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1. 2 ADVANCED OPERATION Go prowiththe cameramodete amp James Hughes Guest Writer the resolution of the resultant captures either stills or video But you can also change the quality of the JPG stills using q qualtty and the quality of the H264 encoding using b bitrate Both these formats use what is known as lossy compression that is they throw away detail in order to compress the files The more detail that is thrown away so the smaller the file It s simply a tradeoff between quality and file size Some examples raspistill w 640 h 480 q 10 o smallpic jpg raspivid w 640 h 480 b 500000 o smallvid h264 The bitrate option is measured in bits per second So in the example above 500000 is 0 5Mbits s This is quite a low bitrate for 1080p video but good enough for the small image size requested here Full HD recording the default is supported which is 1920x1080 at 30 frames per second abbreviated to 1080p30 This requires a higher bitrate to avoid odd compression artefacts It is worth trying out various bitrates just to see how it affects the image quality It is sometimes very surprising how low you can go before the video becomes unwatchable C raspivid t 10000 b 1000000 o highcompression h264 In fact the raspistill application allows us to save in 4 different file formats although JPG is by far the fastest and most common The other formats
2. You can observe the current variables and their values in the Scope Viewer window For example debug the binary tree program Examples gt fractal gt binary tree al and set a breakpoint on line 12 Observe the value of 1t and size in the Scope Viewer with each iteration log scope viewer ed ES Ae ee ara a rE Documentation To learn a language and how to program the most important thing is documentation and sharing experiences The web site contains a complete language reference section and a continuously updated tutorial list The tutorials contain a lot of examples and progressive exercises to help explain each language statement and function Algoid alle How stamp bitmaps works Post a reply Search this topi 17 posts Page 1 of 2 2 How stamp bitmaps works CyaNin by CyaNn Thu May 02 2013 10 43 am Site Ad r Hello everyone This is a mini tutorial to explain hoi nd bitmaps works on Algois First bitmap file loadin aN Moa yar pos pasta Be sts security issue But had implemented este bit ag ig Agoodu dahl cob p spac aes al sample and spa vader include al R of documentatio de dic ae he How to create a stamp Create Sies by cloni nga algo sige parts ne 2darr Tay size sedona2da y a chitem othe nk es ent a color algoid c The size represent the size of the pixel like pixelized old school graphic games Algoid is also a community federated by the forum http forum algoi
3. Open an LXTerminal and issue the following complex command qrencode t ASCII Hello Minecraft sed s g sed S g gt mc qr txt Note the two spaces in s g We have now generated the data that will be the input for our Python program Take a look at it with the cat command or use the Leafpad editor Glueing it all together To build a QR code structure in Minecraft we are going to use the Python application programming interface API That allows us to control our Minecraft world with a program For example we can discover Steve s co ordinates Steve is the protagonist i e your playable character and we can teleport Steve from one location to another We can also add or delete blocks in the world So we have the data built from qrencode and sed and we have a method to read that data and build some blocks in our Minecraft world Let s look at the Python program to do this The program is called mc qr py and have stored it in a directory called python inside the home directory First we import the sys package and add the API directory to the system path so that Python can find the Minecraft Python API packages Note please choose the correct path depending if you installed Minecraft or it came pre installed usr bin python import sys SsysS path insert 1 home pi mcpi api python sys path insert 1 opt minecraft p1 api python Now we can import the API packages to conn
4. Tim s original variable names are not very descriptive For me this added to the fun of working out how the program works My code only uses basic Python constructs The new_gameC function is probably the most complicated part of the program it creates a list of 15 x 15 item sub lists that represents the map This is done by first creating a grid that is designated as all wall but with a few random spaces Then more spaces are added according to the data list Hopefully this will become clearer as you type in the program and play the game Have fun finding Tim s gold TS A look at the diverse range of applications in the Pi Store Two years ago the Pi Store was launched with just 24 titles Today there are over 120 titles and the vast majority are free The MagPi takes a look at some of the diverse content in the Pi Store especially the non free content to help you determine what is worthy of your time and money Digital downloads Apple was one of the first companies to encourage the mass adoption of digital downloads with its iTunes store for music and movies This was later followed with the App store the iBooks store and finally iTunes U for students The App store was the only way you could get applications for Apple mobile devices and later it was extended to Apple s MacBook and iMac computers Amazon pioneered the digital download of books and today most major bookstores have digital download affiliat
5. When in the game you can press F12 to go back to the desktop If you middle click mouse wheel the Jameson task icon you can get access to an Elite Preferences menu where you can configure the game settings see below would suggest turning down mouse sensitivity to 1 or disabling the mouse altogether and playing the game with keys That way the mouse works when you re in the menus and you use keys for flight There is also a save game menu you can access from here YW i aT ReadMe l lite System Docs a vw x v Extras Gisburne Jameson FE Elite Preferences House fm On fm Right handed sensitivity 4 iin ae EF HostFS 8 Apps In the Docs folder above there are some documents that come with the game that you can read The basic idea in Elite is that you start off with a really poor space ship and by trading goods narcotics radioactive material etc you can earn money to buy better stuff for your ship or buy a whole new ship If you want to fly using the mouse this is a skill in itself recommend you press the Caps Lock key to turn on an auto centering feature which makes it 100 easier Mouse button 1 is the fire button while buttons 2 and 3 are for Speed up and slow down respectively On the keyboard the flight keys are S X for pitch and lt gt for roll and Space bar for speed up and slow down and A is fire To jump to another star system press F6 choose the planet yo
6. MT pts a checked forever change x by alegre d a p if key gni aP ry change x by 5 if key WG od TPO ey pressed change y by 5 K SS if key down arrow change y by a clicked nen Forever if touching color E 25 pmm a EPE Sois prudente Bits secs The last part of the script checks to see if one of the game over conditions has been reached There are three conditions which cause the game to finish 1 the 1 car touches the green grass colour 2 the car touches a i Lego brick sprite or 3 the car touches a ballon ball sprite In each case the racing car sprite is changed to costume2 which is the broken car Stop all then stops the game This script block also resets the car position to the bottom of the screen when the game starts x 0 is the middle of the screen in the horizontal direction and 100 is the bottom of the screen in the vertical direction pressed pressed Racing car script The racing car is controlled by a script which has three pieces These three pieces run in parallel which allows the program to check the conditions in each piece at the same time The first block checks the keyboard If the cursor keys are pressed the car moves left right up or down the screen The centre of the stage corresponds to x 0 y 0 The second piece of the script checks to see if the car has touched the grey colour at the side of the road This colo
7. Most games up to the mid late 1980 s are fine but some require additional emulation processing due to additional custom processors in the Original cabinet There is a list of some great games with the game name MAME code revision required and whether samples are needed at http www raspberrypi org phpBB3 viewtopic ph p f 78 amp t 29427 To run many of these MAME ROMs a license is required http www mamedev org devwiki index php title FAQ ROMs Compiling AdvMAME AdvMAME can be compiled on a 256MB or 512MB Raspberry Pi These instructions have been tested with Raspbian Wheezy Open a LXTerminal window from the menu Then before continuing make sure the Raspbian installation is up to date Sudo apt get update sudo apt get upgrade y Download AdvMAME version advancemame 0 106 0 tar gz from http sourceforge net projects advancemame file s advancemame 0 106 0 This older version will produce better results on the Raspberry Pi Newer MAME releases offer greater accuracy in emulation but not optimisation of performance 0 106 0 Compiling AdvMAME is resource intensive Therefore before compilation use Sudo raspi config to disable LXDE on boot This will allow the compilation to use the physical memory on top of the ARM chip rather than accessing swap space on the SD card With no overclocking it will take around six hours to compile Some overclocking will improve the performance of the emulator s
8. find out about them is to play with the camera adjust settings and see what happens To help with this there is a demo mode available which runs through a lot of the options automatically The following example runs for 1 minute changing an effect every 500ms 1 2 second raspistiLl d 500 t 60000 One option not mentioned is the ability to output the image or video stream to stdout so it can be piped to other applications for example network streaming To do this instead of specifying a filename for the o option you use the hyphen The following example outputs the jpg data to stdout where it is passed on to the file image jog The effect is the same as specifying O image jpg raspistill o gt image jpg The MagPI print edition Final words As with everything Raspberry Pi the camera is meant to be a learning experience Many options are available for you to try out some might be useful some not so useful Try them out experiment you cannot break it using any of the options The source code for the applications is publicly available and was written in a very straight forward fashion using C There are lots of comments to make it easier for people to modify it to their own purposes Feel free to pile in change stuff see what it does If you add a great new feature make sure you post about it on the Raspberry Pi forums you never know it might make it into the official applications Ex
9. switch to costume Crashed k rA ae a say for z secs i F H i if color E touching r set fying to HES o main repeat until loop continues to run until the flying status has been reset to zero The say ERES for sece first step within the loop is to reduce the vertical tee velocity component by a small amount This lsuitch ta costume EEEa reduction of velocity is present to simulate the ay crashed for secs effect of gravity on the Lander The next block e within the loop checks to see if the Lander has p touched the surrounding ground If it has ieee A touched it then the costume is changed to the it wy gt and direction D change y by vy stop script crashed version and the flying status is set to zero If it has not touched the surrounding ground then the program checks to see if the landing feet have touched the landing pad or not If they have touched the landing pad then the vertical velocity component and the direction of the Lander is checked If the touch down is not successful the Lander will be shown as crashed If the landing is successful then the Lander will say Landed While the Lander is not in contact with the ground the position of the Lander is updated using the velocity components In this program the speed of the loop regulates how fast time is passing in the simulation To make the game harder or easier try changing the reduction of the vertical velocity in the
10. 4 To ensure OpenELEC has your home workgroup from the main screen select SYSTEM then Settings and click on Services In the SMB client section the Workgroup option is set to WORKGROUP by default If your home network has its own workgroup name then you must change WORKGROUP to your home workgroup name You can find out your home workgroup name from your Windows PC by opening the Control Panel open the System and Security category then click on System The workgroup is shown near the bottom Step 4 Install TV catch up files Add ons need to be added to XBMC in order to use catch up TV Here are some examples that have been tested to work UK amp Ireland BBC iPlayer http code google com p xbmc iplayerv2 ITV player http code google com p xbmc itv player downloads list Channel 4 On Demand http code google com p mossy xbmc repo Irish TV http code google com p mossy xbmc repo Canada https github com irfancharania canada on dema nd repo Australia http code google com p xbmc catchuptv au The Canadian add in is particularly good as it covers 20 stations but just like the BBC and ITV add ins it is region locked Fortunately Australia s Network10 and Ireland s RTE stations appear to be freely available to all Using your PC copy the latest zip files onto a USB memory stick without unzipping them Now plug the USB memory stick into the USB port of your Raspberry Pi and power up the Raspberry Pi To install
11. Creating the Issue 11 cover from blocks to virtuality lan McAlpine created the impressive Minecraft magpie on the cover of Issue 11 The MagPi asked lan how he achieved this _ With the Minecraft API installed See main article text decided wanted to create a large copy a Of the magazine s logo that would be easily recognisable in the game world using Python This was my very first Python program Coding the magpie rather than building manually gave me the freedom to place the magpie anywhere in the Minecraft world The whole thing was very experimental balancing effort in terms of pixelation while still retaining an obviously recognisable image Having identified that was limited to eight shades of black grey white and four shades of blue in terms of Minecraft blocks that partially determined the pixelation Using Gimp on my Raspberry Pi pixelated The MagPi magpie image to 43x44 blocks This seemed to be the right balance but still meant manually mapping 1892 squares to Minecraft blocks It could be made smaller but the pixelation would be more coarse and the magpie less recognisable In Python the image is represented by a list of lists i e a 2 dimensional array Each cell in the array was given a Character 1 8 for black white and shades of grey plus A D for the shades of blue 0 represented the Air block type Five other variables were used three for the x y z coordinates one for the angle
12. home pi Scratch Once the program has loaded click on the Green Flag and your LED should now blink on for 1 second and off for 2 seconds see troubleshooting on the Cymplecy blog if this doesn t happen Article by Simon Walters and Aaron Shaw The Julia Set Over the next four pages we are going to use Scratch to draw some fractal patterns Gaston Julia the French mathematician did the early work on fractals which is why the patterns we will be creating are known as Julia Sets He was badly injured in World War One which is why he wore a patch over the centre of his face The program to draw these patterns is actually quite simple Let s start by deleting the cat sprite and making a new sprite with two tiny costumes Click on the paint new sprite button and then zoom in as far as possible Erase what s there already and draw the smallest possible square with the rectangle tool and fill it in with red Call this costume colour and then make another one the same except black and call that black CRS Sle GTN ae ae a X TES s S JAN ae Gaston Julia 1893 1978 EE Bom p a Benoit B Mandelbrot Mandelbrot continues Julia s work on fractals In the 1970s the Polish mathematician Benoit B Mandelbrot began to use computers to create images based on fractal mathematics His book The Fractal Geometry of Nature was very popular and introduced fractals to a much wider audience The Main Dr
13. used to dream of being able to afford a 16KB RAM expansion To make the ZX81 do 0 a a a SSeS anything at all you had to KNOW a few BASIC commands poate angen Thankfully the computer s manual included a good introduction to ee T EE T ee Fricrocanmiiitewadine Bbc BASIC ing For those interested i dvanced iN ss ois a le COMMODORE 64 DRACON 32 programming For those interested in more advanced f oy a programming magazines like ZX Computing and Creative jj j a we ECRU r a ga ies a a a ae a 7 5 E oo dextra memory on Computing included listings of BASIC programs These were EE TE n orante pge M mostly games that could be typed in played saved and hacked to your hearts content It was great fun and a fantastic way to learn how to program During the early 80s the late Tim Hartnell was a prolific author of BASIC games and published many articles and over 30 books Second hand copies of his books are still readily available online and a few PDFs can be found on vintage computer fan websites Stronghold of the Dwarven Lords Stronghold of The Dwarven Lords is a simple adventure game from the 1984 book Tim Hartnell s Giant Book of Computer Games In my Python translation try to stick as closely as possible to Tim s original BASIC version The Python that follows is written in Python 3 Start by opening the Python IDLE3 shell then press Ctrl N to open a new window suggest typing the program in manually ju
14. 8081 Hardware The hardware in this project consists of a relay that allows the Raspberry Pi to switch a garage door opener on or off To hookup the relay to the garage door opener a Perma Proto PCB was used The relay was soldered directly to the Perma Proto PCB together with all the wires To prevent an electrical short the bottom of the PCB was covered with electrical tape after the components were soldered on A 1N4001 diode was placed across the relay coil pins to avoid damaging the Raspberry Pi GPIO pin This is not optional If the diode is not used it will eventually destroy the Raspberry Pi Use the datasheet for your relay to determine the pinout There is an example below of how a relay can be connected In the example the Raspberry Pi connects to the coil with a diode in between the control red wire and ground black wire pins The garage door is connected to the normally open pin and relay switch pin two grey wires The coil on the relay should be connected to Ground and GPIO 17 on the Raspberry Pi using the female jumper wires EE Sree S Se ee ee 2 oe Pe ee A S AE GG JAE MELU ae pept pep 4p tt To Relay Soldering the Board 1 Cut and strip the two female jumper wires in half J FEHI J eeeee ce eeeee 66 eee GHI gt F 0 55 ABCOE ALLII eeece TILLY ABCOE 3 Next solder the black female jumper wire to the coil on the relay and the red jump
15. Can you tell us about the type of projects they are working on Amy At MadLab s U18 CoderDojo there s always lots of different activities going on For example there s a MaKey Makey kit which most of the younger children love making banana pianos with http bit ly KkiMLO a Lego WeDo kit http bit ly 12wCqup and Bare Conductive inks were bought for the last event http bit ly 16r9C3 The events are always fully booked and there are always volunteers around who can teach the children Scratch Python PHP Minecraft plus a variety of other skills At the last event the Minecraft table all worked together making fireworks and they demonstrated their display at the end MagPi You already have access to some nice gadgets such as laser cutters and 3D printers What technologies are on the horizon that excite you Amy love the idea of conductive inks met Dr Kate Stone http bit ly 5y6TPl at the YRS Festival of Code last year and she showed me a pair of headphones that were made from paper some electronic greetings cards that she d made and also this jazz poster http bit ly 17YXxZA lt was amazing to see what she d achieved with the technology My mum bought some of Bare Conductive s products at the Maker Faire UK recently and can t wait to try out the conductive paint MagPi We re often asked by parents if their kids are old enough for a Raspberry Pi Given your experience what do you think is an ideal age
16. Only one effect can be applied at a time The full set of effects available are negative solarise sketch denoise emboss oilpaint hatch gpen pastel watercolour film blur saturation colourswap washedout posterise colourpoint colourbaLlance cartoon raspistiLll t 5000 ifx negative o image jpg The colour effects option colfx is interesting Internally the image is represented using a YUV colour space YUV represents colour using the luminance Y and blue luminance and red luminance differences UV The colour effects option allows you to specify the values we are going to use for U and V This gives us a quick and easy way to do black and white images we just need to set UV equally to the middle of the range which is 128 So raspistill t 5000 colfx 128 128 o Lmage jpg Other values for U and V give varying blue and red differences from the middle Try some numbers The final image options am going to talk about are more about how the picture is taken rather than what processes are applied to the image These are metering mode mm and automatic white balance mode awb Metering mode specifies what area of the incoming image is used for determining the brightness of the image Internally there is a target brightness that is required and the camera system adjusts the internal gain to hit that target But to do that it needs to know what brightness the incoming image is so it can be boosted to
17. What is more fun than creating your own game The game above contains only 300 lines of source code and this include all the graphics and animated stars You can play it from Examples gt games gt Star battle al Tutorials In this simple tutorial we will see how to animate a spaceship Then features such as typing stamps and events will be discussed The first steps of the program are to hide the turtle create a spaceship and draw it algo hide ship set ship object define its position set x Q set y 150 draw the ship set stamp algo stamp clone array 1 1 1 10 1 1 1 1 1 1 10 1 1 1 1 1 02 10 02 1 1 10 1 02 10 02 1 10 10 02 02 10 02 02 10 10 02 10 1 10 2 10 10 02 02 1 02 02 10 O sil lt i lt 1 il sil Wah a D draw it set draw function algo goTo x y Stamp draw e ee Note how objects are defined set ship object In AL everything is an expression An object is defined in the same way as a number or a string Objects functions and arrays are all declared using the same expression syntax set name something In the case of objects parenthesis are used for inheritance and are used for members Then to define members of an object all you need to do is to define another expression within the object set o object set attribute 7 set
18. and download the file called ArchiEmu 5M We now need to get the ROM file out of the zip file Double click the archi zip file You will see an icon called Boot It s actually a program so don t double click it double clicking on programs runs them Hold down the Shift key and then double click it You ll see another window with a Resources folder Double click the Resources folder to open it Now hold down the Shift key and double click on ArchiEmu You ll see another window with an OS folder Double click the OS folder and now you ll see the file we want It s named ro310 Drag it into the SD card window We now need to change a few properties on this file so that our ArcEm program will recognise it These can each be done by middle clicking mouse wheel on the ro310 file First we must remove its access protection File rO310 gt Access gt Unprotected then set its file type to Data File ro310 gt Set type gt type Data and finally rename the file to ROM File ro310 gt Rename gt type ROM in capitals Open the ArcEm folder again Hold down the Shift key and double click the ArcEm icon That will show the ArcEm program files Drag the ROM file here We can now run the emulator to see if it works Double click the ArcEm icon The screen will go black for a moment and you will see the actual boot up sequence of the original Archimedes computer ources 3 fipp Ko Chars Help If the screen is a l
19. similar to those that you have in Windows We ll be using those later B Boot i K d Help Keyboard i y Screen Sound SpecialF X System a7 Time and date Windows To download the necessary Archimedes emulator and files for Elite we will need to have an internet connection Alternatively you can copy the files over from a USB memory stick To configure network access if it is not already working by default double left click on the desktop icon named Configure and then double click the Network icon on the right From here enable the TCP IP protocol suite in Internet configuration _ Internet configuration TEE Diss cpi Host names User options o Interfaces Routing Enable TCP IP Protocol Suite RISC OS behaves differently to Windows and Linux When you double click an application to start it eg NetSurf it might seem that nothing has happened But look in the bottom right hand corner of the Icon Bar Your application is running just click on its icon to open it To obtain ArcEm load the NetSurf browser navigate to http arcem sourceforge net and download the latest version via the get it here link If you have trouble finding it type the following into the address bar on NetSurf http sourceforge net projects arcem files latest download source files Make sure you download the RISC OS version and not the default Windows version ap x ArcEm The Acorn Archime
20. the arm using the power switch unplug from the USB port plug the arm back in and turn the power back on Getting the code The scripts can be found on Github at https github com peterlavelle maplinarm You can clone the repository directly on to your Pi if you have the Git client installed Installing the Git client on Raspbian is as simple as running the command sudo apt get install git core When you have the Git client installed run the command git clone https github com peterlavelle mapLinarm to pull down a copy of the Python code This command will clone the repository into a subdirectory called maplinarm and should pull down the files listed below git clone https github com peterLlavelle maplinarm Cloning into maplinarm remote Counting objects 35 done remote Compressing objects 100 23 23 done remote Total 35 delta 8 reused 12 delta 2 Unpacking objects 100 35 35 done cd mapLinarm Ls commander py README md commands csv maplinrobot py Making the scripts executable Now we need to make the scripts executable by the Raspberry Pi To do this change into the directory you cloned the repository down to using the cd command and run the command chmod 755 py This will give all files ending in py executable permissions You can double check this with the command ls la py and looking for the x in the left hand column of the output on each line See exam
21. when Space key pressed While the space bar is pressed the velocity of the if flying i Lander is increased according to its current direction _ The sine and cosine operators are used to calculate repeat until not key Space pressed the increase of the x and y velocity components using j lt lt the direction where the velocity components are change by E 35 0 of direction stored in local variables vx and vy respectively The See ee os ee ese direction is zero when the Lander points straight eae upwards 180 when it points straight downwards switch to costume EnginesOt _ positive when it points to the right and negative when it points to the left Stop script The Lander in flight The Lander requires one more script block to control S Sn the flight of the Lander and to check to see if it has point in direction Ghd crashed or landed The script on the left performs this switch to costume EnginesOf functionality go to x pick random foe 1270 Bee et v Jeo D When the green flag is pressed the Lander is reset to set vy tel point straight upwards the engines are turned off and set fing to H its position is chosen at random along the top of the aee fying screen The local variables for the x and y velocity henge vel By components and the flight status are also reset The if color is touching 2 oF color is touching 2 or color i touching set flying to E F
22. 9 13 17 C 7 8 10 18 23 24 27 Python 1 2 3 4 5 6 7 8 9 10 13 14 29 Scratch programming for kids 1 3 4 5 13 17 29 Ada 6 8 SQL 8 22 Charm 10 11 14 VEVEN GE A Lo FUZE BASIC 25 26 27 28 29 10 In the last article we added CUPS printing onto the Raspberry Pi Now that you have got your printer up and running we can look at how to print from within our own applications We are going to be using the Python programming language but we will also take a look at straightforward command line printing which can also be used for printing from other programming languages First we will look at printing from the command line This can be useful within shell scripts or by making a system call within any programming language The Lp or Lpr commands are used for command line printing The names are an abbreviation of line printer although they are seldom used for printing to a true line printer these days Both commands work in a similar way but use different options This is historical from the early days of UNIX Both lp and Lpr are available on Linux so you can use whichever you prefer The command to print a file to the default printer is Lp lt fitlename gt You can select a different printer or specify only certain pages using different command line options You can find details at http www cups org documentation php options html Alternatively look at the help page on your
23. King Wenceslas is a good carol to choose as we can use some of the functions we have discussed The first section of Good King Wenceslas is repeated twice so let s start with 2 times do A lot of this section is the same pattern i e there is a sequence of notes to be played with the same timings SO we can use pLay_pattern_timed Remember the indents play_pattern_timed 55 55 55 57 55 55 0 5 play 50 sleep 1 play_pattern_timed 52 50 52 54 0 5 play 55 sleep 1 play 55 sleep 1 Now we need to tell the program to only repeat this section so we type end Now we can finish off the rest of the tune play_pattern_timed 62 60 59 57 59 57 5 play 55 sleep 1 play_pattern_timed 52 50 52 54 5 play_pattern_timed 55 55 1 play_pattern_timed 50 50 52 54 55 55 5 play 57 sleep 1 play_pattern_timed 62 60 59 57 0 5 play_pattern_timed 55 60 1 play 55 sleep 2 So the finished tune should look something like this 2 times do play_pattern_timed 55 55 55 57 55 55 5 play 5 sleep 1 play_pattern_timed 52 50 52 54 5 play 55 sleep 1 play 55 sleep 1 end play_pattern_timed 62 60 59 57 59 57 5 play 55 sleep 1 play_pattern_timed 52 50 52 54 0 5 play_pattern_timed 55 55 1 play_pattern_timed 50 50 52 54 55 55 5 play 57 sleep 1 play_pattern_timed 62 60 59 57 0 5 play_pattern_timed 55 60 1 play 55 sleep 2 Congratulations you have written your
24. Pi and our components The coding part of this tutorial is in Python a widely used general purpose language It is also very readable so we can break down and explain the function of each line of code The purpose of our code will be to read the I O pin when the switch is pressed Using a switch If you have not already done so start X by typing startx and load the program IDLE3 Since we are starting a new project open up a new window File gt New Window Remember that Python is case sensitive and indentation is fundamental Indentation which is used to group statements will occur automatically as you type commands so make sure you stick to the suggested layout The first line of our code imports the Python library for accessing the GPIO PHYSICAL COMPUTING Brought to you by ModMyPi Buttons and switches with the import RP1i GPIO as GPIO Next we need to set our GPIO pin numbering as either the BOARD numbering or the BCM numbering BOARD numbering refers to the physical pin numbering of the headers BCM numbering refers to the channel numbers on the Broadcom chip Either will do but personally prefer BCM numbering If you re confused use a GPIO cheat sheet to clarify which pin is which GPIO setmodeCGPIO BCM Now you need to define the GPIO pins as either inputs or outputs In part 1 we set BCM Pin 17 BOARD Pin 11 GPIO P17 Pin 11 as our input pin So our next line of code tells the GPIO library to set thi
25. Pi using a powerful IDE which compiles to almost all platforms Not surprisingly Pi Vision was written in Pascal using the Lazarus IDE In fact the Lazarus IDE is part of the Raspbian OS repository You can download and install it directly But should you choose to do so please note that it will consume 0 5GB of storage space on your SD card First install Pascal by entering sudo apt get install fpc Then install Lazarus by entering sudo apt get install lazarus This can take some time to download and install After it has completed you will find Lazarus in the Programming section of your LXDE application menu The Pi Vision project itself can be downloaded and then opened and built using Lazarus Pi Vision is hosted on Github Simply download the entire project unpack it and open it using Lazarus Full instructions can also be found inside the project It should be of interest to note that since you can also install Lazarus on many other operating systems such as Windows or Mac you can open the Pi Vision project and run it on those systems as well Obviously this would be only for review Pi Vision aas Employed Command raspisti pistill p 0 0 800 600 t 5000 mage Jpg e jpg q 100 w 640 h 480 ifx none vf v r o home pi Desktop PiVision RPy ex auto rot 0 mm average 50 co 0 sh 0 sa 0 awb auto ev 5 VES Ki Mai in Photo Video Settings Info Type Size Fli
26. SE E E E O E E a E E E E E E E E E E E E E E E a CE a a a a a E a a E a a A E E E E E E R E E ES E E E E E E E E E E E E E E E E E E E E E E E eee eee eee sce eee eT eT eT E a E peowpoe oe eegreeeveeeveeeeeeveeeveeeeeveeeveeoeveevoeveeeveHheeeeveeveveenevreeveeveeevevee pee oeowe owe ewe eee eee eee eee ee ee OK HH oh OH He Z E E E E E E E E E E E evr ERR RRR a e a ee E ef 8c Severe fe eevee F Cee Cee ee COTES FPoueoeee eeeee QSR Figure 1 LED Test Figure 2 GPIO Test As in Figure 1 above wire up Pin 1 3 3V to at least a 3300hm resistor connect that resistor to the long lead this is the positive lead of an LED and then connect the other end of the LED to Pin 6 Ground This should cause the LED to light up If it doesn t work try reversing your LED as you probably have the polarities reversed Once working you can now move the red or whatever colour you have used lead from Pin 1 to Pin 11 as in Figure 2 above You should now run the special Scratch icon Scratch GPIO on your desktop This is actually a completely normal version of Scratch it just runs a little Python background program to allow Scratch to talk to the GPIO If you have any Python programs accessing the GPIO running already this could cause your Pi to crash when opening Scratch GPIO To avoid this open an LX Terminal window and run sudo killall python To test out the GPIO control in Scratch click File gt Open and select blink11 from
27. Tom Denton Guest Writer Raspberry Pi Then install the latest Raspbian image and type sudo raspi config Select expand the filesystem enable camera advanced option memory split minimum 128 for gpu enable boot to desktop scratch Console finish reboot yes This will enable the camera use all of the SD card for the Linux installation turn off the boot to X and allow the ARM processor to use the maximum amount of memory Next make sure that Raspbian is up to date and install the libraries and programs needed for this project sudo apt get update sudo apt get upgrade y sudo apt get install y python imaging python zmq python matplotlib mencoder imagemagick sudo reboot 12 Taking photos with raspistill The easiest way to use the Raspberry Pi camera is via the rasp1stiLl command It has a time lapse option which many people have used to good effect For an extremely long time lapse finer control over the images taken proved to be better than the automatic settings As a result a Python script was written to take photographs at regular intervals Calculations were used to make sure that the images were of consistent quality Image quality consistency was maintained by the manipulation of shutter speed ISO and post capture alteration The two options that control the brightness of an image are the shutter speed and the ISO International Standards Organization setting The shutter speed controls
