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    Raspbian Raspbian Document Transcript

    • IISSSSUUEE 1122 ­­ MMAAYY 22001133AA MMaaggaazziinnee ffoorr RRaassppbbeerrrryy PPii UUsseerrsshhttttpp::////wwwwww..tthhee mm aaggppii .. cc oo mmRRaassppbbeerrrryy PPii iiss aa ttrraaddeemmaarrkk ooff TThhee RRaassppbbeerrrryy PPii FFoouunnddaattiioonn..TThhiiss mmaaggaazziinnee wwaass ccrreeaatteedd uussiinngg aa RRaassppbbeerrrryy PPii ccoommppuutteerr..GGeett pprriinntteedd ccooppiieessaatt tthheemmaaggppii..ccoommBIGBIRTHDAYCOMPETITIONWin more than£1000of goodies!TThhiiss IIssssuuee......AA YYeeaarr OOff TThhee MMaaggPPii wwiitthh LLiizz UUppttoonnSScchhiissmmTTrraacckkeerr:: DDJJ QQuuiicckkssiillvveerrEEnnccrryyppttiioonn WWiitthh SSccrraattcchhPPeettee LLoommaass IInntteerrvviieeww£1,000
    • Ash Stone - Chief Editor / AdministrationW.H. Bell - Layout / Graphics / AdministrationMatthew Judge - Website / Administration / TesterChris tzj Stagg - Administration / Tester / GraphicsTim meltwater Cox - Administration / Layout TesterLix - AdministrationIan McAlpine - Layout / Tester / GraphicsAaron Shaw - Layout / Graphics / Proof ReadingBryan Butler - Page Design & Theme / Graphics / TesterDavid Allan - TesterSam Marshall - Page DesignThe MagPi TeamColin Deady - Layout / GraphicsMark Tranter - LayoutJames Nelson - Layout / GraphicsSteve Drew - LayoutMatthew Watson - LayoutAdrian Harper - Layout / Proof ReadingPhil Tesseyman - TesterShelton Caruthers - Tester / Proof ReadingSai Yamanooor - Tester / Proof ReadingJeremy Schrock - Proof ReadingChad Longstaff - Proof ReadingPhil Shillito - Proof Reading212Welcome to issue 12 of The MagPi magazine, our 1st birthday celebratory issue.What a year it has been! To mark this incredible achievement Liz Upton from theRaspberry Pi Foundation has kindly agreed to be a guest writer for the magazine and hasproduced an article documenting our first year of publication. Thank you Liz.To celebrate a year of The MagPi, in this issue we are proud to be able to hold our firstmassive birthday give-away. In this competition we are giving readers the opportunity towin over £1,000 of Raspberry Pi goodies! Thank you to all the companies who havesupported us with this... you are amazing.We also take this opportunity to include articles covering some of the less published startup questions in the ‘Beginners Guide’ article and we review some of the operating systemswhich were produced over the last year for the Raspberry Pi. The MagPi’s very own IanMcAlpine provides us with a fantastic insight into the mind of Pete Lomas plus more fromour great authors on coding.Thank you to those who supported our Kickstarter campaign. We have a special update onpage 17. Expect your printed copies very soon!I hope you continue to enjoy The MagPi into our next year of production. If you have anarticle you wish us to include, or have some free time you could spare to help our cause,please email us at editor@themagpi.com.Chief Editor of The MagPi
    • 34 A YEAR OF THE MAGPILiz Upton writes about the first year of The MagPi6 Where can I get help?9 SWEETBOX IIHow to make a case for the Raspberry Pi in 31 4 steps9 THIS MONTHS EVENTS GUIDEMalawi, Swansea, Tokyo and Norwich12 RASPBERRY PI OPERATING SYSTEMSA breakdown of the various operating systems available for the Pi16 STAR LETTERA note of thanks from the ZX generation18 PRINTING WITH CUPS 2Printing from a Python program20 AN INTERVIEW WITH PETE LOMASSharing his thoughts on Raspberry Pi design challenges and the future26 MAKING MUSIC WITH SCHISMProgramming melodies30 A birthday issue bonanza of goodies to be won, worth over £1 ,000!32 BASH GAFFER TAPEEmbedding text and programs34 SCRATCH PATCHUse encryption to code and decode messages39 FEEDBACKHave your say about The MagPiBEGINNERS GUIDECOMPETITIONCover photo plus photo on page 20 by Dean Smith, Camera Crew.10http://www.themagpi.comContentsContentsContents
    • Liz UptonThe Raspberry PiFoundationA Year of The MagPiLooking back at the first yearof The MagPi with Liz UptonLast March, an email came through to my Raspberry PiFoundation address from someone calling himselfJaseman. He and a group of volunteers had been workingon a monthly Raspberry Pi-themed magazine, and theywere intending to give away electronic copies for free.There had been chatter on the Raspberry Pi forums aboutwhat a nice idea a monthly magazine, produced by Piusers, would be; a sort ofreturn to the old days ofreviews, listings and hardwareprojects that some of usremembered from magazineslike Micro User and AmigaFormat. I didn’t for a momentthink that anybody would takethat suggestion and turn it intoa real magazine; this was justafter the Pi’s launchannouncement and we hadn’t really got a feel for just howdynamic the Pi community can be when it comes up with areally good idea.Magazines, you see, are hard. Before I started working forRaspberry Pi in 201 1 I’d spent ten years working inpublishing; first as an assistant editor for a group ofclassical music magazines, before moving into bookpublishing as a chief copy editor. I moved to books for asimple reason: magazines give you sleepless nights. Thepay is awful; you’ll find yourself subsisting on the canapésthey serve up at events so you don’t have to buy food.You’re working on a month-long treadmill that never stopsmoving. You’re corralling a million different contributors,none of whom take your deadline seriously; you’reensuring that everything gets proof-read by three differentsets of eyes before going to press and trying to rememberwhere the accents go in Antonín Dvořák; you’re hoping thatyour advertising department manages to raise enoughmoney this month to keep you alive for another cycle;you’re chatting up theproduction department on the offchance that they’ll be able tocreate a bit more space for thereally great feature that turnedout too long for this issue; you’rethrashing about in an attempt tocome up with a really cleverheadline for that article about theold oboe da cacca-playing gentwith the already-too-punnyname; and then, when the thing comes out, you’d betterbrace yourself for the reader feedback. Letters will arrivewritten in purple ink informing you that the theorbo youpictured on page 1 3 was, in fact, a modern sitar, andcalling for your sacking. (It was a theorbo. I wasn’tsacked.)Seriously: if you think that electronics enthusiasts aregeeks, you ought to meet the early music crowd.I can’t imagine doing all this stuff with a team of volunteers,absent the threat of withholding someone’s fee if they don’t"I can’t imaginedoing all thisstuff with a teamof volunteers"4
    • pitch up on time with their article. I really can’t imaginedoing it without a team of experienced layout, editorial,production, photography, advertising, financial and legalpeople propping the whole enterprise up. But we kept ourfingers crossed and hoped The MagPi team would meetwith the same sort of luck we’d found at the Foundationand we offered them our help if they felt they needed it.(They didn’t.) The core team seemed like a smart bunch ofpeople. We prepared ourselves to be surprised.And we were. The MagPi’s quality, convincing from thestart, has really been cemented over the last year.Graphically it’s gettingbetter and better withevery issue, and thecontents are so good thatthe Raspberry PiFoundation has beenstrongly recommendingthe magazine to schools,parents and after-school clubs to use as part of theirteaching materials. The team working on the magazine hassomehow found time not only to get a magazine out everymonth, but also to run a startlingly successful Kickstarterand, in the case of people like Tim “Meltwater” Cox, to setup some small businesses in the Pi ecosystem as well. I’vereferred people emailing me with questions to themagazine time and time again. It’s a superb resource, andit’s been driven by nothing but the extraordinaryenthusiasm of a group of spare-time volunteers.I met Ash Stone, who edits The MagPi, at an Agileconference in Cornwall last summer. We spent the eveningsitting on the beach in Falmouth with him, drinking beerand eating hogroast, while talking about the magazine. Hehas a very demanding day job, but brings an enthusiasmand a work ethic to his job on The MagPi that mirrorsexactly what we saw at the Raspberry Pi Foundation in thedays when we were a group of volunteers too. We havefound that working for the love of something bringsrewards that the daily grind for a paycheck can’t touch;Ash and the team seem to be experiencing something verysimilar. There’s such a depth and breadth of electronicsand programming knowledge inherent in the group that’scome together to make this magazine. Their impulse toshare that knowledge and make it accessible toeverybody, not just those who have the luxury of being ableto afford a monthly subscription, is really admirable and,we hope, reflects the philosophy behind the Raspberry PiFoundation itself. We believe that access to tools shouldbe something that’s available to everybody. We believethat nobody should be priced out of being able to learn, orbeing able to build. Of course, computing and making isnot for everybody; but everybody should be offered theopportunity to find out whether it’s something they respondto or not.We think there is something compelling, even in a period ofubiquitous e-readers and tablets, about the printed word.We’re proud and excited to see The MagPi’s print editionstake off; even if you’re not buying a print edition, I hopeyou’re printing at least some of the PDF version magazineat home (or at work or school) every month. When youread a piece of code and then use your brain to process itand send a signal toyour fingers to type itinto your Pi, you’recementing whatyou’re learning in aphysical way that justwon’t happen if youuse copy and paste.You will also, hopefully, make mistakes