPD nfa ain AN Xgps screenshot The top portion of the figure is the GPS constellation that is in a real time sky view of the receiver The data shown is almost identical to the satellite data shown on the right hand side
266. rect sunlight where I suspect it might conduct I also purposely left off an ambient light shield to show you the transistor When put in place the light shield will help with false triggers The relay contacts in this module are normally closed when light is not being detected and will open when the laser light strikes the phototransistor This means that the RasPi program will need to be changed to detect a low to high transition provided the same interface is used as is shown in Fig 4 14 That s what is so nice about using the RasPi and Python changes can easily be made in software to accommodate hardware issues Interface Connections All of the interface connections are shown in Figure 4 16 There are three input push buttons to manually trigger focus shutter and flash three output optoisolator connections that allow the RasPi to trigger focus shutter and flash and finally there are two inputs from the sound and light modules This might seem to be a lot but the circuits are quite simple and repetitive 3 3v 3 3v 3 3v LOK ohms LOK ohms LOK ohms Focus Shutter Flash Saitoh SW Gon Switch RasPignd RasPi gnd RasPi gnd pin 18 pin 22 pin 23 220 220 GPIO 1N52258 1N52258 q i i roc Wiener 3V Taner Putter Camera gnd Camera gnd 3 3 20 GPD pin 21 R1 fire 10K ohms 5O GPO pin 74 Point 2 Flash 3y Zener Sound module Flash gnd Rashi gid
267. rectory Make create directory pwa Print out the name of the current directory mm filename Remove delete ffename rmdir directory Remove delete olrectory Python I have chosen to use Python to program the RasPi for several reasons First and most importantly it is a simple programming language to use and most beginners can start to use it immediately with little to no trouble Second despite being simple to use it is a real programming language and shares most of the attributes that are common with other highlevel high powered languages such as C or Java You should visit the official Python website http www python org where you will find a wealth of information regarding Python This site should be your primary resource to use to answer any of your questions regarding the language There are also many good Python books available including Python Programming for the Absolute Beginner third edition by Michael Dawson and Think Python by Allen Downey Another useful reference would be Simon Monk s Programming the Raspberry Pi Getting Started with Python Dr Monk s book is concise with a brief but thorough introduction to Python fundamentals plus the bonus of a few projects at the end of the book Python is classified in computer science terminology as a high level language which roughly translated means that Python users are thinking in abstract terms The C language in comparison is a fairly low level language in wh
268. resenting the test to be performed The prompts are shown on the screen and are also shown here 1 Test the shutter only 2 Test the flash only 3 Test the shutter and flash together QO Exit the program The program is coded as a series of loops that wait for a trigger event from the sound module before activating the requested function s This program is available on the book s website as SoundModTest py Just be aware that you must reset the sound module after it has been triggered because of the latched operation It is a simple matter of a one hand clap to trigger it so that the module LED turns off and the module is in a proper ready state Light Module Test Program The program to test the light module is almost identical to the sound module test program The only changes are in the three GPIO input conditional if statements that need to be changed from if GPIO input 24 False to if GPIO input 25 True These changes are required because the light module is connected to pin 25 in lieu of pin 24 and its relay contacts are normally closed instead of normally open as I mentioned earlier in this chapter To save book space I will not repeat the code listing as the changes are minor This program SoundModTest py is available from the book s website and is named LightModTest py SoundModTest py import time import RPi GPIO as GPIO GPIO setmode GPIO BCM GPIO setup 4 GPIO OUT GPIO setup l GPIO OUT I
269. rk Time Protocol NTP that the RasPi uses when connected to the Internet The NTP is implemented on the RasPi by the ntpd daemon which is configured by a file named ntp conf located in the etc directory Finally I presented a section on how to create your own NTP server based upon a GPS clock source The GPS module first shown in Chap 5 was the source used It communicated with the RasPi using the UART link Several changes had to be made to the ntp conf file to enable the NTP server function I finished the section discussion by demonstrating how to install and use the ntpdate application to test and prove that a client computer on the local network was actually using the RasPi NTP server Index Please note that index links point to page beginnings from the print edition Locations are approximate in e readers and you may need to page down one or more times after clicking a link to get to the indexed material comments 27 equal signs 37 Linux command 17 Linux command 17 A Absorbed dose radiation 176 177 Accessing GPIO pins 23 26 Acknowledgment ACK packets 89 90 Adafruit Industries 16 23 61 62 65 115 117 156 161 171 189 190 ADC see Analog to digital conversion Advanced Linux Sound Architecture ALSA 31 34 Advanced packaging tool apt 26 Aeon Labs 94 alarm py 111 112 Alpha particles radiation 175 ALSA see Advanced Linux Sound Architecture amixer app 33 Amp electron
270. rogrammable 24 25 Pi Cobbler prototype connector for 31 32 pin assignments 9 pin expansion 11 voltage levels 10 General relativity theory of 60 Global Positioning System GPS defined 57 functioning of 58 60 See also GPS project Global Specialties 48 GLONASS system 57 Gmail 109 Google 147 158 GoPro Hero3 173 GPIO connector see General Purpose Input Output connector GPIO library 25 26 GPIO pin expansion 11 GPS see Global Positioning System GPS module for NTP server 195 196 Ultimate GPS receiver 61 66 GPS project 61 71 displaying data 69 70 gpsd apps 69 71 history of 57 58 NMEA protocol 66 69 packet monitor 70 71 Ultimate GPS receiver 61 66 GPS sensor for robotic car 173 gpsd apps 69 71 gpsmon app 70 Graphics processing unit GPU 2 3 Broadcom 2835 microprocessor as 2 Broadcom VideoCore IV 3 on SoCs 1 Gray Gy 176 GSK 409 audio control switch 48 49 GUI desktop 15 16 Gy gray 176 H Half life 175 Hardware 2 13 Broadcom 2835 microprocessor GPU 2 3 connectors 4 10 current limits 10 11 digital signal voltage level 10 GPIO pin expansion 11 interrupts 1 12 Linux s treatment of 143 memory 3 4 Pi Cobbler 31 32 prototype board Pi Plate 23 24 serial protocols 12 13 See also individual projects HD high definition video 3 HDMI High Definition Multimedia Interface connector 5 6 HDMI CEC compliant devices remote control f
271. rs are available especially at the cost of this one Modifications and Expansions One modification to this project that would be useful is to attach a multi line I C LCD display to the box and thereby remove the need for the monitor You would need to make the program start automatically upon boot up but that is relatively easy to accomplish with the many great tutorials available on the web I would definitely use a larger box in order to make it easier to have access to the LiPo battery Recall the warning in the robot car chapters Never use a standard automotive or even a regular power supply to recharge the LiPo battery I just hope no one who builds this project is foolish enough to plug a wall wart into the external monitor socket in hopes of recharging the battery The program may also be extended to report radiation readings remotely Right now the program simply discards old readings but it could be easily changed to record those readings in a log file and to send them remotely to clients using a built in web service Summary This chapter began with a discussion on radioactivity and the origins of radon gas A distinction was made between activity levels and absorbed dose Examples were provided to help you understand how radiation activity and dose levels are related A brief discussion followed on how the project s Geiger counter would function along with a detailed explanation of how to interface the counter to the Ra
272. s 1014 6 millibars so the Barometer Module was reading a bit low The potentiometer mentioned in the module discussion needs to be adjusted to properly calibrate the barometric sensor Packet Sniffing I connected the 1 Wire Sniffer Module to the network to test out the functionality The sniffer was connected to a 64 bit laptop by using a USB to serial port adapter The laptop was running the Windows 7 Ultimate OS I also used the Tera Term program that I previously discussed in Chap 5 with a terminal configuration as listed in the above sniffer module discussion Figure 10 20 Humidity Module results I also decided to test the remote login capability that required me to determine my home network s public IP address The procedure detailed in Chap 8 was used I also set the home network router s port forwarding to 2121 and pointed it to the RasPi s local address Figure 10 23 is a combined screenshot that shows both the owfs opening page along with the Tera Term display of packet data that was created by this action JOWFS onlocahost4304 Bus isting OWES homepage Dalas Maxim foy Pan H Alfie 2 directory COMS 115200baud Tera Term VT i File Edit Setup Control Window Heli how Pighest bevel reeter 2 A i at aha i _ 28 clEA25030000 28 C1EA25030000 directory BH B FA 26 882728010000 26 882728010000 directory god oo soe Riri Rectal 26 827BBC000000 26 27BBC000000 daectory
