tentacle.netprophet/raspberrypi/Raspberry...Table of Contents Raspberry Pi Mechatronics Projects...

RaspberryPiMechatronicsProjectsHOTSHOT

TableofContents


Credits

AbouttheAuthors

AbouttheReviewers

www.PacktPub.com

Supportfiles,eBooks,discountoffers,andmore

Whysubscribe?

FreeaccessforPacktaccountholders

Preface

Whatthisbookcovers

Whatyouneedforthisbook

Whothisbookisfor

Conventions

Missionbriefing

Whyisitawesome?

YourHotshotobjectives

Missionchecklist

Task1

Prepareforliftoff

Engagethrusters

Objectivecomplete–minidebriefing

Classifiedintel

Readerfeedback

Customersupport

Downloadingtheexamplecode

Downloadingthecolorimagesofthisbook

Errata

Piracy

Questions

1.HelloWorld

AquickintroductiontotheRaspberryPi

FeaturesofaRaspberryPi

WherecanIbuyaRaspberryPi?

RequirementstogetstartedwiththeRaspberryPi

OperatingsystemsontheRaspberryPi

GettingstartedwithRaspbian

DownloadingRaspbian

FlashingimageontotheSDcard

Windows

Linux

Acommand-lineinterface-basedapproach

IdentifyingtheSDcardmountpoint

UnmounttheSDcard

FlashtheSDcard

GUI-basedapproach

SettinguptheRaspberryPi

Missionbriefing

Whyisitawesome?


Missionchecklist

Huntingandgathering

Engagethrusters


SettinguptheGPIO

Engagethrusters

InstallingGPIOlibraries


GPIOprogrammingusingPython

Engagethrusters

Analternativetoquick2wire–RPi.GPIO


Electricaloutputofourprogram

Engagethrusters


IntroductiontothePiCrust–aprototypingplatformfortheRaspberryPi

Missionaccomplished

Hotshotchallenge

2.ARaspberryWebIDEExample

Missionbriefing

Whyisitawesome?


Missionchecklist

Installation,features,andusageoftheOccidentalisoperatingsystemfromAdafruit

Prepareforliftoff

Engagethrusters


SetupofaremoteloginintotheRaspberryPi

Prepareforliftoff

Engagethrusters


InstallationoftheRaspberryPiWebIDE

Engagethrusters


PythondevelopmentontheWebIDE

Prepareforliftoff

QuickintroductiontotheI2Cinterface

ConfiguringtheI2CinterfaceontheRaspberryPi

Engagethrusters


TestanddebuggingexamplesusingtheWebIDE

Prepareforliftoff

Engagethrusters


Missionaccomplished

Hotshotchallenge

3.TheArduinoRaspberryPiInterface

Missionbriefing

Whyisitawesome?

WherecanyoubuyanArduino?


Missionchecklist

InstallingtheArduinoIDE

Prepareforliftoff

Engagethrusters


ProgrammingtheArduinousingtheRaspberryPi

Prepareforliftoff

Engagethrusters


RaspberryPiAlaMode

Prepareforliftoff

Engagethrusters


TheWeasleyweatherclock

Prepareforliftoff

Engagethrusters


ControllingthestepperusingtheArduino

Prepareforliftoff

Engagethrusters

Counterclockwiserotationofthesteppermotor


ControllingtheRGBLEDStripusingtheArduino

Prepareforliftoff

Engagethrusters


I2CCommunicationusingtheArduino(optional)

Prepareforliftoff

Engagethrusters

The7-Segmentdisplay

8x8LEDmatrix

BlinkM

Proximitysensor


SerialportcommunicationwiththeRaspberryPi

Engagethrusters

PythonprogramfortheWeasleyclock

Arduinoacknowledgementtocontrolsignal

Controlflowfortheweatherclock

Temperaturedata

ControloftheRGBLEDstrip

Controlofstepperviaserialport

Programmingtheweatherforecastposition

8x8matrixcontrol

BlinkMcontrol


Missionaccomplished

Hotshotchallenge

4.ChristmasLightSequencer

Missionbriefing

Whyisitawesome?

Yourobjectives

Missionchecklist

InterfacethedevicestotheRaspberryPi

Prepareforliftoff

Engagethrusters

ConnectingmultipleappliancestotheRaspberryPi


SettingupthedigitallyaddressableRGBmatrix

Prepareforliftoff

WherecanIbuythem?

Engagethrusters

Howdoesitwork?

LightinguptheRGBLEDstrip

AnArduino-basedcontrol


Interfaceofanaudiodevice

Prepareforliftoff

Engagethrusters


Installingthewebserver

Prepareforliftoff

Engagethrusters

Objectivecomplete–missiondebriefing

Interfacingthewebserver

Prepareforliftoff

Engagethrusters


Missionaccomplished

References

5.InternetofThingsExample–AnE-mailAlertWaterFountain

Missionbriefing

Whyisitawesome?

Yourobjectives

Missionchecklist

Prepareforliftoff

Engagethrusters


InstallationoftheFlaskframework

Prepareforliftoff

Engagethrusters


ControllingRGBLEDsfromawebpage

Prepareforliftoff

Engagethrusters


Setupofthee-mailalertsinthefountain

Prepareforliftoff

Engagethrusters


Missionaccomplished

Hotshotchallenge

6.RaspberryPiasaPersonalAssistant

Missionbriefing

Whyisitawesome?

Yourobjectives

Missionchecklist

Settingupthee-mailfeedparser

Prepareforliftoff

Engagethrusters

Settinguptheparserforremindersandevents

Prepareforliftoff

Engagethrusters

Designinganenclosuredesignforthepersonalassistant

Prepareforliftoff

Engagethrusters

Settinguptheassemblyforthedishmonitor

Prepareforliftoff

Engagethrusters


Settingupsensorsforthekeyalertsystem

Prepareforliftoff

Engagethrusters


Missionaccomplished

Hotshotchallenges

References

7.RaspberryPi-basedLineFollowingRobot

Missionbriefing

Whyisitawesome?


Missionchecklist

AssemblyofthePiPlateforthelinefollowingrobot

Prepareforliftoff

Engagethrusters


Sensorselection,interface,anddatainterpretation

Engagethrusters

LightDependentResistors

Infraredemitter/detector

Machine-vision-basedlinefollowingrobot

Sensorselection


Implementationoflinefollowinglogicbasedonsensordata

Prepareforliftoff

Engagethrusters


Testingthemotordrivercircuit

Prepareforliftoff

Engagethrusters


Preparationofthelinefollowingcourse

Prepareforliftoff

Engagethrusters

Useelectricaltapeandbuildatrack

Designingthechassisforthelinefollowingrobot

Prepareforliftoff

Engagethrusters


Astep-by-stepassemblyoftherobot

Prepareforliftoff

Engagethrusters


Missionaccomplished

Hotshotchallenge

References

8.ConnectFourDesktopGameusingRaspberryPi

Missionbriefing

Whyisitawesome?

Yourobjectives

Missionchecklist

Helloworldexamplewiththepygame

Prepareforliftoff

Engagethrusters

Playingsoundsusingthepygamemodule

Buildingmenususingthepygamemodule


GettingstartedwiththeConnectFourgame(UIandsoundeffects)

Prepareforliftoff

EngageThrusters

Addingamenuforthegame

Addingsoundstothegame


InterfacinggameinputsusingthePiFacemodule

Prepareforliftoff

Engagethrusters


AbriefdescriptionoftheConnectFourGameAI

Prepareforliftoff

Engagethrusters

Maingameloop


Marqueedesignandcontrol(optional)

Prepareforliftoff

Engagethrusters


Setupoftheswitchesusingacardboardbox

Prepareforliftoff

Engagethrusters


Missionaccomplished

Hotshotchallenge

References

9.TheRaspberryPi-enabledPet/WildlifeMonitor

Missionbriefing

Whyisitawesome?

Yourobjectives

Missionchecklist

Installingandtestingthepython-twistedframework

Prepareforliftoff

Engagethrusters


SettingupandtestingSparkCoretointeractwithappliances

Prepareforliftoff

EngageThrusters


InstallingandtestingtheGoogleCoderprojectontheRaspberryPi

Prepareforliftoff

Engagethrusters

Objectivecomplete–objectivecomplete

Abriefoverviewofabirdfeederthattriggersacamera

Prepareforliftoff

Engagethrusters


Alternativesandprojectideastoconsider

Missionaccomplished

Hotshotchallenge

10.RaspberryPiPersonalHealthMonitor

Missionbriefing

Whyisitawesome?


Missionchecklist

Settingupawebservertorecordhealthparameters

Prepareforliftoff

Engagethrusters


AsimpleexercisetoolusingtheRaspberryPi

Prepareforliftoff

Engagethrusters

Aminiprojectidea


Settingupane-mailfeedparsertorefillaprescriptionaswellasremindtheuseraboutanupcomingdoctor’sappointment

Engagethrusters

Settingupareminderfordoctor’sappointments


Asimpletoolthatremindsapersontotakehis/herpills

Prepareforliftoff

Engagethrusters

Otherprojectideas


Missionaccomplished

Hotshotchallenge

11.HomeAutomationusingRaspberryPi

Missionbriefing

Whyisitawesome?

Yourobjectives

Missionchecklist

Asimpleexamplethatcontrolslimitedindoorandoutdoorlightingintheevening

Prepareforliftoff

Softwareprerequisites

Engagethrusters


Alternativesolutionsandsomeprojectideastoconsider

Acustomarywebserverexample

Prepareforliftoff

Engagethrusters


Turningonalawnsprinkleronlywhenthereisnorainforecast!

Prepareforliftoff

Engagethrusters


GainingremoteaccesstoyourRaspberryPitocontrolappliances

Someprojectideastoconsider

Missionaccomplished

12.UsingaRaspberryPiforScienceandEducation

Missionbriefing

Whyisitawesome?


ImprovingyourvocabularyusingtheRaspberryPi

Prepareforliftoff

Engagethrusters


RaspberryPiandKhanAcademy

Someideastoconsider

BuildingasciencefairexhibitusingtheRaspberryPi

Prepareforliftoff

Engagethrusters


SomesimpleeducationalexperimentsusingtheRaspberryPi

Hotshotchallenge

13.TipsandTricks

Missionbriefing

Whyisitawesome?