28. a fan of any of these in emulations and they will be applied when changing the magnification mode as described above However they can be scrolled through in the video options menu Experiment and see if you like any of them 4 If you are old enough to remember amusement arcades did the SAME game seem harder in different venues Well it probably WAS Inside the cabinet are toggle DIP switches that could be set to change difficulty lives extras etc These are emulated in MAME and can be configured options TAB DIP Switches Don t like the command line The Advance suite of software also includes a fully integrated front end for AdvMAME AdvMENU http sourceforge net projects advancemame file s advancemenu A front end is a GUI Graphical User Interface which alleviates the troublesome command line typing for emulator control and execution The front end can also be helpful when your ROM collection gets larger since it can become hard to remember all the MAME codes or what ROMs are in the folder This can be installed using the exact same method as MAME itself Then just run the executable advmenu Older versions better performance Older versions of AdvMAME can often give improved results but require changes to the scripts to compile correctly on the Raspberr Pi suggest downloading 0 94 0 as it requires only a few script changes First modify advance linux vfb c Change MAP_SHARED MAP_FIXED to MAP_
29. alter and interact with the Minecraft world unlocking a whole load of Minecraft hacking How about creating massive structures at the click of a button a bridge which automatically appears under your feet allowing you to walk across massive chasms a game of minesweeper or a huge clock Minecraft is a world of cubes or blocks all with a relative size of 1m x 1m x 1m Every block has a position in the world of x y z x and z are the horizontal positions and y is the vertical X The API works by changing the server which runs underneath the game allowing you to interact with these blocks and the player such as Get the player s position Change or set the player s position Get the type of block Change a block Change the camera angle Post messages to the player Libraries You can interact with the server directly by sending a message to it but the nice people at Mojang also provide libraries for Python and Java which simplify and standardise using the API The libraries are installed along with the game in the mcpi api java and mcpi api python directories The following example is written in Python and uses Mojang s Python API library The first task is to create a directory for your API program API example 1 Create directory 2 Open Idle or your favourite editor and create a program file called minecraft magp1 py in the minecraft magp1 directory 3 Next we import th
30. an industry was born Arcade games began appearing everywhere Dedicated arcades in towns and cities game cabinets in petrol stations Supermarkets restaurants pubs bars used to frequent a chip shop just because it had Centipede Atari Inc 1980 At its peak in 1981 arcade games generated annual revenues of over 5 billion in the USA 12 79 billion in 2013 dollars In 1983 the USA endured The Video Game Crash Financial Retro gaming with MAME mt A SPAA i E iF N 1 markets lost faith in the passing fad of video games The Golden Age of Video Games was over Retro gaming emulation and MAME Peter De Vries an American editor novelist and satirist wrote Nostalgia isn t what it used to be but disagree Old school or retro gaming has a substantial following and not just because of nostalgia but due to the restrictive primitive nature of the hardware Many retro games are defined by their elegant simplicity and gameplay Atari Inc co founder Nolan Bushnell s quote that the perfect game is Easy to learn difficult to master describes the classics from the Golden Age of Video Games An emulator is hardware or software or both that duplicates the functions of one computer system the guest in another computer system the host which is different from the first one The emulated behavior closely resembles the behavior of the real system the guest When running an emulator
31. at other causes First we need to install CUPS from the software repositories sudo apt get install cups CUPS uses the lpadmin group to determine who is authorised to administer the printers To add a printer you will need to add your user to the lpadmin group sudo usermod a G lLpadmin pi We are now going to use the CUPS web based interface PRINTING WITH CUPS 4 d gt y a p N which is provided by default All the functionality is built into CUPS so we do not need to worry about enabling a web server Just point your browser at http 127 0 0 1 631 and use your normal username and password when prompted during configuration or when administering the printers Choose the Administration tab and then Add Printer Er DA ie iy Eriak Irii mi 5 Haa urp ty a PINT ee Svitea CLAS a the gerdardechasee Geen coerce pining pytlem aertaped by Apple ine for Mas co x anii otter UN Et ike Oper nti irgi CUPS for Users CUPS for CUPS for Developers Administrators eet Lina Prinbne aha Aiding Prostar amd Cli stam M ana jing Cpa halen oc emer Gecorny CUPS will search for printers that are physically connected to the Raspberry Pi or that it can see on the local network In my case it found my network printer Epson Stylus Photo PX720WD You will also see some options for HP printers as these are often shown even if there are no HP printers connected After selecting the
32. available on the Pi Store at It is also available on the Google Play store at Install it on your Raspberry Pi and launch it from the Desktop From the Examples menu choose demo alL Click on the Play button and the demo script will run The program contains a function named poly and a loop that draws a rose window Note that the function declaration is really special set poly function size n TA In AL everything declarations are is an expression Example set size 7 set o object C yig In AlgolDE check the Step by step box and click the Play button again Now you can understand where the program is at and what it is doing The number at the right of the check box allows you to change the step by step speed Now uncheck step by step mode and check the Debug mode box Click on the number 12 in the source code margin This will add a new breakpoint Click on the Play button to run the program Three new buttons appear run to the next breakpoint run to the next line and run to the next token The Algoid debugger considers each token as an object path and expression calculation This is perfect to understand the precedence order for example Try each of the three new buttons AOO AlgolDE v0 2 4 beta learning programming made simple and funny File Edit Examples Help Kd onate gt O M Debug mode Step by step mode 150 8 Ik WeAKUNS amp WNre
33. gr py The screen will go blank because the last few blocks are built on top of Steve When it is done drive round to find your QR code in the Minecraft world found needed to build a tower of stone or dirt to get Steve positioned so that the QR code was square on and filled the top half of the screen without any keystoning effects was then able to scan it with my smart phone I d like to thank Konrad my 14 year old son and Minecraft expert for his patience and advice started building the code with diamond block id 5 7 but Konrad suggested using snow for better contrast a a 1 i fi ai ip A e 7 A amp sx Aa gtst b p CLE i J ICS en Ji l L AAOS i Ae CONDUCTIVE a g L 3 i f otics amp Electronic d J d E 2 Q gt i iu AOV Ya W CR ILO y wp S i j oss a R ij Vf iC E TPA f x S L v4 IS UL Ud S Ai x 0 J SparkFun Inventor s Kit Learn to Solder Zoo 4 AE r Widgets Arduinos DXX e E We now stock a massive range of shiny things More stuff to make your things than ever Adafruit PiTFT Assembled http shop pimoroni com BRORBBASS il Made in Sheffield UK RONI ue http pimoroni com Amy Mather In the unlikely case that you haven t already seen the video and don t know the name Amy Mather would like to introduce you to a young lady who hosted quite possibly the high
34. http solderintheveins co uk contact me Where to buy In the UK the robot arm is available from Maplin http www maplin co uk code A37JN or elsewhere from Robotikits hitp www owirobot com codes OWI 535 and 535 USB a asidonanhoqenst es ilsaiingeiug jug Jeniine2ise Jap Ma2 i_ l b Juqslantns2ssp J9g 2p185 qool ts2e sepyres bseidT oni i besidi_tlse 1 Configuring CUPS SKILL LEVEL BEGINNER This is a two part tutorial on configuring printing on the Raspberry Pi In this article am going to explain some of the essentials of setting up printing and adding your printer in Raspbian This could be useful for printing from your Raspberry Pi or to turn your USB printer into a network enabled printer Next month we will look at how we can print from the command line and from within your own Python programs The standard method of printing on Linux is with the Common Unix Printing System better known as CUPS Developed by Apple Inc CUPS is open source software using standards based printing protocols The job of converting an application print request to something that your printer can understand is a memory hungry task therefore recommend using a 512MB model B for printing directly from the Raspberry Pi Even with a 512MB Raspberry Pi you can still run into memory issues If you have problems with printing then it is worth trying with as few applications running as possible before looking
35. initial setup wizard Here you choose your region provide a friendly network name then choose from a list of available wireless connections You will need to know your wireless connection name and security passphrase By default your network IP address and DNS servers will be automatically configured However you may want to change the DNS servers to watch overseas programming using services like htto www unblock us com or you may want to change the IP address to use a Static IP If you want to change the network settings later from the main screen select SYSTEM OpenELEC and then click on Connections Click on your connection and choose Edit from the pop up menu A static IP address tends to be more reliable because it remains fixed and so the remote app on your smartphone will always connect The IP address created using DHCP can vary depending on what other devices are connected to the broadband router Setting up a static IP optional Choose to Edit your connection as described above and click on IPv4 You will see the IP Address Method is currently set to DHCP Click on this and change it to Manual Now click on IP Address and enter an unused address within the range permitted by your broadband router e g 192 168 1 50 You can leave the Subnet Mask e g 255 255 255 0 and Default Gateway e g 192 168 1 254 at their default settings To change the DNS settings for your connection choose DNS servers You will see opt
36. install Pi Vision Pi Vision runs on the Raspbian OS Start the LXDE GUI with the terminal command startx Download the Pi Vision software from hitp neywhatsthebigidea net ddownload 1021 Right click on the downloaded file and choose Xarchiver Click on the Extract files icon and check the option Extract files with full path This will create a new directory called PiVision_RPi Important In order to run the Pi Vision application you need to first set permissions Open the PiVision_RP1 directory and right click on the file rp1CC the Pi Vision application Select Properties and from the File Properties dialog select the Permissions tab There is a small check box which needs to be checked called Make this file executable Double click on the Pi Vision application The start up page of Pi Vision includes a button called Test Camera Preview This will start a 5 second 640 x 480 VGA camera preview in the upper left corner of your screen Assuming that your camera is set up correctly and the preview is successful then you are now ready to start using your camera with Pi Vision You will notice that Pi Vision will display the commands sent in a text area in the upper region of the application Go ahead and experiment with different settings in the Photo Video and Settings sections to see the results Later you can try sending the command instructions yourself To do this take a photo or video and then select and copy
37. method function do something pe set nested object set method function Ie Ire Ire The semi colons in this code are optional Note In AL objects are directly created with their declaration An object can be used imediatelly after it is created If some more objects of the same class are needed it is possible to clone the initial object The next concept to introduce is a stamp A stamp works by cloning creating a new instance of an 122 existing object of the algo stamp object The syntax begins with set set stamp algo stamp clone A stamp contains two pieces of information a two dimensional array of colours and the size of a pixel In AL an array is declared using the array keyword set a array 1 2 3 43 A nested array does not require a keyword set a array 1 2 3 43 5 6 7 This example represents a tree It demonstrates how simple it is to define data structures in AL The AL language is functional and uses the power of map filter reduce similar to Python Numbers can be replaced by a function or objects and array of functions etc Imagine the capabilities of this kind of flexibility Now the image needs to be drawn on the screen There are two steps to draw a stamp algo golo x y Stamp draw lf we draw the stamp again in another position then AL will draw an additional ship This will create two stamps on the screen To create an an
38. my w new PluginUtils Behaviour Qverride public void visite Block lt RuntimeContext gt t RuntimeContext c appContext getIDEPanel showPanel myPanel getName b PluginUtils addMethod my Override public void visite Block lt RuntimeContext gt t RuntimeContext c String text PluginUtils getParam t 0 getString myPanel setFieldText text new PluginUtils Behaviour bx text PluginUtils addMethod my on eck new PluginUtils Behaviour ebobeiiiins public void visite Block lt RuntimeContext gt t final RuntimeContext c PINAN FunctionInstance f PluginUtils getParam t 0 getFunction myPanel addButtonActionListener new ActionListener eOverride public void actionPerformed ActionEvent e MutableVariant text new MutableVariant myPanel getFieldText PluginUtils caliFunction appContext c f text This is the resulting the example panel EEIEIEE POSEI d my button J Once complete just copy the lt pLugin gt jar file to the Algoid plugin folder and that s it With this feature a lot of improvements can be added to Algoid like GPIO communications a true 2D game engine planned for future development mathematical functions etc Everything you want to teach or command can be added with this powerful scripting language Video game development SCORE 273 One principle of Algoid is to be fun because when it is fun learning becomes a pleasure
39. of the sub division of the page The first frameset sub divides the page into two parts where the red sidebar will be 170 pixels wide and the rest is given to the second frameset The second frameset splits its allocated space evenly between two frames with the radio and the status Note that the frames have names which we will later use to direct output to the proper places The file tndexList html1 file that describes the red sidebar on the left is shown here lt html gt lt body bgcolor 990000 text white link white vlink lightblue gt lt br gt lt a href radio html target main gt Radio lt a gt lt br gt lt br gt lt a href http 192 168 xxx xxx target blank gt Kitchen lt a gt lt br gt lt a href http 192 168 xxx xxx target blank gt Living lt a gt lt br gt lt br gt lt a href http www listenlive eu target blank gt ListenLive lt a gt lt br gt lt a href http www internet radio com target blank gt Internet Radio lt a gt lt br gt lt a href http www radio locator com target blank gt RadioLocator lt a gt lt body gt lt html gt We see the usual header and body directives where the red background Is defined Then there is a list of HTML anchors with the links to the respective web pages Note that the anchors have a target directive which directs the browser when you click the link to either a new window with target blank or to a named frame with target main The
40. p1 You should get the familiar screen for Minecraft PATE ktkt Dougie Lawson MagPi Writer and can build a new world Have a play around and when you are done press lt TAB gt to get control of the cursor We can switch to the LXTerminal window and close down Minecraft by pressing the lt CTRL gt lt C gt keys together We will come back to Minecraft later when we are ready to run the Python program that is going to build our structure in the virtual world Getting QR encoder and testing your first QR code Although we could build our own QR code maker in Python to keep things very simple and give us instant results we will use a ready built QR code generator called qrencode Open an LXTerminal and issue the following commands sudo apt get install qrencode qrencode t ANSI Hello World We have now got a QR code displaying in our LXTerminal window You may need to stretch the window size so that the white borders at the top and bottom are visible Get your smart phone and scan that QR code using any QR code app to prove that everything is working correctly CO TEN t The qrencode program can generate QR codes in various formats In our Python program we are going to generate an ASCII plain text format QR code and edit the output with the stream editor sed The qrencode program generates for every black square and a space for every white square in the QR code when we use the t ASCII option
41. printers keys Q conn printFileCprinter_name filename Python_Status_print else print Unable to create pdf file 1f __name__ __main__ main SF iia 7 lt tal ia a a j a i nie 3 z wag Ec i M i r SKILL LEVEL BEGINNER The Raspberry Pi Foundation has launched their first peripheral a 5MP camera Priced at 25 the same price as the Model A its a very small PCB on which is an Omnivision OV5647 camera module It connects to either the Model A or Model B Raspberry Pi using a 15cm 15 way ribbon connector UT TTT atta Ww N wW N WW a D ii A Over the course of this series will take you through initial connection of the camera to your Raspberry Pi and will show you some of the basic commands used to take both still and video imagery At the end some of the more sophisticated features will also be explained Not every option will be covered new options are being added all the time so it s difficult to keep up but hopefully this article will give enough information for you to be able to cover most The Raspberry Pi camera Part 1 2 O BASIC OPERATION Gettingto gripswiththe cameramodeate amp James Hughes Guest Writer image taking tasks First though a description of how the camera module came to be History From its first launch the Raspberry Pi has had a connector on it to attach a camera t
42. putting OpenWRT on it and adding a USB sound card At that time this setup was the only way could figure out how to make an intelligent box that connected to the internet at one end and output music at the other That system located in our kitchen is still in use but when we got a new stereo in the living room it was time to revisit the internet radio situation The Raspberry Pi has all the necessary hardware on board to enable wired or wireless internet connectivity plus analogue and digital sound output Having decided on the hardware some research on the web resulted in the following strategy for the software e Use the music player daemon mpd for sound e Control it with the music player controller software mpc e Use apache2 to serve a web interface with forms and cgi bin functionality to select radio channels from the playlist e Display what is currently playing e Shutdown the Raspberry Pi gracefully via the web interface The last option proved to be tricky but more on that later Discover new radio content bs T Volker Ziemann Guest Writer There is no hardware work involved in this approach only some programming The end result is a system that can be controlled from any computer smartphone or tablet device with web access to the Raspberry Pi For the software approach used Raspbian from the latest release of NOOBS You can download this from http www raspberrypi org downloads assume that y
43. shows the sprite It is then moved to the top of the screen The starting position is chosen at random along the x axis horizontal plane The sprite is then moved down the screen by 5 units at a time until it touches the bottom of the stage When the sprite touches the bottom of the stage it is hidden and the outer loop moves it back to the top The stage To complete the program draw the stage image Similar to the racing car half of the stage was drawn copied and mirrored The green and grey colours used in the racing car script were used for the edge of the road and the grass Possible extensions There are several ways this program could be made better The lines in the middle of the road could be changed for another image to create the illusion of movement Sounds could be added for when the car moves or crashes Some burning rubber marks could be added when the car slows down Instead of a Lego brick and ball try creating some other cars or cars that drive from the bottom of the screen to the top This game could be used as the basis for other games For example vertical scrolling space invaders is quite similar Try swapping the racing car stage picture for a star field Then add in some weird and wacky alien vehicles which come racing down or drop things on the heroic space ship The first thing to do is delete the cat sprite because we won t be using that Right click on it and choose delete Next we need to create
44. stick using screws and spacers Wood was used to avoid any shorting that may occur On the back of the stick attached the SmartUPS to power the Raspberry Pi and make my device more mobile The SmartUPS is powered by three AA batteries and though it has several functions is only used for power in this project On the other end of the wooden stick drilled a hole and attached a rod to be used as a handle This allowed me to easily swing the magic wand around in a circle Installing packages For this program used the OpenElectrons_ LSM303 package installed using the pip package manager If you do not have pip you can get it by opening a terminal window and typing Sudo easy_instalLl pip To install the OpenElectrons LSM303 package type Sudo pip install OpenElectrons_LSM3Q3 This command will install the package aswell as the OpenElectrons_i2c package needed for 12C functions Programming In order to generate the ASCII characters first created a look up table The table is just a dictionary in which each character is a list containing five hexadecimal values Each value generates one vertical line of pixels The example below shows the hexadecimal for the letters B C and D A full alphabet with numbers and symbols can be downloaded in the Python sample programs available from http www openelectrons com pages 63 5x7 ascii characters Lookup table Lookuptable B Ox7f x49 0x49 0x49 0x36 C
45. the raspistill or raspivid command in the text area Open a terminal window by selecting the Terminal button at the lower right region of the application Open the Edit menu and choose Paste o Open source The language of choice for the Raspberry Pi is Python and with good reason Python offers simplicity it is easy to understand and very easy to use It subscribes to the novice developer in particular very well Other ways to create programs applications are also available but when it comes to Rapid Application Development RAD you will need something more advanced For me the choice was Pascal more specifically the Free Pascal Compiler FPC with the Lazarus IDE The Lazarus IDE is an open source development environment to aid writing applications using the Pascal language It is very powerful and includes just about everything necessary to make really great applications very easily and with minimal effort Pascal is not the best language There is no such thing as best The question is what does it take to satisfy the requirements and do it in a good easy and effective way Pascal is a strongly typed language and offers important structured programming techniques It was the teaching language of choice during the 80s and early 90s Additionally the Lazarus IDE and the FPC run on most systems Windows OSX Linux and of course Raspbian That means you can write code and develop applications for the Raspberry
46. the screen before you release the button The final program should look like this in Python import RP1 GPIO as GPIO GPIO setmodeCGPIO BCM GPIO setup 17 GPIO IN while True input_value GPIO input 17 if 1nput_value False printC Who pressed my button while input_value False input_value GPIO input 17 Save the file as button py In order to run the program open a new terminal window on the Raspberry Pi and type the following command sudo python button py At first nothing will happen but if you press the button the program will print the defined message To exit arunning Python script simply press lt CTRL gt C on the keyboard to terminate lf it hasn t worked don t worry First check the circuit is connected correctly on the breadboard as defined in part 1 then check that the jumper wires are connected to the correct pins on the GPIO port If it still fails to work double check each line of the program is correct remembering that Python is case sensitive and check that the indentation is correct find that typing the code out by hand will give better results than a simple copy paste This is a deceptively simple program that can be used for many purposes The same code could be used to read when the pins of separate devices such as a sensor or external micro controller have been pulled high or low Adding an LED We will carry on using the same breadboard as before but we require a couple of extra c
47. to costume costumne TE a play note ina for human time beats tha add to player tones 4 a EIE switch to costume costurnel eet temp to E a har m pa SEN to costume Eosti pene length of a PU tones taai play note eo for time Beate E CPL tone ere itemi of Aa Taek to costume costumel change temp by A i is a H 1 wo s os 9 oe ei A pie a eee gii f T k a i FTN Get Ready Lii Secs switch to costume costurnel om This will install all the necessary extra software and some simple examples If you do not have internet on your Pi then put your SD card into a card reader and try using your browser to right click and save the script direct to your SD card and then put it back into your Pi and run the second instruction Connecting Components Up Extreme care should be taken when connecting hardware to the GPIO pins as it can damage your Pi only do this if you re confident of your ability to follow these instructions correctly At a minimum you should get a breadboard and use some female male 0 1 leads available from RS CPC or your local Maplin Check out some GPIO pin guides to make sure you know what pins do what LEJ gt Cn Connect the resistor to Pin 1 to check that the LED lights orany CERS S up and you have it orany dag the right way around vy OVleadalways goes say toPin6 OMe O E E E E E T E E A e e a a a a ee O E EE SE E
48. to explain to a kid how the for loop works You will discover you need to explain variables conditions boolean expressions and incrementation all just to explain a simple loop ALGOID Programming made simple and fun Algoid s syntax was designed to be as easy to memorise as possible All its structure statements are written the same way variables functions arrays objects 2 Its syntax should be as close as possible to industry standards Learning a language represents a large amount of time so the day the kid wants to use Java Python or C they will not have to learn again unfamiliar syntax and another nuances 3 Its semantic should not be limited to one or two paradigms When I was young was very frustrated by the BASIC language After having understood how imperative statements and procedures work was limited to them To progress had to learn another language and another syntax All things considered AlgolIDE tries to simplify programming and its understanding My first idea was to create a step by step execution mode With two clicks the execution slows down and highlights appear in the source code on the line being executed This is possible with the debugging mode We will see later how it works AlgolDE also has the ability to view the variables in use on its scope viewer and has its own logger Algoid quick tour It is recommended to download the Java version of Algoid from AlgolDE is also
49. to write a couple of applications to make use of the camera to update the GPU firmware to support the camera and to improve the camera tuning as the basic tuning already in place had a number of obvious defects Camera tuning is a complex task which has been covered on the Raspberry Pi website so won t repeat it here Suffice it to say the end results are well worth the extra effort put in by David Plowman while at Broadcom Thanks David So with the history out of the way let s take a look at getting your camera going Setting up Its important to start with a warning Cameras like these are static sensitive You should earth yourself prior to handling the PCB a sink tap faucet or similar should suffice if you don t have an earthing strap There are only two connections to make the ribbon cable needs to be attached to the camera PCB and the Raspberry Pi itself You need to get it the right way round or the camera will not work On the camera PCB the blue backing on the cable should be away from the PCB and on the Raspberry Pi it should be towards the ethernet connection or where the ethernet connector would be if you are using a model A Although the connectors on the PCB and the Pi are different they work in a similar way On the Raspberry Pi you need to pull up the tabs on each end of the connector E Y lt should slide up easily and be able to pivot around slightly Fully insert the ribbon cable int
50. x3e Qx41 0x41 0x41 0x22 D Ox7f x41 0x41 0x41 0x3e With the look up table created then started writing the program by importing any needed files and defining my variables Note that only ACCEL S imported from the OpenElectrons LSM303 file Because the LSM303 chip contains a magnetometer as well as an accelerometer the library contains two separate classes Also notice the str variable This is the string the magic wand will display import time import os sys a 1 from OpenElectrons_i2c import OpenELectrons_12c from OpenELectrons_LSM303 import ACCEL test 1 oe OpenELectrons_i2c 0x38 Lsm ACCEL str MagPi Rocks Length len str index Q test 1 of Seren t 5 print str The while loop starts by turning off the LEDs Next it reads the accelerometer value along the X axis then quickly reads the value again With these two values a simplified calculation of acceleration can be performed while test 1 turn Leds off oe simpLeWriteByte Qxf Ff get first value array Lsm readArray 1sm ACCEL_X_Y_Z 0x80 6 acLraw lsm accl array Q time sleep t get second value array lsm readArray 1sm ACCEL_X_Y_Z 0x80 6 aclraw2 lsm accl array Q divide values to compensate for gravity and subtract to find delta acl aclraw2 g Caclraw g filter approximate still values if acl lt 30 and acl gt 30 acl 0 The following if statement and while loop actually li
51. 7th 2013 a pair of Raspberry Pis with Raspberry Pi cameras were placed in a cottage in Ontario overlooking Georgian Bay About four months later they were found to have performed wonderfully capturing over 40 000 photos at two minute increments Although the shoot was planned for a few months it was not expected to be as successful as it was When the cameras were setup the windows were quite frosted over Therefore the expected outcome was to see the back of an icy window However the windows stayed clear during the entire winter The photographs taken captured ice forming and dissolving on the lake deer passing like ghosts magnificent storms and amazing sunrises The images were compiled together to form the resulting time lapse video given at http inventingsituations net winter on georgian bay In this article there are some code snippets that can be used to make a time lapse video using Python and command line tools In particular the raspistiLl program is used to capture the images and the Python Image Library PIL and mencoder are used to create the final movie Setting up Raspberry Pi and camera Follow http www raspberrypi org help camera module setup to connect a Raspberry Pi camera to a Create a time lapse video with the Raspberry Pi camera SKILL LEVEL ADVANCED i MERS w up Nh Ty ie ye RA G GA HG i of E j K pert be i ee f SeH AR AS EENES A EF J POR Egi EE 4 giy yee fi
52. AC address we wrote down earlier The amp at the end just means that this process will keep running in the background while you do other things like play games Finally test the Wiimote with the command sudo jstest dev input js Game on Now that you have successfully got your controller working why not take it for a spin using one of the games previously mentioned setup an excellent emulator like Picodrive or try some Linux games that can be easily installed Try any of the following games for some light relief sudo apt get install abuse blobwars sudo sudo sudo apt get apt get apt get install install install frozen bubble geki3 hex a hop ltris supertux triplane sudo apt get install xblast tnt xracer sudo apt get install xscavenger intend to write a follow up article where will give examples of how to use each of these different devices from within Python and Linux For all this and much more please visit my Raspberry Pi documentation project at http goo gl EEQ5J Ed I have added this page to my favourites ae 12 combat craft in this classic game SKILL LEVEL BEGINNER Unless you re around my age or older two things are probably true about you One is that you have never played Elite and the other is that the logo below probably looks like it s for a garden centre Fear not am going to let you in on all these strongly guarded secrets After reading this you will be
53. Content Type content text html charset UTF 8 gt lt titlLe gt Garage Control lt title gt lt script type text javascript src webiop1 js gt lt script gt lt script type text javascript gt webiopiC readyCfunctiond Create a Light Labeled button for GPIO 17 var button webiopiC createGPIOButton 17 Garage Append button to HTML element with ID controls using jQuery C controLls append Cbutton Refresh GPIO buttons pass true to refresh repeatedly of false to refresh once webiop1iC refreshGPIOCtrue lt script gt lt style type text css gt button display block margin 5px 5px 5px 5px width 128Q px height 720px font size 1 0pt font weight bold color white gp1017 LOW background color Black gpio17 HIGH background color Yellow lt style gt lt head gt lt body gt lt div id controls align center gt lt div gt lt body gt lt html gt To use the Python script and new HTML file modify the WeblOPi configuration file sudo nano etc webiopi config Find the SCRIPTS section and add the following line garage home pi garage python script py Then find the HTTP line and add the following line doc root home pi garage html Lastly find the REST line and add the following lines gpio export 17 gp10 post vaLue true gp10 post functtion false Then save the file and reboot the Ra
54. Face Python interface Rather than copying the API files the directory where the Python API is can be added to the Starting from a recent Raspbian image make PYTHONPATH variable Use nano to edit the sure that the Raspbian installation is up to date bashrc file sudo apt get update nano bashrc Sudo apt get upgrade y Go to the end of the file and add Then start the raspi config For Minecraft sudo raspi config MCPI_PY HOME mcpi api python if C z PYTHONPATH then export PYTHONPATH MCPI_PY Select the Advanced Options and choose elif PYTHONPATH MCPI_PY then SPI Then set the value to Yas select Ok export PYTHONPATH PYTHONPATH MCPI_PY l i fi and Finish The Python library python unset MCPI_PY pifacedigitalio is already installed in the latest Raspbian image configuration PiFace example Then save the file Python programs can be found in Minecraft traps usr share doc python pifacedigitalio examples There are many actions that could be triggered by hardware input changes In this article some dramatic events that are centred on a given player are used Installing Minecraft If Minecraft is not already installed then type cd HOME Create a new file called McTraps py in the wget https s3 amazonaws com assets minecraft present working directory Add the Python code Nee OL UE p Oe Le LE g shown at the bottom of this page and save the tar zxvf minecraft pi 0 1 1 tar gz l l fil