in your typing,which will mean you’ll have to go over the code again topull out bugs, which will make you think about how thingswork. If you’re like me, you’ll fold the corners of pagesdown and mark interesting bits up with a pen, or stick apost-it note on articles you want to come back to.Scribbling your own notes on hardware instructions helpsyou to remember what they’re for and how things fittogether. We’re looking forward to seeing how the teamdeals with the challenges of producing a physicalmagazine alongside the PDF MagPi; we’re also lookingforward to seeing sets of the print MagPi in schoolclassrooms and libraries.This second year of The MagPi has potential to be evengreater than the first. Everybody here at the Raspberry PiFoundation would like to congratulate The MagPi team ona wonderful year; but most of all we would like to thankyou. You’ve helped spread the word about our littlecomputer; you’ve helped people to learn how to use it.You’ve helped kids to find their first enthusiasm forcomputing and engineering and you’ve helped grownupsget back into a hobby they dropped when machines likethe Amiga and the BBC micro went away. You’re a vitalpart of an ecosystem that the Pi needs to stay importantand relevant in education and we can hold you up as anexample of the passion and skill of the community aroundthe Raspberry Pi.In many ways we wouldn’t be where we are today withoutThe MagPi. So thanks to all of you from all of us: andhere’s to year two!"We think there issomething compellingabout the printed word"5
    • 6DIFFICULTY : BEGINNERAdrian HarperMagPi WriterWhere can I get help?There are numerous guides to getting startedwith a Raspberry Pi that cover the basics ofsetting up your new computer with therecommended Raspbian Wheezy operatingsystem, running through raspi-config etc.However, most setup guides stop once thesystem boots into the windows style interface ofLXDE.I regularly encourage people to buy and useRaspberry Pis, especially if they have kids, buttime and again I hear people asking "Ok Im atthe desktop, whatnow?", and "Howdo Ido suchandsuch?".The official forums at raspberrypi.org are a greatplace to start looking for solutions to problems orquestions that you might have, though they canbe a bit daunting for a beginner. The searchfunctions on the forum are excellent, so pleasetake a few minutes to search the existing postsfor answers to your questions before starting anew thread.The web offers some exceptional free userguides that go into great detail to cover theinstallation of Raspbian Wheezy on an SD cardfrom Windows, OSX and Linux. EngadgetsGetting Started Guide is especially good -http://engt.co/PZbUpT. These guides offer helpwith troubleshooting basic issues as well asproviding ideas for that "What now?" momentwhen everything is running and youre staring ata large raspberry in the middle of the screen. TheRaspberry Pi Guide on the Embedded Linux wikiis also recommended - http://bit.ly/pJfgMr.Even with the user guides and forums, it is worthmentioning the solutions to a few of the mostcommon questions asked by new Raspberry Piowners:I would like to connect x device to myRaspberry Pi. How can I be sure it isgoing to work?Unless you like the challenge of writing driversand figuring out why a piece of hardwareconnected to your computer does not function asit should, before buying any peripherals for yourRaspberry Pi, check the list of verifiedperipherals on the Embedded Linux wiki -http://bit.ly/Ae6JbF.Members of the Raspberry Pi community areextremely active in finding and documentingwhich devices work and which dont, so you donthave to!
    • 7How do I set my screen resolutionwhen using a monitor connected byVGA / DVI?With an HDMI connection the Raspberry Pi candetect and set the resolution correctly (in mostcases) for the screen that is being used. Forthose of us that need to connect a monitor usingan HDMI to DVI cable or an HDMI to VGAconvertor box the resolution needs to be setmanually.While not being as intuitive as selecting aresolution from a preferences screen, a changecan be easily made by editing a config file in theTerminal. To find the correct setting for yourdevice, look up the resolution list on theEmbedded Linux wiki - http://bit.ly/1154mFm.It is normally easier to find the correct resolutionin the second list that shows the screen size inpixels e.g. 1 024 x 768.These values are valid ifhdmi_group=2 (DMT)hdmi_mode=13 800x600 120Hzhdmi_mode=14 848x480 60Hzhdmi_mode=15 1024x768 43Hzhdmi_mode=16 1024x768 60Hzhdmi_mode=17 1024x768 70Hzhdmi_mode=18 1024x768 75HzMake a note of the hdmi_mode=X setting for theresolution you wish to apply.Within terminal enter the following command:sudo nano /boot/config.txtThis will open the configuration file in the Nanoeditor to allow you to make a change. Scrolldown the file to the comment# uncomment to force a specific# HDMI mode (this will force VGA)Remove the # to uncomment the two lineshdmi_group and hdmi_mode and then editthem to read:hdmi_group=2hdmi_mode=xxwhere xx is the number of the resolution modeyou wish to use. Following on from my exampleabove, for a 1 024 x 768 resolution, I would usethe line "hdmi_mode=16".In this example, the relevant section of theconfig.txt file would look like:hdmi_force_hotplug=1# uncomment to force a specific# HDMI mode (this will force VGA)hdmi_group=2hdmi_mode=16# uncomment to force a HDMI mode# rather than DVI. This can make# audio work in# DMT (computer monitor) modes#hdmi_drive=2After saving the file in Nano (CTRL + X, Y toconfirm and Enter to overwrite) and rebooting("sudo reboot") your Raspberry Pi shouldrestart with the new resolution.Note: Ifyou selecta resolution from the firstliston the website, e.g. 720p 60Hz, you mustsethdmi_group to 1.Where there are multiple resolution settings withdifferent refresh rates, e.g. 60Hz, 75Hz etc., youmight need to experiment to find the mostsuitable setting.Most computer monitors support refresh rates of60 and 70 Hz; modern televisions are generallyhigher.
    • 8Why does the screen lock icon in thebottom right corner of the LXDEscreen not work?The basic Raspbian Wheezy image does notcome pre-loaded with a screensaver; hence thelock not functioning and you not being able tofind any screen saver preferences in theapplication menu.Fixing the issue is easy enough; you just need toinstall the LXDE screen saver from the terminalby giving the command:sudo apt­get install xscreensaverOnce installed, find and launch the screen saverpreferences from your application menu. Youshould be immediately prompted that the screensaver daemon is not running. Click ok to launch itnow.Within the preferences dialog you can choosewhich screen saver the system will use, the idletime before it starts and if/when the systemrequires a password to unlock. As soon as thescreen saver daemon is running the screen lockicon will function correctly.What do I have to do to get my nonUK keyboard to work correctly inLXDE?Raspi-config does a good job of easily setting thekeyboard layout correctly in the console, butthose with non UK keyboard layouts oftencomplain about their layout setting not working inLXDE.The solution to this issue is quite simple as longyou know the two letter country code and layoutvariant (if applicable). If you do not know thisinformation you can find it easily from yoursystem (assuming you have selected the correctkeyboard settings in Raspi-config) by using thecommand:cat /etc/default/keyboardand checking the entries XKBLAYOUT andXKBVARIANT.# KEYBOARD CONFIGURATION FILEXKBMODEL="logicda"XKBLAYOUT="ch"XKBVARIANT="de_nodeadkeys"XKBOPTIONS=""With this information to hand, you can edit theLXDE autostart configuration file to add the line"@setxkbmap XX YY" where XX is the twoletter country code and YY the keyboard variant.In my case I would edit the file by using thecommand:sudo nano/etc/xdg/lxsession/LXDE/autostartThen in the Nano editor, append the followingline to the end of the file:@setxkbmap ch de_nodeadkeysAfter saving the file in Nano and rebooting thekeyboard layout should be correct within LXDE.I hope that I have given you some pointers to getstarted with your Raspberry Pi and theencouragement to dig into the availablecommunity resources to resolve any small issuesthat you have.For those looking for additional help I can highlyrecommend the following three books that areavailable in both print and digital formats:• Raspberry Pi User Guide by Eben Upton andGareth Halfacree - http://amzn.to/ZN5ElZ• Make:Projects - Getting Started with RaspberryPi by Matt Richardson and Shawn Wallace -http://amzn.to/ZN5KKl• Programming the Raspberry Pi: Getting Startedwith Python by Simon Monk -http://amzn.to/WyPM97
    • Want to keep up to date with all things Raspberry Pi in your area?Then this section of The MagPi is for you! We aim to list Raspberry Jam events in your area, providingyou with a Raspberry Pi calendar for the month ahead.Are you in charge of running a Raspberry Pi event? Want to publicise it?Email us at: editor@themagpi.comMalawi Raspberry JamWhen: Saturday 4th May 201 3 @ 9:00amWhere: Bishop Mackenzie International School, LilongweThis event will run from 9:00am until 1 2 noon. Further information is available athttp://raspberryjam.org.uk/event/raspberry-jam-malawi/Swansea Raspberry Jam SessionWhen: Tuesday 7th May 201 3 @ 6.00pmWhere: Giakonda IT, 3 Humphrey St, Swansea SA1 6BGThe meeting will run from 6:00pm until 8:00pm. Further information is available athttp://www.giakonda.org.uk/raspberry-pi/Tokyo Big Raspberry Jam 2013When: Saturday 25th May 201 3 @ 1 :00pmWhere: IIJ Corp. 1 -1 05 Kandajinbocho, Chiyoda, Tokyo, JapanThe event will run from 1 :00pm until 6:00pm.Further information is available at http://bigraspberryjamtokyo201 3.eventbrite.com/Norwich Raspberry Pi User GroupWhen: Saturday 1 st June 201 3 @ 1 2 noonWhere: Upper Mezzanine Level, Norwich Arts Centre Cafe, 51 St. Benedicts St., Norwich NR2 4PGThe meeting will run from 1 2 noon until 6:00pm.Further information is available at http://norwichrpi.org9