273. s S wave m s scree vegetal soil 300 700 100 300 saturated shale clay 100 2500 200 800 granite 4500 5000 2500 3300 water 1450 1500 m a As you can see from the table values both waves have higher velocities as the ground composition becomes denser There will not be much of a time delay if only solid granite exists between the epicenter and the detector because the P wave travels at approximately 5000 m s or about 3 mi s Interestingly S waves do not travel through water as is indicated by the n a in the water velocity column Note that I also used average values for both P and S waves in the above discussion regarding expected TOAS Another key parameter of all seismic waves is the period of time between amplitude peaks which can be seen in Fig 6 2 Period Amplitude Time arina Seismic Wave period The inverse of a wave period is frequency and is measured in hertz Hz The average seismic frequency range is 0 5 to 5 Hz which corresponds to a period range of 2 to 0 2 seconds respectively This frequency range is quite low and has a significant impact in the design of a responsive seismic sensor which is discussed in the next section Seismic Sensor Design Figure 6 3 is a basic diagram illustrating the classic design for the garden gate seismic sensor It is so named because of the two pivot points that are in vertical alignment such as would be found in a traditional hinged garden gate A mass is suspended betwe
274. s a radon vent pipe installed in the house that vents any entrapped radon gas up and out through the roof Measuring Radioactivity The International System of Units SI unit for measuring radioactivity is the becquerel abbreviated as Bq One Bq is a very tiny amount of activity Another common unit is the curie abbreviated as Ci One Ci is many orders of magnitude greater than one Bq The exact relation is 1 Ci 3 7 x 10 Bq While the Bq and Ci are great for measuring radioactivity the real question is how much activity is dangerous to humans Table 14 1 is a comparative listing showing radon activity levels and places where these levels might be encountered Table 14 1 Radon Radioactivity Levels Remarks Radon at ocean shore 10 In open air mid continental Typical indoor domestic average 39 Ba mM 1000 Very high concentrations found in homes built on soil with high content of uraniurn ore present 10 000 Working level in a uranium mine 7000 BamM 100 000 Extremely high 1000 000 Occasionally found in unventilated areas of uranium mines Dose Absorbed dose also known as total ionizing dose TID is a measure of the energy deposited in or affecting a medium by energetic or ionizing radiation It is measured in joules per kilogram and represented in SI units by the gray Gy The legacy unit is the rad Absorbed dose now simply referred to as dose is a complex measurement because it depends on both the level
275. s if you wish to do so Another eight position DIP switch labeled Input Ground is used in connection with the input terminals Inputs should be connected as follows 1 Non powered inputs Connect one lead to the positive terminal marked The other lead is connected to the powered screw terminal marked 5v The corresponding Input Ground DIP switch should be in the on up position which is also the default position 2 Powered inputs Connect one lead to the positive terminal marked The other lead is connected to the negative terminal marked The corresponding Input Ground DIP switch should be in the off down position The input polarity is a don t care situation because the input opto isolators are bidirectional as can be seen in Fig 11 2 which shows a portion of the board s schematic You can even use low voltage AC to trigger the input to 1 Wire controller ne Gj gjar EFE e Re Muy wis ax 1 s HAE t l T i Ya a ae peel TEE GT For ESE i i r i i a MiP i X12 KEI ay EFE 8 Channel I O board input schematic The full schematic along with the board s user s manual is available from www hobby boards com Each channel relay is connected in parallel with the 1 Wire controller and the respective input for that channel This means that the relay can be activated by a network command or by an input action such as a contact closu
276. s is a very powerful but fairly simple MP3 player app that will suit our purposes quite well All we need now are some switches to select the songs and some Python code to automate it all Hardware Switch Inputs Let s take a break from the all the software discussions and focus on how to connect hardware Switches to the RasPi and how to respond when a user depresses a switch Recall from Chap 2 that all GPIO connectors can be set into either an input or output mode For the LED blinker I set a pin 18 as an output In this section I will set pin 12 as an input and leave 18 as an output The goal is to have the LED connected to the pin 18 light when a switch connected to pin 12 is pressed I will be using the 3 3 V power supply to trigger pin 12 however it is worth repeating the warning made in Chap 1 All GPIO voltage levels are 3 3 V and are not 5 V tolerant There is no overvoltage protection incorporated on the RasPi and if you inadvertently subject a GPIO pin to 5 V you will wreck your RasPi There is 5 V present on the Pi Cobbler and it is not too difficult to inadvertently connect to that power supply instead of the 3 3 V power supply Just be extra careful and recheck your connections twice before powering up Use the schematic in Fig 3 7 as a guide to connecting the LED the switch and the associated resistors that make up the test circuit Use a solderless breadboard as it readily accommodates the Pi Cobbler and other compone
277. s not contain any built in analog to digital converters ADCs while the PIC microprocessor does have this feature An external ADC chip must be used to convert the analog seismic signal to the equivalent digital format as discussed in the next section Analog to Digital Conversion The electrical signal generated by the thin film piezoelectric sensor is classified as analog because it is a continuous voltage representation of the mechanical vibrations affecting the sensor The RasPi meanwhile can process only digital signals that have just two voltage values 0 and 3 3 V Therefore an ADC process must be used to convert the seismic signal to a suitable digital representation The first step in the ADC process is to sample the analog signal in order to capture a voltage level that will be converted to a number reflecting the sampled voltage level Sample rate is the term used to indicate how often the analog signal level is captured The Nyquist rate is a very specific constraint that determines the real time sample rate This value may be expressed in samples per second sps or sampling frequency fs and is determined as follows fs 2 x fmax where fmax is the highest frequency component present within the signal In our case the seismic signal fmax is 5 Hz as discussed above therefore fs is a minimum of 10 Hz or 10 sps This is a very low value and provides a lot of time between samples to do the necessary digital signal processing
278. s that constitute this module RF Supply Voltage Fite ning System Crystal 32K bytes Flash Memory Z Wave SW API and Appicanan SW pT q l l 2 sri 256 ee pi oe eer RF Front End ee d EJ Ea EJ Ea ma mugt SPI Ctrl a Block diagram of the ZW3102N Z Wave module The ZW0301 microcontroller chip discussed above is also shown in the block diagram It has several of the standard functions that have been discussed in previous chapters including the SPI and UART serial interfaces The chip also has timers interrupts a watch dog monitor power management and brownout detection It has a four channel 12 bit ADC a pulse width modulation controller and an enhanced TRIAC control that has zero crossing detection A total of 10 GPIO lines are available but some are multiplexed or shared with other I O functions The ZW3102N module is very small Fig 7 7 is a photo of it compared to a U S 25 cent coin ZW3102N module compared to a U S 25 cent coin The module does need an external antenna and a few capacitors and inductors to complete a Z Wave device installation The software is fixed in the flash memory and is not available for examination or modification This is where this RasPi project will open up the Z Wave network so that you have a chance to experiment with various configurations and monitor network traffic But