55. McAlpine Issue Editor Layout Testing Aaron Shaw Administration W H Bell Administration Testing Dougie Lawson Testing Bryan Butler Page Design Graphics Age Jan John Stap Testing Matt Judge Website Tim Cox Testing Nick Hitch Administration Claire Price Testing BEGINNERS GUIDE Where can get help Answers to common questions SCRATCH PROGRAMMING Racing game Frogger Simon GPIO interfacing fractals encryption projectile game Mars lander MINECRAFT Programming Minecraft Minecraft and the GPIO adding QR codes AMY MATHER INTERVIEW The future of young hackers TV AND RADIO Use your Raspberry Pi to watch TV and listen to internet radio GAMING Arcade emulation using game controllers Elite Python game PI STORE A look at the diverse range of applications in the Pi Store PHYSICAL COMPUTING Introduction to the GPIO with buttons switches and LEDs HARDWARE PROJECTS Garage door interface Magic Wana controlling a robot arm PRINTING Connect your Raspberry Pi to a printer RASPBERRY PI CAMERA How to use the Raspberry Pi camera plus time lapse video ALGOID Learn to program video games SONIC PI Programming Christmas carols plus get your groove on with samples synths and studio effects FS Where can I get help There are numerous guides to getting started with a Raspberry Pi that cover the basics of setting up your new computer with the recommended Raspbian Wheezy operating syste
56. Q1 Write down whatever was displayed as the MAC address for your Wiimote We will use this later Universal input needs to be setup so it can be used by users other than root users We will edit the Wiimote rules using nano Enter sudo nano etc udev rules d wiimote rules Add the following line to the bottom of the file KERNEL uinput MODE 0666 Save and close the file by pressing lt Ctrl gt lt X gt together then press lt Y gt and lt Enter gt You need to reboot your Raspberry Pi for the changes to take effect Enter the command sudo reboot Wiimote configuration file We have setup and detected all the hardware We must now create a custom Wiimote configuration file using nano that maps the inputs from the Wiimote to buttons Enter nano home pi mywminput Now enter the following mappings Setup for standard Wiimote Wiimote A BTN_A The trigger is button B Wiimote B BTN_B Setup the DPad Wiimote Dpad X ABS_Y Wiimote Dpad Y ABS_X Setup the remaining buttons Wiimote Minus BTN_SELECT Wiimote Plus BTN_START Wiimote Home BTN_MODE Wiimote 1 BTN_X Wiimote 2 BTN_Y Save and close the file by pressing lt Ctrl gt lt X gt together then press lt Y gt and lt Enter gt Finally it is time to test the Wiimote Enter the following command on one line sudo wminput d c home pi mywminput lt Wiimote address gt amp Replace the lt Wiimote address gt with the M
57. SHARED save and close and compile as above In 1999 Billy Mitchell achieved the first perfect PacMan score of 3 333 360 by eating every possible dot power pellet fruit and enemy Steve Wiebe beat Billy s 1982 Donkey Kong record Many others have tried to get higher Hank S Chien is currently the champion with 1 138 600 points G CHOOSE YOUR WEAPON Adding console game controllers Connecting an XBOX360 PS3 or Wiimote controller to a Raspberry Pi Choose your Weapon It is possible and lots of fun to use a variety of today s modern console controllers for your Raspberry Pi projects They are quite easy to install readily available and you get quite a bit of kit for your buck This article describes how to setup a Raspberry Pi to use a Microsoft XBOX 360 gamepad wired and wireless a Sony PS3 gamepad and Nintendo Wiimote For wireless devices you will need either the XBOX gamepad wireless adapter or for the Wiimote and PS3 gamepad you can use an expensive bluetooth dongle See http www elinux org RPi_USB_Bluetooth_adapters for a list of known working bluetooth dongles have tested all the code on a Raspberry Pi Model B as well as on the new Model B board Before installing any of the software ensure you are using a recent version of Raspbian and have updated your system At the command line enter sudo apt get update sudo apt get upgrade To test all of the hardware an easy piece of softwar
58. _LEFTSHIFT b BTN_C x BTN_A y KEY_C Lb KEY_LEFT rb KEY_RIGHT Lt KEY_Z rt KEY_SPACE dl KEY_A dr KEY_D du KEY_W dd KEY_S guide KEY_HOME back KEY_ESC start KEY_ENTER Save and close the configuration file and exit from nano by pressing the lt Ctrl gt lt X gt keys together followed by the lt Y gt key then lt Enter gt Description of the XBOX config file This file is the basic definition of the controller allowing a deadzone It will run silently meaning it will not output additional information to the terminal The file sets up the DPad as buttons and triggers The next few sections are used to map the right analogue stick as absolute values on the x2 and y2 axes and the left analogue stick as mouse relative values on the x1 and y1 axes as 63 lt maps the four coloured buttons a b x and y and sets each one as a different key or equivalent joystick button in this case Left Shift joystick buttons C and A and the C key lt also maps the triggers and bumpers lt rt Ib rb in the same way Finally it maps the DPad du dl dd dr as the classic W A S D keyboard setup It also sets the Back Start and Guide XBOX buttons to the Home Escape and Enter keys respectively You can now physically plug in your XBOX gamepad or adapter if you have not already done so recommend connecting the gamepad or adapter for the XBOX 360 to a powered hub Do a quick list of USB devices to check that th
59. a background To do this click on the white square in the stage area on the bottom right of the screen Then click on backgrounds in the centre panel and use the built in paint apllication to make something like this Next you will need some sprites one that looks something like a frog and six identical logs Click on the star and paint brush in the New Sprite area to create your sprites My attempt at drawing one was not very impressive play oune fanfare TELE Wow made it Sle move 75 Steps You ll need something like this script for your frog The numbers referring to the positions of things may be different depending on how you drew the background I ve used some sounds found online but you could use the ones that come with Scratch you ll need to import them first Click on Sounds in the centre window Now you ll need six logs each with a script In the pictures you can see the first pair of scripts You ll need to experiment with changing the y co ordinates for the other logs until you get them just right Remember the frog moves by 75 steps each leap hope you find this example helpful and go on to make some fun games yourself As a challenge why not try to get the frog to ride along the logs Log script below You need one for each log In each script change the starting x and y coordinates and make the same change to the y coordinate in the se
60. able to go up to older gamers and watch their jaws hit the floor when you hold your own in a conversation about a seminal game from the 1980s ACORN Back in 1987 Acorn Computers released the successor to the BBC Micro It was called the Archimedes and it was tremendously popular It had a new kind of processor called a RISC chip Reduced Instruction Set Computer Acorn Computers evolved over the years into what is now called ARM and you have an ARM processor in your Raspberry Pi So you could say that the Raspberry Pi is the great great grandchild of the Archimedes Up to you but that mantle probably belongs to Acorn s earlier BBC Microcomputer Acorn made an operating system for their RISC chips called RISC OS which was a hugely popular much loved operating system It is still being developed and in November 2012 RISC OS was released for the Raspberry Pi as an SD card image that you can download If you re a fan of drag and drop OSes you will get on fine with it Fly your Cobra MkIll trading and RISC OS ELITE David Honess Guest Writer Elite was a seminal computer game that changed the entire landscape of gaming Back in the early 1980s computer games were all about getting the highest score before your lives ran out Elite was an open ended game that had no score no levels and no bosses just one enormous galaxy within which you could do whatever you wanted This is what people call a sandbox game Elite o
61. ables with O0 The fire variable is used as a boolean where 0 is false and 1 start vel BEZH Ool is true The start_velocity is the initial velocity E cannon_x to GI given to the cannon ball when the ball is fired The centre of the cannon is stored in the cannon_x and _ cannon_y variables The cannon_angLe is the cannon angle to Ef angle in degrees where zero implies that the cannon et Score to 0E j barrel is pointing straight up After the initialisation the cannon reacts to either the pe jeft arrow a EERE cursor keys or the spacebar Pressing the left and a right cursor keys causes the cannon to rotate one degree to the left or one degree to the right Pressing the up cursor key causes the initial soeed given to the ball to be increased by 0 2 whereas pressing the down cursor key reduces the speed as long as it is greater than zero Pressing the spacebar will cause the cannon to fire if fire is also set to Zero The fire variable is used to prevent the cannon ball from being fired when the cannon ball is in flight When the cannon is fired the costume of the cannon is changed to show a flash Then the fire H variable is set to 1 and y position jof Cannon the global variables that describe the position of the cannon are set After 0 5 seconds the flash is removed by resetting the costume d m amrow pressed of annor Cann
62. al GEL Printed COPIES at tnemMAagpl com JENINE E nternet Raadio m Retro Gaming ALATAAKARKL _ _ Y NOLOgrapny am NE ecm TV PHYSICAL Wiad 1R NY ee eee COMPUTING NUN AOVOt ATM A Minecratt anning P ASE REKE To ANA ollie nl sie ee Rasovarry PI is a trademark of Tne Rasooarry Pi Foundation Mage rttoz www inernagoleor This magazins was created Using a rasooerry Pi comouter MagPi Welcome to this Special Edition issue of The MagPi a whopping 132 pages of articles taken from the past 29 issues This is not a best of issue there are many many other fantastic articles in every issue of The MagPi Instead we consider this Special Edition a taster of what you can find in every issue of The MagPi plus it is a great place to start if you have recently got a Raspberry Pi but are not sure what to do with it Whether you are 9 or 92 there is going to be something here to interest you The Raspberry Pi is a very versatile computer that can be used to learn a variety of different programming languages build simple or complicated electronics projects and even control autonomous vehicles Getting to grips with the Raspberry Pi in all of its possible applications introduces many skills that are vital in industry and research It is also a whole lot of fun for hobbyists This Special Edition c
63. and cat etc default keyboard and checking the entries XKBLAYOUT and XKBVARIANT KEYBOARD CONFIGURATION FILE XKBMODEL logicda XKBLAYOUT ch XKBVARIANT de_ nodeadkeys XKBOPTIONS With this information to hand you can edit the LXDE autostart configuration file to add the line setxkbmap XX YY where XX is the two letter country code and YY the keyboard variant In my case would edit the file by using the command sudo nano etc xdg 1lxsession LXDE autostart Then in the Nano editor append the following line to the end of the file setxkbmap ch de nodeadkeys After saving the file in Nano and rebooting the keyboard layout should be correct within LXDE hope that have given you some pointers to get started with your Raspberry Pi and the encouragement to dig into the available community resources to resolve any small issues that you have For those looking for additional help can highly recommend the following three books that are available in both print and digital formats e Raspberry Pi User Guide by Eben Upton and Gareth Halfacree http goo gl 44UTXR e Make Projects Getting Started with Raspberry Pi by Matt Richardson and Shawn Wallace http goo gl mMU5ZP e Programming the Raspberry Pi Getting Started with Python by Simon Monk http amzn to WyPM97 RACING SCRATCH Dodging arcade game Crash bang wallop Create a simple racing car game One way to start progra
64. and thrilling to play In the previous article a simple projectile motion game was introduced The game included gravity and initial velocity These concepts can be used for other types of games too This month s game introduces the simulation of a Spaceship landing on a remote planet where the landing craft obeys the normal laws of physics In this case the Lander has rocket motors to change its direction The idea of the game is to land the spacecraft on the 4 a landing pad If the spacecraft lands on the surrounding 3 MA aa yir a ground then it will explode If the spacecraft does not A ssd touch down on the landing platform correctly then it will explode too The spacecraft must be travelling slowly ma aal when it touches down or it will be destroyed The Lander sprite has three costumes to show the Lander with its engines on when crashed and when the engines are off The costume with the engines off was copied and then modified to form the other costumes The costumes were drawn on their sides such that an angle of zero degrees corresponds to the spacecraft pointing straight upwards More details of the Scratch system of angles are given in Issue 17 astiaa iai Ee eine tem meas etic ea The Stage Two backgrounds were created for the Stage where the size of the landing pad and the amount of surrounding red rock was chosen to be different Once the background images had been draw
65. appropriate printer you can customise the name and location of the printers These can normally be left at their defaults although you could change the name to one that is easier to remember If you are likely to be printing from the command line then it can also be useful to make the printer name shorter and avoid any spaces An option you may like to enable is Share this printer which can be used if you would like to use the Raspberry Pi as a print server for other computers This will allow you to print to that printer from other computers on the same local network The next page will show available printer drivers and attempt to find the closest match If you have a common printer then there is a good chance of finding an exact match but if not then it may be possible to select a different printer with similar functionality Some printer manufacturers do provide Linux drivers that could be installed instead although it depends upon the manufacturer If CUPS is not able to find a suitable match you should try the website of your printer manufacturer to see if they have any Linux drivers and follow their instructions After selecting an appropriate printer you can choose options for paper size and then the printer drivers will be installed You can now view the printer through the Printers tab where you can change any parameters and print a test page also suggest selecting the printer as the Server default printer through that
66. ards the centre of the planet soeed up again and fly towards it for a few seconds Slow down again now point yourself back to the station and you should now see the entrance is pointing towards you the entrance always points at the centre of the planet Soeed up again to about 1 3 and head in for docking You might need to repeat this manoeuvre a few times to get yourself properly lined up When you re happy with your alignment you can try and match your rotation with the rotation of the space station What tend to do is get quite close wait for the letter box to be horizontal and then floor it through To really get into the Elite world you can read Elite The Dark Wheel a short novella by Robert Holdstock It s available at Watch out for the Vipers Commander Jameson The MagPi wishes to thank lan Bell www iancgbell clara net elite David Braben www frontier co uk 3QD Developments Ltd www riscos com Castle Technology Ltd and RISC OS Open Ltd www riscosopen org for their support with this article TEXT ADVENTURE A Tim Hartnell game in Python ise Stopliterati t self coun Stronghold of the e Dwarven Lords Martin Hodgson Guest Writer SKILL LEVEL BEGINNER rA TIMHARTNELL SGIANTBOOKOF COMPUTER GAMES Se In the early 1980s as early home computers boomed in popularity a little programming knowledge was essential My first computer was a Sinclair ZX81 with 1KB of memory
67. are used to move the ball through the air The speed with which the repeat until loop executes corresponds to the time component The ball is hidden unless it has completely cleared the cannon barrel This is achieved by checking if the ball is not touching grey and is touching the colour of the sky Lastly when the script finishes the global variable fire is set to zero to allow the cannon to be fired again 26 The drum script HEER eit There is one drum script which is forever launched when the green flag is pressed j When the ball is launched the global variable fire remains set to one until E ao 7 hon haste the ball touches down on the ground or 3 i 7 the drum Therefore combining the y l fire variable requirement with touching the ball sprite implies that the program will enter the if statement once for one cannon ball flight Once the program has entered the if condition the drum plays a simple sound and increments the global variable score by 10 points if touching Gall 7 and fire change Score Rotating the cannon In order for the cannon to be rotated around the centre of the cannon sprite the Set costume center button should be clicked Then put the crosshairs for both costumes at the middle of the sprite Projectile motion summary The motion of a projectile can be split into vertical and horizontal components Gravity acts in the vertical direction as a downward acceleration In the program docume
68. awing Script This is the main script that draws the fractal image It s crucial to create the variables correctly These variables MUST be For this sprite only iterations Zl ZI2 ZR ZR2 Z Im Z Re x y These must be For all sprites C Im C Real Col offset Max_It X_zoom Y_ zoom 5 F 2 Re Fo eN X ai j set APE A eee In the first few lines of the script we set up which A area of the screen this sprite will draw on CEng e E aoe Ss 3 to Zim Zim This one does a strip 20 pixels wide from x 200 to x 180 eel Im to y Yieoom When you have made this script you need to duplicate it 20 times LUZ IT lite i Oa Then change the values for x so that each sprite does another 20 pixels E 7 R oo z im Es im oa The last sprite should be in charge of i x 180 to x 200 Shanon Iterations The 2 a F go toxi x y This allows the program to draw to several Sra kartons Mase j parts of the screen at the same time which feo RE will speed things up a lot I ve gone with 20 switch to costume black _ strips you could try experimenting with nace l other arrangements switch to costume colour l set color effect to yi iterations Col_otfset tump maa M 2A EE change 1 Here s an example of ha F the type of images you will be able to create Scratch On c 0 7467 0 3515 Complex Numbers When we wo
69. ce the GPIO ports have not been reset yet Exit the program by pressing lt CTRL gt C Then run the program again and hopefully this time no warning messages will appear This extra code may seem like a waste of time because the program still runs fine without it However when we are programming we always want to try and be in control of everything that is going on It is good practice to add this code to reset the GPIO when the progam is terminated ssf WeblOP I SKILL LEVEL BEGINNER Introduction Have you ever opened your garage door but then forgot to shut it later In this article will show you how to open and close your garage door over the internet using a Raspberry Pi a relay and WeblOPi There is even a webcam attached to the Raspberry Pi such that you can visually confirm that the door is really closed Before you start These instructions assume that sshd is running on Raspbian For older images you can enable sshd using sudo raspi config and then enable SSH via Advanced Options Parts needed You will need the following parts e Raspberry Pi Model B e 12V relay e Adafruit Small Size Perma Proto breadboard e female jumper wires e regular hookup wire e 1N4001 diode e webcam that does not require a powered hub Garage door automation with WEB TO HARDWARE Interfacing with a relay Lewis Callaway Guest Writer The tools needed are a soldering iron screwdriver wire strippe
70. chip manufacturer part PCF8574ADW 1x 10uF through hole capacitor ESK106M050AC3AA 2x 82K through hole resistors 271 82K RC 8x 4mm flat top red diff LEDs HLMPM201 Obtaining parts To build the circuit used the Pi Prototyping Kit from m OpenElectrons com Hn It has multiple eal integrated circuit si footprints and iE unwired through it holes for great prototyping flexibility For the accelerometer used the LSM303 breakout board also from a AA Magic wand assembly The circuit build T PENELI A nnan for the magic wand required soldering of through hole components as well as the surface mount PCF8574 chip The datasheet showed the In Out ports of PO P7 to which connected the eight LEDs In the first build placed a bussed resistor array between the 5V power and the LEDs to limit the current but when tested realized the lights were extremely difficult to see in the daylight then shorted the resistor array and the LEDs became much more visible Connecting the LSM303 breakout was by far the simplest part The Pi Prototyping board has two lC female connections for a quick plug in for breakout boards The full schematic for the project is shown below IC1IC 1 o fi Q Y Q v Q v 9 Q 9 io Q o o Apparatus assembly In order to move the LEDs fast enough to see the image attached the Raspberry Pi along with the Pi Prototyping board to a long flat wooden
71. cially attractive not anly becau e it T can be economically ane scentiically rewarding but you can see that the Message al a betaute tcan be an asethete expere nce much has been loaded like composing poetry ar musik ty length 1 The process of preparing programs for a digital computer Here you can see the result of enciphering the opening sentence of Donald E Knuth s classic book The Art of Computer Programming The cipher text is broken up into a series of lines each line is one element in the list textOut te xtO ut CESET a C C PA C C ea UDAZG VA CY AZFL GYFA QWAL H PASSA Poo POE OLAPFR NFA fy PLFAW GL AC QJFAL WN r OPUARN 10 Nias A SAW GYOLA O length pog Search Options Help YA EA XA A FYNFL VA PC FLAP File Edit QL CC AZFL YV FV QJFAL GYQLH 0 Here you can see what the message looks like after it has been exported and opened in leafpad If you get stuck the program is available here http tinyurl com scratch subs Here s the key used in my example in case you want to try deciphering the whole thing Remember it is a reciprocal key Letters at odd numbered indices map to the next letter while letters at even numbered indices map to the letter before Scratch lists begin with index 1 So K is at index 3 and maps to J at index 4 And J maps back to K O KJTVFEIQ ARX DYSPN HZBMWGUCL If you are interested in learning more abo
72. clone of the Cave Story platformer Star Flite a Star Trek retro game plus an emulator for the Atari800 Other excellent games include Freeciv an empire building strategy game Sqrxz 2 Sqrxz 3 and Sqrxz 4 platformers the impressive Open Arena first person shooter and OpenTTD a simulation game based on Transport Tycoon Deluxe Alas the promising Iridium Rising a 3D space game has been offline for over a year so you can ignore it The first commercial game on the Pi Store was Storm In A Teacup It remains one of my favourite Raspberry Pi games but unfortunately it was recently removed from the Pi Store Hopefully it will be back soon Pi Store Apps 0 79 t t Free wv Free DO CO The second largest largest category in the Pi Store there is an incredible selection of titles ranging from utilities to emulators to media programs to heavy weight applications Examples of the latter are Asterisk a PBX system and the brilliant LibreOffice a Microsoft Office compatible and equivalent office suite Four of the eleven paid applications can be found here 100 Tools Swiss File Knife US 1 99 1 99 provides 100 command line tools such as a simple FIP server find replace text in files treesize split join files create check md5 checksums print coloured text to the terminal and much much more OMX Player Remote GUI US 3 00 1 80 provides a web UI that can be used on a smart phone or tabl
73. cond loop You want 3 rows of 2 logs Rows 1 and 3 should move in the same direction Can you get row 2 to move in the opposite direction go to x y eree D M e ae m position Zo change by 2 First make four quarter circle sprites did it by making a circle first and then selecting the bit needed discarding the rest You ll need each one to have two costumes one a dark colour and one lighter to look like a light is on It s easy to make a second costume After you have made your sprite you ll see a tab called costumes in the center panel Click on it and make a new costume a A That s the hard bit done Now we can write some scripts If you get stuck you can download the project from http scratch mit edu projects racypy 26 95321 The Scripts These scripts control a sprite that is just a button with New Game written on it This is the main script that controls the game gave it to the yellow segment sprite but it doesn t really matter which sprite owns it delete all of TPH tones j jet h man player eto F add Gee to TPU tones Each segment sprite will need these BraadinE cand wait scripts You ll need to vary the numbers E for the notes delete hd of plavertones used 60 62 65 and 67 sek DORE player ue D igagth of CPU tones gt ee tunes J p player toner g human p player l l switch
74. ction and perform for your friends Haunted Bells Loop do sample perc_bell rate Crrand 0 125 1 5 sleep rrand 5 2 end FM Noise use_synth fm Loop do p play chord Eb3 minor choose 12 12 choose divisor 01 div_slide rrand 1 100 depth rrand 1 2 attack 0 01 release rrand 0 1 5 amp 0 5 p control divisor rrand Q 001 50 sleep 5 1 2 choose end Driving Pulse define drums do sample drum_heavy_kick rate 0 75 sleep 0 5 sample drum_heavy_kick sleep 0 5 end define synths do use_synth mod_pulLse use_synth_defauLts amp 1 mod_range 15 attack 0 03 release 6 cutoff 80 pulse_width 0 2 mod_rate 4 play 30 sleep 0 25 play 38 sleep 0 25 end in_thread name t1 loop drums in_thread name t2 loop synths tron bike Loop do with_synth dsaw do with_fx slicer freq 4 8 choose do with_fxC reverb room 0 5 mix 0 3 do n1 chord b1 b2 e1 e2 b3 e3 choose minor choose n2 chord b1 b2 e1 e2 b3 e3 choose minor choose p play n1 amp 2 release 8 note_slide 4 cutoff 30 cutoff_slide 4 detune rrand 0 2 p control note n2 cutoff rrand 8 amp Q 120 end end end sleep 8 end a Reader Feedback just wanted to let you know that really enjoyed Martin Hodgson s Python port of Strongholds of the Dwarven Lords plan on sharing it with some of my middle school students Jason K recently di
75. d as an input GPIO IN to detect the voltage change elinux org Switch 1 When a GPIO pin is set to input it doesn t provide any power and consequently has no distinct voltage level defined as floating We need the pin to be capable of judging the difference between a high and low voltage however in a floating state it s liable to incorrectly detect states due to electrical noise To enable the pin to see the difference between a high or low signal we must tie that pin calibrating it to a defined value 3 3V in this case To tie the input pin we connect it to the Vcc 3 3V pin hence when Switch 1 is open the current flows through GPIO IN and reads high When Switch 1 is closed we short the circuit and the current is pulled to GND the input has OV and reads low The large R1 10kQ resistor in this circuit ensures that only a little Current is drawn when the switch is pressed If we dont use this resistor we are essentially connecting Vcc directly to GND which would allow a large current to flow potentially damaging the Pi To make the circuit even safer in case we get something wrong we add the R2 1kQ resistor to limit the current to and from GPIO IN The switch Four point switches are wired in a very similar manner to two point switches They re simply more versatile as you can have multiple isolated inputs into the same switching point Checking the diagrams pins 1 amp 2 are always connec
76. d functional form Native camera Like any camera the Raspberry Pi camera has a wide spectrum of uses It also allows many parameters to be set But it is important to mention that the Raspberry Pi camera is not like a typical webcam What s the difference Well like the Raspberry Pi it is an educational tool The idea is to get started with the workings and functions of a digital camera to learn what impact each setting has to the final image What s more its 5MP sensor takes great HD pictures and video The camera is operated through terminal commands You send commands to control it via the command prompt The two commands to control the camera are raspistiLl and raspivid Enter each command without any paramaters to see its help Please read pages 104 to 111 for more details about these commands 19 Using the command line provides an understanding of how the camera is controlled It allows you to configure commands in almost any combination you want It also invites you to take the next step and create your own interface for It Capturing the interest Most young kids like my kids love playing video games Games are typically the first type of interaction with computers But many will reach a point where they don t just want to play games they also want to make them as well At the very least they want to understand more about what goes on behind the screen But finding an entry point to basic comput
77. d install for example mpdroid on your Android device or MPobD on your iOS device and remotely control the mpd daemon on your Raspberry Pi You would get some functionality but miss out on the fun of learning some HTML and cgi bin controls of your Raspberry Pi HTML At this point the basic audio functionality is established and we need to add the control interface which is provided by the apache2 server Using the IP address of your Raspberry Pi that you determined earlier using any computer on your local network including the Raspberry Pi itself start a web browser and enter the IP address of your Raspberry Pi into the address line You should receive a message that says It works This is the default web page for this server The web server software is running but no content This means that your apache2 web server is running which it should do automatically after installing it if you followed the instructions The web server basically dishes out web pages which are located on the Raspberry Pi The page you were just shown is actually a file named index html that resides in the directory var www by default You can change that location by altering the apache2 configuration files but have assumed you will use the default configuration that came with the installation as do Note that you need root permission to put files there use sudo before each command We need to replace the index html file with anot
78. d net It contains a lot of discussions problem solutions and mini tutorials Another way to learn programming is with other people Some members have created a team to develop games on Algoid When programs are interesting they are included in the next application release Everyone can learn from one another Everything in the Algoid environment is based on sharing source code and knowledge Teaching Triangle Spiral What are the modifications to do into code to obtain this following figure Solution 1 spiral 2 for set 170 i1 lt 450 1 1 10 3 algo go i z algo turnLeft 121 5 i Algoid is also designed for teachers As Algoid is a free tool all help is greatly appreciated for tutorial writing documentation corrections etc Algoid gives teachers the ability to write their own learning plugins A tutorial and an article explaining how to do that is already available Writing a plugin in Algoid is very simple The teacher just needs to have some basic Java and Swing development knowledge Plugin development is divided in two steps 1 Develop the library with objects and functions needed for the course 2 If necessary develop a new Java panel view and bind it with the library A complete range of tools are available to interact with the AL language The tutorial provides a complete Java NetBeans project starter and documentation This is an example of the library development PluginUtils addMethod
79. ddle i e 25 behind and to the left 25 in front and to the right 400 mc setBlocksCpLayerT1ilePos x 25 playerT1ilePos y 1 playerTilePos z 25 pLlayerT1ilePos x 25 playerTilePos y 1 playerTiLePos z 25 block DIAMOND_BLOCK mc postToChatC Now thats a big diamond floor To recap on the functions covered in this article postToChat message communicate with the player s in the game getBlock x y z get a block type for a specific position setBlock x y z blockType blockData set change a block to a specific blockT ype setBlocks x1 y1 z1 x2 y2 z2 blockType blockData set lots of blocks all at the same time by providing 2 sets of co ordinates x y z and fill the gap between with a blockType player getPos player get the precise position of a player setPos x y z set change the players position player getTilePos get the position of the block where the player currently is There are few other functions available in the API which should be explored Using only the small number discussed in this article it is possible with some imagination and a small amount of programming knowledge to create some quite fantastic constructions tools and utilities love Minecraft It is a tremendously creative game and with the Raspberry Pi edition s API it opens up new levels of creativity and will hopefully encourage more people to try their hand at programming
80. des Emulator 3 Sy Q Z http arcem sourceforge net http arcem sourceforge net 02 Re f la Acorn Archimedes Emulator i What is ArcEm ArcEm is a portable open source emulator for the Acorn Archimedes It s capable of running multiple Developer Information operating systems o Development aims including RISC OS and o Developer Resources ARM Linux o Feature Matrix ArcEm runs on Amiga OS Mac OS X Microsoft Windows RISC OS External project links Unix X Windows ArcEm SourceForge Done 0 25 If you re interested in helping the project check out the Note that NetSurf may display an error saying Bad type This is because it does not recognise the automatic download that the Sourceforge site tries to launch Click on the direct link in Sourceforge and the download will start mix Download Archimedes Emulator from SourceForge net lt J D SEU qB http sourceforge net projects arcem files arcem 1 50 alpha arcem sourceforge Browse Blog Heip i 1 50 alpha2 riso a es Archimedes Emulator Your download will start shortly aos Top Downloaded Projects Job Board cag 1 50 alpha arcem 1 50 alpha2 riscos zip iti Wr f mix ___SDFS RISCOSpi poeta E K i a 374 82 kB complete average 74 96 kB s 0 05total e 3 Boot Apps Diversions D Printing Programming blic Ces JA Utilities Tell RISC OS where yo
81. digitalio PiFaceDigitalC self Listener pifacedigitalio InputEventListenerCchip p1facedigital for i in range 4 self Listener register 1 pitfacedigitalLio IODIR_ON self switchPressed def ListenCself Start Listening to the PiFace self Listener activateC printC gt gt Listening to PiFace def shutdown selLf Stop listening to the PiFace self Listener deactivateC printC gt gt Listeners shutdown def nextConnection Cself Change to the connection associated with the next IP in the List seLf connecttonNumber seLf connectionNumber 1 if selLf connecttonNumber gt seLlf numberOfConnection seLf connecttonNumber Q printC gt gt Using connection to s seLlf tpsLSseLf connectionNumber def getConnection CselLf Return the connection associated with the selected IP if not self ips seLf connectionNumber in self connections keys raise ExceptionC Error no connection to s self ips seLf connectitonNumber return seLlf connections self ips seLf connectionNumber def switchPressed self event Handle switch press events If the first switch has been pressed change to the next IP if event pin_num Q self nextConnection C return None Get the current Minecraft connection mc self getConnectionC 1 3 Use the switch number to decide which trap to run if event pin_num 1 printC gt gt Sand trap sandTrap mc elif event pin_num 2 printC gt gt Vo
82. e Then open a second file called mcControl py and add the Python code shown on page 38 import mcp1 from mcpi block import import time def sandTrap mc pos mc pLlayer getTiLlePos mc setBlocksCpos x 10 pos y 15 pos z 10 pos x 10 pos y 18 pos z 10 SAND mc postToChatC Welcome to the beach def volcanoTrap mc pos mc pLlayer getTiLePos mc postToChatC Warning volcano time sleep 1 mc setBlocks pos x pos y 50 pos z pos x pos y 1 pos z LAVA time slLeep 1 mc setBlocks Cpos x 2 pos y pos z 2 pos x 2 pos y 2 pos z 2 LAVA mc postToChatC A bit too hot def holeTrap mc pos mc pLlayer getTilLePos mc postToChatC Watch your feet time sleep 1 mc setBLocks Cpos x 2 pos y 4 pos z 2 pos x 2 pos y pos z 2 AIR as C2 usr bin env python import mcp1 from mcpi minecraft import Minecraft import pifacedigitalio from McTraps import import sys time class McControL def __init__Cself ips self ips self ips ips Open connections with the Minecraft sessions self connections for ip in self ips try self connections ip Minecraft create ip self connections 1p None except printC ERROR cannot connect to Minecraft on s ip sys exit 1 Store the number of connections and initialise the current connection to be the first one self connectionNumber self numberOfConnection len ips Setup an input event listener one per switch on the PiFace pifacedigital piface