Yourobjectives

Missionchecklist

SettingupRaspberryPiasadevelopmentplatform

#1–SimpletrickforPythondevelopmentviaremotelogin

#2WebdevelopmentusingGoogleCoder

#3AdafruitOccidentalis

#4JavaDevelopmentusingtheRaspberryPi

#5TheThingboxproject

RemotelyloggingintheRaspberryPifromanywhereontheInternet

ProblemsthatmightbeencounteredwhileusingRaspberryPi

SDcardcorruption

Powerissues

DevicespoweredbyUSB

Cooladd-onhardwaresourcesdevelopedfortheRaspberryPiplatform

TheRaspberryPimodelBversusB+,modelAversusA+

Projectideasthatcanbeimplementedoveraweekend

UsefulresourcesfortheRaspberryPi

RaspberryPiFoundation’sforums:

RaspberryPiStackExchange:

Element14’sRaspberryPicommunity:

Missionaccomplished

Index

RaspberryPiMechatronicsProjectsHOTSHOTCopyright©2015PacktPublishing

Allrightsreserved.Nopartofthisbookmaybereproduced,storedinaretrievalsystem,ortransmittedinanyformorbyanymeans,withoutthepriorwrittenpermissionofthepublisher,exceptinthecaseofbriefquotationsembeddedincriticalarticlesorreviews.

Everyefforthasbeenmadeinthepreparationofthisbooktoensuretheaccuracyoftheinformationpresented.However,theinformationcontainedinthisbookissoldwithoutwarranty,eitherexpressorimplied.Neithertheauthors,norPacktPublishing,anditsdealersanddistributorswillbeheldliableforanydamagescausedorallegedtobecauseddirectlyorindirectlybythisbook.

PacktPublishinghasendeavoredtoprovidetrademarkinformationaboutallofthecompaniesandproductsmentionedinthisbookbytheappropriateuseofcapitals.However,PacktPublishingcannotguaranteetheaccuracyofthisinformation.

Firstpublished:February2015

Productionreference:1190215

PublishedbyPacktPublishingLtd.

LiveryPlace

35LiveryStreet

BirminghamB32PB,UK.

ISBN978-1-84969-622-7

www.packtpub.com

http://www.packtpub.com

CreditsAuthors

SaiYamanoor

SrihariYamanoor

Reviewers

GuyScheffer

SreedharVaddi

CheukYu

CommissioningEditor

UshaIyer

AcquisitionEditors

UshaIyer

RebeccaPedley

SamWood

ContentDevelopmentEditor

SusmitaSabot

TechnicalEditor

ParagTopre

CopyEditor

JanbalDharmaraj

ProjectCoordinator

MiltonD’souza

Proofreaders

SimranBhogal

MariaGould

AmeeshaGreen

PaulHindle

Indexer

HemanginiBari

Graphics

SheetalAute

DishaHaria

ProductionCoordinators

AparnaBhagat

ManuJoseph

CoverWork

AparnaBhagat

AbouttheAuthorsSaiYamanoorisamechatronicsengineerworkingforaprivatestart-upschoolintheSanFranciscoBayAreawherehebuildsdevicesthathelpstudentsachievetheirfullpotential.HecompletedhisdegreeinmechanicalengineeringatCarnegieMellonUniversity,Pittsburgh,PA,andhisundergraduateworkinmechatronicsatSriKrishnaCollegeofEngineeringandTechnology,Coimbatore,India.Hisinterests,deeplyrootedinDIYandopensoftwareandhardwarecultures,includedevelopinggadgetsandappsthatimprovequalityoflife,InternetofThings,crowdfunding,education,andnewtechnologies.Inhissparetime,heplayswithvariousdevicesandarchitecturessuchasRaspberryPi,Arduino,Galileo,Androiddevices,andothers.Saishareshisadventureswithmechatronicsattheaptlynamed“MechatronicsCraze”blogathttp://mechatronicscraze.wordpress.com/.

IwanttothankmyparentsforencouragingmeinallmyendeavorsandformakingmewhatIamtoday.Iamgratefultomybrotherwhohashelpedshapemycareeralltheseyears.IlookforwardtoworkingwithSriharionsimilarprojectsinthefuture.IsincerelythankMr.S.BalajiRaghavendrawhohasbeenagreatsourceofinspirationtomewhilepursuingmyundergraduatedegree.IamalsothankfultoSusmitaSabotandtheentiresupportteamatPacktPublishingwhowerepatientandunderstoodthecircumstancesduringdifficulttimes.

SrihariYamanoorisanaturephotographerandmechanicalengineerwithexperienceworkinginmedicaldevicedesignandCAD/CAM.Hecompletedhismaster’sinscienceaswellasadegreeinengineeringfromStanfordUniversity.Hisworkandinterestsinmedicaldevicesincludewomen’shealth,cancer,orthopedics,andcardiovasculardiseases,aswellasnewerareassuchasdigitalhealthandelectronichealthrecords.HehasseveralthousandsofhoursofCADexperiencebehindhimandisalsocertifiedamongotherthingsasaSolidWorksexpert,simulationprofessional,andaSolidWorksinstructor.Hisinterestsrangefromengineeringandeducationtosocialentrepreneurship,animalwelfare,andcrowdfunding.

Iwouldliketothankmyparents,NarasimhanandYasodaVenakatakrishnan,fortheirsteadfastsupportinmyeducationandeffortsthroughouttheyears,culminatinginprojectssuchasthisbook.Overthecourseoftheyears,manyfriendshavehelpedbothSaiandmegrowinmanyways.Forthisreason,Iwouldliketosayabigwordofthanks,innoparticularorder,toRikaCatherineHirachi,AnnaLiuJao,ShirupaGupta,PatrickNguyen,VishnuPrasadRamachandran,AndrewEib,ChristopherMa,andKarthikPalaniappan.IamsureIammissingsomenames,andforthis,Iapologizeinadvance.Iwouldalsoliketothankmygraciousmentors,Dr.KevinWaldron,Dr.JamesStubbs,RussellSampson,MukundPatel,andasIfondlycallhim,Cyril“Master”,allofwhomhavegivenmeadviceandshownmetheway.Iwouldliketoespeciallythankmyfirstcat,Squeaky,andthefelinesBob,Saxon,andFishbone,thathavefollowedme,forinspiringmeandpushingmetostayontrackandkeepaneyeonthebigpicture.

http://mechatronicscraze.wordpress.com/

AbouttheReviewersSreedharVaddihas4yearsofexperienceinbigdata,4yearsincloudcomputing,and15yearsinJava.Hisexperienceincludesworkinthefieldsofbigdatasecurity,biomedical/healthcare,mobilesecurity,financialservices(wholesale,mortgage,investment,andbrokerage),theWeb(marketplace,crowdsourcing,andadvertising),newsandentertainment,propertyandcasualtyinsurance,softwareproductdevelopment,andscientificresearch.

Hehashands-onexperienceasanarchitectworkingonenterprisemobileapplications,Hadoop,SaaS,PaaS,IaaS,thecloud,richenterpriseapplications,n-tierenterprisesystems,EnterpriseApplicationIntegration(EAI)inweb-enablinglegacysystems,IBMMainframeandSAP,andSOAwebserviceswithJava2andJEE.

HehasalsoworkedinallphasesofSDLC,namelydesigning,developing,performancetesting,andimplementingWeb-2.0,Web-UI,server-side,middleware,andmobileapplications.HehasalsoworkedwithBig5ConsultingandFortune100companies.Hehasledteamsofsizesvaryingfrom2to80acrosstheglobeindifferenttimezones,cultures,anddialects.

HeisanadministratorofJEEcontainers(Geronimo,WebSphere,Weblogic,JBoss,andTomcat)andCDH.Heisalsoatechnicalconsultantatastealthmodestart-upinanimalcareintheclinicaltrialsindustry.Heisadiligentworkerandquicklearnerwithexcellentproblemsolving,presentation,andmentoringskills.

CheukYuispursuingabachelor’sdegreeinelectricalengineeringattheUniversityofCalifornia,LosAngeles(UCLA),withanemphasisoncircuitandsignalprocessing.HeworkedonmultipleembeddedsystemsprojectsusingvariousmicrocontrollerssuchasArduino,Teensy,andRaspberryPi.AsastudentresearcherfortheELFINCubeSatMissionatUCLA,healsohashands-onexperienceworkingonprintedcircuitboards,includingdesigningandtestingavionicsandgroundsupportequipmentboards.Besidesworkandstudy,heisalsoanamateurradiooperatorandastronomer.

www.PacktPub.com

Supportfiles,eBooks,discountoffers,andmoreForsupportfilesanddownloadsrelatedtoyourbook,pleasevisitwww.PacktPub.com.

DidyouknowthatPacktofferseBookversionsofeverybookpublished,withPDFandePubfilesavailable?YoucanupgradetotheeBookversionatwww.PacktPub.comandasaprintbookcustomer,youareentitledtoadiscountontheeBookcopy.Getintouchwithusatformoredetails.