    • 10Alexandre XanthakisBud AniontinderGuest WritersSWEETBOX IIThe smallest Raspberry Pi caseHow to make a case for theRaspberry Pi in 314 stepsLike so many impatient technology junkies the worldover, the wait to hold our first Raspberry Pi seemedlike it would never end. But when we finally had it inour hands, our plan for it was quite different frommost people.After I saw the Raspberry Pi for the first time, I toldmy associate at Graspinghand about thisunbelievably affordable, powerful computer, designedfor the classroom. I thought it would be cool to makea proper case for it; the Sweetbox II. Designers oftenhave great ideas that never get beyond being just anidea… but this idea was different.It all started like a game. When our Raspberry Piarrived we took extremely precise measurementsduring the summer of 201 2 and built a 3D model. InSeptember we started to play with the basic volumeof the case, just like using Lego blocks. At first wehad other projects running in parallel, but theSweetbox II soon became an obsession.Imagine a macro view of a bare Raspberry Pi – itscomponents forming a fantastic and futuristiccityscape. We wanted to retain this image so a designethos from the very beginning was that the caseshould wrap the components like a skin, creating ashape that would hug the circuit board and becomeone with the Pi. It’s a unique design and also meansthe Sweetbox II is the smallest possible case for theRaspberry Pi. You can easily put it in your pocket!The small size also makes it easy to grasp forplugging and unplugging cables.Components and lights had to remain visible so thatpeople could still see what was going on inside.However, we didnt want the case to be completelyclear as most transparent plastics have a cheap,shiny appearance. So we chose to make theSweetbox II using a matt, translucent material.Another unique feature is the integrated heatsinks.With a form-hugging design, adding heatsinks camelogically in the design process and keeps the Pi cooleven when overclocked. We chose copper for theheatsinks - the second best metallic heat conductorafter silver - but we also have a Sweetbox II versionwith silver heatsinks.We 3D printed the first prototypes in white opaquenylon and they were great… lovely to touch… theshape played with the light beautifully. But then a bigproblem arose; you can’t make an injection mold withthe type of mesh design that we’d used. 3D printingworks with the STL (Stereo Lithography) format, butCNC (Computer Numerical Control) machines need a3D model made of curves and surfaces to mill amould. We had to completely reconstruct thegeometry with a totally different vocabulary and try torecreate the same aesthetic result.
    • 11All the initial attempts that we made were disastrous,far from the shape we had at first, but after weeks offurious work we finally succeeded. The final shapewas slightly different and even better than before. Atlast we had a good 3D model that was CNC readable.We made eleven prototypes during the study withdifferent materials. What was frustrating for us wasthat no 3D printing process seemed to offer thematerial translucency that we were seeking. If youwant to make a translucent model with 3D printing,you first print it transparent then sand it or put avarnish on it. It means the material is only translucenton the surface rather than in the material itself. Atranslucent material is transparent in the first placeand loaded with white powder. One of the reasons wewanted different thicknesses on the case - thicker atthe base and thinner on the top - was to have agradient effect with the tops appearing moretransparent than the bases. On the final prototypesthere is a homogeneous translucency that producessmall differences in refractions, but we will only reachthe gradient transparency that we want when weinjection mould the cases.At first we considered selling our case by 3D printingit. There are already numerous 3D printed RaspberryPi cases available on the market, but prices remainhigh… too high. We have all these exciting toolsavailable to make prototypes which are perfect forsmall volume manufacture. However, if you want tomake a product which is available to everybody youneed larger production facilities, which leads to largercosts. It’s £8,000 to make a mould for the SweetboxII plus additional costs for injection and materials!We were searching for a way to get our project off theground and Kickstarter was the perfect choice.Setting up a project on Kickstarter is an eye-openingprocess; you learn a lot about how to sell what youcreate. It gives you a close relationship with youraudience and because what you are trying to sell isnot produced yet, you can make changes to yourproduct by following peoples advice and good ideas.The first change that we made to the prototype was toadd easy access to the GPIO connector. People wantto be able to experiment with their Pi and still protectthe rest of the components, so we responded bymaking an opening with a removable rubber cap. Wealso added some extra space for a mini SD adapter,the pIO, which makes the overall outer dimensionseven more compact! We are currently working tomake the case perfect for the new Raspberry Picamera board. We added an incision above the CSIconnector to plug it in directly. A possible optionalaccessory is a small articulated arm attached to theSweetbox II that will keep the camera steady.To design a case for the Raspberry Pi is not easy.When we first held a Pi we were in awe at just howsmall it was. With the Sweetbox II we want to retainthat awe and build on it by adding a case thatshowcases the Pi’s size and design while providing aunique enclosure that itself will spark discussion.An interesting consequence of the Raspberry Pi is thenumber of variations of cases that have beenproduced over the past year. We believe that all ofthem deserve their own exhibition; whether they aremanufactured, custom made designs or homemadeDIY cases. Its always fascinating to see how creativeand unexpected some solutions can be. Its likemusic; within the same style you have an infinitespectrum of variations. Two people with the sameinstrument and the same constraints can each stillmake a unique sound.Graspinghand is dedicated to unique productions.Our work always integrates physical properties andmorphogenesis. Every project that we undertake isalways special and proposes something that isgenuinely unique. Our Kickstarter for Sweetbox IIends at 3:38pm GMT on 26 May 201 3. For moredetails please visit http://kck.st/1 09jtN3.
    • 12DIFFICULTY : VARIOUSAlan CoatsGuest WriterRaspberry Pi Operating SystemsAll you can eat Raspberry PiIn only a year the number of operating systems for theRaspberry Pi has grown tremendously. In addition tovarious flavours of Linux and Unix, builds of RISC OS,Plan 9 and even an Amiga compatible offering are nowavailable. Take a look below, there is sure to be somethingof interest to one and all.Default usernames and passwords are given for each OSwhere available. I recommend these are changed.GeneralRaspbianA free operating system based on Debian, optimized forthe Raspberry Pi hardware. It comes with over 35,000software packages.Website: http://www.raspberrypi.org/downloadsUsername: pi Password: raspberryRaspbian Server EditionA stripped version of Raspbian; fewer packages installed.Website: http://sirlagz.net/?p=662Username: root Password: rootRaspbian MinimalBased on the stripped-down Raspbian image, whichsimply runs a Pi with sshd and a lean set of installedpackages so you can start small and install the bits youneed.Website: http://www.pi-point.co.uk/raspbian-minimal/Username: pi Password: raspberrySoft-float Debian “squeeze” / “wheezy”This image is identical to the Raspbian “wheezy” image,but uses the slower soft-float ABI. It is only intended for usewith software such as the Oracle JVM which does not yetsupport the hard-float ABI used by Raspbian.Website: http://www.raspberrypi.org/downloadsUsername: pi Password: raspberryDebian 6The Debian distro for Raspberry Pi is the Cambridgereference filesystem, which is a fully functional DebianSqueeze installation containing LXDE (desktop), Midori(browser) and development tools.NB: Now replaced by Raspbian.Website: http://www.debian.org/ports/arm/Username: pi Password: raspberryArch Linux ARMBased on Arch Linux, which aims for simplicity and fullcontrol to the end user. It provides a lightweight basestructure that allows you to shape the system to yourneeds. Please note that the Arch distribution may not besuitable for beginners.Website: http://archlinuxarm.org/Username: root Password: rootFedora Remix (4GB SD needed)A Linux software distribution containing software packagesfrom the Fedora Project which have been specificallywritten for or modified for the Raspberry Pi, and proprietarysoftware provided by the Raspberry Pi Foundation fordevice access.Website:http://scotland.proximity.on.ca/raspberrypi/Username: root Password: fedoraOccidentalis (4GB SD needed)The distro is based on "wheezy" but comes with hardware