83. e achieved play_pattern_timed 52 48 55 sort 1 Playing two tunes at once When writing a tune we may want to have multiple melodies playing at the same time like when someone is playing a piano with both their right and left hands To do this we use in_thread do in_thread do play 48 Sleep 1 play 52 Sleep 1 end tn_thread do 2 times do play 55 Sleep 1 end end The sections we want to use we encapsulate in 1n_thread do and end so the program knows where to start and finish The program will then play these two sections at the same time We can also use other functions within the in_thread do too inthis case 2 times do Changing the synth pretty_belLL is the default synth but this can be changed There are a number of different synth sounds to choose from These are dull_bell pretty_bell the default synth fm beep and saw_beep C To change the synth we use with_synth followed by the name of the synth we want to use in quotation marks e g with_synth dull_bell Anything that follows this command will be played with this synth Let s try it out with_synth dull_bell play 48 You can hear the note sounds very different even though the same note is being played Try out the other synths and see which you prefer Now let s write a tune in Sonic Pi Good King Wenceslas As it is the Christmas season it seems like a good idea to start by writing a Christmas carol Good
84. e gamepad or adapter has been detected Enter Lsusb You should see an entry for the XBOX gamepad or adapter similar to Bus 001 Device 009 ID 045e 028e Microsoft Corp Xbox 360 Controller or Bus 001 Device 008 ID 045e 0719 Microsoft Corp Xbox 36 Wireless Adapter Finally call the basic configuration mapping using the config switch with your configuration file sudo xboxdrv config XBOX basic_config You can run this command in the background by adding an amp at the end of the command At this point you can either use the command sudo jstest dev input js0 to test the gamepad from the command line or startx and select the joystick configuration tool testing and For the wired gamepad you should be connected and up and running lf you are using the wireless gamepad you will have to sync it to the adapter This is done by pushing the Sync button on the adapter then pushing the Sync button on the gamepad Note Even though the gamepad is connected the XBOX pad quadrant light will continue to flash There is no quick or easy way to turn off the pad once you have finished using it other than temporarily removing the battery pack for a few seconds lf you are keen to test your new setup in Python follow the excellent tutorial provided by Rhishi Despanda in The MagPi Issue 26 pages 12 13 Setting up the PS3 gamepad lf you have the PS3 gamepad wired into a USB hub with the charging cable the Ras
85. e adjusted Since fast movements are not important for time lapse pictures the ISO was kept at 100 as much as possible to ensure high quality images Calculating the average brightness The Python Imaging Library PIL is great for manipulating images in Python import Image im Image openC mypic jpg pixels im size Q im size 1 hist im convertC L histogram br floatCsumC 1 hist 1 for i in range 256 pixels print br This example opens an image and uses the image s histogram to compute the average brightness of the image For a greyscale image there are 256 possible pixel values The histogram counts how many pixels there are for each value The average brightness of the images is calculated by adding up all of the pixel brightness values and dividing by the number of pixels Adjusting the shutter speed To retain the same image brightness as the light increases or decreases either the shutter speed or the ISO setting should be adjusted The brightness from the previous image can be used to adjust the shutter speed deLta 128 br a o ss ss 1 delta 128 where 128 is the target brightness and ss is the shutter speed in the previous Python example To reduce flicker in the time lapse video the average brightness from the last ten or twenty images was used Since the camera used had an infrared filter and the light level was low during the night a brightness threshold was used to avoid storing images in
86. e challenge of writing drivers and figuring out why a piece of hardware connected to your computer does not function as it should before buying any peripherals for your Raspberry Pi check the list of verified peripherals on the Embedded Linux wiki Members of the Raspberry Pi community are extremely active in finding and documenting which devices work and which don t so you don t have to How do set my screen resolution when using a monitor connected by VGA DVI With an HDMI connection the Raspberry Pi can detect and set the resolution correctly in most cases for the screen that is being used For those of us that need to connect a monitor using an HDMI to DVI cable or an HDMI to VGA convertor box the resolution may need to be set manually While not being as intuitive as selecting a resolution from a preferences screen a change can be easily made by editing a config file in the Terminal To find the correct setting for your device look up the resolution list on the Embedded Linux wiki http bit ly 1154mFm lt is normally easier to find the correct resolution in the second list that shows the screen size in pixels e g 1024 x 768 These values are valid if hdmi _group 2 DMT hdmi mode 13 800x600 120Hz hdmi mode 14 848x480 60Hz hdmi mode 15 1024x768 43Hz hdmi mode 16 1024x768 60Hz hdmi_mode 17 1024x768 70Hz hdmi mode 18 1024x768 75Hz Make a note of the hdmi_mode x setting for the resolution you wish to appl
87. e sys package and add the API directory to the system path so that Python can find the Minecraft Python API packages Note please choose the correct path depending if you installed Minecraft or it came pre installed We need to import 3 packages to connect to the Minecraft world build blocks and introduce delays into our program Next we need to use the Minecraft class in the Python library to create a connection to the game s server We will use this object to interact with the game and provide access to all the functions When your program runs the following statement Minecraft will have to be running and you will need to be in a game otherwise you will get errors Using our minecraft object mc we can then interact with the game and send the player a message We will also put a delay in using the time sLeepC function otherwise the whole program will run too fast to see what is going on Hello Mnecraft Horta everything is working Load up Minecraft and create a world or enter an existing one Press ALT TAB to switch to your editor If you re using Idle select Run Module from the Run menu If all has been setup correctly you will see the Hello Minecraft World message in the game Interacting with the player is done through the player class of the mc object allowing us to find and change the position of the player The next block of code finds the player s position using the getPosC command which retu
88. e to use on the Raspberry Pi is jstest gtk and the standard joystick library Enter the following command to install the software sudo apt get install jstest gtk joystick This program should now show up in your desktop ready for you to test You will find the link under Menu gt Other joystick testing and configuration tool Once installed it should display your hardware for example Connecting your hardware A brief note about using the bluetooth adapter have found these can be a little tempremental at times so strong recommend connecting your dongle directly to the Raspberry Pi and connect any other hardware via a powered USB hub e g the excellent Raspberry Pi Hub The bluetooth dongle will work from a powered hub on a low level but the bluetooth stack may not be able to see it Setting up the XBOX gamepad First open up LXTerminal and install the required driver for the XBOX 360 gamepad The same driver is used for both the wired gamepad and wireless gamepad using the adapter Enter Sudo apt get install xboxdrv lt is possible to now use the XBOX gamepad with a variety of Linux games by using sudo xboxdrv siLent However this does not really give you much control over what each axis button does You can use the joystick testing and configuration tool mentioned earlier but it can be difficult to get setup Luckily it is possible to configure the XBOX gamead in a variety of ways Each configuration
89. ect to the Minecraft world and build blocks import mcp1i minecraft as mine import mcp1t block as block Next we create a connection and get the current co ordinates where Steve is standing mc mine Minecraft createC pPos mc player getT1iLePos print Player point pPos x pPos y pPos z Now move Steve teleport him twenty blocks back forty blocks down and twenty blocks to his left and read his new position mc pLayer setTiLePos pPos x 20 pPos y 40 pPos z 20 nPos mc pLlayer getT1iLePos Open the input file generated by qrencode and read every line into an array qrc openC mc gr txt r arrayQR for Line in arc arrayQR append Line qrc close We then initialise the variables we use to position the blocks as we generate them in the Minecraft world rs a print Starting point nPos x nPos y nPos z x nPos x y nPos y 2 NROS Z The file generated by qrencode would come out upside down if we just worked from the first record to the last So we need to read the last line first to build the left hand line of blocks and work backwards to the top right hand line of blocks Python has the reversed function to read arrays from the last record to the first record So each time round this FOR loop the variable 1 is the line we are working on We set the starting position for the height of the block above Steve s position to the length of each record and work down while readi
90. elect the highest turbo overclocking mode that is stable on your Raspberry Pi Compilation is possible with 64MB of RAM allocated to the GPU default setting on a 256MB Raspberry Pi lf more memory is allocated to the GPU it will start to use the swap space a lot more and may fail to compile After completing the configuration exit raspi config and reboot Login using your account and password Install the dependencies libsdl1 2 dev and gcc 4 7 sudo apt get install y libsdl1 2 dev gcc 4 The gcc 4 7 compiler is needed to compile 59 AdvMAME with the least additional effort It is only possible to use the standard system compiler if several of the AdvMAME source files are modified To use the gcc 4 7 compiler type export CC gcc 4 7 export GCC g 4 7 Then unpack the AdvMAME source code configure it and compile tar xvfz advancemame 106 tar gz cd advancemame 0 106 0 configure make The compilation will take four and a half to six hours depending on your overclocking setting When the compilation has finished type sudo make install This is optional but is useful as it negates the need to change directory or set the PATH manually Configuring AdVMAME AdvMAME should be run once to setup all the correct folders and configuration files Type advmame lt will give you a message telling you that it has set up the default options To start LXDE type startx There should now be a hidden fold
91. elle Guest Writer The next step is to add a udev rule to allow the pi user to send commands to the arm To do this create a file called etc udev rules d 85 robotarm rules using the command sudo nano etc udev ruLles d 8 amp 5 robotarm rules with the contents below SUBSYSTEM usb ATTRS 1tdVendor 1267 ATTRS idProduct 0000 ACTION add GROUP pLlugdev MODE 666 To save the file press Ctrl X and then press Y followed by Enter You ll then need to install the Python USB libraries found that the one from the Apt repository was slightly out of date so had to install the Apt version first and then upgrade it using the pip command The command below will do this sudo apt get install python pip y Sudo pip install pyusb upgrade When the Python USB libraries have been installed reboot your Raspberry Pi so that the changes to udev and the pi user account take effect with the command as 7 sudo shutdown r now Connect the arm When the Raspberry Pi has been rebooted connect the arm to a free USB port and turn it on A USB hub should not be needed here To check that the Pi has successfully detected the arm execute the command dmesg grep usb grep 1267 lf the arm has been detected successfully you should see output similar to the line below 252 790554 usb 1 1 3 New USB device found tdVendor 1267 1dProduct 0000 lf you don t see the result above turn off
92. ent Pi3D a Python module that simplifies developing 3D worlds and provides access to the power of the Raspberry Pi GPU In addition to both 3D and 2D rendering Pi3D can load textures models create fractal landscapes and offers vertex and fragment shaders There are also 19 impressive demos Media amp The Pi Store ibrary Upload O Media 12 The MagPi Issue 08 Tr M P 3 Vn ty troduction to sie automatic the lead developer of Akiki Free tii WM The Husseny ssue 06 The MagPi Issue 05 The MagPi Issue 04 munity lec The MagPi is a community The MagPi is a community Krk Free 4 Free Free Free Download Free Download Last but certainly not least is the Media category This is where you will find every issue of The MagPi the first and in my biased opinion the best magazine for the Raspberry Pi and of course it is free There will typically be a short lag between The MagPi being released at the start of each month and it appearing in the Pi Store That is because the Pi Store version is the same version that we use for creating the printed version of the magazine so we are doubly thorough with the quality control Conclusion With over 4 million Raspberry Pis sold worldwide and the Pi Store being located on the desktop of Raspbian it has the potential to be an incredible resource and the go to place for Raspberry Pi content It is easy to upload so why not share you
93. er called advance in your home directory nome pi by default If you cannot see it right click your mouse and tick the Show Hidden box Now download some ROMs As an example the Star Fire ROM can be downloaded from http mamedev org roms starfire starfire zip Then either use the file manager or type mv starfire zip advance rom to move it into place If the selected ROM has samples put those in the samples directory There is no need to uncompress them Next edit the following file nano advance advmame rc and add either device_video_clock 5 50 15 62 50 5 50 15 73 60 on one line for HDMI output or device_video_clock 5 50 15 73 60 for composite output Then change the lines display_resize mixed display_artwork_backdrop yes display_artwork_overlay yes to display_resize fractional dispLay_artwork_backdrop no display_artwork_overlay no Save and close advmame rc MAME can be run from LXDE but using the console will significantly increase the performance and provide a fullscreen display Quit LXDE Running MAME Now that MAME has been fully configured type advmame Name_of_ROM where Name_of ROM is the name of the ROM rather than the game title For example advmame starfire To get started press left cursor key then the right 60 cursor key and repeat a second time To play other games download them and put the ROMs into the advanced rom directory Contr
94. er than b Now a and b can be used to stretch the histogram 1m3 Image evalLCim2 Lambda x x a 255 Cb a where the eval function applies the function given within the parentheses to each pixel in the image and Lambda is an easy way to make a simple function For example the following code snippet prints 12 40000 35000 30000 25000 20000 15000 10000 f Lambda x x 3 print f 4 The histograms above are for the original green and levelled image blue The histogram for the levelled image is quite spread out It is also very jagged because the stretching removes many possible pixel values Fortunately this is not very visible in the levelled image In practice the bounds a and b were based on a rolling average from nearby pictures such that there were no dramatic changes The final levelled image is shown at the bottom right of this page The techniques discussed in this section can be found in the def Licker py script Type deflicker py h for a list of available options The script reads images that are in the present working directory Before After Pi Vision Started Terminal Easily explore all the features of the Raspberry Pi camera SKILL LEVEL BEGINNER Pi Vision is a graphical user interface GUI for the recently introduced Raspberry Pi camera It allows you to control the camera s functions via its command line applications It also displays the co
95. er this you should have a executable file called sixpair Check that your bluetooth dongle is detected by listing the USB devices with the command lsusb You should see your adapter listed for example Bus 001 Device 004 ID 0a12 0001 Cambridge Silicon Radio Ltd Bluetooth Dongle HCI mode Now connect your PS3 gamepad via a USB cable to the Raspberry Pi and use sudo to execute the sixpatir file sudo sixpair If you receive an error about hcitool then again make sure you installed all the above packages The program should list two MAC addresses but they may not be the same For example Current Bluetooth master 00 15 83 0c bf eb Setting master bd_addr to 00 1b dc 0f ed b5 Run the command again and you should see Current Bluetooth master 00 1b dc 0f ed b5 Setting master bd_addr to 00 1b dc 0f ed b5 You have successfully paired your controller with your bluetooth dongle We now need to install the Sixaxis drivers required for the PS3 gamepad to work like a joystick Install the Sixaxis joystick manager We will download the latest archive and compile it To get the driver tarball compressed file enter the following command all on one line sudo wget http sourceforge net projects qtsixa fi lLes QtS1xA 201 5 1 QtS1xA 1 5 1 Sie tar gz Expand the driver with the command tar xfvz QtSixA 1 5 1 src tar gz Naviagate into the driver directory cd QtS1xA 1 5 1 sixad Make the required driver for the Raspb
96. er wire to the coil on the relay Then trim the excess wire from the bottom of the board 4 To prevent the Raspberry Pi from being damaged a 1N4001 diode is needed between the ground and control pins on the relay The silver band on the diode needs to be connected to the control wire Do not connect it to the ground 5 Solder the wires that will connect to the garage door to the normally open pin and ground on the relay Again trim the excess wire after soldering Ro AL E l Ery A ET p a AE TTF s zee ta TEND 4 ae ae r A 4 A a Once this is done the PCB can be connected to the garage door opener Garage door opener connection Be very careful when dealing with higher voltage circuits such as a garage door opener Before making any connections make sure that the electrical power to the garage door is turned off Then use a screwdriver to connect the wires from the relay to the garage door opener If in doubt consult the garage door opener manual to check which wires to use There is a video of the system working at https www youtube com watch v 3glIWNjPUQ pl Information on accessing the Raspberry Pi outside the private local area network is given at http www wikihow com Set Up Port Forwarding on a Router ADC DAC PI 2x 12 bit analogue to digital channels and 2x 12 bit digital to analogue channels Serial Pi RS232 serial communication boa
97. erry Pi book The interaction with Minecraft via the Python API is not limited to just software Input output I O devices that are connected to a Raspberry Pi can react to or produce events in Minecraft This opens up a range of possibilities For example the garage door could open when the Minecraft player goes into the garage or the doorbell could be connected to a Minecraft chat message etc Since the Python API sends commands to the Minecraft server process over a network the Raspberry Pi that is interacting with the Minecraft session could be in the garden monitoring the weather In this article the Minecraft API is used with the PiFace Digital expansion board to create some traps around the selected player PRC takit PI EDITION _ oe W H Bell MagPi Writer PiFace Digital The PiFace Digital expansion board provides a safe way to connect digital devices to the Raspberry Pi via buffered screw terminals The board includes two relays that are suitable for low voltage applications four switches eight digital inputs eight open collector outputs and eight LED indicators The Raspberry Pi communicates with the PiFace via the SPI bus on the 26 pin header There are Python and scratch interfaces that are packaged for easy installation using the Debian package manager More information on the PiFace can be found at http www piface org uk products piface_digital 600 OO Pi
98. es Drag the file into the SD card window just like the other downloads we did and youll now see a file called b5052410 We need to change the type of this file to Zip so that we can extract the game To do this middle click mouse wheel on the file and select File b5052410 gt Set type and enter Zip Now we can extract the zip file into ArcEm s hostfs folder Open the ArcEm folder again then the hostfs folder Double click the 65052410 zip file You will now see the game files Position the hostfs and b5052410 windows so that they are side by side drag the title bar Drag a box around all the game files and finally drag them all into the hostfs folder You will then see a copying dialog box as shown below SDFS RI alx SDFS RISCOSni Arc x SDFS RISCOSpi ArcEm hostfs Copying files Writing DFS RISCOSpi ArcEm hostfs lite Sounds ELmystic CE Programming 3 866 bytes to go 15 files copied Faster Abort Pause support2 Run ArcEm again and this time the game will be available When you get to the Archimedes desktop double click the HostFS icon and you should now see the game Double click the icon named elite to start the game You will be 0 asked if you have a high resolution monitor press Y The game will appear in the bottom right corner as an icon and probably named Jameson the default commander name Click this and you can then start playing
99. es the screen lock icon in the bottom right corner of the LXDE screen not work The basic Raspbian Wheezy image does not come pre loaded with a screensaver hence the lock not functioning and you not being able to find any screen saver preferences in the application menu Fixing the issue is easy enough you just need to install the LXDE screen saver from the terminal by giving the command sudo apt get install xscreensaver Once installed find and launch the screen saver preferences from your application menu You should be immediately prompted that the screen saver daemon is not running Click ok to launch it now Within the preferences dialog you can choose which screen saver the system will use the idle time before it starts and if when the system requires a password to unlock As soon as the screen saver daemon is running the screen lock icon will function correctly What do have to do to get my non UK keyboard to work correctly in LXDE Raspi contig does a good job of easily setting the keyboard layout correctly in the console but those with non UK keyboard layouts often complain about their layout setting not working in LXDE The solution to this issue is quite simple as long you know the two letter country code and layout variant if applicable If you do not know this information you can find it easily from your system assuming you have selected the correct keyboard settings in Raspi contig by using the comm
100. estion mark available within the executing Script In the environment variable QUERY_STRING Here is the content of usr 1l1tb cgi bin pLay sh bin bash echo Content type text plain echo echo if z QUERY_STRING then usr bin mpc play else usr bin mpc play QUERY_STRING fi 56 D The script tests if QUERY_STRING is empty and depending whether it is or not executes the mpc play command with or without the argument Note that is an alternate name for the test command see man The z option returns True if the length of QUERY_STRING is Zero WARNING Please note that do not check the QUERY_STRING variable for illegal characters A malicious user could hack your system in this way use my Raspberry Pi behind a router on a subnet only accessible by friendly users Do not put the system on an unprotected network without adding additional validation Killerqueen So far we have the basic functionality to control the mpd daemon via the mpc program using a web interface All that remains is to turn the Raspberry Pi off using the web interface and that proved to be tricky Just pulling out the power cable works but at the risk of corrupting the file system It s also not very graceful wanted a button on the web interface that would cleanly shutdown the Raspberry Pi My initial attempts to directly call the shutdown command via cgi bin did not work so resorted to a trick From the web i
101. et device to control OMX Player running on the Raspberry Pi Simply enter the given URL in your web browser specify your media folder and then have full control of playlists volume and all the usual media controls FastDosBox US 2 37 1 35 is a fast 386 based PC emulator and is a great way to run 90 s era DOS based games Another similar program on the Pi Store is RPix86 PiCon US 1 00 0 60 is a very flexible configuration manager for hardware tweaking It provides a GUI for overclocking every aspect of the Raspberry Pi but for me its real strength is with its video configuration Visually get the perfect monitor setup quickly and easily No more black bars Multiple presets can be saved so if you take your Raspberry Pi to different locations eg school Raspberry Jam hackspace you can get the best display configuration quickly without changing your home settings was not familiar with XIX Music Player but it is pleasantly surprising and is definitely worth downloading Change the Status to In Progress to see this am using it to listen to internet radio Absolute Radio from the UK Hit FM from Belgium MacJingle Heartbeat from Austria while layout this article using Scribus and all running smoothly on the Raspberry Pi Staying with the music theme there are two music creation applications in the Pi Store Schism Tracker is both a MOD file player and a music composition tool Basic instructions explai
102. first Christmas carol For more information on Sonic Pi see http sonic pi net and have fun creating your next tune SONIC PI 2 0 Get your groove on Bi i yy p amp J 3 JX Discover new samples synths studio effects and Live Coding SKILL LEVEL BEGINNER Live Coding The laser beams sliced through the wafts of smoke as the subwoofer pumped bass deep into the bodies of the crowd The atmosphere was ripe with a heady mix of synths and dancing However something wasn t quite right in this nightclub Projected in bright colours above the DJ booth was futuristic text moving dancing flashing This wasn t fancy visuals it was merely a projection of a terminal containing Emacs The occupants of the DJ booth weren t spinning disks they were writing editing and evaluating code This was a Meta ex gig The code was their musical interface and they were playing it live F iia Samuel Aaron Guest Writer Coding music like this is a growing trend and is often described as Live Coding One of the recent directions this approach to music making has taken is the Algorave events where artists code music for people to dance to However you don t need to be in a nightclub to Live Code As one half of Meta eX and author of Sonic Pi designed version 2 to give you the power to Live Code music anywhere you can take your Raspberry Pi a
103. for kids to be introduced to programming and do you think the tools available are adequate Amy don t think that there is a minimum age if a child can read and type then they can learn to code MagPi As parents what can we do apart from buying a Raspberry Pi obviously to spark our children s interest in computing Amy There are a couple of computing festivals in the UK lnclude in Warwickshire that is aimed at 11 13yr olds and Silicon Dreams in Leicestershire in July Also during the summer holiday in August Young Rewired State hitp bit ly eAtCMI is an event with centres throughout the country holding a week long workshop where children up to 18 years old spend 5 days working with mentors on a project using openly available data sets Then at the weekend all the teams meet up in Birmingham for the Festival of Code where they present their projects MagPi Finally what new projects are you working on at the moment Are you able to give us a sneak peek Amy I ve been offered a touch screen and larger LED array which when they arrive will add into my Game of Life on Pi to show at the Manchester Mini Maker Faire this summer Another idea is a T Shirt of Life which would be a T shirt made from recycled materials with LEDs sewn on the front in a grid formation which would display the Conway s Game of Life What I d really love to see though is a Maker Faire exclusively for U18 s it could be cal
104. ght the LEDS The while loop accesses the look up table for every letter in the string one at time This allows any message inserted into the str variable to be displayed without any other changes in the program if moving from right to left display string if Cacl gt Q time sLeepC 15 while index lt Length for number in LookuptabLle str index oe simplLeWriteByteC number index index 1 turn off leds for a short time to account for letter spacing oe simpLeWriteByte Oxf Ff time sLeep 0015 reset string index Q A link to the code in its entirety is shown below Have fun creating images and messages with your own magic wand LSM303 Magnetometer When creating your own magic wand you may come across various issues with certain wand designs If the wand changes direction at any given time you will encounter a rapid deceleration This causes the static and dynamic accelerometer readings to clash resulting in unwanted input data If you are a mathematician or are extremely knowledgeable about advance physics concepts this may be a fun project for you But for everyone else you may want to use the LSM303 magnetometer The code has a few differences but once you figure out the proper magnetic readings it is very easy The magnetometer reads the Earth s magnetic field so readings will be different depending on direction and location Useful links OpenElectrons com full magic wand project kit and pr
105. he radio station in less than two seconds and should result in some music The first station is a classic rock station 181 fm The Eagle while the second station is a classical music station Venice Classic Radio Italia Look on the taskbar and notice how little CPU is being used approximately 10 To display the current station plus the current artist and song being played enter mpc current To stop listening to internet radio enter mpc stop These are just the basic functions For more details enter the following moc help man mpc You can find a long list of internet radio stations at the following locations http www listenlive eu http www sky fm http www internet radio com and http www radio locator com as 53 Check them out and listen to the diversity To get the required URL look for the streaming file format as used by Winamp iTunes VLC and hardware players This is typically a pls file Download the pls file open it in a text editor and view the URL Add the URL of your favourite Stations to the pLaylList txt playlist file Ed Here are some stations from Canada the Netherlands and the UK to get you started http pub7 sky fm 80 sky_uptemposmoothjazz http pub6 sky fm 80 sky_tophits http ice the musicradio com 80 HeartLondonMP3 http 8573 Live streamtheworld com SKYRADIO_SC http 8343 Live streamtheworld com CHQMFMAAC_SC At this point you could take a shortcut an
106. he LED should also flash on and off three times To exit the program script simply type lt CTRL gt C on the keyboard to terminate it If it hasn t worked do not worry Do the same checks we did before First check the circuit is connected correctly on the breadboard Then check that the jumper wires are connected to the correct pins on the GPIO port Double check the LED is wired the right way round If the program still fails double check each line of the program remembering that Python is case sensitive and correct indentation is needed If everything is working as expected you can start playing around a bit with some of the variables Try adjusting the speed the LED flashes by changing the value given to the time sleep function You can also change the number of times that the LED flashes by altering the number of times that the for loop is repeated For example if you wanted the LED to flash 30 times change the loop to for x in range 0 30 Have a go playing around with both of these variables and see what happens Exiting a program cleanly When a program is terminated due to an error a keyboard interrupt lt CTRL gt C or simply because it s come to an end any GPIO ports that were in use will carry on doing what they were doing at the time of termination Therefore if you try to run the program again a warning message will appear when the program tries to set a pin that s already in use from the previou
107. he Wikipedia article on the Julia set is useful if this rather skimpy explanation has not made the maths clear enough M hide clear The Green Flag Script This script is run when the green flag is clicked You can give it to any of the sprites you ve made I d Suggest giving it to the first The most important thing is to enter the values of the real and imaginary part of C Fea Real eae ofc EALE _ 5e t Real to answer EN ar gt to answer et Col oset za fi julia_ black A monochrome image from an earlier version of the program PETE Let s make a fractal inii 2 Secs Imaginary part aF J and wait The colour image lower down on this page is known as Douady s Rabbit and has the following values for C Real 0 123 Imaginary 0 746 Next you can specify the maximum number of iterations l d suggest you try about 20 at first If you choose more you ll get a smoother range of shades in the picture but it will take longer to draw Setting the zoom allows you to focus in on a smaller area A zoom of 1 is normal size You could see what happens when you enter 2 or 3 instead Complex Numbers to try If you search on line for Julia set fractals you will find plenty of values for C to use in this program Here are a few that have used while testing this program Real 0 4 Real 0 8 Imaginary 0 6 Imaginary 0 156 Real 0 1 Imaginar
108. he amen break to get us started In the main code editor window of Sonic Pi type the following and then hit the Run button sample lLoop_amen Boom Instant drums Go on press it a few times Have fun I ll still be here when you ve finished But that s not all We can mess around with the sample Try this sample Loop_amen rate 0 5 Oooh half speed Go on try changing the rate Try lower and higher numbers What happens if you use a negative number What if we wanted to play the loop a few times over One way to do this is to call sample a few times with some sleeps in between sample lLoop_amen sleep 1 753 sample loop_amen sleep 1 753 sample lLoop_amen However this could get a bit annoying if you wanted to repeat it 10 times So we have a nice way of saying that with code 1 times do sample loop_amen sleep 1 753 end Of course we can change the 10 to whatever number we want Go on try it What if we want to loop forever We simply say loop instead of 1 times Also I m sure you re asking what the magic 1 753 represents and how got it Well it is the length of the sample in seconds and got it because asked Sonic Pi puts sample_duration lLoop_amen And it told me 1 753310657596372 just shortended it to 1 753 to make it easier for you to type in Now the cool thing is we can combine this code and add a variable for fun sampLe_to_Loop lLoop_amen sampLe_rate 0 5 Loop do samp
109. he line usr local bin kiLlerqueen sh amp in the file etc init d rc Llocal This is executed at boot time and starts the ki LLerqueen sh script as a background task We have come quite a way in the process of turning the Raspberry Pi into an internet radio We covered the mpd and mpc combination plus setting up a web server We created simple forms with framesets and interacted with the Raspberry Pi via cgi bin scripts Please be aware that this is not the only way to achieve this functionality but for me it was both fun and instructive All code is available from http Ziemann web cern ch ziemann gadget rasp iradio raspiradio tar gz es 57 HISTORIC ARCADE GAMES ween MAME Multiple Arcade Machine Emulator si amp ee amp rr S lo i Rwa t When arcades ruled remember the first video games arriving in the late 1970 s Historically amusement arcades were located at holiday destinations and filled with electro mechanical games and pinball machines dating back to the 1950 s and 60 s Arcades changed with the introduction of the first commercially successful discrete logic or digital video game Pong Atari Inc 1972 and then with second generation CPU powered machines Space Invaders Taito Midway 1978 Asteroids Atari Inc 1979 Galaxian Namco Midway 1979 Defender Williams Electronics 1980 Pac Man Namco Midway 1980 and Donkey Kong Nintendo 1981 A behemoth of