Atwww.PacktPub.com,youcanalsoreadacollectionoffreetechnicalarticles,signupforarangeoffreenewslettersandreceiveexclusivediscountsandoffersonPacktbooksandeBooks.

https://www2.packtpub.com/books/subscription/packtlib

DoyouneedinstantsolutionstoyourITquestions?PacktLibisPackt’sonlinedigitalbooklibrary.Here,youcansearch,access,andreadPackt’sentirelibraryofbooks.

http://www.PacktPub.comhttp://www.PacktPub.commailto:[email protected]://www.PacktPub.comhttps://www2.packtpub.com/books/subscription/packtlib

Whysubscribe?FullysearchableacrosseverybookpublishedbyPacktCopyandpaste,print,andbookmarkcontentOndemandandaccessibleviaawebbrowser

FreeaccessforPacktaccountholdersIfyouhaveanaccountwithPacktatwww.PacktPub.com,youcanusethistoaccessPacktLibtodayandview9entirelyfreebooks.Simplyuseyourlogincredentialsforimmediateaccess.

http://www.PacktPub.com

PrefaceTheRaspberryPiisaquaintexampleoftechnologicalinnovationsthatcomebyonceeverytwoorthreedecadesandsetoffarevolutionthattoucheseveryaspectofhumanlifefromscientificexplorationtoentertainmenttoeducation.Whatisexcitingthistimearoundisthatthereareseveralsuchinnovationshappeningsimultaneously.Theymightsoundlike,andareinaway,buzzwords,buttheyareinfactreal,andarechangingourlivesinsomanyways,sofewofwhichweareconsciouslyawareof.Wearespeakingofinnovationsinentrepreneurship,suchascrowdsourcingortheemergenceofDIYwithanalmostcult-likefollowingtoinnovationsintechnologythatarecurrent,suchas3DprintingandInternetofEverything,andinnovationsthatareimpendingsuchas4Dprinting,smartmanufacturing,andmuchmore.

TheRaspberryPihasalreadyfoundseveralusesasevidencedbyhundredsofwebsites,projectexamples,andcrowdsourcingcampaigns.PeoplehaveusedthePitobuildrobots,teachprogramming,restoreoldgamingconsoles,streamvideos,collectdata,anddomanyotherthings.ThePiitselfhasgonethroughdesigniterationsandcontinuestospurcompetingsystems.PeoplehavetakenadvantageofthisandhavehookedupthePitomanydifferentecosystems,expandingitsubiquityandutility.

ThepurposeofthisbookistohelpthosewhoareexcitedabouttheRaspberryPiandhaveprojectideasinmind,orwouldsimplyliketogettheirhandsdirtyandpracticeimplementingprojectssothattheycanthenusethatknowledgeforotherendeavors.Wetriedtotakeapracticalapproach,introducingthePiinthefirstcoupleofprojectthatyoucanskipifyouarefamiliarwiththeRaspberryPiandhaveuseditbefore.Wethendiscussprojectsofincreasingcomplexity.WehavealsoattemptedtodiversifytheprojectstodemonstratevarioususesforthePithroughoutthebook.

WhatthisbookcoversProject1,HelloWorld,willintroducetheRaspberryPiandremindyouofthingsthatyoushouldknowasyouproceedthroughthebook.WewillsetuptheRaspberryPiandblinkanLED.

Project2,ARaspberryWebIDEExample,willtakeyouthroughPythondevelopmentusingabrowser.WewillusetheAdafruitWebIDEandleadyouthroughthedevelopmentprocessusingAdafruitproductsaspropsfortheexamples.

Project3,TheArduinoRaspberryPiInterface,isinspiredbytheHarryPotterseries,andinanefforttoshowourloveforthisseries,wehavecreatedaclocksimilartotheinnovativeandendearingWeasleyclockusingtheRaspberryPiandanArduino.Thisproject,ofcourse,allowstheclocktoreportbackweatherconditions.

Project4,ChristmasLightSequencer,discussesholidaysasthebesttimeforDIYprojects,andifyouareeverstarvedofideas,holidaysarethebesttimetocookupideas.WepickedaChristmas-themedprojecttodemonstratecontrollingappliancesconnectedtoalocalnetworkusingRaspberryPi.

Project5,InternetofThingsExample–AnE-mailAlertWaterFountain,followsthethemeofthepreviousproject.Wewillshowyouhowtocontroladecorativefountainsuchthatanytimeyoureceiveanewe-mail,yourfountain’slightwillflashanalert(thiscanalsobeswitchedtoreceiveTwitteralerts).

Project6,RaspberryPiasaPersonalAssistant,willshowyouhowyoucanusethePiasyourpersonalassistant,remindingyouofchores,settingalarms,anddoingeverythingatyourcommand.

Project7,RaspberryPi-basedLineFollowingRobot,willtakeyouthroughthesimplestofallrobots,thelinefollowingbot,withRaspberryPiatthehelm.Thisprojectwillshowyouthewayforthisandothercomplexroboticsprojectsyouwishtoimplement.

Project8,ConnectFourDesktopGameusingRaspberryPi,followstheinstant-classicthemefortheRaspberryPi,whichincludesgames.Allmannersofgamingapplications,includingtherevivalofarchaicgamestonewonesandmods,arebeingcreatedusingtheRaspberryPi.Wewillimplementthegameusingapushbuttoninterface.

Project9,TheRaspberryPi-enabledPet/WildlifeMonitor,willwalkyouthroughafunexampleofabirdfeedermonitorthatallowsyoutotriggeraphotocaptureeachtimethebirdapproachesthefeeder.Youcanthinkofextendingthistootherpets,orsay,theferalcatsinyourcolony.

Project10,RaspberryPiPersonalHealthMonitor,isaprojectwherewesetupasimplewebservertorecordourpersonalhealthparameters,buildasimpletooltoremindourselvestoremainphysicallyactive,andremindourselvestorefillaprescriptionviae-mailalerts.

Project11,HomeAutomationusingRaspberryPi,isaprojectwherewewillshowyouhowtocontrolappliancesusingatwistednetworkwheretheapplianceisconnectedtoa

platformsuchasanArduino.TheRaspberryPiactsasaserverthatcontrolsallsuchnodesinthenetwork.

Project12,UsingaRaspberryPiforScienceandEducation,isaprojectpackedwithexamples,includingavocabularylearningtool,awebhostforKhanAcademy,andawindmillgeneratorscienceexhibit.Havefunlearningandteaching!

Project13,TipsandTricks,isaprojectpackedwithtipsandtricksthatwillhelpyouusetheRaspberryPi!

Youcanalsogetthevideos,tipsandtricks,andmanymorethingsrelatedtotheprojectsathttp://diywithpi.com/.

http://diywithpi.com/

WhatyouneedforthisbookTogetstarted,youwillneedtheRaspberryPi,amonitor,akeyboard,apowersource,andpreferably,alaptoporpersonalcomputerrunningonanyOS—Windows,Linux,orApple.Otherhardwareandsoftwarerecommendationsaremadeintheindividualprojects,andyouarewelcometoreplacethemwithwhatyouseefit.AworkingknowledgeofPythonispreferred,butnotrequired.

WhothisbookisforThisbookisprimarilyaimedathobbyistsanddo-it-yourselfenthusiastsaswellasthoselookingtoimplementspecificprojectsusinglowcosthardwareandsoftwarecenteredaroundtheRaspberryPi.Basicexposuretoelectronics,programming,andInternetusageisassumed.Wehavetriedtotakeapragmaticapproach,implementingtheprojectsandshowinghowyoucandothisonyourown.

ConventionsInthisbook,youwillfindseveralheadingsappearingfrequently.Togiveclearinstructionsofhowtocompleteaprocedureortask,weuse:

MissionbriefingThissectionexplainswhatyouwillbuild,withascreenshotofthecompletedproject.

Whyisitawesome?Thissectionexplainswhytheprojectiscool,unique,exciting,andinteresting.Itdescribeswhatadvantagetheprojectwillgiveyou.

YourHotshotobjectivesThissectionexplainstheeightmajortasksrequiredtocompleteyourproject.

Task1Task2Task3Task4Task5Task6Task7Task8

MissionchecklistThissectionexplainsanypre-requisitesfortheproject,suchasresourcesorlibrariesthatneedtobedownloaded,andsoon.

Task1Thissectionexplainsthetaskthatyouwillperform.

PrepareforliftoffThissectionexplainsanypreliminaryworkthatyoumayneedtodobeforebeginningworkonthetask.

EngagethrustersThissectionliststhestepsrequiredinordertocompletethetask.

Objectivecomplete–minidebriefingThissectionexplainshowthestepsperformedintheprevioussectionallowsustocompletethetask.Thissectionismandatory.

ClassifiedintelThissectionprovidessomeextrainformationrelevanttothetask.

Youwillalsofindanumberofstylesoftextthatdistinguishbetweendifferentkindsofinformation.Herearesomeexamplesofthesestyles,andanexplanationoftheirmeaning.

Codewordsintext,databasetablenames,foldernames,filenames,fileextensions,pathnames,dummyURLs,userinput,andTwitterhandlesareshownasfollows:“Wewillgothroughtheimportantfeaturesofthepygamemodule,whichisnecessarytobuildourarcadegame,includingplayingsoundsandcontrollingthemenu.”

Ablockofcodeissetasfollows:

GPIO.output(25,True)while1:GPIO.output(25,False)sleep(1)GPIO.output(25,True)sleep(1)

Anycommand-lineinputoroutputiswrittenasfollows:

#cp/usr/src/asterisk-addons/configs/cdr_mysql.conf.sample/etc/asterisk/cdr_mysql.conf

Newtermsandimportantwordsareshowninbold.Wordsthatyouseeonthescreen,inmenusordialogboxesforexample,appearinthetextlikethis:“clickingtheNextbuttonmovesyoutothenextscreen”.

NoteWarningsorimportantnotesappearinaboxlikethis.

TipTipsandtricksappearlikethis.

ReaderfeedbackFeedbackfromourreadersisalwayswelcome.Letusknowwhatyouthinkaboutthisbook—whatyoulikedormayhavedisliked.Readerfeedbackisimportantforustodeveloptitlesthatyoureallygetthemostoutof.

Tosendusgeneralfeedback,simplysendane-mailto,andmentionthebooktitleviathesubjectofyourmessage.

Ifthereisatopicthatyouhaveexpertiseinandyouareinterestedineitherwritingorcontributingtoabook,seeourauthorguideonwww.packtpub.com/authors.

mailto:[email protected]://www.packtpub.com/authors

CustomersupportNowthatyouaretheproudownerofaPacktbook,wehaveanumberofthingstohelpyoutogetthemostfromyourpurchase.