    • 13SPI, I2C and one wire support pre-installed. It also hassome things to make overall hacking easier such as sshdon startup (with key generation on first boot) and Bonjour(so you can simply ssh raspberrypi.local from anycomputer on the local network).Website: http://learn.adafruit.com/adafruit-raspberry-pi-educational-linux-distro/Username: pi Password: raspberryFreeBSD (4GB SD needed)Derived from BSD, the version of UNIX® developed at theUniversity of California, Berkeley.Website: http://www.freebsd.orgUsername: root Password: freebsdarmNetBSD (4GB SD needed)A free, fast, secure and highly portable Unix-like OpenSource operating system. NetBSD is developed andsupported by a large and vivid international community.Many applications are readily available through pkgsrc, theNetBSD Packages Collection.Website: http://www.netbsd.org/Username: root Password: <none>Bodhi Linux (4GB SD needed)A Linux Distribution leveraging the fast, customizable andbeautiful Enlightenment Desktop.Website: http://www.bodhilinux.comUsername: pi Password: bodhilinuxRisc OS (4GB SD needed)An operating system designed in Cambridge, England byAcorn. First released in 1 987, its origins can be tracedback to the original team that developed the ARMmicroprocessor. RISC OS is owned by Castle TechnologyLtd, and maintained by RISC OS Open Ltd. This version ismade available free of charge to Raspberry Pi users.Website: https://www.riscosopen.org/content/Plan 9Primarily developed for research purposes as thesuccessor to UNIX by the Computing Sciences ResearchCentre at Bell Labs between the mid-1 980s and 2002.Plan 9 continues to be used and developed by operatingsystem researchers and hobbyists.Plan 9 uses the 9P protocol for accessing local and remoteresources as files, and provides union mounts, animproved proc file system, and native unicode supportthroughout. All system interfaces, including those requiredfor networking and the user interface, are representedthrough the file system rather than specialized interfaces.NB: A very experimental OS, which is loosely based on theoriginal Unix taken to its extremes. It is only suitable forprogrammers at this time.Website: http://plan9.bell-labs.com/plan9/http://plan9.bell-labs.com/sources/contrib/miller/9pi.img.gzMoebiusA very compact ARM HF Debian based distribution. It fitson a 1 GB SD card, has auto resizing features to betteradapt to your SD card size and uses Raspbiansrepositories for installing everything you need. It isdelivered in a small memory footprint and is ideal forworking headless or for interacting with I/O devices.Website: http://moebiuslinux.sourceforge.net/Username: root Password: raspiPiBang Linux (4GB SD needed)PiBang, a Raspbian based distribution, is inspired byCrunchbang Linux. It comes preconfigured with manyhelpful scripts and pipemenus as well as a fork of Raspi-config with extra functionality. One of the heavierRaspberry Pi distributions boasting a complete packageset with favourites such as Abiword, OMXPlayer, GIMP,and VLC all pre-installed.Website: http://www.pibanglinux.orgUsername: pi Password: raspberryGentooGentoo Linux is a source based rolling-release distributionwhich emphasizes choice and flexibility. Gentoo ARM aimsto be the most up to date and fastest ARM distributionavailable.Website: http://intelminer.com/raspberrypiUsername: root Password: piOpenWrtOpenWrt is a highly extensible GNU/Linux distribution forembedded devices. Unlike many other distributions forthese routers, OpenWrt is built from the ground up to be afull-featured, easily modifiable operating system for yourrouter. In practice, this means that you can have all thefeatures you need with none of the bloat, powered by aLinux kernel thats more recent than most otherdistributions.Website:http://wiki.openwrt.org/toh/raspberry_pihttp://www.zoobab.com/raspberry-pi-openwrtDedicatedOpenELECOpenELEC (short for "Open Embedded LinuxEntertainment Centre") is a free and open sourceembedded operating system providing a complete mediacentre software suite that comes with a pre-configuredversion of XBMC and third-party add-ons with retro videogame console emulators and PVR plugins. OpenELEC isan extremely small and very fast booting Linux baseddistribution.Website: http://openelec.thestateofme.com/Username: root Password: openelec
    • 14DarkELECThis fork of OpenELEC aims to remedy the very few flawsin its implementation and to focus 1 00% on the Pi, whilealso sticking to the upstream and incorporating its updates.Website:http://darkimmortal.com/category/raspberry-pi/XBianXBian is a small, fast and lightweight media centre distrofor the Raspberry Pi, based on a minimal Raspbian imagewith XBMC.Website: http://xbian.org/Username: root Password: raspberryRaspbmcBringing XBMC to your Raspberry Pi with enough power tohandle media playback, making it an ideal component in alow HTPC setup. From the developer of the CrystalbuntuLinux Distribution, which brings XBMC and 1 080pdecoding to the 1 st generation Apple TV.Website: http://www.raspbmc.com/Username: pi Password: raspberryChameleonThis is one for you retro gamers: a Raspbian remix fromCarles Oriol that turns your Pi into a whole suitcase-full ofemulated hardware, from the Spectrum to a MAMEcabinet, via the Oric-1 , Atari 2600, Apple II and lots ofother stuff besides.Website: http://chameleon.enging.com/Username: root Password: raspberryUsername: pi Password: spectrum(user login)Elastix VOIP System (4GB SD needed)Elastix has multiple features and functionalities related tocommunication services: IP Telephony, Mail Server, FaxServer, Conferences and Instant Messaging Server,among others. New features, functionalities and servicesare added during the development of new versions.Website: http://uelastix.com/Username: root Password: palosantoInitial web interface login:Username: admin Password: palosantoIncredible PiAn Incredible PBX platform based on Raspbian 7,featuring Asterisk 1 .8 and FreePBX 2.1 0. It includes manyof the best features of Incredible PBX including GoogleVoice for free calling in the U.S. & Canada.Website: http://nerdvittles.com/?p=3026Username: root Password: raspberryRaspberry Pi Thin ClientA project to support Microsoft RDC, Citrix ICA, VMWareView, OpenNX and SPICE on the Raspberry Pi.Website: http://rpitc.blogspot.se/Pi PointTurn your Raspberry Pi into a Wireless Access PointWebsite: http://www.pi-point.co.uk/Username: pi Password: raspberryIPFireAn Open Source firewall distribution that turns theRaspberry Pi into a small router. As the Raspberry Picomputer comes with only one NIC, it works perfectly as a3G router without plugging in additional hardware.A generally small system that provides essential servicesfor networks, it can be enhanced by addons which addnew features to IPFire so the system can be turned into afile server and much more.Website:http://wiki.ipfire.org/en/hardware/arm/rpiPwnPi (4GB SD needed)A Linux-based penetration testing dropbox distribution. Itcurrently has 1 81 network security tools pre-installed to aidthe penetration tester. It is built on the Debian squeezeimage from the Raspberry Pi Foundations website anduses Xfce as the window manager.Website: http://pwnpi.net/ha-piThis Debian squeeze image created to perform "pwn plug"type of attacks using Raspberry pi.Website: http://sourceforge.net/p/ha-pi/wiki/Home/Username: root Password: piQtonPiOriginally intended as an end-to-end platform, it enables adeveloper to boot straight into a controlled environmentwhich can be deployed, via a single click, inside anassociated Qt SDK.Website: http://qt-project.org/wiki/Qt-RaspberryPiUsername: root Password: rootmeAROS BroadwayThe AROS Research Operating System, formally theAmiga Research Operating System, is aimed at beingcompatible with AmigaOS at the API level. Undercontinuous development for several years, work hasstarted on porting to the Raspberry Pi (note: this is flaggedas "experimental").Website: http://www.aros-broadway.de/files/efika-raspberrypi.htmlAROS: http://aros.sourceforge.net
    • 1 5
    • 16Michael DiamondStar WriterA Note of Thanksfrom the ZX GenerationI was 23 when I saw a full page advertisement inthe Sunday Times advertising Clive Sinclair’s£70 ZX81 . I had no idea what a computer wasbut convinced my father to fork out the money tobuy me one. It arrived a few weeks later, a littleplastic box, light as a feather, and a huge blackpower supply weighing five times as much.I plugged it in.Until that moment, I never really knew myself. I’dstudied law at Glasgow University, for no otherreason than my brother did before me. I was inthe middle of my law apprenticeship when theZX81 arrived.From the moment I switched it on, I was hooked.I went through the manual, a page at a time,realising that each line of BASIC was infinitelyvariable. A little tweak here, a minor adjustmentthere, and the ZX would do anything I wanted. Ispent months with that little thing, fiddlingaround, copying lines of BASIC out ofmagazines, and writing my own programs to playmastermind, hangman, and even multicolouredbeeping music.That was 30 years ago - when Eben Upton wasjust four years old.While my family humoured me, my legal friendscouldn’t grasp what I was talking about; they’dlaugh disdainfully at my enthusiasm about a littleplastic box.Little did any of us know that computers wereabout to change the world.Captivated as I was, eventually my professionaltraining got in the way; younger kids withcomputer education went on to open softwarehouses, while I watched from the legal sidelines.Half a lifetime later, and the Raspberry Pi is born.I have my own grown up kids now, andcomputers to them are like pen and paper wereto me. When I told them about the Raspberry Pi,they didnt get it. I bought one anyway - the sameurge that brought me the ZX81 years ago.It arrived six weeks ago - and I’ve stepped backin time.In those six weeks I’ve learned so much. Untilthen, I had no idea what Linux was, or GPIOports, or HDMI, SSH, or how transistors work. Ididn’t know what a breadboard was, or a webserver, or a breakout board, or a 555 timer, orphp. I didn’t know what a static IP address was,or Dynamic DNS or how to forward a port in myrouter. In a month and a half, I’ve learned all ofthese things and more. At first I lit a single LED.Then for £2, I bought a relay and progressed toswitching on a reel of them. Then I did it byremote control - in the house - from my smart-phone. The next step was obvious - hook it to theinternet.