279. s the status for an up and running service piaraspberrypi T ble File Edit Tabs Help pigraspberrypi sudo service bluetooth status Il ok Bluetooth 15 running pidraspberrypi a Bluetooth status If the status shows that it is not running enter this command sudo etc init d bluetooth start Reenter the above status command to confirm that the service is now running Enter the following command to check on the adapter s address sudo hcitool dev Figure 13 9 shows the resulting screen display of the address of the Bluetooth adapter The address is not really needed but it does check that the hcitool application was loaded with the Bluetooth package pi raspberrypi hcitool dev Devices _ he10 00 19 0E 11 16 DA Bluetooth adapter address The stage is now Set to start scanning for Bluetooth enabled devices Gather up your Wiimote and ensure that it has fresh batteries installed Enter the following command to start the scan sudo hcitool scan J You will see Scanning displayed on the console screen Simultaneously press the 1 and 2 buttons on the Wiimote to put it into the discovery mode Don t fret if it takes several tries to discover the remote The screen will show a time out if the RasPi doesn t discover the remote within 5 to 10 seconds Just try again Eventually you will be rewarded with a display as shown in Fig 13 10 pigraspberrypi hcitool scan Scannin
280. sPi We then looked at an initial test configuration with sample readings taken from both background radiation and a uranium ore sample The controlling Python program was also discussed Next came a detailed construction procedure on how to convert the test configuration into a portable instrument A demonstration of this portable Geiger counter along with its networking capability followed Finally I suggested some modifications and expansions to further improve the utility of this project Serving up Time with an RTC and NTP Introduction This project is focused on how the RasPi keeps track of time both locally and through a network As designed the RasPi contains no means to set or track time This design decision was made both to keep the cost down and to minimize the printed circuit board PCB size In addition the capability would be available in the rev B model because it has a network port that is able to connect to a public Network Time Protocol NTP server An automatic NTP connection is also built into the standard Wheezy Raspian Linux distribution designed for the RasPi The RasPi A models and B models without Internet access do not have public NTP service and thus require another means to set and track time This is where a hardware peripheral known as a real time clock RTC becomes very handy First we ll discuss the RTC and then take a comprehensive look at the NTP service Real Time Clock RTC The RTC module whi
281. scription Lighting Activate lights based upon a schedule motion sensor or remote control Dim lights per schedule Control lighting LAW time of day or ambient light conditions Shades privacy Actuate moter controllad shades per schedule room temperature and or privacy concerns Home security Activate door locks based on sensor input Initiate alarm notification based upon sensor type and location to include fire smoke water pipe Breaks sump pump operation gas and or glass breakage Audio visual Distribute A V to specific rooms per schedule Maintain a room intercon Send control signals to a multimedia system Energy management Measure energy consumption by whole house individual appliances and or HVAC Control other domestic systems including Irrigation system with moisture sensors Garage door operation Appliance operation such as a coffeemaker i Pool maintenance including preset backwash filter operation Spa operation including beginning a warm up at a preset time and or Pet feeding system There are numerous base system technologies available that have been developed over recent years to implement home automation The most popular are listed in Table 7 2 with a brief description Table 7 2 Popular Home Automation Technologies Description X 10 is the oldest of all these tec hnalogMes that use the powerline for communications It is often limited by phas
282. sed BYTE 4 You should be rewarded to see the value 127 just as you expected It s not really too hard after all Now it is time to try out a Python program to exercise the 8 Channel I O board You first need to enable all the relays by putting all the Relay Control DIP switches to the on up position Python Test Program This program cycles relays 2 and 4 every 10 seconds forever unless stopped by a keyboard interrupt that is done by pressing the control and c keys simultaneously AC I also included a statement to autoload the 1wire directory so that the command shown in step 12 does not have to be explicitly entered The file object statement will have to be modified to suit your installation since it has the unique address for my 8 Channel I O Board hard coded into it This file is named ow_eight py and is available from the book s companion website www mbhprofessional com raspi Type the following at the command line prompt sudo python ow eight py Relays 2 and 4 should click and the associated LEDs should blink on for 5 seconds then off for 5 seconds This program should be used as a starting point from which you can develop your own control program to match your desired application Remember that a given I O channel may be used either as an input or an output but not as both simultaneously This is precisely the situation with the RasPi GPIO pins where a particular pin may be set as an output for one part of an
283. set interval I created the program using only the shutter function as I believe that will be its primary use Normally time lapse photography is done outdoors without the need of a flash Also it doesn t make sense to incorporate the sound or light triggers for this function The program is quite simplified as compared to the previous programs and is listed below It is also available from the book s website as TimeLapse py OTE The interval should be entered as a decimal if you need fractions of a minute i e an interval of six seconds would be entered as 1 Operational Code The four test programs CameraControl py SoundModTest py LightModTest py and TimeLapse py should serve as templates to create whatever style operational program meets your needs It is impossible for me to create the wide variety of control programs that are possible because there are so many different environments that would need to be accommodated It is easy to add additional functionality to any of these programs by simply adding the desired input and or output triggers For instance if you needed a flash for the time lapse function you would add GPIO output 27 GPIO HIGH after the GPIO output 17 GPIO HIGH statement and do a similar add after the GPIO reset Also note that I used 27 in lieu of 21 due to the rev 2 board I used TimeLapse py LILLE t CL import RPi GPIO as GPIO GPIO setmode GPIO BCH GPIO setup 1l7 GPIO OUT max input En
284. sing a preset tag ID to be detected and an LED to be lit to show that the tag had been detected The chapter concluded with suggestions for further improvements modifications and expansions 1 Wire Weather Station Introduction As the chapter s name implies I will be showing you how to build a weather station This station will be quite basic measuring only temperature pressure and humidity but it may be easily expanded to measure other weather components such as wind speed and rainfall All the weather sensors are connected to the RasPi with a very clever interface known as 1 Wire which makes it very easy to add additional components The RasPi runs on a software package named ow s short for 1 Wire File System This open source software contains every function required to interface the RasPi with all the system components used in this project Weather Station Design Figure 10 1 is a system block diagram that shows the components or modules involved in this project 1Wire to USB Power Pressure es ire to Atte ress Raspberry Pi te eter N s adapter AA i Module uA Iire edule DAT iire Humidity Madi Wire Temperature Module Weather station block diagram The system is a point to point interconnection starting with the USB to 1 Wire adapter that is plugged into a port on a powered USB hub which in turn is connected to one of the RasPi USB ports I didn t show the hub on the diagram because it sho
285. ss mp3 MPEG 2 0 Layer III Freq ee mode Joint Stereo modext 2 BPF 209 Channels 2 copyri ght No Ort ginal Yes CRC No emphasis O Bi trate 64 kbit s Etenen value onclassical_demo_latry_bach_fugue_in_d_major_bwv 532_live_cut version Album Genre Unknown 680 5212 Time 00 17 76 02 16 15 RVA off vol 100 100 An MP3 playing Project Expansion I have shown you a basic MP3 player that can be expanded in a variety of ways to meet future requirements The display could be changed from a standard monitor to a multiple line serial liquid crystal display LCD For now it is sufficient to focus on the simpler aspects of using the RasPi for project control Another aspect that you might have wondered about is the use of a separate push button dedicated to a specific function such as skip to the next track Right now you simply press the f key to do this Incorporating a unique button capability entails a lot of software rework because the mpg123 app expects control key input from what is logically known as the stdin or standard input device i e the keyboard Changing or paralleling the input device is not a trivial change so I felt it was not suitable to include it in a beginning project book Adding MP3 songs to be played is rather easy as all you need to do is copy them into the default directory using the RasPi s USB port The program does have to be changed to reflect the new song names However the