DownloadingtheexamplecodeYoucandownloadtheexamplecodefilesforallPacktbooksyouhavepurchasedfromyouraccountathttp://www.packtpub.com.Ifyoupurchasedthisbookelsewhere,youcanvisithttp://www.packtpub.com/supportandregistertohavethefilese-maileddirectlytoyou.

http://www.packtpub.comhttp://www.packtpub.com/support

DownloadingthecolorimagesofthisbookWealsoprovideyouaPDFfilethathascolorimagesofthescreenshots/diagramsusedinthisbook.Thecolorimageswillhelpyoubetterunderstandthechangesintheoutput.Youcandownloadthisfilefromhttp://www.packtpub.com/sites/default/files/downloads/6227OT_ColoredImages.pdf.

http://www.packtpub.com/sites/default/files/downloads/6227OT_ColoredImages.pdf

ErrataAlthoughwehavetakeneverycaretoensuretheaccuracyofourcontent,mistakesdohappen.Ifyoufindamistakeinoneofourbooks—maybeamistakeinthetextorthecode—wewouldbegratefulifyouwouldreportthistous.Bydoingso,youcansaveotherreadersfromfrustrationandhelpusimprovesubsequentversionsofthisbook.Ifyoufindanyerrata,pleasereportthembyvisitinghttp://www.packtpub.com/submit-errata,selectingyourbook,clickingontheerratasubmissionformlink,andenteringthedetailsofyourerrata.Onceyourerrataareverified,yoursubmissionwillbeacceptedandtheerratawillbeuploadedonourwebsite,oraddedtoanylistofexistingerrata,undertheErratasectionofthattitle.Anyexistingerratacanbeviewedbyselectingyourtitlefromhttp://www.packtpub.com/support.

http://www.packtpub.com/submit-erratahttp://www.packtpub.com/support

PiracyPiracyofcopyrightmaterialontheInternetisanongoingproblemacrossallmedia.AtPackt,wetaketheprotectionofourcopyrightandlicensesveryseriously.Ifyoucomeacrossanyillegalcopiesofourworks,inanyform,ontheInternet,pleaseprovideuswiththelocationaddressorwebsitenameimmediatelysothatwecanpursuearemedy.

Pleasecontactusatwithalinktothesuspectedpiratedmaterial.

Weappreciateyourhelpinprotectingourauthors,andourabilitytobringyouvaluablecontent.

mailto:[email protected]

QuestionsYoucancontactusatifyouarehavingaproblemwithanyaspectofthebook,andwewilldoourbesttoaddressit.

mailto:[email protected]

Chapter1.HelloWorldItisaHotshotcustomtobeginlearninganythingnewwithaHelloWorldexample.Sincewewillbedoingreallycoolthingsinthisbook,wewillsay“HelloWorld”inauniquefashion.Inthisproject,wewillusetheRaspberryPitocauseanLEDlighttoblink.ThisprojectisdirectedtowardsthosewhoarerelativelynewtotheRaspberryPienvironmentasawarm-upexercise.FeelfreetoskipaheadifyouhavealreadydonethiswithyourPi,thoughwesuggestyoulookthroughandmakesureyouhaven’tmissedanything.

AquickintroductiontotheRaspberryPiIfwesearchforthetermRaspberryPiovertheweboropentheRaspberryPiFoundation’swebpage,wewillfindthattheRaspberryPiisacomputerthatisthesizeofacreditcard.

PartsofaRaspberryPi

FeaturesofaRaspberryPiTheRaspberryPiFoundation(http://www.raspberrypi.org/)initiallyreleasedtheRaspberryPimodelB.ThiswasfollowedbytheRaspberryPimodelA.In2014,theRaspberryPifoundationreleasedvariantsB+andA+.TheRaspberryPimodelsAandA+(costing25USDand20USDrespectively)donotcomewithanEthernetport,aUSBportand256MBRAM.ThemodelA+replacedmodelAwhilethemodelB+replacedmodelB.ThemodelB(price:35USD)camewithanEthernetport,2USBports,and512MBRAM;modelB+,whichsupersedesmodelB,comeswith40pinGPIOheaderasopposedto26intheearliermodels,andhas4USBportsandamicroSDcardslotinsteadoftheSDslot.PertheRaspberryPiFoundationwebsite,modelB+(aswellasmodelA+)consumeslowerpower,hasbetteraudioandabetterformfactor,whichwecertainlyconcurwith.ThemodelA+alsocomeswitha40pinGPIOheaderandamicroSDcardslot.ThemodelsA+andB+haveninemoreGPIOpinsthantheirpredecessors.

NoteTheRaspberryPi2wasreleasedafterwefinishedwritingthebook.Pleaserefertothebook’ssitetofindoutmoreaboutgettingstartedwithmodel2.

TheobjectiveofthisbookistobuildcoolprojectsusingtheRaspberryPi.WewilldiscussthecomponentsofRaspberryPifromthisperspective.IfyouareinterestedinfindingoutmoreabouttheRaspberryPi,theRaspberryPiFoundation’swebpagehaspublishedthetechnicalspecificationsofallthecomponents.

First,wewilldiscussthecomponentsavailableontheRaspberryPiandtheuseofthesecomponentsinourprojects.ThecomponentsoftheRaspberryPiinclude:

2USBports(1USBportavailableinmodelA)Ethernetport(availableonlyinmodelsBandB+)RCAoutputHDMIoutputAudiooutputLowlevelperipherals,whichinclude:

GPIO(GeneralPurposeInputOutput)UART/SerialPort(UniversalAsynchronousReceiverTransmitter)I2C(twowireinterface)SPI(SerialPeripheralInterface)

http://www.raspberrypi.org/

WherecanIbuyaRaspberryPi?Element14andRSComponentsarethemostcommondistributorsoftheRaspberryPiintheUnitedStates.TheRaspberryPimodelAwasroughlypricedat25USD,whileitssuccessormodelA+waspricedat20USD.ThemodelBwaspricedat35USDandthemodelB+ispricedat40USD.TherearealsoaneverincreasingnumberoflocaldistributorssuchasAdafruitandFry’sElectronicsintheUSthatselltheRaspberryPiforamargin.PleasechecktheRaspberryPiFoundationwebsiteandothersourcesformorevendors.

RequirementstogetstartedwiththeRaspberryPiInthissection,wewilldiscusstheitemsrequiredtogetstartedwiththeRaspberryPi.Wewillneedallthesamethingsthatarerequiredtouseacomputer/laptop.Theyare:

DisplayKeyboardMouseWi-FiAdapter/Ethernetcable

NoteItispossibletousetheRaspberryPiviaremoteloginusingasecureshell.ThismightseemdifficulttothosewhoarenewtotheLinuxenvironment.ThesetupoftheRaspberryPiforremoteloginisexplainedinProject13,TipsandTricks.

TheRaspberryPieLinuxwiki(http://elinux.org/RPi_Hub)haslistedperipheralsthathavebeentestedandconfirmedtohaveworkedontheRaspberryPi.Youhavethefreedomtochooseperipheralsaccordingtoyourchoice.

Display:TheRaspberryPiisprovidedwithanHDMIoutputandanRCAoutput.ItispossibletoconnectamonitorthathasanHDMIinput.ItisalsopossibletoconnectmonitorsthathaveaDVIinputwithanHDMItotheDVIcable.Powersupply:SincetheRaspberryPiconsumes700mAforitsoperation,itisrecommendedthatthereaderusespoweredUSBhubstousedevicessuchasWi-FiadaptersasopposedtopluggingindevicessuchastheWi-FiadaptersdirectlytotheUSBportoftheRaspberryPitoavoidthedeviceresettingitself.

OperatingsystemsontheRaspberryPiTheRaspberryPifoundationrecommendsthefollowingoperatingsystemsontheRaspberryPi.Theyare:

RaspbianArchLinuxARMRISCOS

Youarewelcometochooseanyoperatingsystemofyourchoice.Forbeginners,westronglyrecommendtheRaspbianOSforprojects.TheRaspbianisequippedwithtoolstogetstartedeasily.TheRaspberryPi’sfirmwareisimplementedsuchthattheoperatingsystemisloadedfromanSDcard.

http://elinux.org/RPi_Hub

GettingstartedwithRaspbianInthissection,wewilldownloadanimagefromtheRaspberryPiFoundation’swebpagetoacomputer,flashanSDcardwiththeimage,andsetuptheoperatingsystemontheRaspberryPi.Wewillalsotrytowriteandexecuteourfirstexample.

DownloadingRaspbianThelatestRaspbianimageishostedontheRaspberryPiFoundation’swebpage(http://www.raspberrypi.org/downloads/).ThelatestimageatthetimeofwritingthisbookwasRaspbianwheezy.Weneedtodownloadtheimageandextractittothefolderofourchoice.

RaspbianwheezyontheRaspberryPiFoundation’swebsite

FlashingimageontotheSDcardWewilldiscussflashingtheSDcardwiththeRaspbianimageonbothWindowsandLinuxmachines.

Windows

Extractthefilestoalocationofyourchoice.TheWin32DiskImagertoolisrequiredtopreparetheSDcardwiththeRaspbianimage.