    • 17I showed the interface to my office staff, tellingthem, “when I click this switch, a light goes on inmy house.”“How do you know?” came the intrigued reply.“Hmm,” I thought. “How do I show them?”So this weekend I hooked up a webcam to myRaspberry Pi. Now, when I click the switch,through my browser, I can show them the LEDscome on. When it crashed, I reset the whole thingfrom afar - amazing even myself.If someone had suggested to me two months agothat I’d be capable to doing something like that injust six effortless weeks, I’d have said she’scrazy. Yet here I am.I’m sure I’m slower than the younger folk, but at54, with no formal technical experience, I’m filledwith satisfaction and gratitude for the thousandsof people out there who are sharing theirknowledge on YouTube and blogs. I cantcontribute much technical knowledge to thecommunity, but I can express the gratitude of theZX81 generation to Eben and his team for re-igniting our Sinclair days, three decades later.Many, many thanks for your enthusiasm andgood work. I am sure there are thousands ofpeople out there just like me, tinkering, hackingand crying out with excitement when their littleproject bursts into life.MichaelDiamondThank you again to everyone who has supported our Kickstarter campaign to bring The MagPi to themasses in hard copy form. As unpaid volunteers this was a massive challenge for us and one we arevery proud to have accomplished. I would like to take this opportunity to once again apologise for thelong waiting times between ordering and us dispatching; as with any challenge, we have experiencedhurdles on the way to meeting our goal plus we significantly under-estimated the required effort.Additional time has been taken to convert issues one, two and three from our original format intoScribus. This meant effectively starting from scratch; a massive task. Bleeds had to be adjusted onevery page of all issues. On top of this we faced and overcame problems at our printers, issues withour proofs and very narrow timelines to meet. Looking back at the effort, it’s amazing we have got thisfar!To minimise delays, we got the hardware orders from pledges out to our supporters. This resulted inextra shipping costs, but as a team we felt it was worth it to give you something to play with and reflectour appreciation of your patience.We are pleased to write that almost all 256 pages have been revisited and updated, providing you withcurrent information and URLs, in The MagPi style and layout that we used in later issues. Thiseffectively translates to creating 1 2 magazines in four months, three per month including this issue youare reading. We have been very busy!With that said, I am very pleased to say that as we speak, our printers and distributor are working hardbehind the scenes to package up your bundle. Expect yours in the post soon!Many thanks once again, we appreciate your patience. We hope you continue your support of thelargest and only community led Raspberry Pi magazine as we continue into the future.Ash Stone
    • 18DIFFICULTY : INTERMEDIATE Stewart WatkissGuest WriterPrinting with CUPS2 - Printing from PythonLast month, we added CUPS printing onto the RaspberryPi. Now that you have got your printer up and working wecan look at how to print from within our own applications.We are going to be using the Python programminglanguage, but we will also take a look at straightforwardcommand line printing which can also be used for printingfrom other programming languages.First, we will look at printing from the command-line. Thiscan be useful within shell scripts or by making a systemcall within any programming language. The lp or lprcommands are used for command-line printing. The namesare an abbreviation of line-printer, although they areseldom used for printing to a true line-printer these days.Both commands work in a similar way, but use differentoptions. This is historical from the early days of UNIX. Bothlp and lpr are available on Linux so you can usewhichever you prefer.The command to print a file to the default printer is:lp <filename>You can select a different printer or specify only certainpages using different command-line options. You can finddetails at:http://www.cups.org/documentation.php/options.htmlor by looking at the help page on your own CUPSconfiguration page which we used in the previous article.Unlike the original commands which could only handle textfiles, the lp and lpr commands installed through CUPS canhandle other formats as well. When you use the commandswith a PDF, postscript or image file then CUPS will convertthe files using the printer drivers. We will be using thisfeature later when we print a PDF file from a Python script.In some programming languages and GUI toolkits (seebox) it is possible to generate printer output using similarinstructions to how you generate graphical content for thescreen. This is the case in PyGTK,PyQt and WxPython;but whilst the GTK and Qt toolkits are commonly used withother programming languages they are less used and lesswell documented on Python. WxPython can be useful if youare using Wx toolkit already, but the most commongraphical toolkit on Python is Tkinter, which has verylimited support for printing.Instead of using toolkit support I have chosen to generate apdf file using xhtml2pdf which is sent to the printer using aCUPS library called PyCups. This is easy to use and hasthe advantage that it doesnt need to be used in a graphicalenvironment so can be used from within a command-lineprogram or a daemon application running in thebackground.First, we will install some additional packages. The python-cups library provides the module so that Python cancommunicate with the CUPS printers, python-pip will makeinstalling xhtml2pdf easier and the python-dev libraries areneeded to allow pip to install some of the libraries used byGUI toolkitA GUI toolkit provides a standard set of buttons,frames and other components to make creatinggraphical programs easier and with a consistent lookand feel. Some include additional printer libraries thatmake it easy to convert the graphical screen output to aformat ready for printing.
    • 19xhtml2pdf. Install these using the normal apt-get install:sudo apt-get install python-cups python-pippython-devThen install xhtml2pdf using pip:sudo pip install xhtml2pdfThis last stage will take a while to run as it will downloadand compile some additional libraries.You can now use xhtml2pdf on the command-line toconvert from a HTML page to a PDF file. You could tryusing a saved web pages, but in many cases it will onlypartially work due to the common use of Javascript whichisnt rendered by xhtml2pdf. Instead I recommend creatingthe pages using standard HTML markup.Below is a Python script which will list the available printersand then print to the first printer in the list. This is anexample created to show how you can add printingcapability to your own program. If you are including thisinto your own application then you should add additionalerror checking as well as a way for the user to select theappropriate printer (if multiple printers are installed).Line 4 imports the cups library and line 5 the xhtml2pdflibrary (note that it is imported as pisa which is the formername for the library and is how we will refer to it later).Lines 1 1 to 1 4 generate some basic HTML formattedcontent. Whilst you could include the usual HTML headersand head section, which you would normally include in ahtml page, I have just added the content of the bodysection which is sufficient for xhtml2pdf. We then useCreatePDF on line 1 6 to convert that to a file and save it tothe file specified in variable “filename”.I have included a very basic check for PDF errors at thispoint as invalid HTML could cause this to fail. This is only ageneric error message which you may like to improve on inyour own programs.Line 1 9 is very important. The file needs to be closed sothat the write completes and its possible to read the fileback in. Without this then nothing will print, and in my caseI spent a lot of time tearing my hair out trying to work outwhat was going wrong.We create a connection to CUPS and use the getPrinterscommand to get a list of the available printers. Ivedeliberately included the print command on line 27 which isthe standard Python command to print a line of text tostdout (screen). It is nothing to do with sending anything tothe printer, so dont let that confuse you.Finally on lines 29 and 30 we select the first printer andprint the file using the printFile command.When creating the script you need to create a name thatdoesnt conflict with any of the names of the library filesimported. For instance do not call the script “cups” as thatwill conflict with the cups library. I used cupsprint.py duringmy testing.This has shown one of the ways that you can add printingto your own Python application. This method has beenchosen as its easy to implement and can be used forcommand-line and server applications as well as graphicalapplications. So over to you; what projects do you havethat need to be able to print?1. #!/usr/bin/env python2. # Print a file to the printer3.4. import cups5. from xhtml2pdf import pisa6.7. def main():8. # Filename for temp file9. filename = "/home/pi/print.pdf"10.11. # generate content12. xhtml = "<h1>Test print</h1>n"13. xhtml += "<h2>This is printed fromwithin a Python application</h2>n"14. xhtml += "<p style="color:red;">Coloured red using css</p>n"15.16. pdf = pisa.CreatePDF(xhtml,file(filename, "w"))17. if not pdf.err:18. # Close PDF file - otherwise we cantread it19. pdf.dest.close()20.21. # print the file using cups22. conn = cups.Connection()23. # Get a list of all printers24. printers = conn.getPrinters()25. for printer in printers:26. # Print name of printers to stdout(screen)27. print printer,printers[printer]["device-uri"]28. # get first printer from printer list29. printer_name = printers.keys()[0]30. conn.printFile(printer_name, filename,"Python_Status_print", {})31. else:32. print "Unable to create pdf file"33.34. if __name__=="__main__":35. main()
    • IanMcAlpineMagPi WriterPete Lomas shares his thoughts onRaspberry Pi design challenges andthe future.Pete Lomas is one of the trustees of the Raspberry PiFoundation. He is also the man responsible for thefinal hardware design of the Raspberry Pi. The MagPimet up with Pete at the Vancouver Hack Space, whilehe took time out from a recent vacation to Canada.[MagPi] How did you first get involved with theRaspberry Pi?[Pete] It was a chance meeting with Alan Mycroft atImperial College where my company, NorcottEngineering, had been commissioned to do somework. I was discussing with Alan that graduatesinterviewing at Norcott were not "engineer-ready" -they were "half-baked" because they didnt have thepractical skills. Alan agreed that they had observedthe same problem with students coming toCambridge University. However, he then explainedthat a chap at Cambridge called Eben Upton had theidea of building a small, single board computer thatthey could give to undergraduates before the start oftheir first semester. The implication was if youcouldnt do anything useful with it, dont come back! Ithought this was brilliant because the introduction ofthe PC started to package computers and remove theability to "tinker" that was rife during the homecomputer boom of the 80s. During the last ten yearsespecially, consumer electronic products havebecome so polished that kids today are becomingpure consumers and not creators. The skill of"tinkering" is lost. I recognised that Eben wanted toencourage "tinkering" and so I got involved.[MagPi] I was 1 4 years old in 1 982 and wasfortunate that my parents bought me a BBC MicroModel A. It didnt work! The case was only held on byfour screws and there was a large slot at the back toeasily peek inside. I removed the case, spotted abadly seated IC and also discovered the TV antennacable had not been soldered. Thirty minutes later andit was working. The BBC Micro Model A cost £299back in 1 982. Imagine trying to open up or repair anequivalent priced computer today! Last year Irestored that very same computer back to full workingorder, while waiting for my Pi to be delivered.[Pete] Precisely. Back then you were encouraged to"tinker". Today not only do manufacturers not wantyou to "tinker" but the financial repercussion ifsomething goes wrong is significant. Price is one ofthe most important aspects of the Raspberry Pi. Ithad to be cheap enough that it could be given to eachchild. Its theirs to do with whatever they want withoutany fear... and if they do break it, its not the end ofthe world.[MagPi] Now that you have brought up the topic ofbreaking the Raspberry Pi, some of our readers haveasked if you could relocate the large capacitorbeside the micro USB connector in a future revision?20