286. t not at the same time This mode of operation is known as half duplex with data transmission being unidirectional The master initiates all communication on the bus with the slaves responding only to commands sent by the master All data is sent by serial bits in a specific timed sequence Bit timing is asynchronous with no external clock required since all timing is based on the signal transitions from the master All communication flow between the master and slaves involves three activities as shown in Fig 10 10 Receive and perform command Detect and select aatce testis 1 Wire communication flow 1 Reset lIn the first phase the bus master must issue a reset command that synchronizes all elements on the 1 Wire bus All slaves must respond to the reset or the bus will not function as desired 2 Detect and Select A specific slave device is next selected to receive commands from the master in the next phase This selection is a multipart process that is started by using a binary search algorithm to discover all the slaves currently connected on the bus Remember all 1 Wire devices have a unique serial ID permanently programmed into their onboard ROM The search algorithm reads and records all the IDs and records these values in a dynamic table that is hosted in the master The master can then use a specific ID to send commands to a slave with that ID while all other slaves ignore the command 3 Receive and Perform Comma
287. t at https www adafruit com products 801 It comes as a kit of parts however a fully assembled Pi Plate mounted on a RasPi is shown in Fig 2 1 E a fe fy a A A r 20000 5 G O G G D0 0 61 afafa i AS i i xhi 9 oe a Pi Plate mounted on Raspberry Pi The Pi Plate attaches to the 26 pin GPIO connector as you can see in the figure All the active connections are brought out to the top of the Pi Plate both to 0 1 inch on center female header strips as well as to 3 5 mm screw clamp connectors This makes for a very easy access to the GPIO pins Please note that the pins on the Pi Plate are marked with both RasPi and BMC designations which can be confusing Please use Table 1 2 from Chap 1 to cross reference all the designations and ensure that you know what connection you are making The Pi Plate does not provide any electrical buffers whatsoever so be extremely careful and ensure that you do not accidently apply 5 V to any RasPi pin Soldering I thought this would be an appropriate time to discuss soldering since you will need to assemble the Pi Plate The assembly operation is very straightforward and Adafruit provides a step by step illustrated assembly guide at learn adafruit com adafruit prototyping pi plate I have also included a photo of my trusty soldering station in Fig 2 2 l TEEREFEN aa a Trusty soldering station It s not the prettiest or the snazziest station ava
288. t it may be related to an issue with the hub power supply Protected Security Zone Figure 8 3 is an actual image capture from the webcam It shows the protected zone which in this case is the exit to my home s back deck I will discuss how images may be captured later in the software section It is now important to show the intended protection zone because it greatly affects how the laser trip assembly will be deployed as part of the overall security scheme ifs tev sae 25 Pa 85 0AA Protected Zone Laser Trip Assembly I reused the same laser trip device that I used in the camera controller project Figure 8 4 shows this assembly mounted on a single piece of Lexan The only difference in this trip setup is that I used a mirror to reflect the beam back to the detector s phototransistor when an object interrupts the beam between the laser pointer and the detector in the protected zone The height at which you mount the laser and the detector board is your choice but I found that about four inches above the floor worked quite nicely The total path length of the laser beam was about 14 feet which was not an issue with this system Laser trip assembly Figure 8 5 shows the laser trip assembly operating in the evening This photo was taken with a flash to clearly show all the components including the mirror to the right Operational laser trip assembly I took another photo but this time in almost total darkn
289. t of the same content might take about 2 MBs a 15 1 compression ratio Of course the trade off is the quality of the music reproduction Most people find the MP3 format acceptable especially if reproduced on a device such as a smartphone or tablet computer Furthermore the RasPi audio reproduction is not the finest as previously discussed Playing a WAV File It is quite easy to play a WAV file if you use another app contained in the alsa utils package This app is named aplay and all you need do is call the app along with the name of the WAV file to be played I have placed public domain WAV and MP3 files named class wav and class mp3 onto this book s website www mbhprofessional com raspi Please download them into the pi directory You will use class mp3 in the next section Now open a terminal window and type sudo aplay class wav J Ensure that your powered speaker is attached to the analog audio jack and that the jack is selected per the amixer command line shown on page 33 You should now be hearing the beautiful sounds of a Bach fugue The musical score lasts for about 2 5 minutes It can be stopped at any time by pressing Ac The MP3 version of the same music file is approximately 1 2 MB as compared to the WAV file that is over 25 MB in size You will have an opportunity to play the MP3 version in the next section after I introduce you to a software MP3 player That should give you an excellent opportunity to compare the sound qu
290. t the Motion software was created years before the RasPi came on the scene and probably was based on using much higher clock speed PCs The key feature that is used from the Motion package is the built in web server This server receives the video stream from the webcam and sends it off in TCP IP format over a predefined port All you need to remotely view the webcam video is a browser pointed to the RasPi IP address and port number nothing more This feature makes the viewing exercise extremely simple But there is more Motion provides for using more than one webcam You can set up multiple webcams each with its Own port number so that it can monitor multiple locations throughout the home Each webcam video feed is handled by what is known as a thread within the Motion software I saw provisions for four threads in the Motion configuration file from which I presume four webcams could be handled However I seriously wonder if the RasPi has the processing power to manage four simultaneous video feeds In any case this project is only concerned with one feed that I know works very well Motion Features Motion has a substantial number of features that enable it to accomplish an amazing number of functions The user manual is on line at http www lavrsen dk foswiki bin view Motion WebHome and it is over 100 pages in length It would take a complete book to document all the features However the configuration file itself contains many self documentin
291. tement checks what immediately follows it and if the expression evaluates to a logical True will loop or repeat all statements below the conditional that are indented at least four spaces The logical value of True that follows the while statement thus causes the looping to continue forever Pausing the program is a result of calling or invoking the sleep function a part of the time library The actual call is the statement time sleep 5 This is not the first time you have seen this call type I used it several times in the original program i e GPIO setup 18 GPIO OUT The period in the statements represents a special operator known as the member of operator Restating the time sleep 5 call with this operator translates to call the sleep function that is a member of the time library with an argument of 5 Don t worry if this discussion is somewhat confusing all I am trying to do is to gently introduce you to the concept of object oriented programming something that I will pursue in later chapters Now back to the Blinker program Make the modifications to the original program and then run it You should be rewarded with a blinking LED for all your efforts Congratulations Show all your family and friends Summary I started this chapter with a discussion on the Pi Plate prototype plate that serves as an excellent project experimental platform Next I briefly mentioned some good soldering tips that have helped me over