110. he positive sign 3 Plug in your switch When breadboarding make sure all of the legs are in separate rows To achieve this straddle the central channel on the breadboard 4 Add the 10kQ resistor Connect this from Switch pin 1 to the positive rail of the breadboard Orientation of standard film resistors is unimportant 5 Connect the switch to Ground Use a breadboard jumper wire to hook switch pin 3 to the ground rail 6 Connect the switch to the 1kQ resistor Add this resistor between switch pin 1 and the 10kQ resistor and take it to a clear rail 7 Connect the switch to the Signal Port We ll be using GPIO P17 to detect the 3 3V signal when the switch is pressed Simply hook up a jumper between GPIO P17 pin 11 on the Raspberry Pi and the 1kQ resistor rail That s our circuit built In the next article we ll write a simple program in Python to run when we press the switch All breakout boards and accessories used in this tutorial are available for worldwide shipping from the ModMyPi webshop at www modmypi com Raspberry Pi Part 2 Buttons and switches are a fundamental part of physical computing This beginners tutorial is designed to teach the basics of physical operation with the Raspberry Pi using a simple momentary switch setup In the previous article we discussed and built our switch circuit In this part we will go through the steps of programming and interacting between the Raspberry
111. her one that provides the internet radio interface will show you how in a minute but here is a screenshot of what ended up with Eile Edit View History Bookmarks Tools Help 192 168 1 102 e Radio ann zimmer che Stop BBC WBJC NDR2 Whatis playing Available Stations Turn OFF Radio WohiaLnnek et addr 1192 168 1 102 Bcast Bpr 168 1 255 Mask 255 255 255 0 et addr 127 0 0 1 Mask 255 0 0 1 fm The Ea agle Your Home For REAL Classic Rock Fleetwood Mac Gold Dust Woman eas Public eee http 7279 tiv streamthew ae 1 443 piel ig nara htt TP ioe a STL nati evhhew _mpl_ws eieuk pr 25 100 57 8010 e e Ch assic Radio Italia Fra patsy relay feet fm 18130 http Nb je streamgu ys 0rg aoe FM wae Fro ntPo rch Blue egrass From The FrontPorch Al Batten And The Blue Grass Reunion The Old Cro Schubert 1797 1828 Impromptu No 3 Op 90 Trascrizione di Fritz Kre ttp 12139 i7 be http into ati e p2 192 On the left hand side there is a red area with several useful links like the different internet radios scattered in my household links to Swedish TV programmes links to sites with internet radio stations and other useful things On the right hand side in the upper half of the screen there is the radio interface with buttons to start and stop listening plus move to the next or previous station Below that there are twelve buttons for the twelve
112. how long the camera collects light to create an image where a longer shutter speed will create brighter images but will be more likely to have motion blur if there is movement in the frame On the Raspberry Pi the slowest shutter speed available is about 2 5 seconds longer speeds will cause the camera to hang and not take pictures until the Raspberry Pi is rebooted To be safe the maximum shutter speed was set to two seconds Shutter speeds in raspistill are measured in microseconds Therefore a shutter speed of 1000000 implies one second The ISO setting controls the sensitivity of the sensor within a range of 100 low sensitivity to 800 high sensitivity When the ISO setting is high brighter images are taken but they will also tend to be much more noisy The command raspistill can be used to take a photograph with a set shutter speed and ISO setting The automatic settings should be avoided apart from AWB auto white balancing raspistiLl awb auto n t 10 ss 1000000 ISO 100 o mypic jpg Python can be used to run raspistill by using a subprocess call import subprocess SS 1000000 1S0 100 command raspistiLll n t 10 command ss str Css command ISO str iso o mypic jpg sSubprocess caLlLCcommand shell True The goal for the project was to keep images at about the same brightness over the course of a day The brightness of each image was measured Then the shutter speed and ISO setting wer
113. ian build sudo make Make a directory to store different profiles for the PS3 gamepad with the command sudo mkdir p var 11b sixad profiles Finally install the required driver that you have just made Enter as 6 sudo make install sudo checkinstall The last command automatically creates a package for you so you can easily uninstall it later if you no longer need it or want to use a different system To uninstall enter the command sudo dpkg r sixad Now to test it launch temporary a sixad daemon Sudo sixad start lf the gamepad is still plugged in unplug it and then press the PS button on the Dualshock gamepad If you feel a vibration then it works Congratulations You may not feel a vibration but it should display some sort of connection on the screen For example you should see somethink like sixad bin 6860 Connected Sony Computer Entertainment Wireless Controller 04 76 6E F1 74 3E Note On both the PS3 gamepads that have tested NEITHER vibrated Although both are correctly detected using the joystick testing and configuration tool one of the gamepads shows no signs of connection no red flashing LEDs while the other continuously flashes Both are offical Dualshock 3 Sixaxis gamepads but both are also second hand and cannot vouch for the working vibration as do not have a PS3 To make the sixad daemon run automatically every time you start the Raspberry Pi enter the follow
114. iark greenend org uk sgtatham putty download html You also need to set OpenELEC to allow a SSH connection From the XBMC main screen select SYSTEM then OpenElec and click on Services Select the SSH option and click to enable it Reboot the Raspberry Pi Once PuTTY is installed on your Windows PC simply run the file putty exe After the PuTTY screen has opened enter the IP address of your Raspberry Pi Leave the Port as 22 and choose SSH as the connection type Click on Open then enter the username and password For OpenELEC the default username is root and the default password is openeLec Session Basic options for your PuTTY session i Logging y a Teminal i Keyboard Specify the destination you want to connect to Host Name for IF address Poort E bpa 192 168 1 93 2 i Features Connection type Window Raw Telnet Rlogin SSH Seral h Appearance Behaviour Translation i Selection Raspberry Pi Colours Defaut Setings i Raspbemy Ph RES n Connection a Data TNC 270 Tupe i Telnet Delete Rlogin H SSH i Serial Load save or delete a stored session Saved Sessions Close window on exit Ci Aways Never Only on clean exit Open Cancel OOT R ALINE MHH INTERNET RADIO powered by Raspberry Pi TT TTT across the world SKILL LEVEL INTERMEDIATE A few years ago hacked a network router to become an internet radio device by
115. if c lt 2 or c gt 14 or b lt 2 or b gt 14 a b c x d eS l for f in Crange 0 136 2 b datal f c data f 1 alb c s aLz Ly s Makes sure the gold isn t in a wall m 15 return def show_map GOSUB 480 help in original BASIC version global b m apte CNI OS print North J IS while b gt 0 strng for c in Crange 1 16 mir GLO kel a a strng C elif b d and c e strng elif a b c s strng print Cstrng a g3 b 1 print South m 15 ald e s Here I ve omitted two lines from the BASIC version 600 FOR J 1 TO 2000 NEXT J Makes the prgram pause 610 CLS Clear screen Not possible in Python Shell def move Lines 50 to 410 Main game script from BASIC version global m d e m 1 one Wane O eE N print STEP NUMBER m if ald 1i e s print C NORTH OPEN elif a d 1 e x printC NORTH WALL if a ld 1 e s print C SOUTH OPEN elif a d 1 e x printC SOUTH WALL if ald e 1 s print C EAST OPEN elif ald e 1 x printC EAST WALL if ald e 1 s print C WEST OPEN elif a d e 1 x printC WEST WALL print THE DWARVEN SOURCE BEAM READS 100 abs Cz d 10 abs y e print C Which direction do you want to move a_string input N north S south E east W west H help a_string a_string upper Convert Lowercase to upper case if a string H
116. imation we will limit the number of simultaneous stamps on the screen algo setStack 1 only one stamp in stack The object can now be animated with an event util pulse function O ship draw j 40 AL is a complete functional language Functions can be passed as parameters and returned as results Events are based on a callback mechanism If a function is passed as a parameter then it is only called when necessary In this case every 40 milli seconds Up to this point nothing is moving To show some animation let us modify the position each time like this utiL pulse function ship y Update position ship draw bey aD Now we will add the ability to move the ship according to the mouse position with the event algo onMove C algo onMove function x y ship x X Note The mouse coordinates are given in the x and y parameters of the callback function Thus it is possible to connect the ship x and y coordinates to the mouse x and y coordinates That s it Now you are able to move a stamp in Algoid This example can be used as the basis of a complete game The steps of the program are 1 Define objects their coordonates their graphic stamp s their draw method etc 2 Hide the turtle 3 Determine how many stamp should be drawn simultaneously 4 Create frame drawing with util pulse 5 Create behaviours with Algoid s events like onMove onClick or onTouch onG
117. in the if condition If input_value False that we created in our original program Add the following below the line print Who pressed my button line 9 making sure the indentation is the same for x in range 3 Any code below this function will be repeated three times Here the loop will run from O to 2 therefore running 3 times Now we will add some code in the loop such that the LED flashes on and off GPIO output 18 True time sleep 1 GPIO output 18 False time sleep 1 The LED is triggered on with the command GP1 O output 18 True However since we do not want to immediately turn it back off we use the function time sleep 1 to sleep for one second Then the LED is triggered off with the GPIO output 18 False command We use the time sleep 1 function again to wait before the LED is turned back on again The completed program should be of the form import RP1 GPIO as GPIO import time GPIO setmodeCGPIO BCM GPIO setup 17 GPIO IN GPIO setup 18 GPIO OUT while True input_value GPIO input 17 if input_value False printC Who pressed my button for x in range 3 GPIO output 18 True time sleep 1 GPIO output 18 False time sleep 1 while input_vaLlue False input_value GPIO input 17 Save the file and open a new terminal window Then type the following command sudo python button_Led py This time when we press the button a message will appear on the screen and t
118. in the vertical plane 0 90 180 or 270 degrees and a variable to indicate if the magpie should be plotted or deleted A nested for loop iterates through the 2 D array and plots the blocks Because some block types cannot be placed in free space it is important that you build from the bottom up When deleting i e replacing all blocks with block type Air you need to delete from the top down If you delete from the bottom up some bricks will fall before they can be deleted thus leaving a pile of rubble on the ground You should take a backup copy of your world before creating large structures like this as you will likely use the wrong coordinates My 10 year old daughter Emily was very unhappy when obliterated her village Take a copy of the hidden minecraft directory in your home directory use Ls A to see all hidden files in a folder plus also the games directory in the mcpi directory es Interfacing Minecraft with PiFace Digital SKILL LEVEL INTERMEDIATE Minecraft is a very popular game that has more recently been used as a teaching tool to encourage programming The Raspberry Pi version of Minecraft is available for free The game is packaged with a Python application programmer interface API which allows interactions with players and blocks An introduction to this API was given in the previous article There are also additional teaching resources such as Craig Richardson s Python Programming for Raspb
119. ing command Sudo update rc d sixad defaults To end the connection with your gamepad once you are finished using it run the following two commands Sudo sixad stop Sudo service bluetooth stop This will free up your PS3 gamepad and it should return to sleep Nintendo Wiimote You will need to use a bluetooth dongle It is recommend to always plug the bluetooth dongle directly into one of the USB ports on the Raspberry Pi not the USB hub Ensure that the bluetooth driver is correctly installed with the command sudo apt get install bluetooth To check the status of the bluetooth driver enter the command sudo service bluetooth status You should see something similar to ok bluetooth is running lf you do not see this then enter the command sudo service bluetooth start Now install the CWiiD WMInput and WMGui packages These are required to use a Wiimote Sudo apt get install python cwiid Sudo apt get install wminput wmgui Run the hcitool to check the bluetooth adapter sudo hcitool dev Start the Wiimote in detection mode by either 66 pressing the small red sync button or holding buttons 1 and 2 on the Wiimote until the lights flash Now run the hcitool scan command to locate your bluetooth Wiimote Enter sudo hcitool scan After a short period of time it should list your Wiimote as a Nintendo RVL For example you should see something like Scanning Q00 1D BC FB 79 FQ Nintendo RVL CNT
120. ing is easier said than done Fortunately the Raspberry Pi s camera is proving to be that entry point It not only captures their interests but also seems to be maintaining it My kids can now type in commands that do something simple but rewarding and which provide immediate visual feedback The trick here is to get the kids to take pictures of themselves usually while pulling funny faces It is enough for them to type in another command and make another picture Pi Vision Where does Pi Vision fit into all this Pi Vision is a simple open source application which attempts to leverage the entry point The incentive of Pi Vision is to allow for easy use of the Raspberry Pi camera while also serving as an instructional tool Pi Vision Started Client Screen Size 1680 x 1050 Main Photo Video Settings Info Pi Vision A Simple Controller for the Raspberry Pi Camera Test Camera Preview Terminal Each time a picture or video is captured with Pi Vision it shows you what commands are sent to the Raspberry Pi to control and operate the camera This assists novice users in understanding the command structure What s more since Pi Vision is open source you can review and copy the code plus make changes to suit your needs and interests In the next section of this article you will find more details about the Pi Vision open source project For now assuming that you already have your Raspberry Pi camera setup and running lets
121. installed and then hide the Raspberry Pi behind the HDTV e Use a remote control app on your Android iOS or Blackberry smartphone to control XBMC via your home Wi fi so you can select and watch catch up TV programmes on your HDTV e No Linux commands are needed to install or use OpenELEC with the Raspberry Pi My style of television watching over the last few years has switched from live viewing and recording to predominantly using catch up TV Catch up TV is particularly helpful when a missed programme gets a good review the next day from friends or from TV reviews in newspapers or on the web am going to show you how to install catch up TV services using XBMC and the OpenELEC distribution on a Raspberry Pi to work with your HDTV It takes about 60 minutes to set up and requires no use of Linux commands either Permanent components e Any Raspberry Pi e Good quality 5V power adapter for the Raspberry Pi minimum 700mA or greater e HDMI cable to connect the Raspberry Pi to your HDTV e Wi fi nano USB dongle if you do not have easy access to a wired internet connection the Wi fi dongle from hitp www thepihut com uses built in drivers and does not require a powered USB hub e 8GB SD card loaded with the latest NOOBS software from http www raspberrypi org e Android iOS or Blackberry 10 device with a downloaded app to remotely control XBMC e g XRMT for Blackberry 10 OS or Official XMBC Remote for Android o
122. int You can now use xhtml2pdf on the command line to convert from an HTML page to a PDF file You could try using a saved web page but in many cases it will only partially work due to the common use of Javascript which isn t rendered by xhtml2pdf Instead recommend creating the pages using standard HTML markup usr bin env python Print a file to the printer Below is a Python script which will list the available printers and then print to the first printer in the list This is an example created to show how you can add printing capability to your own program If you are including this in import cups from xhtml2pdf import pisa def main your own application then you should add additional error checking as well as functionality for the user to select the appropriate printer if multiple printers are installed Line 4 imports the cups library and line 5 the xhtml2pdf library note that it is imported as pisa which is the former name for the library and is how we will refer to it later Lines 11 to 14 generate some basic HTML formatted content While you could include the usual HTML headers and head section which you would normally include in an HTML page have just added the content of the body section which is sufficient for xhtml2pdf We then use CreatePDF on line 16 to process the conversion and save the PDF to the file specified in the variable filename have included a very basic check for PDF errors at
123. ions Of course the instant gratification advantages of digital downloads were not lost on game console manufacturers with Microsoft Sony and Nintendo all introducing digital download stores for their respective game consoles Digital app stores are less prevalent for Windows based PCs with notable exceptions being game centric Steam and Origin Introducing the Pi Store Ultimately all of the previously mentioned digital download stores have a commercial interest for the host company But this was not the case for the Raspberry Pi Foundation when they launched the Pi Store Instead of thinking how much money could be made they saw all the advantages of having an app store dedicated to the Raspberry Pi a place where developers of all ages can share their creations with the Raspberry Pi community a place where complete beginners can install and remove great Raspberry Pi titles without having to go near a command line a place where every Raspberry Pi user can discover new content for their computer Unfortunately some did not see this and criticised the Foundation for teaching kids capitalism But is this any different from giving kids pocket money for doing chores Having said that there are currently 100 apps and at the time of writing only eleven cost money and you can buy them all and still have change from US 20 00 13 00 The Pi Store content is divided into five categories Games Apps Tutorials Dev Tools a
124. ions to enter IP addresses for up to three nameservers By default these will already have the IP addresses of the DNS servers from your internet provider but you can choose to use others For example OpenDNS provides enhanced security using its own free to use DNS server IP addresses at http www opendns com Ed ag changed these to the Unblock Us DNS servers so as an ex pat can still watch BBC iPlayer content in Canada At this point it is a good idea to click the Power button on the main screen and reboot the Raspberry Pi When OpenELEC restarts you should have a working network connection Step 3 Other important XBMC features 1 Is the display too large for your screen or do you see a black border To change the screen size select SYSTEM then Settings and click on Appearance In the Skin section change Zoom up and down keys to set an appropriate reduction 2 Stop RSS feeds across the bottom of the Confluence screen From the Confluence screen select SYSTEM then Settings and click on Appearance In the Skin section click on Show RSS news feeds to turn it off 3 To allow remote wireless control of XBMC select SYSTEM then Settings and click on Services In the Webserver section click on Allow control of XBMC via HTTP to turn this option on Note the default username is xbmc with no password You can optionally change these In the Remote control section click on Allow programs on other systems to control XBMC
125. iption for each can be found below base anti clockwise Rotates the base anti clockwise base clockwise Rotates the base clockwise Shoulder up Raises the shoulder shoulder down Lowers the shoulder elbow up Raises the elbow eLbow down Lowers the elbow wrist up Raises the wrist wrist down Lowers the wrist grip open Opens the grip grip close Closes the grip Light on Turns onthe LED in the grip Light off Turns the LED in the grip off stop Stops all movement of the arm Try this out yourself by editing the commands csv file in the repository and replacing the contents with your own instructions to the arm Running your program Running your program is as simple as running the command commander py commands csv from the command line on your Raspberry Pi The script will output each step of your program as it runs You can find a sample output of my terminal below as an example run using the commands csv file in the repository commander py commands csv Running command shoulder up for a duration of 1 000000 second s with a pause of 1 000000 second s Sending command shoulder up The series of commands will then finish with Done AlL commands executed Stopping the arm That s it If you have any ideas on how this could be improved or expanded maybe by adding some sort of control logic to the commands file for example then feel free to contact me via the contact form on my blog at
126. is easy to use and has the advantage that it doesn t need to be used in a graphical environment Therefore it can be used from within a command line program or a daemon application running in the background First we will install some additional packages The python cups library provides the module that enables Python to communicate with the CUPS printers python pip will make installing xhtml2pdf easier and the python dev libraries are needed to allow pip to install some of the libraries used by xhtml2pdf Install these using the normal apt get install Finally on lines 29 and 30 we select the first printer and print the file using the printFile command sudo apt get install python cups python p1ip python dev When creating the script you need to create a name that doesn t conflict with any of the names of the library files imported For instance do not call the script cups as that will conflict with the cups library used cupsprint py during my testing Then install xhtml2pdf using pip sudo pip install xhtmL2pdf This last stage will take a while to run as it will download and compile some additional libraries This has shown one of the ways that you can add printing to your own Python application This method has been chosen as it s easy to implement and can be used for command line and server applications as well as graphical applications So over to you what projects do you have that need to be able to pr
127. it the Run button again You should hear the note go higher Try changing the attack release and cutoff parameters Listen to the effect they have Notice that attack and release change the length of the note and that cutoff changes the brightness of the sound Try changing the synth too fun values are prophet dsaw and supersaw Press the Help button for a full list There are lots of other things we can do now but unfortunately I m running out of space in this article so I ll just throw a couple of ideas at you First we can try some randomisation A really fun function is rrand It will return a random value between two values We can use this to make the cuffotf bounce around for a really cool effect Instead of passing a number like 70 to the cutoff value try rrand 4 120 Also instead of only playing note 45 let s choose a value from a list of numbers Try changing 45 to chord a3 minor choose Your play line should look like this play chord a2 minor choose attack release 0 3 cutoff rrand 40 120 Now you can start experimenting with different chords and range values for cutoff You can do something similar with the pan value too play chord a2 minor choose attack release 0 3 cutoff rrand 40 120 pan rrand 1 1 Now throw some FX in mess around and just have fun Here are some interesting starting points for you to play with Change the code mash it up take it in a new dire
128. ittle stretched you can fix this by pressing F12 and a small command prompt will appear at the bottom of the screen Type wimpmode 28 and press Enter twice Now you should have a 4 3 screen ratio 640x480 at 256 colours You can make screen mode 28 permanent by setting it as the default screen mode in the Archimedes configuration First double click on the Apps icon in the bottom left and then double click Configure It will appear in the task area in the bottom right Click on it and then click the screen icon Set the Default screen mode setting to 28 You can click where the current number is and edit it as text In the bottom left corner of the screen you ll see an icon named HosiFS This corresponds to the hosifs folder back in Raspberry Pi land that you may have noticed before see below Anything you put in here can then be accessed by the emulated Archimedes Guess what we need to put in here The game ak ea 4 T i ay IArcEm COPYING The emulator does not shut down very gracefully if you middle click on the Acorn icon bottom right you can choose Exit from the context menu But this just causes a hang Until this bug is fixed you need to power cycle your Pi turn it off for a second then back on again It is perfectly safe to do this When the Pi has rebooted open NetSurf again and navigate to http www iancgbell clara net elite arc The file we want is marked Click here to download Arc Elite 419 Kbyt
129. ively click the make key button It s vital that your contact has a copy of your key so that he she will be able to decipher your message Right click cipherAlpha and choose export to save it to a text file for sharing add item index of PlainAlpha to CipherAlpha delete index of plainAlpha Sprite 5 loads plain text from the getText list into a variable called inputText It puts in a character to stand for line endings oe _ of getText inputTeet to fl Sprite 6 loads cipher text you ve imported into getText It pa ta ignores any spaces these are put in to separate the cipher L til _ count length text into 5 character words PS e gettext set index to eet length te length of gettext i i set inputet fto E set letter jto letter i index of lina set CHN fto lt j count gt length line to item aunt of Getlext Ebr inngi 3 oe n input Text to ane join inputText line E Sprite 2 is run when the encipher button is clicked and sprite 3 does the deciphering Both call the cipher script before outputting the properly formatted text to the textOut list set ee to letter index of autputText E line to join dine E j lime to t stOut set letter to letter index of autputText i count fto E Se tire 7 to gt join letter set lire ite join line letter change index by isi ee index add line to textOut He ange Af
130. lcano trap voLcanoTrap mc elif event pin_num 3 printC gt gt Hole trap holeTrap mc else raise ExceptionC ERROR pin number is out of range Lf __name__ __main__ If no command line options are provide assume that the localhost is running Minecraft ips if LenCsys argv 1 ips L LocaLhost else ips sys argv 1 Start the MineCraft connections and PiFace Listeners The Listeners are shutdown went the program exits mcControl McControl ips try mcControL ListenC while C1 time sLeepC1000 except KeyboardInterrupt mcControl shutdown C Minecraft The IP address of a Raspberry Pi can Set the mcControl py fil table et the MCUONTrol py THe aS executa be found by typing chmod 755 mcControl py l l ifconfig Then use a new terminal window to start Minecraft using the local Raspberry Pi in a terminal window cd mcpi Once the mcControl py program is running minecraft pi pressing switch 0 on the PiFace will cause the program to change the connection used for the Once Minecraft is running and a world has been tricks This is useful when more than one created Click on the tab key to break the Minecraft session is in the connection dictionary window focus Then select the original terminal Buttons 1 2 and 3 run the sandTrap window and type volcano Trap and holeTrap functions respectively mcControl py To prevent a lot of CPU being used the By defau
131. le sampLe_to_Loop rate sample_rate sleep sampLe_duration sample_to_Loop rate samplLe_rate end Now you can change the Loop_amen to any of the other loop samples use the auto complete to discover them Change the rate too Have fun For a complete list of available samples click the Help button 129 Adding Effects One of the most exciting features in version 2 0 of Sonic Pi is the support for studio effects such as reverb echo and distortion These are really easy to use For example take the following sample trigger code sample guit_e_fifths To add some reverb to this we simply need to wrap it with a with_fx block with_fx reverb do sample guit_e_fifths end To add some distortion we can add more fx with_fx reverb do with_fx disorttion do sample guit_e_fifths end end Just like synths and samples FX also supports parameters so you can tinker with their settings with_fx reverb mix 8 do with_fx distortion distort 0 8 do sample guit_e_fifths end end Of course you can wrap FX blocks around any code For example here s how you d combine the Lx1_techno FX and our drum loop with_fx 1x1t_techno do Loop do sample lLoop_amen sleep sample_duration loop_amen end end For a complete list of FX and their parameters click the Help button Live Coding a Synth Loop Now we ve mastered the basics of triggering samples sleeping and looping let s do the same with some synths a
132. lePos z mc setBlockCplayerTilePos x 1 playerT1ilePos y 1 playerTilePos z bLockBeLowPLayerType mc setBlockCplayerTilePos x playerTilePos y 1 playerTilePos z 1 blockBelowPlayerType mc setBlockCplayerTilePos x 1 playerT1ilePos y 1 playerTilePos z bLockBeLowPLayerType mc setBlockCplayerTilePos x playerTilePos y 1 playerTilePos z 1 blockBelowPlayerType mc postToChatC Trapped you time sLeep 5 Minetrah Pi editien Lsieisisicisic We have now trapped our player within four blocks providing he doesn t break out In order to set him free we need to remove a block Removing blocks is done using setBLock but rather than making the block solid like WOOD or STONE we set it to AIR mc setBlock CplayerTilePos x 1 playerT1ilePos y 1 playerTilePos z block AIR mc postToChatC Be free time sleepcs A full list of all the available blocks can be found in either the Minecraft API specification or in the block py module in the Python API library mcpi ap1 python mcp1 block py The API also allows you to set many blocks at a time allowing you to create cuboids very quickly using the setBLocks C command It works by specifying 2 sets of x y z coordinates between which it then fills the gap with a certain block you pass as the final parameter The following code will create a diamond floor underneath our player 50 blocks across x 1 block up x 50 blocks along with our player in the mi
133. led the Mini Makers Faire It would be great if it were run like YRS with a week long workshop beforehand using Hack Spaces and FabLabs with volunteer mentors and then at the weekend the children would present what they ve made at the Mini Makers Faire If anybody out there would like to help me do this please get in touch Amy is a prime example of why we should be getting Raspberry Pis into the hands of as many kids as possible It is young people like her that provide inspiration and drive to those within the Raspberry Pi Foundation The MagPi and the wider community to keep doing what they re doing This certainly won t be the last time you hear of Amy in The MagPi She is currently working on a number of articles for the magazine to help us encourage and challenge our younger readers CATCH UP TV Avoid missing your favourite programme How to configure OpenELEC so you can watch TV programmes Do you want to watch TV programmes using your Raspberry Pi e No need to buy a smart TV to get your HDTV to connect to catch up TV services such as BBC iPlayer and ITV Player in the UK or CTV and Space and Bravo in Canada or RTE1 and RTE2 in Ireland or Network10 in Australia e No need to have your Raspberry Pi keyboard and mouse and their cables spoiling the look of your HDTV e Use a Raspberry Pi with a Wi fi USB dongle running OpenELEC a compact high performance Linux distribution that has XBMC media centre software
134. light presentation of the 2013 Manchester Jamboree and who certainly has a bright future ahead of her in computer science Amy s Game of Life presentation is available on YouTube http tinyurl com amyjamboree and would encourage you to watch the video first and then come back to read the remainder of this MagPi article After watching the first time was astounded at Amy s confidence and ability and had to watch it a second time couldn t help but think that Amy is a shining example of what all our kids could be if they are given the right resources teaching and encouragement to experiment without fear MagPi Most people have watched your presentation and have been astonished by your achievements with the Raspberry Pi what has been the feedback from that video Amy The feedback from the Jamboree video has been amazing with people asking me to do more talks at other conferences interviews such The future of young hackers as this and even a request to design a website There have been so many lovely comments from people that I ve never met I m really grateful to Alan O Donohoe for giving me the opportunity to Speak was so surprised when was asked to talk alongside the likes of Steve Furber and Rob Bishop MagPi How did you first come across the Raspberry Pi Amy My Mum found out about the Raspberry Pi on Twitter and ordered one for me on the day of release It took a few weeks to arrive but as
135. loop the effect of gravity or try changing the effect of the thrusters The lander could be given a limited amount of fuel by counting the number of times the space bar is pressed 80 The Raspberry Pi is helping millions of kids write their first print t heuo wortd We d like to thank you for making cool projects spreading the word and also for buying sweet sweet swag Your generous support helps us do more http swag raspberrypl org Hello World is alright but we ve got to teach kids 20 GOTO 10 as well Minecraft Pi Edition SKILL LEVEL INTERMEDIATE The game Minecraft is a game which has achieved monumental success almost 30 million copies across all its versions have been sold not bad for a game which doesn t really have a point It is classified as an Indie Sandbox game If it does have a point it is to make stuff and people have really made stuff from fully functioning computers to scale models of the Starship Enterprise to The MagPi bird nected i adhtioi Now Minecraft has come to the Raspberry Pi and the two best things about Minecraft Pi Edition are it is free and comes with an API two things you do not get with any other version of Minecraft certainly not yet anyway Installing If you have the latest version of Raspbian then Minecraft already comes preinstalled If you do not have the lastest Raspbian then let s get going by installing Minecraft a
136. lt the program uses the localhost To McControl class creates a InputEventListener access one or more remote Minecraft games a DE object This listener is then used to associate the ype switchPressed function with one of the four mcControl py 192 168 1 20 192 168 1 21 switches being pressed Once the listener activate function has been called the etc where the IP addresses are the IP program continues to listen for PiFace switch addresses of the Raspberry Pis running Changes until itis closed with CTRL C as Build QR Code structures inside Minecraft SKILL LEVEL BEGINNER In this article am going to show you how you can dynamically display QR codes inside Minecraft Pi Edition You can use these for many ideas from displaying clues to puzzles in your Minecraft world to linking to websites If you skipped them encourage you to read the other two Minecraft articles Getting started lf you have the latest version of Raspbian then Minecraft already comes preinstalled If you do not have the latest Raspbian then let s get going by installing Minecraft and testing that it works Open an LXTerminal window and enter the following commands cd wget https s3 amazonaws com assets minecra ft net pi minecraft p1 1 1 tar gz tar zxvf minecraft p1i 0 1 1 tar gz Make a note of home p1 mcp1 ap1 python as we will need that later Test Minecraft with the following commands cd mcp1 minecraft