    • This will stop it from snapping off if your finger slipswhile trying to insert or remove the power cable![Pete] The Raspberry Pi was designed using thebest engineering practices. C6 is not essential if youhave a good power supply. Ideally it should be fitted,but dont worry if you have broken it off. Interestingly,Ive used hundreds of Raspberry Pis and never oncebroken off that capacitor. People tend to hold theRaspberry Pi tentatively; they are afraid it might breakand that is what causes fingers to slip. Instead justgrab the Raspberry Pi firmly and yank out the powercable. Look carefully at the micro USB power socket.It is mechanically attached to the circuit board. Wewent to great lengths to ensure that the power socketwill not snap off.[MagPi] Would the use of USB fuses on the revision1 board be an example of good engineering practice?[Pete] With the benefit of hindsight, the USB fuseswill forever be one of those points of regret. Bestengineering can still be a compromise on price /performance (except, of course, when lives are atrisk). We intended to limit the current to these devicesbased on the testing we had done with mice andkeyboards. However, we did not fully appreciate theinventiveness of the people that started to use theRaspberry Pi. We had focused on the strategic goalof the education market and somewhat forgot thehobbyist market that wanted wi-fi dongles, bluetoothand USB hard drives. Of course the problem wasresolved with the revision 2 board but that is alwaysthe problem with design; you can be over cautiousand it will bite you at one end, or under cautious and itwill bite you at the other end![MagPi] What were the biggest hurdles withdesigning the final version of the Raspberry Pi?[Pete] Keeping the cost of the Model B at $35 wasparamount. That barrier simply could not be brokenso I had to be ruthless about every single component.At one point I wanted to remove the ethernetconnector but Eben, Jack and Rob all grabbed me bythe throat and strongly encouraged me to leave it on!The focus on cost also meant making the RaspberryPi as small as possible but also within the constraintsof the physical connectors.At a trustee meeting someone mentioned it should becredit card sized. I drew a credit card sized outline onthe CAD system and discovered I could makeeverything fit![MagPi] Using an SD card for the operating systemand for storage has advantages and disadvantages.What was the rationale for using SD cards?[Pete] SD cards are commonplace, robust andinexpensive. They are frequently used in digitalcameras so it is quite likely you already have some.They are also quick and easy to flash. If somethinggoes badly wrong, simply reflash the SD card andyou are back with a new Raspberry Pi. You can alsohave different SD cards for different uses; a card forschool, a card for home projects, a card for RISCOS,a card for XBMC... and each one can completelytransform your Raspberry Pi.[MagPi] If you could change anything on theRaspberry Pi, what would it be and why?[Pete] If I had known just how rubbish some 5V USBpower supplies are, I would have taken measures toensure a clean 5V is delivered to the various systemsin the Raspberry Pi. Thanks to the communityhowever, that problem is largely behind us as peoplenow know to only use a quality power supply.[MagPi] Does the education version of the Raspberry21
    • Pi exist and if so will there be any difference betweenthis version and the current version (Revision 2) ofthe Raspberry Pi?[Pete] The education version is in development - weare actively working on it at the moment and it willhave a case. There are some things that we plan toaddress. For example, with an install base of1 ,000,000+ units many people use HDMI-VGAconverters to repurpose old VGA monitors. A yearago these were expensive, but the demand fromRaspberry Pi users is such that these now cost lessthan $1 0! I want to adjust the power to the HDMIconnector so that these converters can be reliablyused.[MagPi] The Raspberry Pi branding pays homage tothe BBC Microcomputer Model A and Model B. Arethere plans for a Raspberry Pi Model B+ or Master?[Pete] We have doubled the RAM on the Model B to51 2MB so that is the equivalent of the BBC MicroModel B+! The Raspberry Pi Foundation does nothave the same mandate as a commercial business.We dont need to release new versions or newproducts every quarter to please share holders. Wedo not want to disenfranchise early adopters of theRaspberry Pi. We may revisit it again in a couple ofyears as technology changes, but not yet. The Piwould not be as successful as it is were it not for thecommunity. We want the community to continue togrow with the current hardware.[MagPi] Another success story for the Raspberry Piis that despite its low cost, it is being manufacturedand assembled in Wales, in the UK; British designedand British built.[Pete] People have no idea of the lengths that SonyUK have gone to get the manufacture error rates andcosts down as low as they are now. They are worldclass and the attention to detail is mind boggling. Buteven more impressive is that Sony UK havecompletely taken onboard the Raspberry Piphilosophy. They host factory tours for bus loads ofkids and they dont skimp... they do everything toensure that everyone has a fantastic time. They, likeus, want to educate kids that engineering is exciting,rewarding and fun.[MagPi] What can you tell us about the new camera?[Pete] The camera is currently going through theproduction process and people in Cambridge areoptimising the drivers to get the very best quality. Buteven when you run as hard as you can, everythingstill takes time. If you dont take the time to do thingsright then you just make rubbish! The camera shouldbe available in May 201 3 and Im sure that, once inthe hands of the Pi community, we can look forwardto some inventive uses for this new hardware.[MagPi] What about plans for other add-ons, forexample displays using the DSI connector?[Pete] We do have the intention to make displaysavailable for the DSI connector, but its not on ourpriority list. The camera integrated onto theRaspberry Pi is a priority because it broadens thehorizons of what you can do with it. But a plethora ofdifferent displays and screen sizes are alreadyavailable today that use either the HDMI, compositevideo, GPIO or I2C interface, so there is less urgencyto develop a dedicated DSI display.[MagPi] Why was the decision made to create theRaspberry Pi when other low cost devices such asthe Arduino were already available?[Pete] If the Arduino could run Linux out of the box,had an HDMI connector and a GPU, then weprobably would have used it. But it doesnt... its avery different product that allows you to do veryintricate, time-dependent things with its I/O that youcannot do with a Raspberry Pi. They complementeach other; they do not compete.[MagPi] Indeed, we have published articles in issues7 and 8 showing how to use the Raspberry Pi andArduino together.[Pete] But remember we needed something to getkids excited, so we had to have good video andsound. You can configure the Raspberry Pi to start inwhatever programming environment you want whenyou switch it on. When you turned on a BBC Micro orZX Spectrum and saw the blinking cursor, you knewthe computer was waiting for you to tell it to dosomething. You were the master... and this can be22
    • very empowering for kids. You show them Scratchand the cat moving around the screen then comeback 5 minutes later and the cat is doing all sorts ofinteractions. All the code building blocks are down theside of the screen and kids think, "I wonder what thatdoes?" and they try it out and learn. The Raspberry Piis small and its circuitry is visible so kids know thereis no magic. The Raspberry Pi will only do what theytell it to do, so the ownership value is very high.[MagPi] The physical computing side of theRaspberry Pi is very exciting, not just for me as anengineer, but even my two pre-teen daughters arevery impressed that they can use Scratch or Pythonto turn on LEDs or interact with the Raspberry Piusing physical switches.[Pete] Look at the articles we publish on theraspberrypi.org website. Fifty percent havesomething to do with connecting the Raspberry Pi tosome other hardware. That means we are hitting aniche that no iSomething will ever meet.[MagPi] One year on, what projects have impressedyou the most?[Pete] The Raspberry Pi inspires the maker in all ofus. I immediately think of projects like the "Brew Pi"and of course Dave Akermans "Pi In The Sky". Buteven more impressive is watching what kids aredoing with the Pi. If Im slogging through some workor feeling down, watching videos of kids like AmyMathers at the Raspberry Jamboree or the TEDxvideo of the girls from Charlotte Latin School andseeing their passion and enthusiasm really gives mea boost to get on and continue working.Hacker SpacesPete was presenting at the Vancouver Hack Space(VHS) to a packed room of over 40 makers. What anamazing place with all manner of tools, componentsand equipment including several 3D printers and alaser cutter. The MagPi spoke to several makersthere, including Richard Sim and Loial (MatthewPeters). Having built a couple of "off-the-shelf" 3Dprinters, Loial thought he could design and build abetter one... so he did! The TS300 is a 3D motionplatform that prints twice as fast as most other 3Dprinters and its powered by a Raspberry Pi! TheTS300 will soon be available on Kickstarter. Visithttp://www.tesseractindustrial.com for more details.Commenting on the Vancouver Hack Space, Loialexplained, "Having access to tools and equipmentmeans people can create projects that they wouldnormally not be able to do. But more than theequipment, the Hack Space brings together verycreative people with a can do attitude from all walksof life. It is their collective knowledge which hascertainly helped me bring my project to reality."As we concluded the interview Pete quipped, "When Ifinally pass on, my epitaph will not say Peter Lomas -RIP, it will say Peter Lomas - RPi"!On behalf of The MagPi I would like to thank PeteLomas for taking time out from his vacation to talk tous. I would also like to thank the VHS for their kindhospitality. They regularly host Raspberry Pievenings. To find out about upcoming VHS meetings,visit http://vancouver.hackspace.ca. To find a hackspace near you, visit http://hackerspaces.org andclick on the Active hackerspaces link.23
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    • 26DIFFICULTY : BEGINNERDavid HonessGuest WriterBELLISSIMAby DJ QuicksilverCreating music using theRaspberry Pi - Part 2Welcome back folks. If you missed part 1 of thisarticle please go and check it out in The MagPi issue#2. Above is a quick reference sheet for the SchismTracker function keys that you can keep referringback to while you read this article. It can be helpful toprint this out and put it on your wall.What were going to doBy the end of this we should have programmed themelody for DJ Quicksilvers Bellissima. This is afamous dance tune that came out in 1 997. Youveprobably heard it before, but you just dont know it byname. You can Google it if you want to. The tune hasquite a simplistic melody but a catchy one and it isideal for getting to grips with Schism Tracker.Setting upIm going to assume were using Raspbian for this.Firstly we need to install the Schism Trackerprogram. You can either use the Pi Store toinstall it, you will find it under Apps, or youcan use the commandsudo apt-get install schismIf you install it via the Pi Store you can launchthe program via the Pi Store > My Libraryarea or, if you used apt-get, you can findSchism Tracker listed in the LXDE desktoplauncher menu under Other.First we need to create some folders to store our files.We need one folder to save songs files and anotherfor sound effect files (instrument sounds). Start theLXDE desktop if you havent already (startx). Openthe File Manager. It should display your Home folder.From the top menu select; File > Create New >Folder. Name the folder schism.Open this folder and inside it create two more folders,one called songs and another called samples.Run Schism Tracker and press the F1 2 key. At thebottom part of the screen you should see an arealabelled Directories. There should be three rows;Module, Sample and Instrument. Dont worry aboutInstrument for now. Change module so that it says/home/pi/schism/songs and change Sample so that itsays /home/pi/schism/samples. Once youre doneclick Save all Preferences.