292. ter maximum time minutes interval input Enter interval time minutes need a variable to keep track of total elapsed time elapsed 0 keep looping until elapsed time exceeds max time while elapsed lt max the sleep function argument is in seconds so we must multiply by 60 time sleep 60 interval Shutter only operation GPIO output 17 GPIO HIGH time sleep 2 GPIO output 17 GPIO LOW elapsed elapsed interval print Al done Summary This chapter started with a project requirements list that also served as a list of goals that you needed to accomplish Requirements drive all projects and you should spend a great deal of time analyzing and determining what the essential requirements or needs are before proceeding to any design work I next discussed how a DSLR camera with an electronic flash could be remotely controlled I elected to use optoisolators where appropriate to lessen any chance of damaging voltages being introduced into the RasPi interface circuits I also mentioned that you could use a non DSLR camera set to a long exposure with the electronic flash function to capture stop action events In a detailed discussion regarding optoisolators I explained that they are very handy for completing interface circuits that incorporate a high level of voltage isolation I also provided a triggering circuit for those brave souls with a high voltage electronic flash I went through my buil
293. terested in monitoring the 1 Wire network activity while the ow_eight py program was running Figure 11 9 is a screenshot from my laptop running the Tera Term program that I discussed in Chap 10 The laptop was connected to the Sniffer Module using a USB to serial adapter and cable BE BE BH C3 aa pa BA c3 Ba ga C3 se33e see Ma a DD a a aT iR a wo GA G G a a er ta r r T LLLE IMMOMONMONOAAAAAAeN mia Paka Net i Gee Cee Seda asa Matt atl Natl i n SS AA BA BA Be Be A Be A BB Be Be Be E EEE 8880 d 88 BB C3 Ba BH c3 Ba Bh Co Ge BH C3 d Be HH oS 1 pa BH C3 68 68 88 Ca Be BA Be CF SSSESSSSSES SESSSSSSSSSS SSSSSESSSESE FSESSESSSES 288225322333 223222322333 228222322333 228228222 GET GT GN G A a ara er GA EAI G r Re T Sniffer packet activity The figure shows the repeated activity of switching the selected channels on and off which was expected What was not expected is the periodic polling of the 1 Wire network taking place every two minutes That may be deduced by observing the shorter packets interspersed among the repeated control packets initiated by the ow_eight program The two minute interval was calculated by knowing that each repeat packet was issued every 10 seconds While not critical for program development the sniffer is a very handy tool that helps you understand what is occurring within the 1 Wire network Android Remote Control In this se
294. the RasPi and a laptop computer Finally I will show you how to connect a very capable GPS receiver to the RasPi and subsequently use a Series of applications to decode and display target position and velocity TPV information on the RasPi screen Brief GPS History The GPS system was initially deployed in the early 1970s by the U S Department of Defense DoD to provide military users with precise location and time synchronization services Civilian users could also access the system however the services offered to the public were purposely degraded to avoid national security risks The DoD was concerned that the system might help potential enemies in their activities This intentional degradation was lifted by order of President Reagan in 1983 to allow civilian use of full and more accurate GPS services In 2000 an even higher level of accuracy without any degradation was implemented for all users The current GPS system has 32 satellites in high orbits over the earth A representative diagram of the satellite constellation is shown in Fig 5 1 The satellite orbits have been carefully designed to allow for a minimum of six satellites to be in the instantaneous field of view of a GPS user located anywhere on the surface of the earth A minimum of four satellites must be viewed in order to obtain a location fix as you will learn in The Basics of How a GPS Functions section d 4 gt N Ei s 2 ka foal Em
295. the following at a terminal command prompt cd libnfc 1 6 0 rel J sudo nano libnfc buses uart posix c l You need to add tty AMA to the following line in the file char serial ports device radix CtyUSB ttys NULL Figure 9 9 shows the file content after the edit has been done char serial ports device radix tty SLAB USBtoUART NULL elif defined FreeBSD defined OpenBSD J char serial ports device radix cuau cuau NULL elif defined _ linux char serial_ports_device radix ttyUSB ttyS ttyAMA NULL IA The uart_posix c source code edit Ensure that you use double quotes around ttyAMA or the logical device will not be recognized The strange fact is that the file will compile OK but the device ttyAMA will never be recognized and the board will never connect A frustrating experience to say the least 7 libnfc must next be configured to operate with the RasPi and the breakout board Type the following at a terminal command prompt sudo configure with drivers pn532 uart enable serial autoprobe Figure 9 10 shows the end results of the configure operation Just confirm that the line pPN532 uart Yes appears as the last line configure creating config status creating config status creating config status creating config status creating config status creating config status creating config status creating c
296. the response of the human ear This means that the filters are narrower at lower frequencies and become wider as the frequency increases Applying white noise to this filter bank would result in an upward or positive sloped response White noise is prefiltered or predistorted if you may such that the conditioned noise signal that comes out of the one third octave filters is a flat response Any deviation from a flat response would therefore be caused by the system under test not the applied noise signal This preconditioned noise is called pink noise Figure 3 5 is a screenshot of an acoustical analysis program measuring the analog audio output producing pink noise from the speaker test app E SpectraPiurs sc Sound Card Edition bo Ean Mode View Opiom Unite Conk License Window Help vi E ag fico Peak Hsia iadur LasdGertgaraton o i BEE al HELE A mAT J Ja eS SSGI2Zelpes Fa TL rate eo ric LLENE Raspberry Pi one third octave acoustic analysis The audio output is far from being flat as you can see from the irregular curve The good news is the magnitude of these curves is not so severe as to appreciably distort the audio Audio purists would probably use a multiband equalizer to compensate for these response deviations Audio File Formats A brief discussion of the audio file formats will help you understand the pros and cons of using different formats when creating audio apps There are three broa
297. the years Next there was the discussion regarding the GPIO library that may have overwhelmed some of you a bit but that was necessary in order to set the stage for the LED project The good news is that we will simply use the GPIO library from this point on in various projects That s software reuse at its best The last sections of this chapter focused on a real world project of first turning on an LED and then blinking that same LED Now we move on to bigger better and more interesting projects And yes you will still learn and gather a good education as you progress through the remaining projects MP3 Player Project In this project I will show you how to create a fairly simple yet fully functional MP3 audio player I will also describe how to use the GPIO pins as inputs which will allow the player to use some hardware push button switches to select the MP3 songs it will play We will also explore the Advanced Linux Sound Architecture ALSA software package that drives the Linux sound production and provides some utilities essential to helping us complete this project Prototype Connector Let s first focus on a piece of hardware that I will use to connect the project hardware switches with the RasPi s GPIO pins This prototype aid is different from the Pi Plate introduced in the last chapter Called the Pi Cobbler it is shown in Fig 3 1 without the interface ribbon connector in order to show all the pins clearly ee a
298. threshold default on noise tune on Despeckle motion image using rode or djillate or l jabel Default not defined Recommended value is EedDl Any combination and number of of E e d and D is Valid ljabeling must only be used once and the 1 must be the last letter Comment out to disable despeckle EedDl Detect motion in predefined areas 1 9 Areas are numbered like that 1 2 3 A script on_area detected is started immediately when motion is 45 6 detected in one of the given areas but only once during an event 7 8 9 One or more areas can be specified with this option Default not defined area detect value PGM file to use as a sensitivity mask Full path name to iDefault not defined mask file value Dynamically create a mask file during operation default 0 Adjust speed of mask changes from 0 off to 10 fast smart mask speed 0 Ignore sudden massive light intensity changes given as a percentage of the picture hh h w area that changed intensity Valid range 0 100 default 0 disabled CHANGED lightswitch 0 Picture frames must contain motion at least the specified number of frames in a row before they are detected as true motion At the default of 1 all motion is detected Valid range 1 to thousands recommended 1 5 CHANGED minimum motion frames 5 Specifies the number of pre captured buffered pictures from before motion was detected that will