137. m running through raspi config etc However most setup guides stop once the system boots into the windows style interface of LXDE regularly encourage people to buy and use Raspberry Pis especially if they have kids but time and again hear people asking Ok I m at the desktop what now and How do I do such and such The official forums at raspberrypi org are a great place to start looking for solutions to problems or questions that you might have though they can be a bit daunting for a beginner The search functions on the forum are excellent so please take a few minutes to search the existing posts for answers to your questions before starting a new thread The web offers some exceptional free user guides that go into great detail to cover the installation of Raspbian Wheezy on an SD card from Windows OSX and Linux Engadget s Getting Started Guide is especially good These guides offer help O with troubleshooting basic issues as well as providing ideas for that What now moment when everything is running and you re staring at a large raspberry in the middle of the screen The Raspberry Pi Guide on the Embedded Linux wiki is also recommended Even with the user guides and forums it is worth mentioning the solutions to a few of the most common questions asked by new Raspberry Pi owners would like to connect x device to my Raspberry Pi How can be sure it is going to work Unless you like th
138. m Image open mypic jpg hist im convertC L histogram pLt pLotChist pLt savefigC myhist png The matplotlib package can also be used to plot the histograms of many images at once import Image glob import numpy as np from matplotlib import pyplot as plt M for x tn glob glob jpg im Image open x M im convertC L histogram pLt pcoLormesh np array M plt savefigC mymanyhist png This example reads all of the jpg files in the present working directory In the resulting image each horizontal line of pixels is one image in the time lapse The brightness of a pixel indicates how many pixels in the original image have a given intensity Some of the images captured were slightly grey This implies that there is not very much contrast because A most of the pixel values are clustered in the middle of the histogram In these cases there were no completely black pixels and only a few completely white pixels The image at the bottom left of this page illustrates an example grey image To improve the balance the image histogram can be used and stretched out to fill the whole range from 0 to 256 The first step is to find the bounds a and b pixels 1m si1ze Q im size 1 a Q count 0 while count lt 03 pixels count hist a a 1 b 255 count 0 while count lt 05 pixels count hist b b 1 where a and b are defined such that 97 of the pixels are brighter than a and 97 are dark
139. m button py Save this file as button_Led py and open it Since we want the LED to flash on and off we will need to add a time function to allow Python to understand the concept of time We therefore need to import the time module which allows various time related functionality to be used Add another line of code underneath line 1 import time Next we need to define GPIO P18 Pin 12 as an output to gt S PHYSICAL COMPUTING Brought to you by ModMyPi power our LED Add this to our GPIO setup section line 4 below the input pin setup line GPIO setup 18 GPIO OUT Once GPIO P18 Pin 12 has been set as an output we can turn the LED on with the command GP1IO output 18 True This triggers the pin to high 3 3V Since our LED is wired directly to this output pin it sends a current through the LED that turns it on The pin can also be triggered low OV to turn the LED off by the command GP1O output 18 False Now we don t just want our LED to turn on and off otherwise we would have simply wired it to the button and a power supply We want the LED to do something interesting via our Raspberry Pi and Python code For example let us make it flash by turning it on and off multiple times with a single press of the button In order to turn the LED on and off multiple times we are going to use a for loop We want the loop to be triggered when the button has been pressed Therefore it needs to be inserted with
140. main frame is the radio area We will use this feature later to direct output to the status section of the page The status page is rather trivial It just contains the opening and closing html and body directives and some dummy text This will be overwritten dynamically later CGI BIN The file radio html contains all the fun interactive stuff This is where the interaction with the Raspberry Pi actually takes place The interface is built as a horizontal table sandwiched between lt TR gt and lt TR gt tags Each entry in the table is declared between the lt TD gt and lt TD gt tags In between these tags a lt FORM gt is defined that executes an action on the Raspberry Pi as defined by the instruction action cgi bin play sh lt html gt lt head gt lt title gt Internet Radio lt title gt lt head gt lt body gt lt hi gt Internet Radio Interface lt h1 gt lt hr gt lt table border 0 gt lt tr gt lt td width 100 align center gt lt form action cgi bin play sh method POST target status gt lt input type submit value Play gt lt form gt lt td gt lt tr gt lt table gt lt hr gt lt table border 0 gt lt tr gt lt td width 100 align center gt lt form action cgi bin play sh 1 method POST target status gt lt input type submit value Eagle gt lt form gt lt td gt lt tr gt lt table gt lt body gt lt html gt as 55 This u
141. mmands sent The project was written in Pascal and developed using Lazarus a professional free Pascal integrated development environment IDE It has been released as open source Pi Vision makes it easy to control the camera plus it is also instructional and fun Building block lf had to name one of the most interesting and inspiring gadgets to come out in recent years it would probably be the little Raspberry Pi Its low cost small foot print and the fact that it runs Linux makes it an obvious choice for all sorts of projects a building block that sparks the imagination to do just about anything However the idea that makes the Raspberry Pi so unique is that it was designed and introduced as an educational tool something to familiarize ourselves with actual computing Not just at a user level but at the programming and integration level as well The recently introduced Raspberry Pi camera aligns itself with that same idea You probably have an i something a tablet device or PI VISION A GUI for the Raspberry Pi camera pe Camera B J Rao Guest Writer a smart phone and you likely work and play on a Windows Mac or even a Linux machine But the Raspberry Pi in all its minimalism maximizes on the means to allow people to get started with actual computing So much so that the Raspberry Pi is becoming a form of expression a means of allowing so many of us to transform our imagination into a more tangible an
142. mming is to write simple video games Scratch has several handy functions which speed up the construction of basic games This article demonstrates how to produce a racing car dodging game The game can be easily extended and the principles can be used when writing games using Python or C The idea of the game is to drive the car around several objects which scroll down the screen The game ends if the car goes on the grass or touches one of the objects The first step to produce this game is to create or choose the sprites The racing car was drawn with the Scratch sprite editor To make the sprite symmetric half was copied and then mirrored Once the working een 1 car has been produced go to the Costumes tab of the pee prea sprite and click on copy Then click on Edit for the u tme CS CS EES second sprite E Eere an oH ff E _woitureCours G Bia amp BE sanna h r ss T a iy i 1 d a er iff a ci i _ at na Scripts Y Pow ae i 5 Costumes The second costume will be used for the broken car The Scratch editor was used to make the car look PERETTI nee een broken Before writing the script for the car some oo objects are needed In this case the ball and the Lego piece were chosen from the Scratch sprite library The E library of sprites can be viewed by clicking on the folder sag ese rca aA op aR icon just below the stage
143. n the Lander sprite was resized to match landing pad by the right clicking the mouse on the Lander sprite The colours used for the surrounding ground and the landing pad for the two backgrounds were chosen to be the same to allow tests based on the colours of the z es sprite and the background Then a simple script was A whket li Se 1 Po 2 written to select a random Stage background when the green flag is pressed Controlling the Lander The Lander is controlled with the left and right arrow keys and the space bar To prevent the controls from moving the lander when the game is not taking place a local variable was created called flying If the flying variable is set to one then the controls will change the angle of the Lander sprite Tapping on the left arrow causes the Lander to turn 15 degrees to the left and tapping on the right arrow pep ies By causes the lander to turn 15 degrees to the right turn 15 degrees when lf arw key pressed The space bar is used to fire the thrusters to slow down the Lander and manoeuvre it to the landing pad When the space bar is pressed the costume of the Lander changes to the version that shows the engines as burning The costume continues to show the engines turn G E degrees burning while the space bar is pressed When the space bar is released the costume changes back to show the engines as being off when ght arom key pressed flying Stop script
144. n you tell us a little about these resources and the benefits you get from going there Amy Without MadLab http bit ly rranU wouldn t be talking to you today They are AWESOME I ve met so many great people there who are always willing to share their knowledge and teach me new things At MadLab have met Mike Little wno was my mentor for YRS2012 Ben Nuttall who runs the Manchester Raspberry Jam _ http bit ly YUE2yY Alan O Donohoe who organised the Raspberry Jamboree John Beckerson a senior curator from Manchester s Museum of Science and Industry who invited me to display at the Mini Maker Faire Dr Lucie Green who is a space scientist plus lots and lots of other very kind people who have taught me so much I ve also been to lots of workshops held by Manchester Girl Geeks http bit ly PYSHEL and have started helping to teach at their workshops there s just so much going on there Bob Clough from HacMan http bit ly jJGLhtz showed me how to use Inkscape to control the laser cutter when was making the case for my Conway s Game of Life on Pi All the people at the hackspace are happy to help people with any problems that they may have wish there was a MadLab HacMan in every town to help other children discover their inner geek ORT T O O ee mane 82 EA Amy shares her knowledge by teaching others MagPi Are there many other kids around your age going to the hack spaces on a regular basis
145. nd testing that it works PRC takit 4 PI EDITION o oe Martin O Hanlon Guest Writer Open an LXTerminal window and enter cd wget https s3 amazonaws com assets minecra ft net pi minecraft pi 0 1 1 tar gz tar zxvf minecraft pi 0 1 1 tar gz Make a note of home pi mcpi api python as we will need that later Test Minecraft with the following commands cd mcpi minecraft pi Playing Minecraft The Raspberry Pi edition of Minecraft is a cut down version of the pocket edition and currently only offers one playing mode Classic which is all about exploring and building Click create world and start exploring and building You control your player with the mouse and keyboard Moving the mouse changes where you look while the arrow keys move you forward backward left and right Up and down pressing space will make you jump while you are walking Double tapping will start you flying While you are flying space will make you move up and shift will make you go down Inventory you can cycle through your inventory using the mouse scroll wheel or keys 1 8 and change the blocks in your immediate inventory the Strip along the bottom by pressing E which brings up all the blocks you can use BA Destroy blocks press hold the left mouse button Place blocks press the right mouse button Back to menu press escape The API The API allows you to write programs which control
146. nd Media Before we explore each of these areas here are some navigation tips that will help you find the content you want In the Explore tab of the Pi Store there is an option to filter the content by status and also an option to specify the sort order If you want to explore content which is still work in progress then change the status filter to In Progress You can also set it to Show ALL to see all Pi Store content There are many sort options but the most useful are Most Played Newest First and Top Rated Note that currently the Pi Store does not store these settings so the next time you open the Pi Store the status will likely be reset to Finished and the sort order will be reset to Price Highest Several programs in the Pi Store do not run on LXDE and require a reboot before they start Although there is a warning on the application page in the Pi Store there is no final Are you sure after you click on Launch So make sure you have everything saved first Don t forget to tip When you receive good service you leave a tip Almost everything in the Pi Store is free If you enjoyed playing a game or found a title useful consider showing your appreciation by leaving a tio for the developer It s easy to do In your library select the title you want to tip then click View Details In the details page click Tip this Project to send 1 00 1 00 by default Games Pi Store g The Pi Store Explore My Library Upl
147. nd a pair of headphones or some speakers Once you reach the end of this article you ll be programming your own beats and modifying them live Where you go afterwards will only be constrained by your imagination Getting Sonic Pi v2 0 For this article you will need version 2 0 of Sonic Pi Sonic Pi is now included in the latest release of Raspbian You should see the Sonic Pi icon on the Raspberry Pi desktop If you are using an older release of Raspbian you can update to sonic Pi version 2 0 with sudo apt get install sonic pi You can also open Sonic Pi by clicking on the main menu and looking within Education gt Sonic Pi What s New Some of you may have already had a play around with Sonic Pi Hopefully you all had fun making beeps of different pitches You can take all the music coding skills you ve learned with version 1 and apply it to version 2 For those of you that have yet to open Sonic Pi now is definitely the time to give it a try You ll be amazed with what you can do with it Here s a quick list of the major new features Ships with over 20 synth sounds Ability to play any wav or aiff sample file Ships with over 70 samples Extremely accurate timing Support for over 10 studio effects reverb echo distortion etc Support for Live Coding changing the code while it runs Let s have a look at all of these features Playing a drum loop Let s code up a simple drum loop We can use t
148. nd then jump head first into live coding territory Loop do use_synth tb3Q3 play 30 attack release 0 3 sleep 0 5 end So what do the numbers mean in this example Well you could stop it playing change a number then start it and see if you can hear the difference However all that stopping and starting gets quite annoying Let s make it possible to live code so you can instantly hear changes We need to put our code into a named function which we loop define play_my_synth do use_synth tb303 play 30 attack release 0 3 sleep 0 5 end Loop do play_my_synth end Now when you run this it will sound exactly the same as the simpler loop above However now we have given our code a name in this case play_my_synth we can change the definition of our code while things run Follow these steps 1 Write the code above both the define and loop blocks 2 Press the Run button 3 Comment out the loop block by adding at the beginning of each line 4 Change the definition of your function 5 Press the Run button again 6 Keep changing the definition and pressing Run 7 Press Stop For example start with the code above Hit Run Comment out the Loop block then change the play command to something different Your code should look similar to this C define pLay_my_synth do use_synth tb3Q3 play 45 attack release 0 3 cutoff 70 sleep 0 5 end Loop do play_my_synth end Then h
149. ndition This part will run as usual except when a keyboard interruption occurs lt CTRL gt C If an interruption occurs the GPIO ports will be reset when the program exits The finally condition is included such that if our program is terminated by accident if there is an error without using our defined keyboard function then the GPIO ports will be cleaned before exit Open button_led py in IDLE3 and save it as button_cleanup py Now we can add the code previously described into our script The finished program should have the form import RP1 GPIO as GPIO import time GPIO setmodeCGPIO BCM GPIO setup 17 GPIO IN GPIO setup 18 GPIO OUT try while True input_value GPIO input 17 if input_value False printC Who pressed my button for x in range 3 GPIO output 18 True time sleep 1 GPIO output 18 False time sleep 1 while input_value False input_value GPIO input 17 except KeyboardInterrupt GPIO cleanup Program will end and GPIO ports cleaned when you hit CTRL C finally GPIO cleanup Notice that only the loop part of the program is within the try condition All our imports and GPIO set ups are left at the top of the script It is also important to make sure that all of your indentations are correct Save the file Then run the program as before in a terminal window sudo python button_cleanup py The first time you run the file you may see the warning message appear sin
150. ng the line from left to right Trust me that gets the QR code turned through 90 degrees but it is not back to front QR codes have the property that you can read them up down left or right those three large squares in the corners tell the QR code reader how the code is oriented As we read the file if the character is a space white square we build a block of snow block id 80 in the world If the character is a hash black square we build a block of obsidian block id 49 You can find the block id codes on the Minecraft Wiki at http minecraft gamepedia com Data_values Block_ Ds for i in reversedCarrayQR y pPos y Len 1 for j in range len i if GU block 80 if i j block 49 yay oot mc setBlock x y z block Ce aL Finally we teleport Steve back to his original position mc player setPos pPos x pPos y pPos z Display the QR code in Minecraft To get everything running we need to start Minecraft then when it is running we start our Python program So we need two LXTerminal windows In the first LXTerminal window enter the following commands cd mcp1 minecraft p1 Login to your Minecraft world and find an area without too much terrain we don t want trees blocking our view Then press the lt ALT gt lt TAB gt keys together to switch to the second LXterminal window In that second window enter the following commands cd python chmod 755 mc qr py mc
151. nger you face is from the layout of the cavern system itself rather than from Guards of the Stronghold In STRONGHOLD OF THE DWARVEN LORDS you are in a cavern which holds the gold Each time you play this game the gold can be in one of three places The only information you get as to your progress is information provided by the Dwarven Source Beam which you found as you made your way into the cave system This gives you feedback after each move as to the location of the gold but you need to learn how to interpret the information it gives you before you ll be able to make much use of it When the game starts you are shown a map of the cavern system with your position indicated as an asterisk Your aim is to find the hidden gold with the minimum number of steps Each turn you are given a brief description of your surroundings and must choose the direction to take next Once the map scrolls off the screen you are only allowed to look at it again by choosing H for help However each time you ask for help you are penalised 15 steps How the program works For those with a basic understanding of Python you will see that the main parts of the program are structured as follows e At the beginning there are a few data lists of numbers that are combined together to make one big list e There are the functions new_gameC show_mapC move and win e Then finally there is the main program which calls the functions in order to initiate the first game
152. ngs to check to ensure it is set up correctly 1 Are the ribbon connectors all firmly seated and the right way round 2 Is the camera module connector firmly attached to the camera PCB 3 Have you run sudo apt get update sudo apt get upgrade 4 Have you run raspi config and enabled the camera So if things are still not working try the following Error raspistill raspivid not found This probably means your update upgrade failed in some way Try it again Error ENOMEM displayed Camera is not Starting up Check all connections again Error ENOSPC displayed Camera is probably running out of GPU memory Check config txt in the boot folder The gou_mem option should be at least 128 107 Ls EE eT 583768716 287 3 z ii ag i M p ki w The Raspberry Pi camera Part 2 SKILL LEVEL BEGINNER Welcome back to part 2 of The MagPi mini series covering the fantastic Raspberry Pi camera module In part 1 we covered setting up your camera and its basic operation In this issue we begin to introduce you to some of the advanced features that the module is capable of allowing you to capture images like a professional Prototype camera board left and final camera board right Sizing options Lets begin by looking at sizing options You can easily specify the size of your captures using the w width and h height options These do exactly what you might expect they change
153. ning its operation are in issues 2 12 and 13 of The MagPi With PXDRUM you will have a lot of fun creating CO cool beats You can simultaneously play eight different percussion instruments and change their sound by loading different drum kits Start with one of the demo songs and get your groove on Tutorials o Pi Store mOway Scratch Guide Official Educational Manual Raspbian OS Setup Free peen Free meee Python Free teiewtrek tanahne o Python SQL Database totter Free teint Freet rit Fies Free Download The Tutorials category contains several very useful guides including the Official Raspberry Pi Educational User Manual Other guides include Python SQL Database a tutorial on how to create database applications using SQL and Python plus Raspberry Invaders a Python programming course with 17 lessons where you learn how to create a space invaders style game using Python Dev Tools 5 Pi Store eat The Pi Store Library Upload oO Explore Hud Sprite Pack Pi3D Effects Sprite Pack A setof HUD sprites and pickup texture Progra A collection of static and a Ak Free wiry Free 4 Free This is the smallest category in the Pi Store yet it contains useful collections such as HUD Sprite Pack Effects Sprite Pack and Audio Effects Pack for your Python and Scratch games plus Michelle s Minetools and GLG Toolkit of course all free to use There is also the very excell
154. nnect the resistor between the cathode of the LED and the negative rail on the breadboard This protects our LED from burning out by way of too much current a f v 4 j d f And that s our circuit built Next time In the next article we ll add a timer function to our script and a trigger function for our LED As the script will be more complicated it requires a proper clean up function so we ll code that in too All breakout boards and accessories used in this tutorial are available for worldwide shipping from the ModMyPi webshop at www modmypi com Buttons and switches with the Raspberry Pi Part 3 In the previous article we built a simple button circuit connected to our Raspberry Pi via the GPIO ports and programmed a Python script to execute a command when the button was pressed We then expanded our circuit with an LED In this tutorial we will be expanding our script to include timer and trigger functions for our LED As the script will be more complicated it requires a proper clean up function Start by reading the previous two articles before trying this one Adding LED control code Now that our LED expansion circuit has been built we will add some code into our previous program This additional code will make the LED flash on and off when the button is pressed Start by booting your Raspberry Pi to the Raspbian GUI startx Then start IDLE3 and open the previous example progra
155. nted in this article air resistance is neglected Therefore the horizontal velocity component is constant and the horizontal distance the projectile travels is found by multiplying the initial horizontal velocity by the time it is in the air The time the projectile is in the air is determined as the difference between the start time and when the vertical position is equal to the ground While the projectile is in flight gravity continues to decrement the vertical velocity until the projectile hits the ground If the initial vertical velocity component is small it will not take long for gravity to bring the projectile down Notice that within this simple program the vertical position is evaluated in two steps rather than in one equation There is one step to evaluate the change in velocity and another to update the horizontal position Possible extensions The drum could be replaced with other objects that move around to make the game harder There could be a time limit for the player to hit all of the targets with the cannon The equation of motion used in this game does not include drag Drag can be expressed as a constant force for a given velocity squared The problem of estimating the drag could be made harder by introducing wind which would cause the relative velocity of the ball with respect to the air to be higher 27 10 em 7 E o Space arcade game Adding natural physics processes to games can make them more real
156. nterface create an empty file in the tmp directory called killerqueen remember that Queen song In the background need another program that periodically checks the existence of the tmp kiLlerqueen file and calls shutdown if it exists Here is the shutdown sh script that creates the tmp killerqueen file if the button on the web interface is pressed bin bash echo Content type text plain echo echo touch tmp killLerqueen echo Shutting down The file that periodically checks its existence every two seconds is called killerqueen sh which placed in the usr local bin directory It contains the following bin bash rm f tmp kiLlerqueen while True do if e tmp killerqueen then echo file exists removing rm f tmp killerqueen sbin shutdown h now fi sleep 2 done After initially removing any forgotten tmp killerqueen file it enters an infinite loop and checks the existence of the file If it exists it removes the file and calls shutdown Then the Raspberry Pi comes to a halt and after a few seconds you can turn the power off safely Ed If you have Raspberry Pi switches from companies like Pi Supply UK hito www pi supply com or Mausberry Circuits USA htto www mausberrycircuits com then these will automatically power off your Raspberry Pi What remains is to start the kiLLerqueen sh script automatically when the Raspberry Pi is booted This is easily done by placing t
157. o the slot ensuring it is straight then gently press down the tabs to clip it into place The camera PCB itself also requires you to pull the tabs away from the board gently insert the cable then push the tabs back ad The PCB connector is a little more awkward than the one on the Pi itself There is a video at http youtu be GlmeVqHQzsE which shows the connections being made So we now have the hardware all attached we now need to make sure we have the correct software installed As explained above there are some command line apps to install and a firmware upgrade with the camera driver and tuning to install This process may not be necessary in future as newer distros are a 09 released which already contain the required files To update the firmware libraries and applications execute the following instructions on the command line sudo apt get update sudo apt get upgrade Now you need to enable camera support using the raspi config program you will have used when you first set up your Raspberry Pi sudo raspi config Use the cursor keys to move to the camera option and select enable When you exit raspi config it will ask to reboot The enable option will ensure that on reboot the correct GPU firmware will be running with the camera driver and tuning and the GPU memory split is sufficient to allow the camera to acquire enough memory to run correctly Running a camera and associated encoder does take
158. o the GPU the VideoCore 4 Graphics Processing Unit on the Raspberry Pi This connection uses the CSI 2 electrical protocol and is a standard used in most mobile phones It is an extremely fast connection which on the Raspberry Pi is capable of sending 1080p sized images 1920x1080x10bpp at 30 frames per second or lower resolution at even higher frame rates It had always been intended at some point to release a camera module that could use this connection as the ability to stream high speed video data through the GPU without any interaction with the ARM processor would always make the camera much more efficient than any USB attached webcam It would also enable the use of the GPU s ability to encode H264 video or JPEG images in hardware lt turns out that productising a tiny PCB like the camera board is not a quick task The prototype was re designed to remove some unnecessary components but more importantly to move the camera crystal used for timing to the PCB itself ug dog Electromagnetic compatibility EMC testing had shown that the 25Mhz clock provided by the GPU caused too much interference as it passed up the ribbon cable to the PCB Adding a crystal to the PCB itself stopped this interference A couple more board designs later to help with production line manufacture and testing and eventually about a year after the first prototypes the production board was ready Meanwhile work had been ongoing
159. oad Pacmar wk kk Free yi Free rink Free Unsurprisingly this is the largest category in the Pi Store With 48 titles at the time of writing there is something for all gamers here In Dr Bulbaceous Puzzle Solver US 2 99 1 99 you drop different coloured objects and when 3 or more are touching they disappear The goal is to clear the screen before the objects reach the top Although found the game too easy kids will enjoy it It is colourful and well implemented Tip To swap your current object for something more potent press the Enter key lt looks like the mouse should work but it didn t for me Martian Invaders 1 60 1 00 is a retro space shooter that allows keyboard or joystick control DmazebD is a lot of fun You search a maze for the key to the exit but it is dark so you have a limited field of vision Listen out for the monster that is also in the maze with you Another game found myself thoroughly enjoying is The Little Crane That Could Through dexterous use of your crane and its many movements you complete a series of increasingly difficult tasks Many folks of a certain age like myself use their Raspberry Pi to relive the golden age of home computing and there is no shortage of games inspired from that decade In the Pi Store these include Abandoned Farmhouse Adventure and King s Treasure classic text based adventures Chocolate Doom play all versions of Doom NXEngine a
160. ogram http www openelectrons com pages 63 OpenElectrons com SmartUPS http www openelectrons com pages 33 a e o ef i hy SSB BBE RE oil gt e viar a iii a ex r an 6 0C OO CO Ae iy ecceeces SH 299008 amp ew ey 96 ge 3 i Controlling the Maplin OWlrobot robotic arm SKILL LEVEL BEGINNER Introduction This article expands on the work by Jamie Scott etal in the Wikihow article at http www wikihow com Use a USB Robotic Arm with a Raspberry Pi Maplin and allows you to control the movement of the arm using a sequence of instructions read from a CSV Comma Separated Variables formatted file by a Python script This article assumes you are using the Raspbian distribution but you should also be able to get this working using the Occidentalis distribution from Adafruit More information about this distribution can be found at http learn adafruit com adafruit raspberry pi educational linux distro overview Configuring your Raspberry Pi Before you can start using the script there are a few things you will have to do to get your Raspberry Pi ready The first thing you will need to do is add the user account you are using on the Raspberry Pi to the plugdev group Assuming you are using the default pi user account the command to do this will be sudo usermod aG pLugdev pi 5 KW L K Z A PYTHON CONTROL Control using a Python script Peter Lav
161. ols Control is with the cursor keys The fire and jump buttons are generally Left Ctrl Space and Left Alt respectively Joysticks and gamepads can also be configured and used All options for control settings video sound DIP switches etc are easily modified in the options menu and can be saved for general All Games or individual games This Game Other controls are 5 Add Coins 1 1 Player 2 2 Players TAB Options Menu use Cursor Keys and Enter ESCape Exit Other configuration options MAME seitings can be infinitely customised The defaults in advmame rc are perfectly acceptable for several games but there are a few exceptions 1 The default display_color is auto Vector games Asteroids Star Wars etc will suffer from an incorrect application error so DON T change advmame rc In the Options Menu TAB navigate to Video Color and change auto to ogr16 then Save for this Game 2 The default display_mode is auto and display_magnify is 1 Certain games suffer from an incorrect application error in Aspect Ratio e g Burger Time Data East 1982 I Robot Atari Inc 1983 and Track amp Field Konami 1983 Again DON T change advmame rc In the Options Menu TAB navigate to Video Magnify and change 1 to 2 then Save for this Game 3 Consider changing display_resizeeffect from auto to none Personally I m not
162. omponents An LED light emitting diode any colour you like ModMyPi s Ridiculous Resistor Kit RK995 3300 resistor Orange Orange Black Black Brown An output pin on the GPIO port can be set to either OV low or 3 3V high Our expansion circuit will wire up an LED between an output pin and a ground pin on the Raspberry Pi s GPIO port We ll be using Python to trigger our output pin high causing a current to pass through the LED lighting it up We also add a 330Q resistor to limit the current that is passed through the LED For this exercise we will connect the LED to GPIO P18 Pin 12 which will be defined later in 8 our program as an output We will use the same ground pin GPIO GND Pin 6 as before which is already connected to the negative rail on our breadboard Building the Circuit 1 Connect GPIO output to breadboard Use a green jumper wire to connect GPIO P18 Pin12 on the Pi to an empty row on the breadboard 2 Add an LED Insert the long leg anode of the LED into the same row as the green jumper wire and insert the shorter leg cathode into another empty row on the breadboard Note Make sure the LED is inserted the correct way round as it will only allow current to pass through it in one a F D lt e r i a a e Ki _ i 4 Fe This article is sponsored by ModMyPi direction If it s wrong it won t light up 3 Add the 330Q resistor Co
163. on ball scripts The cannon ball has two scripts one to hide the ball when the green flag is pressed and another to control go to x cannon N y cannon_y the motion of the ball point in direction cannon angie set velocity_x to Inithl_speed cos of cannon_angle set velocity_y to iInitial_speed sin jof EP cannon_angle repeat until touching color 7 or touching 8096 or touching Orum change Velocity_y by F change x by we locity x F change y by valocity y al if n t touching color M touching color e show i set fire to fj pene Soman When the spacebar is pressed the global variables cannon_x cannon_y and cannon_angLe are used to set the position of the ball and its initial velocity Unlike other programming languages that use radians clicked Scratch uses degrees for the functions sine and cosine The 90 degree offset is used to convert the angle of hide a cannon such that zero degrees corresponds to the Ser Sore cannon pointing horizontally to the right The sine and cosine functions are then used to set the initial velocity components The cannon ball moves through the air until it touches either the colour green the edge of the stage or the drum While none of these conditions are met the vertical velocity component is decremented by 0 05 This decrementation corresponds to the acceleration due to gravity Next the current x and y components of the velocity