TipAstandardRaspbianimageisabout1.8GBbig.ItisstronglyrecommendedthatyouuseanSDcardthatisatleastof4GBbig.

http://www.raspberrypi.org/downloads/

TheWin32DiskImagertool

WecanflashtheSDcardinthreesimplesteps(asshownintheprecedingscreenshot):

1. SelecttheSDcardthatneedstobeflashed.2. SelecttheRaspbianimagelocation.3. ClickonWrite.4. ClickonYestoconfirm.

ConfirmoverwritingtheSDcard

5. Itcantakeawhilebeforethewritecycleiscompleted.

Linux

TherearetwoidenticalmethodstoflashanSDcardonaLinuxmachine.Thetwoapproachesinclude:

AGUI-basedapproachAcommand-lineinterface-basedapproach

Acommand-lineinterface-basedapproach

TheSDcardcanbeflashedinthreesimplestepsusingacommand-lineinterface.Thesestepsareasfollows:

1. IdentifytheSDcardmountpoint.2. UnmounttheSDcard.3. FlashtheSDcard.

IdentifyingtheSDcardmountpoint

AssoonasweinserttheSDcardintoaUSBcardreaderoranSDcardslotfoundonalaptop,weneedtoopenaterminalonourLinuxmachine.Weneedtoidentifyourdevice’smountpointonthemachineusingthefollowingcommand:

df–h

Thedevicesenumeratedonthemachinewillbelistedasshowninthefollowingscreenshot:

Storagedevicesidentifiedbytheoperatingsystem

UnmounttheSDcard

Inthepreviousexample,the/dev/sdb5pathisthestoragedeviceofinterest.Theremaybemorethanonestoragedevicethatmightbeconnectedtoamachine.Weneedtomakesurethatwehaveidentifiedtherightdevice.Oncewehaveidentifiedthedevice,ithastobeunmountedusingthefollowingcommand:

umount/dev/sdbFlashtheSDcard

Now,wewillflashourSDcardusingthefollowingcommand:

ddbs=4Mif=~/2012-09-18-wheezy-raspbian.imgof=/dev/sdb

Theif=argumentpointstothelocationoftheimageandof=referstotheSDcardmountpoint.ThewriteoperationtakesawhiletocompleteanditisreadyforuseontheRaspberryPiuponcompletion.GUI-basedapproach

OnaDebianLinux-basedoperatingsystem,thereisapackagecalledusb-imagewriter.TheImageWriterpackageperformsthesameoperationsrequiredtoflashanSDcard.

AUSBImageWriteronUbuntu

SettinguptheRaspberryPiNowthattheimageisflashed,let’sgetstartedwithsettinguptheRaspberryPiforthefirsttime.WewillhavetoinserttheSDcardslotfoundontheothersideoftheRaspberryPi.

AflashedSDcardintheslot

Whenthekeyboardandthemouseareconnected,wecangetstartedbypoweringuptheRaspberryPi!

OncetheRaspberryPiispoweredup,theoperatingsystembootsuptoRaspi-config.Theraspi-configisthetoolusedtosetupdesktopoptions,keyboardsettings,storagesettings,andsoon.TheRaspi-configscreenisshowninthefollowingscreenshot:

TheRaspi-configscreen

Inthissection,wewilldiscusseachfeatureoftheraspi-configtool:

info:Asthenamesuggests,thissectiongivesthegeneralinformationaboutthetool.expand_rootfs:WhiletheSDcardisflashedwiththeoperatingsystemimage,theSDcardispartitionedjustaboutthesizeoftheimage.Thiscommandaidstoexpandthepartitionsothattheremainingspacecanbeusedforfilestorage.overscan:ThisisanoptionusedwhentheRaspberryPiisconnectedtothetelevision.configure_keyboard:Thisoptionisusedtoconfigurethechange_typeoptionofthekeyboard.change_pass:Thedefaultpasswordisraspberry,andifnecessary,thisoptionletsyouswitchtoastrongerpassword.change_locale:Theoptionletsyouchangethelanguagepreferences.change_timezone:Wecansetourcurrenttimezoneusingthisoption.memory_split:ThisoptionletsussplitthememorybetweentheARMprocessor’sCPUandthegraphicsprocessor.overclock:Thedefaultclockspeedis700MHz.Thisoptionletsyousettheclockspeedto1GHz.ThismightvaryforRaspberryPi2.ssh:Thisoptionenablesthesecureshellserver.ThisisrequiredtoremotelylogintheRaspberryPiandcontroldevicesremotely.ItisenabledbydefaultonRaspbian.boot_behaviour:Thisoptionenablesyoutobootdirectlyintothedesktop.

TipItisimportantthatyouenablethisoptiononasthedefaultoptionbootsintoanormaltext-basedconsole.

update:IftheRaspberryPiisconnectedtotheInternetusinganEthernetcable,theraspi-configtooldownloadsanypackagethatmightbeavailable.

OncewecompletethesetupprocessbyselectingFinish,theRaspberryPirebootsandexpandsthefilesystemifnecessary.

MissionbriefingInthisproject,wewillsetuptheGPIO(GeneralPurposeInputOutput)peripheralontheRaspberryPiandwriteourfirstprogramtocauseanLEDtoblink.Attheend,wewillrepeatthesamestepswithaRaspberryPiadd-onboardcalledPiCrust.Thiswillallowyoutogetyourfeetwetandensureyouhavealltherighttoolsgoingforward,andshouldyouneedto,troubleshootanyproblemsyoumightidentify.

Whyisitawesome?Thinkofsaying“HelloWorld”asbothanodtoprogrammingtraditionandadryruntoensureyouarewellequipped!

YourHotshotobjectivesTheobjectivesforthismissionarequitesimple,andyettakeusallseveralmilestonesfurther!HerearetheobjectivesoftheHelloWorldmission:

CollectallthenecessarytoolsSetuptheGPIOperipheralIntroduceourselvestotheRaspberryPienvironmentTurnalightemittingdiode(LED)onandoffwitha1seconddelay

MissionchecklistGoovertheprevioussections,andmakesureyouhaveallthetools.DownloadtheGPIOlibraries,andensureyoucanlogintotheRaspberryPiremotely,andyouareallset!

NoteTherearetwodifferentwaystouseaRaspberryPi.Theyare:

ConnectingamonitortotheHDMIportortheRCAjackandakeyboardtotheUSBportoftheRaspberryPi.RemotelyloggingintotheRaspberryPifromthereader’sworkstation.

Ifyouareabeginner,itisbesttousethefirstmethodwhilethesecondmethodcanbeusedifyouarefamiliarwiththeLinuxoperatingsystemandremotelogincapabilities.

OncewecompletethesetupprocessbyselectingFinish,theRaspberryPirebootsandexpandsthefilesystemifnecessary.

HuntingandgatheringAsstatedbefore,youwillneedtomakesureyouhaveallthetools.So,goahead,huntandgatheraway.Grabatleastoneofeachofthefollowingandmorethanoneofeach,ifyou,likeus,arepronetoaccidents:

AlaptoptodownloadtheRaspberryPiimageandsetupeverythingRaspberryPi—ModelB/B+(preferred),akeyboard,andamousefortheRaspberryPi(optional)SDcardwith4GBmemory(SDcardpreparationwasexplainedearlierinthisproject)USBPowerAdapter(Rated1.0A)andMicroUSBpowercableEthernetcableWi-Fiadapter—(optional)refertotheeLinuxwikiforRaspberryPiforverifiedperipheralsBreadboardJumperwiresDiscreteResistorValuesAworkbench(oracleanworkingsurface—hopefullyyouhaveone)Goodthoughtsandacan-doattitudeLotsofcoffee,tea,orasafebeverageofyourchoice

EngagethrustersYouwillneedallofthetoolslistedintheprevioussectiontogetthroughthisproject.Takeyourtimeandmakesureyouhaveeverythinghandy!

Objectivecomplete–minidebriefingDoyouhaveallthetools?Readytogo?Thenontothenexttask!

SettinguptheGPIOWeneedtoenabletheGPIOperipheralsinourRaspbianinstallationtogetstarted.Inordertodownloadtherequiredtoolsandsetthingsinmotion,theRaspberryPineedstobeconnectedtotheInternet.

TheGPIOpinisapinthatisavailablefromtheRaspberryPi’sprocessorthatenablesinterfacinginputandoutputdevicestotheRaspberryPi.Inthissection,wewilltalkaboutsettinguptheGPIOforinterfacinganoutputdevice.Thereisa26-pininterface(40inModelB+)availableontheRaspberryPiandabout17ofthose26pinsareGPIOpins(26oftheminModelB+)whiletheothersaremiscellaneouspinssuchaspower.Thepinsaredrivenbya3.3VrailandeachGPIOpinisratedforabout17mAandthetotalcurrentdrawnotexceeding50mA.

EngagethrustersWealsoneedtoknowtheGPIOperipheralsavailabletoconductourexperiment.ThefollowingfigureshowstheGPIOmapsoftheRaspberryPiRev1andRev2:

GPIOmapforModelsA,B,andB+.(ImagepublishedwithpermissionfromRaspi.tv)

TheletterP1showninthefollowingimagecorrespondstoP1-1oftheGPIOmap.P1-1correspondstothefirstpinontheleftinthefrontrow,whileP1-2correspondstothefirstpinontheleftinthebackrow.

TheRaspberryPiGPIOperipheral

Inthisbook,wewillbemostlyusingPythonprogramminglanguage.Pythonisaverysimpleandeasylanguagetolearn.Wemaywanderofftootherprogramminglanguagesfromtimetotime,butwewillmostlysticktoPython.Withthisinmind,let’sgetstarted.

InstallingGPIOlibrariesTherearealotoflibrariesavailabletoaccesstheGPIOperipheral.Theeasiesttoinstallanduseisthequick2wirepythonAPI.TheAPIisusedtocontroltheGPIOperipheralsandI2CdevicesconnectedtotheRaspberryPi.

NoteTherearedifferentlibrariessuchastheRPi.GPIO,Pi4J,andsoon.Weareusingthequick2wireAPIinthisexampleasabeginnermightfinditeasytouse.Youarewelcometouseotherlibrariesofyourchoice.Thequick2wire-gpio-admintoolenablescontrollingtheGPIOpinswithoutrootaccess.

Onedisadvantageofusingthequick2wiremoduleisthatitprovidesaccessonlytoGPIOpins0through7.

Theterminalcanbelocatedintheleftcornerofthedesktopandhasbeenhighlightedinthefollowingscreenshot:

ACommand-lineterminalontheRaspbiandesktop

1. Thequick2wirelibraryinstallationisbasedonapostonthequick2wirewebsite(http://quick2wire.com/articles/how-to-add-quick2wire-as-a-raspbian-software-

http://quick2wire.com/articles/how-to-add-quick2wire-as-a-raspbian-software-source/

source/).Inordertoinstallthequick2wire-pythonlibrary,therepositoryneedstobeaddedto/etc/apt/sources.list.