299. ting the solderless breadboard The solderless breadboard mounts to the Lexan board with an adhesive backing You should carefully align the breadboard to the Lexan plate before pressing it on It is just about impossible to remove the breadboard once it is attached The remaining mechanical piece is the Lexan support plate for the portable monitor if you should so choose to install it It is a fairly simple piece to install with the only tricky part being cutting clearance holes for the RasPi USB ports and the additional LiPo battery that is used to power the monitor Figure 12 17 is a dimensioned sketch of the Lexan support that I used Your support piece will likely vary a little from mine since your RasPi placement may also vary from my installation bent at 45 degrees Senay Lexan monitor support piece The support is made out of one 2 5 x 8 inch Lexan sheet bent at a 45 angle in the middle of the long dimension I used a hot air gun to soften the Lexan so that it could be easily shaped The support is attached to the chassis front with three 0 5 inch 4 40 screws and nuts as shown in Fig 12 18 Monitor support plate attachment This last step completes the robot car mechanical construction phase The electrical connections will be shown in Chap 13 You may however have an immediate issue if you have only one RasPi You need to program the RasPi to run the car which is very hard to do when it is installed in the c
300. tion of precision Geoid Altitude correction due to non spheroidal earth curvature The dilution of precision DOP numbers are relative indicators of GPS accuracy due to the Satellite receiver configuration Lower numbers are better as shown in Table 5 3 Table 5 3 Meaning of DOP Numbers Remarks Ideal best accuracy Moderate accuracy Poor may be as much as 300 meters in error ina position report Summary The chapter began with a brief history of the GPS system followed by a tutorial example that explained the basic underlying principles governing the system Next I discussed the Ultimate GPS receiver focusing on its excellent receiver characteristics as well as the easy serial communication link I discussed how to setup and test a serial console link using a USB to serial TTL cable as well as serial terminal control programs for both a Windows laptop and the RasPi The serial comm link between the GPS receiver and the RasPi was setup and a series of communication tests were demonstrated to verify the proper operation of all system components The NMEA 0183 protocol was thoroughly examined to illustrate the rich set of messages that are created by the GPS receiver This project uses only a small subset of the data but you should be aware of what is potentially available A parsed GPS message was also shown along with a brief explanation of how to interpret latitude and longitude data The remaining port
301. tions to trigger an electronic flash with your point and shoot camera set to a long exposure in a darkened room The flash will illuminate the subject sufficiently to enable you to do stop action photography You will have to experiment with different exposure times to get the desired result but you do have the basic equipment to be successful DSLR owners will learn how to activate the focus and shutter controls in the optoisolator section after reading the electronic flash discussions which are next Electronic Flash The electronic flash or strobe is the unit that produces a very bright light for a very brief instant in time It is used to sufficiently illuminate a photographic subject where ambient light is too low in intensity or not suitable for the subject The electronic flash replaced the one time use flash bulb many years ago and is now almost universally used in modern photography Most digital cameras from one steps to DSLRs have a built in flash unit that automatically activates based upon the lighting conditions that the camera sensor detects While this arrangement may suit most users for this project we cannot make use of the built in unit but instead must rely on an external electronic flash that can be remotely triggered Figure 4 7 shows the Canon 420EX electronic flash that I will use in this project It is several years old and has been replaced by the model 430EX For our purposes however the differences between the mod
302. to be made programmable in order to blink the LED Being made programmable means that the pins are set to either sense an input voltage or set an output voltage The pins are accessed by using a high level name such as pin 18 that you can readily identify in this case GPIO pin number 18 We must use a software library that contains the required high level abstractions and hardware associations to enable us to control the GPIO pins with a Python program This library is named Rpi GPIO 0 4 1a tar gz and is readily available as a Linux archived file from http code google com p raspberry gpio python downloads list Figure 2 4 shows this website raspberry gpio python Padan bray E PA koeru oo pee A Pragect Home Cavesinads Wiki lames Sao Sekar Curd Stemi T Bi ik i TT Flare F Sarema Label Listed Hele r rer Ck card I a5 Le pee ae ee ipen pia br Pree J Sep H fe The KB E4 i Pree ee i d e h Ape pes pga oe Pha F Sake 7 See 2 iF FOR ola r LEl ED ir ger Hera 0 4 ts Sep Senge 3d ee to Gir i Jal GPIO library download website The archived file must be downloaded extracted and stored in an appropriate directory I would suggest creating a new directory named Python located in the pi parent directory Open an LXDE terminal window and type the following commands in the terminal window pi raspberrypi pi raspberrypi S pwd displays the current directory home pi pi raspberrypi S ls J list the
303. tor functions Table 8 1 Motion Configuration File Changes Section Change From Change To Daemon daemon off daemon on Live Webcam Server webcam port 0 webcam port 8081 Live Webcam Server webcam localhost on webcam localhost off HTTP Based Control control port 0 control port 8080 HTTP Based Control control localhost on control localhost off Again start a nano editor session as follows sudo nano etc motion motion conf Save the changes and exit the nano editor Now you must start the Motion server which is done by typing sudo service motion start One nice feature of having the Motion web server running as a daemon is that it is automatically Started each time you boot the RasPi You may also stop or restart the service by typing sudo service motion stop sudo service motion restart l That s it for the changes to make in the configuration file I do want to briefly discuss why these changes were made The change from daemon off to daemon on is obvious it was needed to run Motion as a daemon The next change to make the port number 8081 is a bit historical since the Motion web service has traditionally been assigned to this port It is not a required port number and you can easily change it to any number that you desire as long as it is greater than 1024 and less than 65535 This range avoids the well known ports and goes to the maximum possible port number My recommendation is to leave it at 8081
304. trolled locking mechanism to unlock when an authorized tag is detected In most cases there will be more than one authorized tag holder who will need access to a protected area or building This will require a list of authorized tag IDs to be checked because each tag contains a unique ID Python accommodates several ways to do this function Tag IDs could even be placed in a database that the program could query This is actually the way such an access function is accomplished in real world situations that use commercial systems Such systems are also very expensive extract_data py import time import og import RPi GPIO as GPIO GPIO setwarnings False GPIO setmode GPIO BCM GPIO setup 23 GPIO OUT nfc id None while nfc id None nic id os system sudo libnfc libnfc 1 6 0 rel examples nfc poll gt nfc data txt inFile open nfc_data txt lines inFile readlines inFile close buffer j for line in lines line content line split if not line content 0 UID pass else buffer append line content print buffer str buftfer 0 id str str 2 str 3 str 4 str 5 print id str if id str bd0eb923 printi match GPIO output 23 GPIO HIGH time sleep 10 GPIO cutput 23 GPIO LOW else print no match Another expansion might be to have the program send a preset e mail when a specific tag is detected The e mail program shown in Chap 8 could easily be incorp
305. u would need to explore the open Z Wave software to see how a software trigger could be created based upon a state change on one of the network nodes I showed a window sensor being activated in Chap 7 but that state change was only shown in a GUI I am certain that the underlying logical variable representing that state could be polled and the result sent to the alarm program alarm py import subprocess import smtplib import socket from email mime text import MIMEText import datetime import og import RPi GPIO as GPIO import time def send alarmi put the destination e mail address here to youremail isp com put your user gmail account here gmail user user gmail com Fput your gmail password here gmail password password everything is verbatim from this line on down smtpserver smtplib SMTP smtp gmail com 587 emtpserver ehlea emt pserver starttls emt pserver ehlo smtpserver login gmail user gmail password today datetime date today arg lip route list proc subprocess Popen arg shell True stdout subprocess PIPE Aata nrac cammnicated i split data data 0 split local ip split_data split_data index sre 1 public ip os system wget http ipecho net plain O q gt test txt echo public ip open test txt r read msg content Alarm detected Public ip is s 8081 local ip is ts public_ip local ip msg MIMEText