164. ontains some excellent Scratch and Python programming articles that are suitable for the complete beginner They introduce concepts that can be expanded and implemented in other programming languages There are also several hardware projects We introduce you to the GPIO with simple buttons and LEDs then explain how to control your garage door and a robot arm The Raspberry Pi camera is a popular addition to the Raspberry Pi and we have several articles that show you how to get the best out of this device Media is another popular topic and we explain how the Raspberry Pi can be used to listen to internet radio watch TV programmes plus how to get your groove on with Sonic Pi Since the first issue of The MagPi appeared in May 2012 we have produced over 1 200 pages of content created by 100 different authors There have also been over 50 volunteers who helped layout the magazine tested the hardware and code plus proof read the text Hundreds of hours of work goes into creating each issue of The MagPi for your enjoyment and education and it s free lf you want to know when each issue of The MagPI is available we invite you to join the 5 000 other people who are following us on Facebook at hitp www facebook com MagPiMagazine We hope you enjoy this collection as much as we did putting it together Thank you from everyone at The MagPi The MagPi Team Ash Stone Chief Editor Administration Colin Deady Testing Proof Reading lan
165. oo small and deducted points each time you got it wrong If you got one of the best scores then it asked you for your name and saved it to a high scores list MagPi No matter the country there are often articles in the press about the poor IT and Computer Science teaching in schools How have you found this to be in your case Is there much interest in gaining a deeper knowledge of computer science with your friends and classmates Amy No most of my friends at school use a bit of HTML to update their Tumblr blogs and have done Scratch Alice and Dreamweaver in ICT lessons but they don t really seem to want to take it any further think that if the Raspberry Pi and Arduino were incorporated into ICT lessons e g Introduction to Python from age 11 Textiles lessons e g Arduino Lilypad or Product Design Resistant Materials lessons e g robots then that could show them that programming can actually help you create some pretty awesome stuff Hopefully that would be enough to inspire them to start hacking and coding their own projects outside of school MagPi Are there Raspberry Pis available in your school already Amy No unfortunately there aren t any Raspberry Pis in my school at all but I d like to change that MagPi What more can we do as a community to get more young people both boys and girls into computer science How could our readers get involved Amy think that we need to set up more communi
166. ou already have your Raspberry Pi connected to your network either by cable or wireless If not wired ethernet normally works out of the box if you have a DHCP server on your network Most routers offer this by default If you have a wireless network and a USB wireless network adapter for your Raspberry Pi the easiest way to connect is to start the LXDE window interface by typing startx on the command line and then run WiFi Config which you can find on the desktop Once you are connected to your network you need to find out the IP address of your Raspberry Pi From the command line enter ifconfig This will display the settings for each network adapter Find the line that starts with inet addr and the four numbers that follow e g 52 192 168 1 97 is the IP address of your Raspberry Pi You will need this later when controlling the radio from your smartphone etc If you are connected by both cable and wireless ifconfig will list two interfaces ethO and wlan The IP address of either network interface will work for the internet radio Now we proceed by installing the required packages From the command line enter Sudo apt get update sudo apt get install mpd mpc apache2 Once installed for good measure suggest you shutdown then reboot the Raspberry Pi If you do not use the HDMI cable for sound to your monitor then while the system is shutdown it is a good time to connect the Raspberry Pi to some acti
167. ow scroll down from the top of the app click on Settings and change the Auto connect by clicking on openeLec below it Close the settings screen The app is now ready to use Once you have installed an XBMC remote app on your smartphone you are ready to control XBMC without a mouse or keyboard Simply use the remote control app to navigate the XMBC Confluence screen select VIDEOS and then select Add ons Your add ons will be displayed simply click on an add on such as iPlayer to run it Enjoy the catch up TV programmes Interesting extra facts and tips HDMI connections Are all the HDMI sockets on your TV in use with other devices such as a PVR bluray player and games console Not enough HDMI sockets on your TV for your Raspberry Pi The solution is to use a 2 in 1 out HDMI switch e g Belkin Thus both the Raspberry Pi and the other device are connected to the HDTV The Belkin product has a button on it for selecting which of the 2 inputs to currently use XRMT connection issue lf you have been using a mouse to control XBMC you may find that your Blackberry XRMT won t connect Unplug the mouse and reboot the Raspberry Pi and then XRMT should connect Command line access Do you want to access the OpenELEC operating system with Linux commands from your Windows PC You can do this using a program called PuTTY PuTTY uses the SSH protocol to connect to the Raspberry Pi Download the latest version of PuTTY from hitp Awww ch
168. own CUPS configuration page which we used in the previous article Unlike the original commands which could only handle text files the Lp and Lpr commands installed through CUPS can handle other formats as well When you use the commands with a PDF postscript or image file then CUPS will convert the files using the printer drivers We will be 2 Printing from Python SKILL LEVEL INTERMEDIATE using this feature later when we print a PDF file from a Python script In some programming languages and GUI toolkits see box it is possible to generate printer output using similar instructions to how you generate graphical content for the screen This is the case in PyGTK PyQt and WxPython but while the GTK and Qt toolkits are commonly used with other programming languages they are less used and less well documented on Python WxPython can be useful if you are using Wx toolkit already The most common graphical toolkit on Python is Tkinter which has very limited support for printing GUI toolkit A GUI toolkit provides a standard set of buttons frames and other components to make creating graphical programs easier and with a consistent look and feel Some include additional printer libraries that make it easy to convert the graphical screen output to a format ready for printing Instead of using toolkit support have chosen to generate a PDF file using xhtml2pdf which is sent to the printer using a CUPS library called PyCups This
169. p JPY vi 64 0 x 480 Horizontal Quality Effect 100 Bl ere T Vertical Raw Duration Dela 5000 l Enable Time Lapse Take a Picture Taspistill Camera App vl Terminal Width 6 i ede u Height 480 quality 10a io Fi Links Pi Vision http neywhatsthebigidea net projects pi vision a raspberry pi camera controller Pi Vision Project Github Repository https github com local vision Pi Vision Lazarus Free Pascal Compiler http www lazarus freepascal org Ua N Learning to program video games Two years ago my 10 year old son asked me Daddy what is your job replied that write computer programs which give the computer some tasks didn t have to wait long for the second question Ok but how do you tell the computer what it has to do How does a program work That was when decided to write Algoid to teach him what computer programming is and how to do tt Originally Algoid was designed to run on the Android platform but recently discovered the Raspberry Pi this low cost credit card sized computer exactly designed for education What is AlgoIDE AlgolIDE is a combination of an integrated development environment IDE and its own language AL designed together to simplify the understanding of programming Principles The AL language was developed with three ideas in mind 1 Its apprenticeship should be as progressive and memorisable as possible Try
170. page as that will make it easier to print using the command line tools The printer should now be available in any printer enabled applications e g office tools web browsers and printing should be similar to that implemented on other operating Skuiter build a robot 1 2 3 6 8 16 Play and create computer music 2 12 13 19 23 GPIO interfacing for beginners 17 18 19 21 23 27 Command line Bash 2 3 4 5 10 12 16 21 23 Customise the LXDE menu 4 Pumpkin Pi get ready for Halloween 6 Arduino and Raspberry Pi 7 8 15 16 17 28 Home automation 8 21 systems If you need any help then online help is included within the CUPS web page http 127 0 0 1 631 help On my Raspberry Pi have installed AbiWord which is a lightweight word processor that runs well on the Raspberry Pi You can see the standard print dialog in the screenshot You can install AbiWord with sudo apt get install abiword In the next article we will look at printing from the command line and how to print from your own Python applications SD card backup and storage 9 10 29 RISCOS 9 11 13 15 Operating Systems 12 BrickPi 17 18 23 Project Curacao 18 19 20 21 24 29 Quadcopter 19 20 Environment monitoring 21 23 24 29 Raspberry Pi oscilloscope 24 25 26 28 Robotics 25 26 28 29 Mashberry monitoring homebrew 26 Git mastering version control 27 28 29 C 3 4 5 6
171. pberry Pi should detect the gamepad and work almost immediately You may have to press the PS button to start though Alternatively you can use a bluetooth dongle Again connect the bluetooth dongle directly into one of the Raspberry Pi s USB ports not via the USB hub The following drivers and settings will only work with genuine PS3 gamepads Cheap imports simply do not seem to work Save your money and buy an official second hand PS3 gamepad Wired PS3 gamepad To test a wired PS3 gamepad list the USB devices with the command Lsusb You should see something similar to Bus 001 Device 008 ID 54c 0268 Sony Corp Batoh Device PlayStation 3 Controller Either test from the console with the command sudo jstest dev input js0 64 Or startx and use the joystick configuration tool testing and Wireless PS3 gamepad Install the required libraries to start bluetooth This may seem like a lot but it will save time and bother later Enter sudo apt get install bLuez utils sudo apt get install bluez compat sudo apt get install blLuez hcidump sudo apt get install checkinstall Sudo apt get install libusb dev Sudo apt get install libbLuetooth dev Next download the drivers for pairing the bluetooth dongle to the PS3 gamepad Enter sudo wget http ww pabr org s1xLinux s1 xpair c gcc o sixpair sixpair c Lusb Note If this second command fails ensure that you have installed 11 busb dev properly Aft
172. perience hundreds of pages of Raspberry Pi hardware projects software tutorials reviews of the latest expansion boards and interviews with the makers and creators involved Originally funded through Kickstarter The MagPi printed bundles of Volumes 1 2 and 3 bring all the information of this peer reviewed magazine within arms reach Volume 1 Issues 1 8 Volume 2 Issues 9 19 Volume 3 Issues 20 29 5502 27a a i NN The j ene A a MagRi Available worldwide fom these resellers Interview with Eben Upton Mo itoring an Aquarium Portable Raspberry Pi PIR Motion Detection Weather Station Linux Toolshed Internet Radio swag raspberrypi org www modmypi com www pi supply com thepihut com www adafruit com USA Win a GEEK case Pi NolR camera GPIO Cobbier SD cards amp more www buyraspberrypi com au Australia The MagPi is also available on special offer to schools for a limited time only www themagpi com education Basaan T TRP A wel AS be i SE a a me ae i Da sion Maghi box agPl fee SMe Heirons soe rill Lalesi o lt 7 eae w TPF b J i fie lt ieee tf Sitti SSUES nov aid j ARTTA i EQ FES IS bw TE E Re w M P TE i T P p y oe MagPl F E a L Ps p r Remoto Sensor Mecitoning P ATMEL Wiroha v om Fla Zultinsiddaee Rago e r b RASPISTILL Python time lapse amp image processing On December 2
173. ple listing below rwxrwxr x 1 pete pete 1726 May 19 14 11 commander py rwxrwxr x 1 pete pete 2388 May 19 14 11 mapLinrobot py Programming the arm Ok now on to the good part The script commander py will read in commands from a CSV file passed to it as an argument There is an example file called commands csv in the Git repository to help you get started So let s open this file up and take a look with the command nano commands csv Contents are included below for reference shoulder up 1 00 1 00 eLbow down 1 00 2 0 base clockwise 4 00 1 00 shouLder down 1 00 1 0 grip close 1 00 1 00 base ant1 clockwise 4 00 2 00 grip open 1 00 1 0 eLbow up 1 00 2 00 98 As you can see here the basic format for each command is command duration pause command any valid command found in the maplinrobot py script duration the time in seconds to execute the command for Make sure all values are entered to two decimal places e g for 1 second specify a value of 1 00 here pause the time in seconds to wait before executing the next command in the sequence Make sure all values are entered to two decimal places e g for 1 second specify a value of 1 00 here The commander py script will execute each line in the CSV file as a separate command for the duration you set and will wait for the number of seconds set in the pause value before moving on to the next command in the sequence Valid commands and a descr
174. r Official XMBC Remote for iOS Note On a Model A B the USB ports may not be able to supply enough current for certain Wi fi dongles This can result in video stuttering If you have a good connection the solution is to use a powered USB hub with a minimum 2A power supply or use a Model A B Some hubs will also back power the Raspberry Pi so you only need one power supply Check http elinux org RPi_Powered USB Hubs for a list of good hubs fm 5V2A bis l N USB Power HDMI ie supply Y D a d pan e HDMI f cable to s HDTV i RasPi lt Model B in case USB port Wifi so FF VS od im se a See m USBHub Installation instructions Step 1 Get NOOBS Copy the latest NOOBS distribution onto a 8GB SD card When finshed insert the SD card into the Raspberry Pi plug in the Wi fi USB dongle and use a HDMI cable to connect the Raspberry Pi to your HDTV The first time you start NOOBS you will be asked to choose what operating system to install Choose OpenELEC This will take a few minutes to install after which you can reboot your Raspberry Pi Step 2 XBMC and networks Note If you are using a Raspberry Pi Model A A then for this section you will temporarily need to use a powered USB hub so you can connect both the Wi fi dongle and a mouse After your Raspberry Pi has started XBMC will present its main screen known as Confluence blue bubbles background followed by an
175. r original programs or tutorials with others The Pi Store is there for your benefit and the benefit of the community so go use it a ra Raspberry PI Buttons and switches are a fundamental part of physical computing This beginner s tutorial is designed to teach the basics of physical operation and programming with the Raspberry Pi using a simple momentary switch setup The tutorial requires a few simple components that are available from ModMyPi product codes in brackets Medium Breadboard BB2 for laying out our components amp circuit Male to Female Jumper Wires JW8 for jumping between the Raspberry Pi amp breadboard PCB Mount Switch TACO01 a four point basic momentary switch ModMyPi s Ridiculous Resistor Kit RK995 to protect your Pi amp calibrate the float voltage 10KQ Resistor Brown Black Black Red Brown 1KQ Resistor Brown Black Black Brown Brown Breadboard Jumper Wire Kit 140KI for easy jumping on the breadboard The circuit The purpose of this circuit is to enable the Raspberry Pi to detect a change in voltage and run a program when the button Switch 1 is pressed This requires three GPIO pins on our Raspberry Pi the first will provide a signal voltage of 3 3V Vcc the next will PHYSICAL COMPUTING Brought to you by ModMyPi Buttons and switches with the ground the circuit GND and the third will be configure
176. radio stations in my playlist file playList txt The three buttons in the bottom row What is playing Available Stations and Turn OFF Radio are self explanatory Finally below the buttons is a status area where the information from the button presses is displayed In the above example pressed the Available Stations button and the twelve links are displayed Having described the interface we now turn to the implementation To set up the main window we divide it into three parts the left red sidebar the button interface and the status display use HTML framesets The index html file that replaces the default one in var www looks like lt html gt lt head gt lt title gt Internet Radio lt title gt lt head gt lt frameset cols 170 frameborder 0 framespacing 0 border 0 gt lt frame src indexlist html name index gt lt frameset rows 50 50 frameborder 0 framespacing 0 border 0 gt lt frame src radio html name main gt lt frame src status html name status gt lt frameset gt lt frameset gt lt html gt The head contains just the title information Then there are two nested framesets The first contains a frame with a file named indexlist html which contains the content in the red sidebar The second frameset contains two frames one for the radio interface radio html and one for the status page Status html The frameset instructions contain specifications
177. ravity and other sensors on Android Conclusion Algoid is a great free tool to learn or to teach programming For further questions suggestions or ideas you can contact me at cyann74 gmail com or try the forum at hitp forum algoid net 123 A i a a SONIC PI AT CHRISTMAS Learningto et with Sonic Pi j WU WLU UT Good King Wenceslas Sonic Pi was developed by Sam Aaron and is an speakers or a pair headphones assuming you excellent easy and creative way to learn cant get sound through your monitor screen programming especially as Ruby is embedded Plug them into the sound jack port on your lt uses the MIDI note numbering system to play Raspberry Pi see Model A B diagram below sounds and this means you don t have to be a i musical genius to make some music A good f MIDI reference table can be found at http www midikits net midi _analyser midi _note_ numbers _for_octaves htm th oy f uw JACK i820 86 ETHERNET only Getting started If you are using the latest version of NOOBS or Raspbian Wheezy then Sonic Pi should already be installed If you do not see it on your Raspberry Pi desktop you can find Sonic Pi yy OG HOM under Programming in the main menu at EN However if you have older versions of these you e either need to download the latest image files or you could type in the following into your terminal T sudo apt get update No
178. rd Control your Raspberry Pi over RS232 or connect to external serial accessories ADC PI 8 channel analogue to digital converter l C address selection allows you to add up to 32 analogue channels to your Raspberry Pi 1 Wire Pi 1 Wire to I C host interface with ESD protection diode RIC PI Real time clock with battery backup and 5V C level converter for adding external 5V I C devices to your Raspberry Pi Servo PI 16 channel 12 bit PWM controller suitable for driving LEDs and radio control servos electronics P cae Build a magic wand with an accelerometer Persistence of Vision displays create an image by quickly displaying one column of pixels at a time When the device moves rapidly along a linear path the human eye can view the image as a whole as it is built up column by column When say rapid mean rapid at least one twenty fifth of a second At this speed an afterimage is seen in the retina and the viewer perceives the rapid succession of LED blinks as a full image Operation The magic wand displays five columns of pixels for each specific letter in a user defined string The accelerometer is used to determine which direction the wand is swinging to avoid displaying the string in reverse N QX J Project parts list 1x Raspberry Pi 1x Pi Prototyping kit OpenElectrons com 1x LSM303 breakout OpenElectrons com 1x SmartUPS OpenElectrons com 1x PCF8574
179. require the same timing between each note e g play 48 Sleep 1 play 52 Sleep 1 play 55 Sleep 1 There is nothing wrong with writing the code as in the example but we could write it another way play_pattern_timed 48 52 55 1 This is a great way to write Sequences as it is more concise and reduces the chance of error as you do not need to repeatedly type play and sleep We can also use this format to shuffle reverse and sort the notes we want to play By adding shuffle the program will play the notes in a random order play_pattern_timed 48 52 55 shuffle 1 Note the shuffle comes after the notes If it is placed after the sleep command i e 1 then the notes will be played in the exact order we have written them Try it and see plLay_pattern_timed 48 52 55 1 shuffle We can also reverse the order of the notes we have asked the program to play by using reverse play_pattern_timed 48 52 55 reverse 1 Again if we put reverse after the 1 the notes will be played in the order they have been typed We can also use sort to order the pattern of notes we have written This works particularly well if we have written a sequence of notes in any sequence and then decide what we really want is for the notes to be played in numerical order For instance we might type play_pattern_timed 52 48 55 1 but what we actually want is for the notes to be played 48 52 55 By adding sort this can b
180. requires a setup text file which you provide when launching the gamepad and driver Through this you can turn one of the analogue sticks into a mouse and the buttons into keypresses etc This will make it usable with programs like Minecraft Doom Quakes plus all known emulators The possibilities are endless and exciting Let us make a directory to store these setup files which contain the button mappings Enter cd mkdir XBOX cd XBOX Create a configuration text file called basic_config You can use any editor but nano is quick and simple Enter nano basic_config Now enter the following mappings This file 1s the Basic Definition of the controller allowing a deadzone It will run silently Setup the DPad as buttons and triggers xboxdrv si lent true deadzone 6000 dpad as button true trigger as button true Map the right analog stick as absolute values x2 and y2 and the left analog stick as mouse relative x1 and y1 ui axismap x2 ABS_X y2 ABS_Y x1 REL_X 10 y1 REL_Y 10 Map the four coloured buttons a b x and y and set each one as a different key or equivalent joystick button In this case Left Shift joystick buttons C and A and the key C Map the triggers and bumpers in the same way Lt rt Lb and rb Map the DPad du dl dd dr as WASD Map the Back Start and Guide XBOX buttons to Home Escape and Enter H FR HHH KH HHH H u1 buttonmap a KEY
181. riginally came out in 1984 on the BBC Micro above and had wireframe graphics By the time the Archimedes version was released in 1991 they had improved the graphics a fair bit The Archimedes version of Elite is widely regarded as the best version of the original game so in the instructions that follow am going to explain firstly how to get the game running and secondly how to play it Our goal here is to run the Archimedes version of Elite on your Raspberry Pi Unfortunately Arc Elite will not run natively on the Raspberry Pi because the Archimedes processor is 26 bit whereas the Pi processor is 32 bit So we need to use an emulator This is a program that will 68 basically fool the game into thinking it s running on a real Archimedes computer and thus will run normally We will use ArcEm which gives you a fully functional Archimedes desktop environment to work in within which we will run the game The first thing we need to do though is install and boot RISC OS This was covered in Issue 9 of The MagPi see http goo gl XsCqoL If you don t have a UK keyboard you ll want to change the keyboard setting Double click on the Configure icon then click on the Keyboard icon Change the keyboard to your locale A quick note about the RISC OS mouse This had three buttons Clicking the mouse wheel on your modern mouse will do the job of the middle mouse button button 2 It s actually the middle click that gives you context menus
182. rk with we often use it as part of a complex number A complex number has a real part and an imaginary part C a bi In this equation C is a complex number and it is made by adding the real part a to the imaginary part b multiplied by f The mathematics of the Julia set requires us to use complex numbers When we make our fractal images you should picture the x axis of the screen as representing the real part of the complex number a and the y axis as showing us the value of the imaginary part b Generating a Julia Set As you will see on the next page we give the program the values for the real and imaginary parts of C Then the sprites visit every pixel in the region of the screen we are drawing on treating it as a graph of the complex plane this is what we call the visualisation of complex numbers that explained above The current values for x and y are taken as the initial real and imaginary parts of Z Z Real and Z_ Im Then we iterate over a function Zz zZz c If the value of the sum of the squares of the real and imaginary parts of z is more than 4 we consider that this location has escaped if we carried on iterating the number would get bigger and bigger and we use the number of iterations completed so far to set the colour of the pixel If the values stay lower than 4 within the maximum iterations we have chosen the location is considered to be part of the Julia set and the pixel is coloured black T
183. rmated as 4 digits long and use preceding O s to pad out those 4 digits resulting in image0001 jpg image0002 jpg image0010 jog being saved See the printf format specifier documentation man printf on a console command line for more information Changing image parameters Just like a compact camera there are lots of options that can be applied to the images to change their effect or the way they were taken The following options are equally applicable to stills or video mode Also note that some options may not be fully implemented at this stage and you may see no effect when using them This is because the applications were written to the full Camera API application programming interface available not necessarily what was actually implemented under that API I m only going to describe working features here Feel free to try all the options to see the effect they provide and whether they actually do anything First we have the basic image operations These are sharpness sh 100 to 100 contrast co 100 to 100 brightness br 0 to 100 and saturation sa 100 to 100 All these settings are commonly found on cameras or even LCD televisions Try them out with different numbers to see what effect they have here s a starting point raspistiLl t 5000 sh 100 co 50 br 25 sa 50 o image jpg 109 Image effects i1fx are quite fun These apply interesting filters to the image like negative or emboss
184. rns an object of x y z coordinates The setPos C command is then used to move the player 50 blocks up by adding 50 to the player s y coordinate We then add a delay so there is enough time for your player to fall down to the ground playerPos mc pLlayer getPos C mc player setPos playerPos x playerPos y 5 playerPos z mc postToChatC Don t Look down time sleep cs You can use the position of the player as a starting point for interacting with blocks This way you can find out what block the player is standing on or place blocks around the player There is however a challenge as the x y z coordinates returned by the getPos C function are decimals aka floats as the player can be in the middle of a block To interact with blocks we need to use whole numbers aka integers so we need to use the function getTilePos which returns the block or tile he s Standing on The following code gets the player s tile position It then calls the Minecraft API s getBlock function to find out the type of block the player is standing on by subtracting 1 from the y coordinate before using setBLock C to create blocks of the same type the player is standing on around him So if your player is standing on DIRT he will end up with DIRT surrounding him however if he is standing on STONE STONE will appear playerT1ilePos mc pLayer getTilePos blLockBeLowPLlayerType mc getBlockCplayerTilePos x playerTilePos y 1 playerTi
185. rs and wire cutters Ed Check the specification of your garage door and choose a relay that is appropriate for the voltage and current It may be necessary to use a transistor FET driver with the relay Installing WeblOPi The framework we are going to use to control the relay is WeblOPi Ed Web OPi was first introduced in issues 9 and 10 of The MagPi To install this package from the command line enter wget http sourceforge net projects webiopi files WebIOP1 0 7 tar gz tar xvzf WebIOP1 7 0 tar gz cd WebIOP1 0 7 sudo setup sh Then configure WeblOPi to start when the Raspberry Pi boots and then reboot cd sudo update rc d webiopi defaults sudo reboot Wait for a minute after rebooting the Raspberry Pi Then open a web browser and enter the IP address of the Raspberry Pi followed by the port number of WeblOPi which is 8000 e g http 192 168 2 15 8000 When connecting to the Raspberry Pi using the web browser a login screen will appear Authentication Required The server http 192 168 2 15 3000 requires a username and password The server says webiopi User Name Password Log In Cancel The default login is User Name webiopi Password raspberry The next screen shows a virtual representation of the Raspberry Pi s GPIO pins The relay can be connected between a ground pin and a GPIO pin To activate the relay click on the corresponding button to set it as an OUTpu
186. ry Anyone is welcome to play around with it and alter it for their particular purposes The code is well commented and uses the Doxygen commenting scheme so you can produce HTML documentation directly from the source code So on to the applications themselves They are command line applications and do not need to be run from a desktop environment since the preview output from the apps is superimposed over the top of any desktop or console being used Typing just the name of the application or adding help or to the command line will produce a list of all the available options The list is quite long so you may want to pipe the output into less so you can scroll up and down to read it raspistiLll less raspivid Less Basic options Both applications use the t option to specify the length of time in milliseconds they should continue running So raspistill t 3000 will run the camera for 3 seconds In the stills case and if a filename is specified the capture of the still will take place at the end of the time period In the video case and again if a filename is specified the capture starts straight away and will be as long as the time period To specify the filename of the output file you use the o option The following command runs the camera for 2 seconds and at the end of the period will take a still image saving it to the file image jpg raspistill o image jpg t 2000 This command
187. s execution of the program The program will probably run fine but it is good practice to avoid these sorts of messages especially as your programs become larger and more complex To help us exit a program cleanly we are going to use the command GP1O cleanup which will reset all of the GPIO ports to their default values For some programs you could simply place the GP1lO cleanup command at the end of your program This will cause the GPIO ports to be reset when the program finishes However our program never ends by itself since it constantly loops to check if the button has been pressed We will therefore use the try and except syntax such that when our program is terminated by a keyboard interruption the GPIO ports are reset automatically The following Python code is an example of how the try and except commands can be used together to exit a program cleanly 86 Place any variable definitions and GPIO set ups here try Place your main block of code or Loop here except KeyboardInterrupt GPIO cleanup Program will end and GPIO ports cleaned when you hit CTRL C finally GPIO cleanup Note that Python will ignore any text placed after hash tags within a script You may come across this a lot within Python since it is a good way of annotating programs with notes After we have imported Python modules and setup our GPIO pins we need to place the main block of our code within the try co
188. s pin as an input GPIO setup 17 GPIO IN In part 1 of the tutorial the input pin was tied high by connecting it to our 3 3V pin The purpose of our Python program is to check to see if the input pin has been brought low e g when the button has been pressed To check the high low status of the pin we are going to use a True or False statement within an infinite loop We need to tie our True statement to the high value of our input pin To do so we need to create a new variable called input_value and set it to the current value of GPIO P17 Pin 11 while True input_value GPIO input 17 The next step is to add a condition that will print something when the button is pressed For this we will use a False condition The input_value is False when the button is pressed and the associated signal is pulled low This can be checked with a simple Python it statement 1f input_value False printC Who pressed my button When the button is pressed the program will now display the text Who pressed my button Feel free to change this to anything you want while input_value False input_value GPIO input 17 The last two lines in the above code are very important they create a loop that tells Python to keep checking the status of GPIO P17 Pin 11 until it s no longer low button released Without this the program would loop while the button is still being pressed meaning the message will be printed multiple times on
189. scovered your fantastic magazine which brought back great memories of typing in code from magazines into my VIC 20 look forward to getting to know my little computer better through your magazine Lynn W Keep up the good work and make sure you keep the simple type in code each issue Allan really enjoy the magazine with my 10 year old daughter DEWie Your publication is outstanding The variety of well composed articles in each issue are incredibly helpful Please keep up the good work T Gomez If you are interested in writing for The MagPi or would like to join the team in the production of the magazine then please get in touch by emailing the editor at editor themagpi com
190. ser what content type to expect plus two empty lines The setup with the forms in the HTML causes the output to be piped to the status section of our web page The HIML interpreter of the browser that receives that information is instructed by the lines that there is just plain text following and therefore the browser has an idea how to format it The line with usr bin mpc stop executes the mpc stop command on the Raspberry Pi and whatever output it generates ends up in the status window The last echo command writes Radio stopped to the status window Finally we need to make the file executable sudo chmod x usr 1ib cgi bin stop sh This changes file permissions by adding the execute bit with chmod x The script files for Next Previous and the buttons in the bottom row all work in the same fashion First there s the bin bash line followed by the Content stuff with the three echo commands Then there is just whatever mpc commands are required with the output piped to the status window Retrieving command line arguments The only exception is the play sh command because pass arguments to It from the browser You can see from the radio html code on the previous page that pass the station number from the playlist in the FORM tag with action cgi bin play sh 1 So how do we recover the string 1 when executing the file pLlay sh The FORM tag with cgi bin actually makes the arguments that follow the qu