Inthecommandline,therepositoryisaddedbyusingthenanotexteditor:

sudonano/etc/apt/sources.list

Thefollowinglinesneedtobeaddedtothefile:

#Quick2WireSoftwaredebhttp://dist.quick2wire.com/raspbianwheezymaindeb-srchttp://dist.quick2wire.com/raspbianwheezymain

ThefilecanbesavedbytypingCTRL+X.ThefilecanalsobesavedbypressingYkeywhileexitingtheeditor.Alternatively,thelinescanbeaddedusingagraphicaltexteditorsuchas,leafpadandsavingit:

sudoleafpad/etc/apt/sources.list

2. Inordertoensurethatthepackagesaredownloadedfromthequick2wirerepository,weneedtoauthenticatethepackagesusingakeyavailablefromquick2wire:

wgethttps://raw.githubusercontent.com/quick2wire/quick2wire-software-users/master/[email protected]@quick2wire.com.gpg.key

3. Thecacheisupdatedandthelatestsoftwarepackagescanbedownloadedasfollows:

sudoapt-getupdatesudoapt-getupgrade

4. Thequick2wiretoolisinstalledasfollows:

sudoapt-getinstallquick2wire-gpio-adminsudoapt-getinstallquick2wire-python3-api

Objectivecomplete–minidebriefingNow,wasn’tthateasy?Let’sgetmorefamiliarwiththeGPIOinput/outputoperations.

GPIOprogrammingusingPythonInthissection,wewillensurethatthelibraryiscorrectlyinstalledandaddtheusertothegroup.ThiswillenabletheusertousetheGPIOpinswithouthavingrootprivileges.ThiswillbefollowedbythesectionongettingstartedwithGPIOcontrolprogramminginPython.

EngagethrustersInordertogetstartedwithprogrammingintheRaspberryPi,wewilllaunchPythonIDLE3fromthedesktop.

LaunchingIDLE3fromthedesktop

1. Now,wehavetogetstartedwithprogrammingtheLEDblinkingexampleinIDLE3.2. ThisLEDblinkingsamplecodeisasfollows:

fromtimeimportsleepfromquick2wire.gpioimportpins,Out

withpins.pin(7,direction=Out)asout_pin:whileTrue:out_pin.value=1sleep(1)out_pin.value=0sleep(1)out_pin.unexport()

3. Wewillimportthesleepclassfromthetimemoduleinthefirstline.Thisisrequiredtointroducea1-seconddelaybetweenturningtheLEDonandoffeveryothersecond:

fromtimeimportsleep

4. Wealsoneedthepinclassfromthequick2wireGPIOlibrary:

fromquick2wire.gpioimportPin

5. Weneedtosettheoutputpinthatwewillbeusingintheexample:

LED_output=Pin(8,Pin.Out)

6. Wecansetthepintothelogicalhigh(3.3V)asfollows:

LED_output=1

7. Wewillsetthepintothelogicallow(0V)asfollows:

LED_output=0

8. Wewillexecutethesamethingusinganinfinitewhileloop:

whileTrue:LED_output=1sleep(1)LED_output=0sleep(1)

9. ThiswillmaketheLEDblinkwitha1-seconddelay.Weshouldalsonotetheindentontheblinksequence.Theblinksequencehasadifferentindentcomparedtothewhileloop.Hence,thecodethatisatadifferentindentisexecutedinfinitely.

10. Whentheprogramisinterrupted(bypressingCTRL+Conthekeyboard),weneedtounexportthepinsatexit:

out_pin.unexport()

Analternativetoquick2wire–RPi.GPIO1. AnotheralternativeistouseRPi.GPIO(https://pypi.python.org/pypi/RPi.GPIO).It

comesasastandardpackagealongwiththeRaspbianWheezyOS.Let’sperformaquickreviewofthecode:

importRPi.GPIOasGPIOfromtimeimportsleep

GPIO.setmode(GPIO.BCM)GPIO.setup(8,GPIO.OUT)

GPIO.output(8,GPIO.LOW)

whileTrue:GPIO.output(8,GPIO.HIGH)sleep(1)GPIO.output(8,GPIO.LOW)sleep(1)

GPIO.cleanup()

2. Afterimportingtherequiredmodules,wegetstartedwithsettingupthepinnumberingmode.Therearetwotypesofpinnumberingmodes,namely:

TheBCMPinnumberingmode:Thepinnumbersarebaseduponthepin

https://pypi.python.org/pypi/RPi.GPIO

numbersoftheBCMchip.TheBoardnumberingmode:ThepinnumbersarebaseduponthepinnumbersoftheRaspberryPiGPIOheader.Inthisexample,wewillsettheBCMnumberingmodeandsetpin8astheoutput:

GPIO.setmode(GPIO.BCM)GPIO.setup(8,GPIO.OUT)

3. Wecansetthepintologicalhigh(3.3V)asfollows:

GPIO.output(8,GPIO.HIGH)

4. Wecansetthepintologicallow(3.3V)asfollows:

GPIO.output(8,GPIO.LOW)

5. Now,theLEDcanbemadetoblinkwitha1seconddelay:

whileTrue:GPIO.output(8,GPIO.HIGH)sleep(1)GPIO.output(8,GPIO.LOW)sleep(1)

6. WhentheprogramisinterruptedbytypingCTRL+C,wehavetocleanupandreleaseanyoccupiedGPIOresources:

GPIO.cleanup()

Objectivecomplete–minidebriefingInthissection,wefinishedwritingaprogramtomakeanLEDblink.Inthenextsection,wewillputacircuittogetherthatmakesanLEDblink.

ElectricaloutputofourprogramIntheprevioussection,wewroteaprogramtomakeanLEDblink.Let’slookattheelectricalconnectiontoobservetheoutputofourprogram.WewillconnectaresistorbetweentheGPIOpinandtheanodeoftheLED.WewillconnectthecathodetothegroundpinoftheRaspberryPi.

EngagethrustersWewillconnecttheLEDandtheresistortotheGPIOpinandthegroundpin,asshowninthisimage:

LEDblinkingcircuit

NoteIfwearenotcarefulwiththehandlingoftheRaspberryPiGPIOpins,itmayeithertemporarilyresettheRaspberryPiorsometimesevenpermanentlydamagetheGPIOpin.ThereareseveraltutorialsinbasicelectronicsavailableovertheWeb.Itisimportantthatyoufamiliarizeyourselfwiththebasicsofelectronics.

Onceweconnectthecircuitasshownintheprecedingimage,wewillbeabletoexecutetheprogramandconcludeourexperiment.

Wecanexecutetheprogrambyrunningthemodule,asshowninthefollowingscreenshot:

ExecutingthePythonexample

Objectivecomplete–minidebriefingThat’sit!WehavewetourfeetbysayingHelloWorldbyblinkinganLED!Onourwaytobiggerandbetterthings,let’sstopandexaminethePiCrustforamoment.

IntroductiontothePiCrust–aprototypingplatformfortheRaspberryPiNowthatourHelloWorldexampleisdone,wewillleaveyouwithonemorething.Throughoutthisbook,wewillreviewsomeadd-onhardwaretoaccesstheGPIOperipheralsontheRaspberryPi.Inthisproject,wewilldiscussthePiCrustboardfortheRaspberryPi.

ThePiCrustboardwasdesignedbyJoeWalnes.ItisaboardthatisstackableontheRaspberryPiandeliminatestheneedforabreadboardtoprototypecircuits.

APiCrustboard

ThePiCrustisanopensourceadd-onhardwareandcostsapproximately$14tobuildoneourselves.Thedesigncanbedownloadedfreeofcostfromhttp://picru.st.

So,itisuptoyoutodecidewhetheryouwanttosimplybuyone,buildone,orasweare

http://picru.st

pronetoencourage,improveuponitandopensourceitforotherstobenefit!

ThemainadvantagebehindPiCrustisthatitisaidsprototyping.ItallowseasyaccesstotheI2Cinterface,SPIinterface,UARTport,andtheGPIOpins.ThefollowingfigureshowsBlinkM—anI2C-drivenRGBLEDmountedontopofthePiCrust.

PiCruststackedontopoftheRaspberryPi

MissionaccomplishedNowthatyouhavetraveledthisfarwithus,howdoyoufeel?Doyouneedabreak,ormorecoffee?Beforeyoudoeither,let’sreview.

Inthisproject,wegotstartedwiththeLEDblinkingexampleusingtheRaspberryPi.WediscussedthesetupofGPIOperipheralsandusingtheminanexperiment.YouarewelcometocontinueexperimentswiththeGPIOperipheralswithprojectssuchasLEDsequencing,threebitcounter,andsoon.

Intheforthcomingprojects,wewilllookintoI2Ccommunication,SPIcommunication,andUARTcommunication(serialport).

HotshotchallengeWelldone;youhavetaughtyourPitosay“HelloWorld”!However,wearesureyoucandomore,muchmore.HaveyouwatchedthemovieCloseEncountersoftheThirdKind?Well,ifnot,youshould.However,thisisnotachallengeinitself.Inthemovie,thehumanbeingsattemptatcommunicationwithwhattheybelieveisaliensbybuildingapatternoflightsthataresettomusic.CanyoumakeapatternofLEDsrepeatthatorsomethingsimilar?

Chapter2.ARaspberryWebIDEExampleInthisproject,wewilllearnhowtodevelopprojectsusingtheWebIDEfromAdafruitIndustries.WewillflashanSDcardwiththeRaspbianOS,installtheOccidentalistool(https://learn.adafruit.com/adafruit-raspberry-pi-educational-linux-distro/occidentalis-v0-dot-3),setuptheweb-baseddevelopmenttool,andtestthesetupusinganexample.

NoteOccidentaliswasinitiallyavailableasaRaspbianOSimagebyAdafruitIndustries.ItcomprisedofthetoolsetthatenabledtogetstartedwithprojectdevelopmentusingtheRaspberryPi.TheOSimagewasdeprecatedandreleasedafterwefinishedwritingthebook.Wehavetakenourbestefforttoupdatethebook.Pleaserefertothisbook’swebsiteformoreinformation.

https://learn.adafruit.com/adafruit-raspberry-pi-educational-linux-distro/occidentalis-v0-dot-3

MissionbriefingInthisproject,wewilldiscussinstallingatool,Occidentalis,andaWebIDEthatenablesprogramminginthePythonlanguageontheRaspberryPi.WewillalsodiscussoneexamplefromtheAdafruitrepositoryandanotherexampleofdrivinganRGBLED.