    • 27Downloading a sampleWe have a prepared sample ready to use for the mainmelody. You can either use Midori or wget from acommand prompt to download it:https://dl.dropbox.com/u/1 41 25489/RaspberryPi/Schism/bellissima.raw. Save this file into the samplesfolder that we created before (or save it anywhereand then move it to the samples folder).Loading the sampleGo back to Schism Tracker. Dont load any songs -just leave it blank. Press the F3 key. This is thesample list page. Dont worry about all the stuff onthe right hand side. Look at the list on the left, thiswill be where each sound effect or vocal will beloaded in your song. One can be loaded for eachrow. Select any row you like and press the Enter key.You should now see a row showingbelissima.raw. Select it and press Enteragain. You should now be back on thesample list page. Keep the belissimasample selected (put the cursor overPlay) and run your finger left and rightbetween Q and P on your keyboard.Youll see this is like the notes of apiano. Some of the number keys on therow above represent the black keys too.Try thisStay on the sample list but press thesekeys with the belissima sample selected(keep the cursor over Play).6 6 6 e e e y y 5 5 5 u u y 9 yYou should be able to make out the melody of thetune! Now we have to program it into a sheet ofmusic, known as a pattern, so that the melody isstored somewhere.Programming the melodyPress the F2 key to go to the pattern editor screen.You are now looking at a pattern number 000 (thinkof it like a sheet of music). Youll see across the topChannel 01 , Channel 02 etc and down the left handside numbers running from 000 to 063 (so 64 rows intotal).The way this works is that we select a samplefrom the sample list (F3) go to the pattern editorscreen (F2) and program notes into the availablerows of a channel. Ideally you should always use aseparate channel for each sample but you dont haveto. When the computer plays the patternit moves down the screen playing all thenotes that occur on each row (across allchannels). The effect is that soundsfrom each channel are played togetherat the same time (mixed together) toform the overall sound of the song. Letsput our melody into Channel 01 . Thecursor (a small white square) shouldalready be inside the channel, you canmove it around using the cursor keys orwith the mouse. Start at row 000 and onevery other row type in a note from themelody sequence:-6 6 6 e e e y y 5 5 5 u u y 9 y
    • 28You should finish up on row 030 (seebelow). Now press the F6 key to playback the pattern. Watch how the whitehighlight in the row numbers moves downthe left side. Press F8 to stop.You will notice that there is a gap ofsilence before the melody starts upagain. This is because we have not putany notes below row 030 in the pattern.If you now go to row 032 and repeat thesame sequence of notes finishing on row062 the melody will now loopcontinuously when you press F6. PressF8 again to stop.Congratulations you have justprogrammed your first pattern! Now we need tomake this pattern part of the actual song. Youllnotice that if you now press F5 to play the song, likewe were doing in the previous section, nothinghappens. This is because the pattern order list hasnot been set yet. Press the F1 1 key for this.Once youre on the pattern order list screen dontworry about the middle and right hand columns. Theleft hand column is where the pattern order is kept.Go to the first row and enter 000 as shown above(this is the number of the pattern you have justprogrammed). Now if you press F5 youll hear themusic (just like when you play a normal song file).Press F8 to stop the playback and go back to thepattern order list again (F1 1 ). On the second rowenter 001 . Now press F5 again. Youll hear themelody play and then it will go silent for a bit. This isbecause we have not programmed anything intopattern 001 yet.Copy and pastePress F2 again to go back to the pattern editor. Youcan use the + and - keys to switch between patterns.Notice the pattern number changes at the top of thescreen where it says Song Name, File Name, Order,Pattern and Row.Before you start worrying that you have to type in allthe notes again, there is a copy and paste function.This is ideal if you want the next pattern in the song tobe the same but with one extra sound for instance.Go back to pattern 000 and put the cursor at the topof Channel 01 . Hold down the Shift key and use thecursor/arrow keys to select the entire column (fromrows 000 to 063). Press Alt – C to copy the notes intomemory. Now press the + key to go to pattern 001 .Place the cursor at the top of Channel001 and press Alt – P to paste.We need another sample to make itsound like something is happening in thesong. Use Midori or wget to downloadthis  sample:https://dl.dropbox.com/u/1 41 25489/RaspberryPi/Schism/kickdrum.raw. Save itinto the samples folder like before. Thisis a meaty sounding kick drum which willwork quite well with the melody wealready have. In Schism Tracker pressF3 to go to the sample list, select a blankrow and press Enter. Select thekickdrum.raw file and press Enter again.
    • 29You can now test it out with the Q to P keys again. Inmy opinion the I key sounds best.With the kick drum sample selected switch back tothe pattern editor, F2, and put the cursor at the top ofChannel 02. Use the I key to place kick drum beatsevery 4 rows. Make them follow the highlighted linesas shown below. Go all the way down to line 60.If you now press F5 to play the entire song, youll hearthe melody loop play twice before the kick drumcomes in. Cool hey?Saving to diskOkay lets save the song to disk now. Press the F1 0key, enter a file name and press Enter.Congratulations, you have just made your firstmodule! It might be time to turn the volume up,marvel at what you have just done and annoy yourparents a bit!
    • It has now been a year since the first issue of The MagPi wasreleased. The year has gone by very quickly and we havebeen very busy… but dont worry, we left enough time toorganise this huge competition to celebrate our 1 st Birthdayin style! Think of it as a small way for us to say a big thankyou for all of your support, patience and understanding overthe last 1 2 months. To be in with a chance of winning one ofthese fantastic prizes, all you have to do is answer themultiple choice questions below (and optional text questions)at www.themagpi.com/birthday. All correct entries will be putin to a prize draw, with the first 1 5 drawn winning a prize inthe order listed. Winners will be notified by email and thewinning names will be posted on The MagPi website.Full terms are available at: www.themagpi.com/birthdayThe MagPis HUGE Birthday CompetitionOver £1,000 worth of prizes to be won!30How many times on average each month is The MagPi downloaded or read online?a) 1 ,500 timesb) 1 6,000 timesc) 1 75,000 timesQUESTIONSQ1Q2Q3Q4Q5Q6Q7In how many of the 204 countries of the world have people NOT read The MagPi (based on our Google Analyticssite hit data as of 1 st April 201 3)?a) 1 07 countriesb) 52 countriesc) 8 countriesHow many pages of the The MagPi have been created from Issue 1 through to issue 1 2 inclusive?a) 256 pagesb) 384 pagesc) 404 pagesIn which issue is there an article about Arch Linux?a) Issue 3b) Issue 9c) Issue 7In which issue is there an article about computer music?a) Issue 1 1b) Issue 6c) Issue 2Optional: In Issue 1 0 we introduced a new layout style. What is your opinion of the new layout and what could wedo to further improve our presentation?Optional: what articles or types of article would you like to see more of in The MagPi?