191. ses the POST method and directs the output of whatever the play sh script produces to the status window To execute the form we define a button through the lt INPUT gt tag which displays Play and submits the request to execute the pLay sh script on the server See the excerpt from the radio html file on the previous page The lt TD gt block between the lt TR gt tags is repeated four times to produce four rows of buttons In between there are four blocks with the lt TD gt tags and the enclosed form Notice that Supply an argument to the play sh script by appending a question mark and a number You may wonder what these scripts are and where they reside on the Raspberry Pi When the apache2z server is installed a directory called usr 1l1tb cgi bin is automatically created and you just put the scripts in there Note that you need root permission to put files there use sudo Let s begin with the stop sh script because it is one of the simplest Here is the content of the file usr 11b cgi bin stop sh bin bash echo Content type text plain echo echo usr bin mpc stop echo Radio stopped The first line with bin bash tells the operating system that the contents of this file should be treated as a sequence of bash commands where bash is a common shell or command interpreter for Linux The empty lines in the file are just for structuring and to guide the eye The three lines with echo tell the brow
192. show_mapC elif a_string N d 1 elif a stringy 5 ol Ih elif a_string E e 1 elif a_string W e 1 else printC nPardon I don t understand Inform the player that the command isn t recognised if z d and y e win if alLd Le x In the original you could walk through walls Now you can t printC nOuch You just walked into a wall if a_string N d 1 elif a_string S d 1 elif a_string E e 1 elif a_string W e 1 def win print C nYou found the Dwarven riches in just m Steps n show_mapC This feature has been added The original version would just END new_gameC show_mapC 74 MAIN PROGRAM new_gameC sShow_mapC while 1 moveC How to play First read the following introduction by Tim Hartnell whose prose revealed his great enthusiasm for game programming STRONGHOLD OF THE DWARVEN LORDS Deep beneath the earth you go far into the Dwarven Heartland Danger is on every side as you descend but your greed draws you on Searching through the dusty stacks of uncatalogued manuscripts in room 546B of the British Museum you came across a faded and almost illegible map to a Dwarven hoard of gold Since that day you have been obsessed with the idea of finding it As you go down into the labyrinth you realise that the Dwarven Lords who secreted the gold here 7389 years ago have long since become extinct So the main da
193. sleep followed by the number of seconds we want to wait between notes For instance if we want a 1 second wait we would type sleep 1 Let s try putting this into what we have just written Type in the following play 48 Sleep 1 play 52 sleep 0 5 play 55 Press Run Can you hear how changing the timings between the notes changes how the melody sounds Writing chords We may want to introduce chords into our tunes The easiest way to do this is to use the po Lay_chord function play_chord 48 52 55 This tells the program we want to play notes 48 52 and 55 at the same time By adding the sleep function after pLay_chord we can change the timings between notes see previous section Try this out by typing play_chord 48 52 55 Sleep 1 play 52 Using loops lf we wanted to repeat this section we could rewrite everything we just typed or we could use a loop This is achieved by using times do By writing a number in front of times do we can get the program to repeat the section that many times So if we write 2 times do everything will be repeated twice If we write 3 times do everything will be repeated three times and so on Adding end at the bottom of this section tells the program we only want to repeat this section 2 times do play 48 Sleep 1 play 52 sleep 0 5 end 125 Press Run You should hear all the notes played twice in the loop Playing patterns In our tune we may have a series of notes that
194. soon as got hold of it took it to Ben Nuttall s first Manchester Raspberry Jam There improved upon my Scratch version of Pacman http bit ly L51Ycg using a photograph of my face as the Pacman sprite plus made a bat game for my little brother MagPi Before the Raspberry Pi came along what was your experience with computers and electronics Did you work with other platforms Amy After Alan s first Hack to the Future in February 2012 a very generous geek sent me an Arduino kit through the post had a school homework project to do at the time which was to make and label a volcano for geography so decided to incorporate my Arduino into that When it was finished was asked to demonstrate it at MadLab in response to a call for makers for the Manchester Mini Maker Faire that was being held a couple of months later Around the same time attended a Manchester Girl Geeks workshop that introduced me to Codecademy loved it so much that went home and carried on I ve now got 50 badges and have worked on CSS JavaScript Python PHP and HTML5 courses MagPi Obviously you are quite the accomplished programmer now What was your first project with the Raspberry Pi Amy My first project on the Raspberry Pi was a guessing game in Python It used the random library to choose a different number each time for the answer and you had to guess which number had been picked It told you if your answer was too big or t
195. spberry PI 90 sudo reboot Motion setup The motion package can be used with a webcam to check the garage door s status While this article uses a USB webcam the Raspberry Pi camera can also be used There are specific instructions for using the motion package with the Raspberry Pi camera at http ronrpi wordpress com project list setting up wireless motion detect cam To use UVC camera support make sure the latest stable firmware is installed by updating the Raspbian installation sudo apt get update sudo apt get upgrade y Then install the motion package sudo apt get install motion Next open the configuration file in nano sudo nano etc motion motion conf Change daemon off to daemon on This will Cause motion to run as a daemon process that runs in the background The default resolution of 320x240 is a reasonable choice Change webcam_LocaLlhost on to off This allows the camera feed to be viewed from another device instead of just from the Raspberry Pi Now save the file To simply the setup motion can be configured to start when the Raspberry Pi boots by editing sudo nano etc defauLt mottion In this file change start_motiton_daemon no to Start_motion_daemon yes Then save the file and reboot the Raspberry PI sudo reboot Now that motion has been configured plug in a Debian Wheezy compatible webcam The webcam should then stream video to your Raspberry Pi s IP Address followed by
196. st like we would have done 30 years ago Try to work out how it works as you go along 72 STRONGHOLD OF THE DWARVEN LORDS v2 1 Martin Hodgson November 2013 Translated from Tim Hartnell s original BASIC version with a couple of updates Now you can t walk through walls import random VARIABLES LISTS datal 2 2 2 3 2 4 2c One 7 dataz 3 7 4 7 5 5 60 5 5 5 4 5 3 6 3 datas 7 3 7 4 7 5 7 6 70 7 7 8 7 9059 561 data4 9 9 10 8 10 7 10 6 10 5 10 4 8 8 data5 10 3 11 3 12 3 13 3 14 3 14 2 7 10 data6 6 10 5 10 4 10 3 10 2 10 2 11 2 12 data7 2 13 2 14 6 11 6 12 6 13 6 14 7 12 data amp 14 12 8 12 8 14 9 12 9 13 9 14 10 12 data9 11 9 11 10 11 11 11 12 12 9 13 9 13 10 data10 13 11 13 12 13 13 13 14 14 14 data datal data2 data3 data4 data5 data6 data7 data8 data9 datald FUNCTIONS def new_game GOSUB 640 in original BASIC version global a b Zz y X S m a e d ONLINE CO See Vi input STRONGHOLD OF THE DWARVEN LORDS nNew Game Press Enter Item zero and the zero at the beginning of each sub List will be ignored as the BASIC program uses indices 1 15 a L0 LQ L0 Lo LO LOJ LO LO LOJ LOJ LO LO LOJ LO LO COJ b random randint 1 3 Z y 14 14 Lip o 28 y iif e Ses amp Zz X s l2 for b in Crange 1 16 for c in Crange 1 16 aLb append x if random randint 1 10 gt 8 alb c s
197. such as MAME Multiple Arcade Machine Emulator it may seem odd that some games may be slower on the Raspberry Pi Despite the increase in processing power 32bit ARM vs 8bit Z80 6502 or 16bit 68000 emulation is VERY processor intensive A host system often has to be many times more powerful than its guest system MAME was started in 1997 by the Italian programmer Nicola Salmoria to emulate the hardware of arcade game systems It was originally written for MS DOS to emulate Pac Man Pengo Sega 1982 Crazy Climber Nichibutsu 1980 Lady Bug Universal Taito 1981 and Rally X Namco Midway 1980 It now supports over 10 000 ROMs although not all are playable With MAME you play the Original game code of classic arcade games without the highly collectable and expensive Original cabinets or inserting any coins ROMs and samples ROM files will be required to run specific games There are some ROMs available for non commercial use at hittp mamedev org roms MAME requires the correct ROM revision for individual versions of the core program Luckily it will display and name the missing ROM files so just try another ROM revision some early arcade games used additional discrete logic circuits for sound Astro Blaster Sega 1981 Berzerk Stern Electronics 1980 Donkey Kong certain sounds e g The Jump Gorf Bally Midway 1981 etc MAME cannot emulate these so samples are required to run correctly
198. supported are PNG GIF and BMP These are all lossless formats no data is thrown away in order to decrease file size and the file sizes are therefore much larger than JPG They also take longer to save as there is no dedicated hardware acceleration in the GPU for them You can select the type of file to output using the e encoding option raspistill t 1000 e png o image png Timelapse mode The raspistill app has a very useful feature called timelapse mode Instead of just taking one picture it takes a sequence of pictures at a specified interval use tl until the timeout limit t is reached So to take a picture every 5 seconds over a period of 50 seconds use the following raspistill t 50000 tl 5000 o image d jpg The t and tl options are fairly obvious but what is that odd filename specification Well if you just specified something like raspistill t 50000 tl 5000 o image jpg then all your pictures would be saved to the same filename image jpg So you end up with just one picture By adding a d in your filename specifier the image number is added to the filename at the place where the d is So our first example above would save a set of files as image1 jpg image2 jpg image10 jpg In fact the filename is generated using the same formatting as the C language printf statement so you can do something like this raspistill t 50000 tl 5000 o image 04d jpg which specifies the number will be fo
199. t instead of an INput Now when the GPIO pin is selected it will send a voltage to the relay connected to it 33v E EA sv GPIO 2 E Fi 5 0V GPIO 3 EA 6 GROUND GPIO 4 Ei ra UART TX 3 3V 18 GPIO 2 GPIO 10 19 20 GROUND cpio 9 PAE PI crio 25 GPIO u By TU Grios GROUND 25 TA GPIO7 Configuration To make the interface cleaner WeblOPi can be configured to offer one button instead of many small ones Create folders to store the files mkdir p garage html mkdir garage python The next step is to create a python file that helps the HTML file control the garage door opener nano garage python script py Now copy the code below into the new file import webiopi GPIO webiop1 GPIO Garage 17 GPIO pin using BCM numbering setup function is automatically called at WebIOP1 startup def setup set the GPIO used by the light to output GPIO setFunctionCGarage GPIO OUT loop function repeatedly called by WebIOP1 def Loop gives CPU some time before Looping again webiop1 sleep 1 Then press CRTL X and then Y to save the file WeblOPi will access this python script using an HTML page that contains the single button Use nano to create a new HTML file nano garage htmL index html Then copy the HTML from the next page of this article into the file and save it lt DOCTYPE html PUBLIC W3C DTD HTML 4 01 Transtttonal EN gt lt html gt lt head gt lt meta http equiv
200. ted as are pins 3 amp 4 However both pin pairs are disconnected from each other when the button is not pressed i e pins 1 amp 2 are isolated from pins 3 amp 4 When the button is pressed the two sides of the switch are linked and pins 1 2 3 amp 4 are all connected In momentary switches the circuit disconnects when pressure is removed from the button as opposed to toggle switches when one push connects and the next push disconnects the internal switch circuit Where does it all go WARNING When hooking up to GPIO points on your Raspberry Pi care must be taken as connecting the wrong points could permanently damage your Raspberry Pi Please use a GPIO cheat sheet and double check everything before switching it on will denote each GPIO point by its name and physical location for example GPIO P17 is actually located at pin 11 denoted GPIO P17 pin 11 The irregularities are a result of the pin names being referenced by the on board chip rather than their physical location 1 Connect the Raspberry Pi to the Ground Rail Use a black jumper wire to connect GPIO GND pin 6 on the Pi to the Negative rail on the breadboard the rail on the edge of the board with the negative sign 2 Connect the Raspberry Pi 3 3V to the Positive Rail This article is sponsored by ModMyPi Use a red jumper wire to connect GPIO 3 3V pin 1 on the Pi to the Positive rail on the breadboard the edge rail with t
201. ter calling the cipher block these scripts prepare the text for output If we are preparing cipher text it is broken up into lines each of which can have up to five five character cipher words If we are preparing plain text any symbols result in a newline being added while a is changed into a space The resulting text is then available in textOut and you can export to a text file if you wish This is the cipher script It just goes through each character that is in inputText If the letter is a space it changes it to a when I receive Cipher before enciphering it If we are deciphering the dummy spaces will already have been removed eet Gounk Cty repeat length of inputText It then looks through the key until it finds the letter In the key 2 9 letters are grouped in pairs So if the index of the letter is an i even number the letter is replaced with the next letter in the if latter E m list Otherwise it is swapped for the letter before it seat Index to Fepeat untit letter item mdex of cipherAlpta change Pea by i z ete Scratch On set OuLpULTExE to join GutputText item index of Ciph ralpha else get OCuULpULTEXE to join outpetText item index 4 of cipherAlsha Ls p change Count by iy stop script I getTest In this example I ve made the ana The process of preparing programs fora digital inputText variable visible so computer if e pe
202. the required level The area of the image that is used to determine that incoming brightness is what is defined by the metering mode There are two usefully distinct options average and spot Spot takes the very centre of the image and uses that while average uses the whole image So if you have a scene with a very bright point in the centre using spot will almost certainly underexpose In that case you should use average raspistiLl t 5000 mm average o image jpg AWB stands for automatic white balance This is a complicated subject but in very simple terms it is the adjustment made to the image to compensate for different lighting conditions to make whites look white For example different types of office light produce different lighting conditions and the system needs to compensate for those conditions so the white walls still look white in the photograph By default the AWB selection is done automatically using Bayesian analysis of the scene to make an educated guess on the lighting conditions However you can specify the AWB approach being used depending on the scene being captured The options are auto sun cloud shade tungsten fluorescent incandescent flash horizon So to set up the AWB for a room lit by tungsten filament bulbs you would use raspistill t 5000 awb tungsten o image jpg Anything else We ve covered many of the features available on the Raspberry Pi camera but the best way to O
203. these add ons from the main menu select VIDEOS then Add ons and click on Get More At the top of the list click on i e two dots At the top of the next list again click on i e two dots Now click on Install from zip file A new window will pop up Select your USB memory stick If it is not visible remove it and insert it again Navigate to the first add on you wish to install and click it It gets installed at this point within about 30 40 seconds but it is not obvious You will be returned to the InstaLl from zip file menu and you may momentarily observe bottom 50 right of the screen that the new add on has been installed Check by returning to VIDEOS and selecting Add ons and you should see the name of the add on you just installed If it is absent wait a few minutes for it to appear and if it is still absent then reboot your Raspberry Pi Repeat for each add on one at a time Step 5 XBMC remote control Download and install the Official XBMC Remote app to your Android or iOS device or install XRMT for your Blackberry 10 OS device As an example here is how to configure XRMT on your Blackberry 10 OS device Once installed open the app and click the three dots icon bottom right and select Add Server For Server name enter openelec lower case For Server IP address enter the address that you set up for the Raspberry Pi in step 2 on page 49 Leave the Port code as 9090 then click the icon at bottom left N
204. this point as invalid HTML could cause this to fail This is only a generic error message which you may like to improve on in your own programs Line 19 is very important The file needs to be closed so that the write completes and it s possible to read the file back in Without this then nothing will print and in my case spent a lot of time tearing my hair out trying to work out what was going wrong We create a connection to CUPS and use the getPrinters command to get a list of the available printers I ve deliberately included the print command on line 27 which is the standard Python command to print a line of text to stdout screen It is nothing to do with sending anything to the printer so don t let that confuse you WOON DUBWNE Filename for temp file filename home pi print pdf generate content xhtml lt hi gt Test print lt h1 gt n xhtml lt h2 gt This is printed from within a Python appLication lt h2 gt n xhtml lt p style coLlor red gt Coloured red using css lt p gt n pdf pisa CreatePDFCxhtml fileCfilename w if not pdf err Close PDF file otherwise we can t read it pdf dest close print the file using cups conn cups ConnectionC Get a list of all printers printers conn getPrinters for printer in printers Print name of printers to stdout Cscreen print printer printers printer device ur1 get first printer from printer list printer_name
205. ty hackspaces or places like MadLab that welcome kids through their doors Readers could set up these kid friendly spaces and run events specifically for under 18 s like MadLab s CoderDojos or set up code clubs in their local primary schools http bit ly HLRWwT Your local STEMnet team http bit ly B0z2q could help with setting this up if you re unsure Raspberry PI to Arduino to LED matrix Amy is not limited to software hacking MagPi If you were able to influence the Raspberry Pi design team and introduce a new model what changes would you bring to the table Amy wonder if it would be a good idea to attach a 16x2 LCD screen to the board so that once you ve written your code for a project and i s on the Pi you could then just plug in a keyboard and a terminal like environment would come up on the LCD screen This would mean that you could run your code without having to plug in a monitor making it easier to incoporate into projects would also like to see if the design team could introduce a new board that could be used in wearable electronics along the lines of an Arduino Lilypad but even better like the fact that the Lilypad is washable lightweight and can be easily attached to fabric with conductive thread If they could improve upon this it would be great MagPi What are the best resources out there that you can recommend for young Raspberry Pi programmers or people in general that are gi
206. u want and then press H for hyperspace This will give you a 10 second count down to your jump Manually docking with space stations is especially hard To help here is a video of someone doing this on the BBC version of Elite The basic idea is that you need to find the space station get yourself lined up with its letter box shaped entrance then fly into it as straight as you can If you get it wrong you re dead the game is actually that brutal Here is how usually do it After you do a hyperspace jump you ll see a planet somewhere near you Head towards it and press J to jump If another ship gets near you a message saying MASS LOCKED will appear you can t fire your jump drive when something else is near you If it s a pirate you ll need to fight Often getting them to crash into your shields is enough to kill them Keep heading towards the planet It should get bigger as your approach If you look at the game screen shot to the left you ll notice there is a square box with a green cross hair just below the E in MISSILE This is used to help you locate the space station It will show as a white dot if the station is in front of you and a red dot if behind Try and get the white dot in the centre of the cross hair That then means you re flying directly towards the space station When you get near it start slowing down and get ready to do what you saw in the video above Fly roughly near the station slow right down then point tow
207. u want the downloaded file to go by first double clicking the SD card icon in the bottom left then use button 1 to drag the icon within the NetSurf Download box into the SD card window as above The zig zag on the downloaded file is because it is a Zip file it has other files compressed inside it With some of the download mirrors the file type is not set to Zip You can tell when this happens because the download icon will be green with the word Data and not a folder with a zig zag To fix this move your mouse over the icon and click the middle mouse button scroll wheel choose File arcem 1 50 riscos gt Set type gt then change Data to Zip ie type Zip The next thing we need to do is create a new folder to unzip the emulator into Middle click mouse wheel somewhere in the SD card folder and a context menu will appear Choose New Directory gt move the mouse over the arrow type ArcEm into the box and double click the new ArcEm folder An empty window will display Double click on the Zip file and you will see two folders Open the Apps folder then the Misc folder You will see 3 files ArcEm COPYING and hostfs Select and drag these files into the ArcEm folder Before we can run the emulator we need to give it a ROM file This is an image of the original Archimedes operating system that the emulator will boot up into We will use RISC OS v3 10 Open NetSurf navigate to http nome tiscali nl jandboer
208. up a big chunk of memory as PURER RAURRRUEE i 6 e o Irs sx s o fae P Rev AS 4 Py Rasp the images are large and there needs to be at least two of them in memory at any time in order to provide a double in some cases triple buffer which prevents tearing of images during display Checking it works OK we have connected the hardware and installed the software Now we need to see if it Is all working correctly The quickest way is just to type in raspistill t 5000 This runs the stills capture program for 5 seconds or 5000 milliseconds Note that all times used are in milliseconds You should see the whole display replaced with a moving image of whatever the camera is looking at If you don t see the preview appear or there are error messages displayed go straight to the Troubleshooting section at the end of this article So what can it do As with any camera it can work in two ways We can capture still images just like a camera or we can capture video like a camcorder The two demo applications provided handle these tasks separately Although it would be quite possible to combine them into one application that makes the code more complicated and as demo code a lot of effort was put in to make it as easy to understand as possible As an aside the C language source code for the applications is publicly available from the Foundation s github reposito
209. ur has to be the same as the colour used on _ the stage for the program to work When the racing car touches the edge it says Sois prudente be careful for one second when clicked Eee O Fee 100 switch to costume costume forever a if touching color s Aip switch to costume costumes a a at stop all touching LEg9 gt witch to costume costume men ee e e e e stop all F if touching Dalion switch to costume costume stop all i Lego brick and ball HREN The lego brick and ball are controlled by the hide same program To start writing the script for the Lego brick click on the Lego brick sprite icon point in i direction under the stage window Then create the script set y to given on the left of this page When the script n has been written select all of it and click on copy Then click on the ball and paste the script For the ball change the wait statement from 2 2 show seconds to 3 seconds As long as the two wait point in direction statements are not multiples of each other the ap y to two objects will not arrive at the same time Sini re Secs F set xto pick ick random 120 m20 W The script for the Lego brick and ball starts by gpm hiding the sprite The sprite is then put at the top foe EERE touching edge gt of the screen pointing down The script then change yh by enters a loop Each time the loop runs the script waits and then
210. ut cryptography try this website www simonsingh net The_Black_Chamber a g ere vie BALLISTIC Target practice arcade game Physics of a cannon ball In this article we will create another simple snnonx Emz arcade game Similar to the racing car game SS cannon_angle TI there is plenty of scope for expanding or ne E modifying this game too e The idea of the game is to try to hit the drum with the cannon ball The cannon is controlled by the cursor keys and the spacebar where the left and right keys change the angle of the cannon the up and down control the initial speed of the ball and the spacebar fires the cannon There are three sprites in this program the cannon the cannon ball and the drum The cannon was drawn using the rectangle tool Different shades of grey were used to give the appearance of a round barrel Then the picture was copied using the Copy button The original picture was named ready and the copy was named fired A muzzle flash was added to the fired costume The cannon ball is a marble taken from the Scratch library The Drum is also from the Scratch library Both of these sprites were resized to the correct size he gun carriage is part of the stage where the cannon was positioned on top within the cannon script Cannon script The cannon script starts by setting the position and costume of the cannon to the default Then the script initialises all of the global vari
211. ve loudspeakers with a built in amplifier Alternatively you can connect it to the Aux Line In input of your stereo amplifier For this you might need a cable that has a 3 5mm jack connector attached to the Raspberry Pi audio output and RCA phono connectors that are attached to the amplifier lt is time to test the basic software functionality The mpd program is a daemon background process that is started automatically at boot time We interact with the daemon using the mpc program In order to play the radio stations we need to inform the Raspberry Pi about the channels For this prepared a small text file that contains the internet addresses of the radio stations want to listen to one station per line with the URL and port number separated by a colon Using either Leafpad in LXDE or nano from the command line create a sample file with the following http 108 61 73 118 8030 http 109 123 116 202 8022 and save it as pLaylist txt the actual name does not matter just pick any you prefer We can now add our stations to the mpc playlist From the command line enter cat playlist txt mpc add To check that the playlist was added enter moc playlist This will list the stations by their URL or by their name if they have been played Let s make some noise To play the first station in the playlist enter moc play 1 and to play the second station enter moc play 2 Normally the play command connects to t
212. very dark conditions Installing the scripts To install the scripts type git clone https github com sdenton4 pipic cd pipic chmod 755 timelapse py chmod 755 deflicker py The time lapse program can be run with the default settings timeLapse py or the available options can be listed timelapse py h When the time lapse program runs it writes the pictures into the pictures directory To start the time lapse program when the Raspberry Pi boots type sudo nano etc crontab and add reboot pi python home p1 timeLapse py Then save the file and exit nano Making the movie file After running the time lapse program for a long time the photographs should be assembled into a movie This can be done very easily with mencoder mencoder mf jpg mf fps 18 type jpg ovc lavc lavcopts vcodec mpeg4 mbd 2 treLll vbitrate 3000 vf scale 512 384 oac copy o movie avi This command uses all of the jpg files in the present working directory and assembles them into a movie A sound track can be added to the movie using an existing audio file mencoder ovc copy audiofitle MYMUSTC mp3 oac copy movie avi o movieWithMusic avi Post processing The movie can look a bit too grey To create more contrast PIL s image manipulation capabilities can be used The greyscale histogram of a single image can be plotted using Python and matpLotL 1b import Image from matplotlib import pyplot as plt 1
213. ving programming a go for the first time Amy Obviously the MagPi magazines are a great resource but think that the Super Scratch Book http bit ly MVKOw8 looks like a great book to help younger users of the Raspberry Pi For older users Simon Monk s Python book http bit ly VXJZrl provides a great introduction to the language There are some very helpful resources online really like GeekGurlDiaries http bit ly 1088jKG Adafruit http bit ly LEQbiB MakeZine http bit ly 13Xr44a Instructables http bit ly 4kLr49 Arduino Tutorials http bit ly vim8A The Twitter feeds mykidcancode and codingforkids often have great links too MagPi Conway s Game of Life can be quite daunting What projects would you encourage new young programmers to begin with Amy Scratch http bit lyjy 4Mw is probably the best place for young programmers to begin but if you prefer working towards goals then Codecademy http bit ly oDjwOj will probably be more helpful On the Codecademy website you can choose to learn a particular language or work on a project e g one of the first games you ll make in the JavaScript course is Fizz Buzz Alternatively simple guessing games or rock paper scissors type games are a good place to start and there are plenty of internet forums where you can search for help with any queries that you may have MagPi In your presentation you mentioned Madlab and Manchester Hackspace Ca
214. w we have everything set up let s make some sudo apt get install sonic p1 music lt is important that you update Raspbian before downloading Sonic Pi otherwise Sonic Pi won t Making sounds work Open up Sonic Pi You will see three panes see jv OB Workspace 1 Workspace 2 Workspace 3 Workspace 4 gt 3 times do play 55 playing pretty_bell sleep 0 5 with note 53 play 56 Output with note 50 playing pretty_bell with note 56 playing pretty_bell with note 59 In the large pane type in play 48 By typing this we are telling the program you want to play MIDI note 48 which is the equivalent of playing a C on a piano To hear it we need to press Run This is the triangle button at the top of the page We should hear a note and in the output pane which is found on the top right of the screen we will see what is happening i e note 48 is playing If you make a mistake while typing in the code don t worry The bottom right hand pane will show you your mistake Try typing in ploy 48 and see what happens when you press Run To create a tune we need to play multiple notes Let s type in the following play 48 play 52 play 55 Press Run You will notice the three notes are played together This is great if we want to play a number of notes at the same time but no good if we want to play separate notes So to make sure the notes play one after another we need to type
215. will do the same but will save a 2 second H264 video file called video h264 raspivid o video h264 t 2000 You don t need to specify a filename for the output if you don t then no capture is done but the preview will still be run for the specified time If you don t specify a time then 5 seconds is used as a default The following will take a picture after 5 seconds raspistill o image jpg So we have made some files but how do we see what they look like Well to view JPG images the FBI program is quite useful You can install it quickly using sudo apt get install fbi Then you can easily display your JPG images Zoom in and out use and etc fbi i1mage jpg To view video you can use the already installed omxplayer omxpLayer video h264 Preview options You can specify whether you want the preview disabled n or whether it is to appear full screen f or in a window p You can also specify what opacity op the preview window is to have so you can see the desktop underneath if necessary To display the preview in a window at position 100 100 width 500 height 400 and at 50 opacity 0 transparent to 255 opaque enter raspistiLll p 100 100 500 400 op 128 o image jpg To disable preview completely enter raspistill n o image jpg In the next article some of the more advanced features will be discussed Troubleshooting lf your camera is not working there are a number of thi
216. y Within terminal enter the following command sudo nano boot config txt This will open the configuration file in the Nano editor to allow you to make a change Scroll down the file to the comment uncomment to force a specific HDMI mode this will force VGA Remove the to uncomment the two lines hdmi group and hdmi mode and then edit them to read hdmi _group 2 hdmi _mode xx where xx is the number of the resolution mode you wish to use Following on from my example above for a 1024 x 768 resolution would use the line hdmi_mode 16 In this example the relevant section of the config txt file would look like hdmi force hotplug 1 uncomment to force a specific HDMI mode this will force VGA hdmi _group 2 hdmi _mode 16 uncomment to force a HDMI mode rather than DVI This can make audio work in DMT computer monitor modes hdmi drive 2 After saving the file in Nano CTRL X Y to confirm and Enter to overwrite and rebooting sudo reboot your Raspberry Pi should restart with the new resolution Note If you select a resolution from the first list on the website e g 720p 60Hz you must set hdmi_group to 1 Where there are multiple resolution settings with different refresh rates e g 60Hz 75Hz etc you might need to experiment to find the most suitable setting Most computer monitors support refresh rates of 60 and 70 Hz modern televisions are generally higher Why do
217. y 0 651 Real 0 7467 Imaginary 0 3515 Download If you get stuck you can get the code here http tinyurl com gastonjulia Douady s Rabbit SUBSTITUTION CIPHER Pretty poor privacy SKILL LEVEL BEGINNER antiloquax MagPi Writer This program shows you how to implement a simple substitution cipher with a reciprocal key In a reciprocal key pairs of characters are mapped to each other This makes life easier as we can use the same key to encipher and decipher messages The resulting cipher texts are not too difficult to crack but it s a start The first thing to do is make some sprites that will be the buttons we click to make things happen in our program see the examples on the right To create a new sprite click the paint new sprite button just below the stage You can delete the cat F when Sprites clicked delete all Y of plainAlpha delete al of Cipheralpha SAE E KECOEFGHIIKLMNOPORSTUVWAYTZ Here s the script that the make key button set length to length of alphabet activates the remaining scripts are on the set Count ito P following pages To load a key you have repeat length already made make the cipherAlpha list add EELS Lom IBEREOES py plainalphe visible on the stage then right click it and j Import the key from the file in which it has change C CUTE by F been saved repeat length am index te pick random b to length of plainalpha Alternat

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