Thefollowingtableliststhebillofmaterialsusedinthisproject.Thesearejustexamples,andalternativeproductsthathaveasimilarspecificationmayalsobeused.

Item EstimatedCost

RaspberryPiModelB 35USD

AdafruitCobbler(https://www.adafruit.com/product/914) 7USD

Adafruit7-segmentLEDBackpack(https://www.adafruit.com/product/879) 10USD

Blinkm(https://www.sparkfun.com/products/8579) 13USD

https://www.adafruit.com/product/914https://www.adafruit.com/product/879https://www.sparkfun.com/products/8579

Whyisitawesome?TheAdafruitWebIDEincombinationwiththeOccidentalisoperatingsystemenablesdevelopmentinthePythonlanguageonaRaspberryPiusingjustawebbrowser.ItalsoenablesaccesstosampleprojectsdevelopedbyAdafruitviaBitbucket,asourcecontroltool.(IfyouarenotfamiliarwithsourcecontroltoolssuchasBitbucket,Git,andsoon,theexamplesinthisprojectareagreatwaytogetstarted!)TheAdafruitWebIDEisatooldevelopedforhobbyistsandcomeswithexamplesfortechniquessuchaspulse-widthmodulation(usedinlightingsystemcontrol)andI2Ccommunication,andalsoprovidesexamplesforcontrollingproductsfromAdafruit.

NoteTheAdafruitWebIDEisnowabetareleaseanditmaynotworksuccessfullyacrossdifferentplatforms.TheAdafruitlearningsystemhasindicatedthatthisdevelopmenttoolwasdirectedtowardsadvancedhobbyists.Wehavetakenourbesteffortstoexplainitassimplyaspossible.

Pulse-widthmodulationisatechniqueusedwidelyinmotorcontrol,lightingsystems,andsoon.Itisatechniquewheretheaveragevoltageappliedtoadeviceisvariedbychangingthewidthofthepulse.Thereareseveraltutorialsonpulse-widthmodulation(https://learn.sparkfun.com/tutorials/pulse-width-modulation)availableallovertheWeb.

I2Ccommunication(https://learn.sparkfun.com/tutorials/i2c)isaformofserialcommunicationinterfaceusedtoconnectmultipleslavedevices(usuallysensors)withamasterdevice(RaspberryPioramicrocontroller)throughacommoninterface.

https://learn.sparkfun.com/tutorials/pulse-width-modulationhttps://learn.sparkfun.com/tutorials/i2c

YourHotshotobjectivesInthisproject,wewilldiscussthefollowingfeatures:

BootstrappingyourRaspberryPibyinstallingOccidentalisSetupofremoteloginintotheRaspberryPiInstallationoftheRaspberryPiWebIDEPythondevelopmentontheWebIDETestanddebuggingexamplesusingtheWebIDE

NoteThisprojectshouldnotbeconsideredasanattempttopromoteAdafruitIndustriesortheirproductsdevelopedfortheirplatform.ThisprojectmerelydemonstratessimplificationofdevelopmentontheRaspberryPiusingatoolfromAdafruitIndustries.

MissionchecklistInordertogetstarted,thefirststepistoinstalltheOccidentalisdistro,whichisaderivativeoftheRaspbianoperatingsystem.

Thethingsrequiredtogetstartedareasfollows:

A4GBSDcardflashedwiththeRaspbianOSAnOccidentalisimage.AnEthernetcable

Installation,features,andusageoftheOccidentalisoperatingsystemfromAdafruitThefirststepisinstallingOccidentalisontheRaspberryPi.

PrepareforliftoffThefirststepistheinstallationoftheAdafruit-Pi-Findertool.Thetoolcanbedownloadedfromhttps://github.com/adafruit/Adafruit-Pi-Finder/releases/latest.ItisavailableforWindows,Linux,andMacplatforms.

https://github.com/adafruit/Adafruit-Pi-Finder/releases/latest

Engagethrusters1. YoucanfinddetailedinstructionsoninstallingtheOccidentalistoolat

https://github.com/adafruit/Adafruit-Pi-Finder.2. Alternatively,astep-by-stepinstructionisalsoavailableonthisbook’swebsite.We

cannotincludethemheresincechangesweremadetoOccidentalisinstallationprocessafterwefinishedwritingthisbook.

https://github.com/adafruit/Adafruit-Pi-Finder

Objectivecomplete–minidebriefingOncetheinstallationiscomplete,wehavetoensurethattheRaspberryPiaswellasthedevelopmentmachineareconnectedtothenetworkviatheEthernetportoraUSBWi-Fidongle.

SetupofaremoteloginintotheRaspberryPiInthissection,wewillremotelylogintotheRaspberryPiusingasecureshell.SincetheRaspberryPicomeswithsshdenabled,itispossibletologinremotelyusingthelocalname,raspberrypi.local(Duringthebootstrappingprocess,theavahi-daemontoolisinstalledandhence,itispossibletoremotelylogintotheRaspberryPiusingthelocalname,raspberrypi.local).Alternatively,onaWindowsmachine,youcanuseatoolsuchasAdvancedIPScanner(http://www.advanced-ip-scanner.com/)tofindtheIPaddressoftheRaspberryPi.Asnapshotofthistoolisshownlaterinthisproject.

NoteIfyouareusingaWindowsmachine,theBonjourPrintServicesdrivershavetobeinstalledtoremotelyloginusingthelocalname,raspberrypi.local.TheBonjourPrintServicesdriversareavailablefromhttp://support.apple.com/kb/DL999.

http://www.advanced-ip-scanner.com/http://support.apple.com/kb/DL999

PrepareforliftoffTheIPaddressoftheRaspberryPicanbeidentifiedusingtoolssuchasAdvancedIPScanner,asshowninthefollowingscreenshot:

AlistofdevicesandIPaddressesconnectedtoanetworksimilartotheRaspberryPi

Engagethrusters1. OnceweknowtheIPaddress,weuseanSSHclientsuchasPuTTYonWindowsora

command-lineterminalonaLinuxoraMacmachinetoremotelylogintothemachine(inthiscase,weshowthisonaWindowsmachine).

2. OnaWindowsmachine,weeitherusetheIPaddressoftheRaspberryPioritslocalname(raspberrypi.local)andlogintotheRaspberryPi,asshowninthefollowingscreenshot:

3. OnceweentertheIPaddress/localnameinthePuTTywindow,weloginasfollows:

loginas:[email protected]'spassword:raspberry

Alternatively,wecanalsologinusingtheIPaddressoftheRaspberryPiinsteadofthelocalname,raspberrypi.local.

Objectivecomplete–minidebriefingIftheusernameandpasswordareenteredcorrectly,weshouldbeabletoremotelylogintotheRaspberryPitoinstallthewebserver.

InstallationoftheRaspberryPiWebIDEWewillgetstartedbyusingaremoteloginclientsuchasPuTTYtoremotelylogintotheRaspberryPiandinstalltheAdafruitWebIDE.InordertogetstartedwithexamplesfromtheAdafruitrepository,weneedaBitbucketaccount,andAdafruitprovidesdetailedinstructionsforthisathttp://learn.adafruit.com/webide/getting-started.

http://learn.adafruit.com/webide/getting-started

Engagethrusters1. Oncewehaveloggedin,theAdafruitlearningsystem’swebsiterecommends

executingthefollowingtoinstallthewebserver:

curlhttps://raw.githubusercontent.com/adafruit/Adafruit-WebIDE/master/scripts/install.sh|sudosh

2. Itshouldtakeaboutfiveminutestofinishtheinstallation.Iftheinstallationwassuccessful,weshouldbeabletoseethemessagemarkedinthefollowingscreenshot:

SuccessfulcompletionoftheAdafruitWebIDEinstallation

3. Assumingtheinstallationwassuccessful,weshouldbeabletolaunchtheAdafruitWebIDEusinghttp://raspberrypi.local.

http://raspberrypi.local

AdafruitWebIDElaunchedforthefirsttime

4. InordertomakeuseoftheexamplesfromAdafruitIndustries,weneedtocreateaBitbucketaccount(itispossibletocreateonewithaGoogleaccount)andintegratetheWebIDEwiththeBitbucketaccount.Theinstructionsforthisareprovidedonthewebpage,asshownintheprecedingscreenshot.

Objectivecomplete–minidebriefingIftheinstallationwassuccessful,aftercompletionoftheregistration,wearedonewiththistask.Let’smoveonandlearntocodeusingtheWebIDE!

PythondevelopmentontheWebIDEInthissection,wewillusea7-segmentLEDbackpackandtheAdafruitCobbleralongwitha26-pinribboncable.WewilltestanexamplefromtheAdafruitrepository(https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code).Inthisproject,thenewadd-onhardwarethatwewilldiscussistheAdafruitCobbler.TheCobblerisasmallboardthataidsprototypingcircuitsonabreadboard.TheAdafruitCobblercostsabout7USDwhiletheribboncablecostsabout3USDandthe7-segmentbackpackcostsabout10USD.

NoteTheearliermentionedproductsaremerelyexamplestodemonstratetheAdafruitWebIDE.Therearealternativeprototypingplatformsandproductsavailableforahigherorlowerprice.

TheCobblermountedonabreadboard

https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code

PrepareforliftoffInordertogetstartedwiththeprototyping,the26-pinribboncableisusedtoconnecttheGPIOinterfacetotheCobbler,asshowninthefollowingimage.Wehavetoensurethatpin1oftheGPIOheadermatchespin1oftheAdafruitCobbler.(TheCobblercomeswithashroudedheader,andhenceitisfoolproof.However,pin1oftheRaspberryPineedstobematchedcorrectly.)

QuickintroductiontotheI2CinterfaceTheI2CinterfacewasinventedbyPhillipsSemiconductors.Itisaformofserialcommunicationinterfaceusedtoconnectmultipleslavedevices(usuallysensors)withamasterdevice(RaspberryPioramicrocontroller)throughacommoninterface.Eachdevicehasauniqueaddressthatisusedbythemastertoreadorwritedata.ThereareplentyofresourcesavailabletofamiliarizeourselveswiththeI2Cinterface.Wewillmoveontothenextstageofconfiguringtheinterface.