    • 31SPONSORSThe MagPi volume 1 bundle, Adafruit Raspberry Pi Starter Pack - Includes a Raspberry Pi ComputerAdafruit Prototyping Pi Plate Kit, Adafruit Pi Cobbler Breakout Kit, Adafruit microSD card adapterBare Conductive House Kit, Programming Raspberry Pi Book (S. Monk), LEDborg, PicoBorg, BerryClipPi Supply Kit, Python for Kids book, Quick2Wire full kits (each with interface kit, port expander kit and analogue kit)For the complete list visit www.themagpi.com/birthday1st2nd3rd4thPRIZESBare Conductive Card Kit, Pi Model B, Case, power supply and SD Card (from RS components), LEDborgPicoBorg, BerryClip, Pi Supply Kit, Quick2Wire full kit (each with interface kit, port expander kit and analogue kit)plO micro SD adapter, Super Scratch Adventure books, Programming Arduino book (S. Monk)Proto Armour case, Bare Conductive House Kit, LEDborg, PicoBorg, BerryClipPi Supply Kit, Quick2Wire full kits (each with interface kit, port expander kit and analogue kit)plO micro SD adapter, Python for Kids book, Programming Raspberry Pi book (S. Monk)CPC vesa mount case, Bare Conductive Card Kit, LEDborg, PicoBorg, BerryClip, Pi Supply KitplO micro SD adapter, Super Scratch Adventure book, Programming Arduino book (S. Monk)
    • 32DIFFICULTY : MEDIUM W. H. BellMagPi Writer2 - Embedding text and programsChallenge solutionHow did you get on with the challenge problem in Issue1 0? Here is a solution to the problem,Bash (Bourne Again Shell) provides a lot of functionality,but one of its key strengths is the way other scriptinglanguages or programs can be lashed together to producea final application.Embedded filesOpen a terminal window and use the nano editormentioned within the last tutorial session. Then create anew script file containing,save it and make it executable (chmod u+xscript. sh). Execute the script and look at theinput_file. txt that it produces. Theinput_file. txt matches the text given between the<<EOF and EOF statements. For this script to work, theremust not be a space after <<EOF. The syntax of the scriptstates that the text following <<EOF is redirected to the fileinput_file. txt until EOF is reached. The redirectoperator (>) works in the same way as mentioned in thelast tutorial, truncating the output file andthen appends to it. The <<EOF syntax canbe very helpful for embedding parts ofconfiguration files within a script, ratherthan using many echo commands.Splitting input linesIf a file is read using a standard for loop, then each word(separated by one or more spaces) becomes a value withinthe loop. This can be helpful for some problems, but theline number information is lost. The read commandprovides a solution,In this example, the outer loop reads each line of the fileinto the variable $line. Then in the inner loop, eachword within a line is considered by the for loop. The-n in the echo command means that echo does notadd a newline character after printing the line. The inputfile is associated with the while loop by using inputredirection (<).#! /bin/bash# A script to gzip all of the files in the present working# directory. The script does not consider gzip files which# have the . gz ending.for file in $(find $PWD -maxdepth 1 -type f | grep -v . gz); dogzip $filedone#! /bin/bashcat > input_file. txt <<EOFColumnA_row1 ColumnB_row1 ColumnC_row1 ColumnD_row1ColumnA_row2 ColumnB_row2 ColumnC_row2 ColumnD_row2ColumnA_row3 ColumnB_row3 ColumnC_row3 ColumnD_row3ColumnA_row4 ColumnB_row4 ColumnC_row4 ColumnD_row4EOF#! /bin/bashwhile read line; dofor word in $line; doecho -n "$word "doneecho ""done < input_file. txt
    • 33Using PerlPerl is a great language for string manipulation and can beeasily used within Bash scripts,In this case, the outer while loop is the same as theprevious example. "$line" is used to make sure thewhite spaces are also sent to the perl command. Using thepipe operator causes the output of the echo command tobe the input for the Perl command. The -ne options allowPerl to be embedded in this manner. The $_ variablecontains the value present in the variable $line. Then thesplit command splits the words with one or more spaces(s+) into the array @words. The second and third arrayelements correspond to the c and d columns of the file,where the first column is the zeroth element. Similar to C,each Perl statement is terminated by a semicolon. Moreinformation on Perl can be found at http://www.perl.org/.Once a line has been split into different strings, one of thestrings can be used as a signal that the rest of the fileshould be printed,This time the Perl part of the script checks the array sizeand only uses the third element if there are three or morearray elements. The first if statement ignores zero lengthc variables, which would be caused by there being lessthan three words in a given line. Then as soon as found isset to one, the rest of the file is printed to the screen.Using other programsSeveral different programs can be embedded within thesame script. For example, gnuplot used in previous CCave can be used to produce a png file illustration of amathematical function. In this case, the <<EOF syntaximplies that thecommands arepassed to thegnuplot program.The -persistgnuplot option isused to keep thegnuplot session open, such that it reads the commandsafter the <<EOF. More information on gnuplot can befound at http://www.gnuplot.info/.The gnuplot script can be used to plot any function given atthe command line by replacing sin(x) with $1. Thenadd,before gnuplot -persist <<EOFThe first if statement protects against a missingargument. The second if statement checks that theargument provided is a function of x. Try running the scriptby typing, . /script. sh "cos(x)"Challenge problemWrite a Bash script which contains a Python program tocalculate mathematical functions. Start from,The solution will be given next time.#! /bin/bashgnuplot -persist <<EOFset terminal pngcairoset output sin. pngset key inside right topset yrange [-1. 2: 1. 2]set samples 60, 60plot [-6: 6] sin(x)EOF#! /bin/bashfound=0while read line; doc=$(echo "$line" | perl -ne @words=split(/s+/, $_); if($#words > 2) {print STDOUT $words[2]; } )if [[ -z $c ]]; thencontinuefiif [[ $c == "ColumnC_row2" ]]; thenfound=1fiif [[ $found == 1 ]]; thenecho $linefidone < input_file. txtif [[ -z $1 ]]; thenecho "Usage: $0 <f(x)>"exit 1fiif [[ $1 ! = *"(x)"* ]]; thenecho "Usage: $0 <f(x)>"exit 2fipython <<EOFimport mathfrom math import *EOF#! /bin/bashwhile read line; doc=$(echo "$line" | perl -ne @words=split(/s+/, $_); print STDOUT $words[2]; )d=$(echo "$line" | perl -ne @words=split(/s+/, $_); print STDOUT $words[3]; )echo $c $ddone < input_file. txt
    • 34DIFFICULTY : EASY antiloquaxevil geniusPretty Poor PrivacySubstitution CipherThis program shows you how to implement a "simple substitution" cipher with a reciprocalkey. In a reciprocal key, pairs of characters are mapped to each other. This makes life easieras we can use the same key to encipher and decipher messages. The resulting cipher textsare not too difficult to crack, but its a start!The first thing to do is make some sprites that will bethe buttons we click to make things happen in ourprogram (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!Heres the script that the "make key"button activates (the remaining scriptsare on the following pages). To load akey you have already made, make the“cipherAlpha” list visible on the stage,then right-click it and “import” the keyfrom the file in which it has been saved.Alternatively, click the “make key”button. Its vital that your contact has acopy of your key so that he/she will beable to decipher your message. Rightclick "cipherAlpha" and choose "export"to save it to a text file for sharing.
    • 35Sprite 5 loads plain text from the getText list into avariable called "inputText". It puts in a "|" characterto stand for line-endings.Sprite 6 loads cipher text youve imported into"getText". It ignores any spaces (these are put in toseparate the cipher text into 5-character "words").Sprite 2 is run when the "encipher" button is clicked and sprite3 does the deciphering. Both call the cipher script beforeoutputting the properly formatted text to the "textOut" list.
    • 36This is the "cipher" script. It just goes through eachcharacter that is in "inputText". If the letter is aspace, it changes it to a "~" before enciphering it. (Ifwe are deciphering, the dummy spaces will alreadyhave been removed).It then looks through the key until it finds the letter.In the key, letters are grouped in pairs. So if theindex of the letter is an even number, the letter isreplaced with the next letter in the list. Otherwise itis swapped for the letter before it.After calling the "cipher" block, these scripts prepare the text for output. If we arepreparing 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 availble in "textOut" and you can export to a text file if you wish.In this example, Ive madethe "inputText" variablevisible so you can see thatthe message has beenloaded.Scratch On!
    • 37Here you can see the result of enciphering theopening sentence of Donald E. Knuths classicbook The Art of Computer Programming.The cipher text is broken up into a series oflines, each line is one element in the listtextOut.Here you can see what the messagelooks like after it has been exported andopened in leafpad.If you are interested in learning more about cryptography, try this website:www.simonsingh.net/The_Black_Chamber/If you get stuck, the program isavailable here:http://tinyurl.com/scratch-subsHeres the key I used in my example, in case you want to try deciphering the wholething. Remember, it is a reciprocal key. Letters at odd numbered indices map to thenext letter, while letters at even numbered indices map to the letter before. Scratchlists begin with index 1. So, K is at index 3 and maps to J at index 4. And J mapsback to K.O| KJTVFEIQ~ARX, DYSPN. HZBMWGUCL
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