306. uired the assistance of an appropriate professional should be sought TERMS OF USE This is a copyrighted work and McGraw Hill Education and its licensors reserve all rights in and to the work Use of this work is subject to these terms Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work you may not decompile disassemble reverse engineer reproduce modify create derivative works based upon transmit distribute disseminate sell publish or sublicense the work or any part of it without McGraw Hill Education s prior consent You may use the work for your own noncommercial and personal use any other use of the work is strictly prohibited Your right to use the work may be terminated if you fail to comply with these terms THE WORK IS PROVIDED AS IS McGRAW HILL EDUCATION AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE ACCURACY ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE AND EXPRESSLY DISCLAIM ANY WARRANTY EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE McGraw Hill Education and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free Neither McGraw Hill Educat
307. uite figured out what to do when an object such as my cat or dog decides to sleep in the path of the laser beam I could set a maximum number of e mails to be sent which would be the sensible thing to do or I could enable the RasPi to sound a loud buzzer which might be the fun thing to do I will leave that modification up to you Additional Sensors I am sure you realize that additional sensors may be incorporated into this minimal security system The software at present is designed to work with wired sensors so it would be trivial to add additional door and window sensors All you need to do is to wire them to selected GPIO pins and simply add the activation checks in the main forever loop As mentioned before up to four webcams can be managed by the Motion software However it is doubtful that the RasPi can handle four webcams I would suggest that the send_alarm module be modified to take an argument indicating which sensor has been activated The send_alarm module could use this argument to modify the e mail to indicate which protected area has been tripped for example showing that a living room window has been opened You could also incorporate the sound sensor from the camera control project to indicate Suspicious sounds such as glass breaking There really are many ways to easily expand this security system with little expense You can even include wireless sensors for readers who have built the Z Wave project in Chap 7 Yo
308. uld be considered as part of the basic RasPi configuration All the modules and the USB adapter are available in the United States from www hobby boards com Similar modules are available from www sheepwalkelectronics co uk for international readers These items are listed in Table 10 1 Table 10 1 Listing of Weather Station Modules and Adapters Module Name Hobby Board Sheepwalk Electronics Remarks USB to 1 Wire Adapter DS9490R P D59490 Temperature T4 R1 A SWE Barometer BI R1 4 Measures pressure Hurnicity H3 R1 A SWE3 Power Injector PI2 R1 4 SWES 1 Wire Sniffer SNI R A Not required for weather station but helpful to debug and program The first element shown connected to the RasPi in the system diagram is an adapter in the physical form of a USB dongle as shown in Fig 10 2 It has a USB connector at one end and a 1 Wire connector at the opposite side USB to 1 Wire dongle The 1 Wire socket shown in the figure is a standard RJ12 six pin telephone style connector A special RJ12 to RJ45 cable is required to go from the dongle to the first 1 Wire module which in this case is the Power Injector Module This special cable is shown in Fig 10 3 and is typically provided when you purchase the 1 Wire to USB dongle RJ12 to RJ45 cable Most 1 Wire modules use the standard eight pin RJ45 connection standard which is exactly the Same as a regular Ethernet patch cable In fact I used normal Ethernet patch ca
309. ures 55 to 125 C Measures 10 to 85 C with a 0 5 C accuracy Has its own 64 bit ID Powered from 3 to 5 5 V may be parasitically powered Converts 12 bits within 750 ms Figure 10 12 shows the DS18B20 block diagram There is an awful lot crammed into a TO92 case noses Y TEMPERATURE SENSOR 64 BIT ROM INTERNAL Von aed ALARM HIGH TRIGGER Ti ii REGISTER EEPROM GND 1 Wire PORT SCRATCHPAD ALARM LOW TRIGGER T1 REGISTER EEPROM CONFIGURATION REGISTER EEPROM BIT CRC GENERATOR DS18B20 block diagram Powering the 1 Wire Bus There are three ways that the 1 Wire bus can be powered These are 1 External power supply 2 Parasitic supply using a capacitor and diode 3 Powering the data line using a strong pull up metal oxide semiconductor field effect transistor MOSFET The first way using an external supply is the one we used in this project by incorporating the Power Injector Module You were also shown how to connect a local power supply to a specific module using a terminal board located on the PCB It should be noted that the Power Injector Module is wired to provide power to all bus devices while a local power supply powers only the device to which it is wired The second way is called parasitic because the module power is obtained by charging a capacitor from the 1 Wire data line while it is idling at a 5 V level Figure 10 13 shows the simple charging circuit 1 Wire
310. ury These readings are sent to chip U1 a Maxim DS2438A the same chip that was used in the Humidity Module The U1 chip is not visible in this figure because it is surface mounted to the backside of the board The twice mentioned terminal board is also visible A potentiometer is located on the upper right side to precisely calibrate the module to a known air pressure I will discuss the Packet Sniffer Module in a later section Next I will discuss the 1 Wire protocol which is the base technology for this project 1 Wire Protocol The 1 Wire protocol is the registered trademark name given to a digital serial communications protocol by Dallas Semiconductor the company that first introduced it in the early 1990s However the trademark does not affect any software implementing the protocol Dallas Semiconductor was merged with Maxim years later but still manufactures 1 Wire products along with many other components This is the reason why 1 Wire products have a DS prefix 1 Wire uses a master slave multi drop architecture with an open drain connection with pull ups to 5 V This means that devices may be added or removed without any change to the hardware configuration being specified All devices are discovered through software techniques Also all 1 Wire devices have a unique 64 bit identification number that is encoded in a ROM by the manufacturer The master and all slaves act as transceivers meaning that they can both transmit and receive bu
311. ussed in the Android section is available using a browser Using a browser in this manner makes configuring GPIO pins very easy without the need to create any Python code to test basic I O for a hardware project I highly recommend that you consider using this approach to speed up your project development 3 3V C E 5 0V nei sva E 5 0V I2C1 SCL C 6 GROUND GPIO 4 8 UARTO TX GROUND 9 UE UARTO RX GPIO 17 TA GPIO 18 OUT GPIO 27 13 TE GROUND GPIO 22 G GPIO 23 OUT 33v KIA TE croz Melki GPIO 10 RUN GROUND GPIO 9 EN EVE GPIO 25 OUT GPIO 11 EE J crios FN GROUND a GPIO7 ALTO WebIOPi web page using a browser Internet Access You will need your router s public IP address to be able to remotely control the RasPi s GPIO pins Determining this address has already been discussed several times in previous chapters You will also need to enable port forwarding on the router so that any browser or smartphone using port 8000 will automatically be forwarded to the RasPi s local IP address I had no problem in setting this up on the Android smartphone and on a remote computer s browser The only issue is to remember which GPIO pins are connected to which devices It would definitely be a problem if you wanted to turn on your home s front outdoor light but accidently started the lawn irrigation system The WebIOPi GUI may be customized to use different widgets and labels to suit your particular application It does requi
312. ust Aave the i ghtscontrol server running befor E Acre ssing the web interface On the first use go to devices then Isport To kill the Lightscontrol server type ki llor io Start the basic server type basic and go to http openzvave local basic t contral your lights BOTH oOp n Eyvave se cannot be running at the same time AOT Stay Funning The coesmane LLOZK will also kill the basic server I normally wait Fa fore few second Ween ach start stop and a fev seconds be h 4 load ng che BE The command webroot will take you to the nginx root directory To edit this message or make it go away sudo nano etc motd PTHPSEP SHEEP ECE PETE TREE EAE EEE AEE TEER eae Lmst login Wed Dee 12 23 31 37 012 piflopenzwave lightscontrol 1 223 pifopenzvave gt noOhup ignoring input and redirecting stderr to stdout pifopenzwave F lightscontrol web server preamble screenshot Now you should minimize the terminal control window keeping in mind that there is still an underlying active SSH connection that will allow you to input commands to the RasPi We are going to need putty after experimenting with the first web server Next open a browser and enter this for the URL http openzwave local This should take you to the initial lightscontrol server page as shown in Fig 7 14 Lights Control Control Scenes Scheduler Seflings Admin Home s Control
313. uteCom 65 67 cwlid package 169 D DAC digital to analog converter 77 Dallas Semiconductor 129 187 Data analysis earthquake detector project 82 83 Data storage 81 82 Dawson Michael 17 DC direct current 5 DHCP Dynamic Host Configuration Protocol 8 Differential mode ADC 77 Digital repeater digipeater 88 Digital signal voltage level 10 Digital Single Lens Reflex DSLR shutter 44 45 Digital Video Interface DVI converting from HDMI to 6 Digital to analog converter DAC 77 Dilution of precision DOP numbers 71 DIP dual in line package 47 Direct current DC 5 Display Serial Interface DSI connector 9 DoD U S Department of Defense 57 Donationware 147 DOP dilution of precision numbers 71 Downey Allen 17 Downloading GPIO library 25 26 DRAM dynamic random access memory 3 DrGPIO app 147 150 Drive motors robotic car project 156 160 DS18B20 chip 128 130 131 DS1307 chip 187 189 DS2438A chip 128 130 DSI Display Serial Interface connector 9 DSLR Digital Single Lens Reflex shutter 44 45 Dual in line package DIP 47 DVI Digital Video Interface converting from HDMI to 6 Dynamic Host Configuration Protocol DHCP 8 Dynamic random access memory DRAM 3 E Earthquake detector project 73 85 analog to digital conversion for 76 77 connecting testing MCP3008 79 82 operational system 83 84 seismic data analysis 82 83 seismi
314. vices in earthquake detector project 78 in weather station project 129 in Z Wave networks 91 sleep seconds function 28 29 Smartphones 115 147 150 Sniffers local and remote logic controller project 147 1 Wire weather station project 132 135 137 SoC System on a Chip technology 1 2 SoF Start of Frame byte 89 Software 13 20 apt get command for 26 IDLE application 18 20 initial startup 13 15 Linux fundamentals 16 17 preparing SD card 15 16 Python 17 20 reuse of 18 updates for 26 See also individual projects Soldering 23 24 sony 6 SoundModTest py 54 Speaker 31 34 Speaker test app 33 Special relativity theory of 60 SPI see Serial Peripheral Interface SPI serial protocol 12 SS synchronous serial data link 78 SSH see Secure Shell SSI Synchronous Serial Interface 12 See also Serial Peripheral Interface SPI Start of Frame SoF byte 89 State values 169 Static controllers 91 92 Static Update Controller SUC 92 stdin standard input device 41 Stereo speaker 31 34 Stop action pictures 43 44 Strings storing data as 81 82 Strobe 45 47 SUC Static Update Controller 92 SUC ID Server SIS 92 Successive approximation register SAR 77 sudo command 16 Super user 16 Sv sievert 177 Swarm behavior for robotic car 173 S waves earthquakes 73 74 Switches 37 38 48 49 Synchronous serial SS data link 78 Synchronous Serial Interface
315. volved however at this stage in the book you should be fairly comfortable dealing with such activities Now we Il look at the 1 Wire external control board 1 Wire External Control Board The 1 Wire board I m using is the Hobby Boards 8 Channel I O v2 0 board as shown in Fig 11 1 It is part of the series 29 family and is fully compliant with the 1 Wire protocol fi a at F amp a 9 o E S i qil eij sih sH SA H ee FET aza GAE Aa ADG BDG ban ata Hobby Boards 8 Channel I O v2 0 board Significant board specifications are listed in Table 11 1 Table 11 1 8 Channel I O Board Specifications Component Description Contradler Dallas Semiconductor D52408 1 Wire chip Connections Dual R45 connectors for the 1 Wire network AIO connections to the board use screw terminals 2 1 mm barrel type power connector 5 DE screw connections available for external use 100 mA max Outputs 8 SPOT relays with LED indicators Max rating 25 A 250 AC Each relay has Common crn Normally Open NO and Normally Closed NC terminals connected to its own screw terminal 8 opte isolated inputs Each input has the positive negative and 5 Y DE 5v5 terminal connected to its own screw terminal Power Required 2o0 ma is Y DC Provided by 15 Y DC wall wart supply jumper option to power the Wire network An eight position DIP switch labeled Relay Control is on the board It can disable any of the relay
316. were demonstrated as well as the ability to sense motion in a room Home Security Controller Introduction For this chapter s project you learn how to connect a webcam to the RasPi so that a homeowner can view a Selected home area when an intrusion signal is detected by the RasPi A laser trip device serves as the intrusion sensor When the RasPi detects an intrusion signal the RasPi will send an e mail notification to a preset e mail address to notify the homeowner that the laser has tripped thus indicating that a possible intruder is on the premises The homeowner will then open a browser go to a website where the webcam video is available and examine the ongoing activity The homeowner could then determine whether to call the police or simply to disregard the alarm if it had been innocuously tripped Motion is the name of the software package installed on the RasPi It is a very sophisticated suite of vision applications that provides the project s webcam monitoring function Many other features are also available and will be discussed in the software section Webcam Selection The webcam used in this project is a fairly new Logitech C920 as shown in Fig 8 1 Q g Logitech C920 webcam The webcam has a high definition camera capable of producing excellent videos however the software used with it in this project will limit its performance With that in mind note that many different webcams may be used In addition
317. windows to execute commands as most of the time I will have the GUI desktop running There are two flavors of terminal windows available the Lightweight X11 Desktop Environment LXDE for normal users and a root level terminal The only effective difference between the terminal windows is that I have to type sudo in the LXDE terminal while this is not required in the root terminal since it already operates at that level You will also need to create some Python code to program the RasPi I use a very simple but effective text editor named nano All you need to run the editor is to open a terminal window and type nano test_my_project py if you wanted to either create or open an existing file named test_my_project py The editor program has all the important commands listed at the bottom of the editor window For example to save the editor buffer you have to press and hold the control key while simultaneously pressing the o key This is shown as o on the help screen A few of the very common Linux commands are shown in Table 1 9 It might be helpful to refer to this table when you are trying to understand why I entered a particular command as you progress through the projects Table 1 9 Commonly Used Linux Commands Linux Command Description Refers to current directory Refers to parent directory cat filename Print out the text in filename cd Change directory cd Change to parent directory E List Current directory contents mkdir di
318. y named simultaneous appeared in the listing This new entry was created by owfs and FUSE after the programs recognized that the new module was part of the Temperature Module virtual file properties This dynamic recognition and autoconfiguration is a very powerful concept which contributes to making 1 Wire networks so easy to install and use Test Sequences for the 8 Channel I O Board What follows are some quick and simple terminal commands to test the basic board functions Figure 11 7 shows the test setup using a laptop that is controlling the RasPi with an SSH session i e running the Pi headless 1 Wire test setup If you haven t yet done it mount the 1wire directory using the command from step 12 shown above Remember attempting to remount after doing it once will result in a Permission Denied error To clear the error all you have to do is reboot the RasPi and reissue the mount command Next you need to change directories to be in the 8 Channel IO board directory For my system the command entered was ed mnt lwire 29 B82E08000000 WH Your command will be slightly different because the board s unique serial number and family name make up the directory name Simply cd into mnt 1wire and then ls if you haven t previously recorded the board s directory name Testing the Outputs Once you are Safely in the device directory do another 1s to see all the different files owfs and FUSE h

Raspberry Pi Projects for the Evil Genius (2014)- Donald

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