ConfiguringtheI2CinterfaceontheRaspberryPiIntheOccidentalisdistribution,theI2Cdriversareinstalledandenabledbydefault.Hence,wecangetstartedbyconnectingtheAdafruit7-segmentbackpacktotheAdafruitCobbler,asshowninthefollowingimage.(ConnectionsbetweentheCobblerandthe7-segmentbackpackareClockpin,SCL(C)-SCL(B)DataPin-SDA(C)-SDA(B),3V3(C)to+(B)GND(C)to-(B),whereCistheCobblerandBisthebackpack):

7-segmentbackpackconnectionsonabreadboard

NowthatwehaveconnectedtheRaspberryPi,theAdafruitCobbler,andthe7-segmentbackpack,let’sgetstartedwiththedetectionofthebackpackontheRaspberryPi’sI2Cinterfaceandprogramanexample.

Beforewegetstartedwiththeexample,weneedtodeterminetheI2Cbustowhichthedeviceisconnectedbyusingthefollowingcommand:

sudoi2cdetect–y0

Thecommandoutputsatablethatcontainsthelistofdevicesforthatparticularbus.Sincetherearenodevicesconnectedtobus0,wescanfordevicesonbus1.Inthisexperiment,wearetestingtheAdafruit7-segmentbackpack.Inthefigurethatfollows,the7-segmentbackpackisconnectedtobus1andthedeviceaddressis0x70.Refertothefollowingscreenshot:

Thei2cdetectoutput

Weshouldchangethebusaddressinthecodetodrivethe7-segmentbackpack.Line11intheAdafruit_I2C.pyfileneedstobechangedinthecodeaccordingtothebustowhichthedeviceisconnected.Hence,line11shouldbe:

def__init__(self,address,bus=smbus.SMBus(1),debug=False):

Engagethrusters1. The7-segmentbackpackisadevicecontrolledviaanI2Cport.AnyI2Cdevicehas

fourpins,namelyclock,data,powersupply,andground.TheI2CdeviceneedstobeconnectedtotheCobbler,asshownintheearlierscreenshot.

2. ThereareseveralexamplesavailablefromAdafruitintheWebIDE.Let’slocatetheex_7segment_clock.pyexample(intheIDE,itislocatedatAdafruit_Raspberry-Pi-Python-Code|ex_7segment_clock.py).Thisisasimpleexampletodisplaythecurrenttimeonthe7-segmentbackpack:

Theex_7segment_clock.pyfilelocationintheWebIDE

3. Let’sdoaquickreviewoftheprogram.WegetstartedbyimportingthedatetimeandAdafruit_7Segmentmodules:

ThesegmentvariableisinitializedasaninstanceofanI2Cdeviceattheaddress0x70.Weenteraninfiniteloopandgetthecurrenttimeusingthedatetimemodule:

now=datetime.datetime.now()hour=now.hourminute=now.minutesecond=now.second

Sincethe7-segmentLEDbackpackconsistsoffourdigits,wewritethecurrenttimeateachpositionasfollowsalongwithacolon:

#Sethourssegment.writeDigit(0,int(hour/10))#Tenssegment.writeDigit(1,hour%10)#Ones#Setminutessegment.writeDigit(3,int(minute/10))#Tenssegment.writeDigit(4,minute%10)#Ones

#Togglecolonsegment.setColon(second%2)#Togglecolonat1Hz#Waitonesecond

Thisexerciseisrepeatedwithaonesecondinterval.

4. TheprogramisexecutedbyclickingonRunfoundintheIDE.Ifourconnectionswereright,weshouldbeabletoseethecurrenttimeonthe7-segmentdisplay(showninthefollowingfigure).

Objectivecomplete–minidebriefingWewereabletotestanAdafruitproductusingtheirWebIDEinthissection.

A7-segmentbackpackconnectedtotheCobbler

TestanddebuggingexamplesusingtheWebIDEInthisexample,wewillconnecttheBlinkMtotheRaspberryPi.ABlinkMisanRGBLEDthatcanbeconnectedtoyourRaspberryPiviatheI2Cinterface.Itispossibletoexecutelightscriptsusingtheport.TheconnectionstotheBlinkMaresimilartothatofthe7-segmentbackpack.

BlinkMconnectedtotheCobbler

NoteItisimportanttopayattentionwhileconnectingdevicestotheGPIOheaderoftheRaspberryPi.IftherearedevicesthatdrawalotofcurrentfromtheGPIOpins,itmayresetthePiorpermanentlydamageitintheeventofashortcircuit.Itisassumedthatyouarefamiliarwithbasicelectronicsandcapableofhandlingsuchdevices.

PrepareforliftoffSimilartothepreviousexperiment,weneedtodeterminethebustowhichthedeviceisconnectedusingthei2cdetectcommand.Asshowninthefollowingscreenshot,thedeviceisconnectedtobus1andthedeviceaddressis0x09:

Blinkmconnectedtobus1

Engagethrusters1. TheBlinkMdatasheet

(thingm.com/fileadmin/thingm/downloads/BlinkM_datasheet.pdf)providesstep-by-stepinformationtoexecutethelightscripts.

2. AlistofscriptsavailableontheBlinkMisshowninthefollowingscreenshot:

AlistofscriptsavailableontheBlinkM

3. Let’sseethecodetoexecutealightscript(forexample,scriptnumber6)ontheBlinkMusingtheAdafruitWebIDEinterface.Inordertoexecuteascriptforever,thedatasheetmentionsthatthefollowingcharactersshouldbewrittenattheI2Cdeviceaddressinthefollowingsequence:'p',,0,0.Let’sdiscusshowtoexecutethisusingaPythonscriptontheRaspberryPiinterfacedwiththeBlinkMLED.ThePythonscriptofthisexampleiscalledPlay_blinkm.py:

http://thingm.com/fileadmin/thingm/downloads/BlinkM_datasheet.pdf

ThePlay_blinkm.pyfilecanbeexecutedbycreatinganewfileintherepositorythatwascreatedwhenyousignedupforaBitbucketaccount.Whenthefileissaved,thechangesaresavedtoyourBitbucketaccount.Thecodeforthisisgivenasfollows:

#!/usr/bin/python#python-smbusimportsmbus#createi2cobjectbus=smbus.SMBus(1)#refertodatasheetforscriptsequence#Playscriptbywriting0x70orponthebusbus.write_byte(0x09,0x70)#playscriptno:6bus.write_byte(0x09,0x06)#playthescriptinfinitelybus.write_byte(0x09,0x00)bus.write_byte(0x09,0x00)

Thefirstlineofthiscodeiscalledshebang.ItindicatesthatthescripthastobeexecutedusingPython.Weneedtoimportpython-smbustoexecutethelightscript:

importsmbus

WeneedtocreateanobjectforI2Ccommunication.Weneedtowritethecontrolscriptviabus1.Thisisdonebythefollowinglineofcode:

bus=smbus.SMBus(1)

Inordertoplayascript(scriptnumber6inthiscase)forever,wewrite'p',,0,0ontheI2Cbusasfollows:

bus.write_byte(0x09,0x70)bus.write_byte(0x09,0x06)bus.write_byte(0x09,0x00)bus.write_byte(0x09,0x00)

4. ThiswouldcausetheBlinkMtoexecutescriptnumber6aslongasthedeviceispoweredanduntilanotherinstructionhasbeenissuedtothedevicethroughtheI2Cinterface.

5. Now,itispossibletodebugourprogrambyexecutingitstepbystep.Thishelpsidentifyanyproblemswiththeprogram.Let’sreviewsomeoptionstodebugaprogram.Wecanlaunchtheprogramfortroubleshooting/debuggingbyclickingonDebug.

TheAdafruitWebIDEtoolbar

Thisopensuptwoconsoles,DebugOutputandDebugVariables(shownin

thefollowingscreenshot).ThewindowDebugOutputprintsanyoutputoftheprogram.Ifweincludedanyprintstatementsinourprogram,theoutputisdisplayedinthiswindow.Thiswindowcanbeusedtoviewanyresults,ensurethataparticularcallbackfunctionwasexecuted,ordeterminewhethertheprogramexecutiongotpastaparticularlineoftheprogram.TheDebugVariableswindowdisplaysthestateofvariablesastheprogramisbeingexecuted.BoththewindowsarehelpfulindeterminingwhetheraPythonscriptwaswrittenasintended.

Debugterminals

WhenwestartdebuggingaPythonscript,thetoolbaratthetoppresentsuswithtwooptions,namelyStepOverandStepIn,asshowninthefollowingscreenshot:

TheAdafruitdebugtoolbar

Inthisexample,itispossibletotesttheexecutionofcommandsbysteppingthrougheachlineofthescript.Thisisreallyusefulwhendevices(forexample,apressuresensor)arenotprovidingtheintendedoutputtoidentifytherootcause.

Objectivecomplete–minidebriefingInthissection,weinterfacedandcontrolledanRGBLEDusinganI2CinterfaceanddiscussedsomeoptionsavailablefordebuggingintheAdafruitWebIDE.

TheAdafruitWebIDEcanconsiderablyreducetheturnaroundtimeforanyprojectdevelopmentactivity.

MissionaccomplishedInthisproject,weworkedontwosimpleexperimentsusingtheI2CinterfaceontheRaspberryPi.ThetwoexamplesdiscussedusingtheAdafruitWebIDEreflectthefactthatthetoolcanhelpsavetimeforanyelectronicsprojectinvolvingaRaspberryPisinceitcomeswithsomeoftheprerequisitesinstalledalongwithawebinterfacethatjustmakesremotedevelopmenteasier.

WehopethatyouhadfuntakingtheOccidentalisdistributionforatestdriveandfinditusefulinyourprojects.

HotshotchallengeInthisproject,weusedtwodifferenttypesofI2Cdevices,thatis,anLEDbackpackandanRGBLED.ItispossibletoconnectmultipleI2Cdevicestothesameinterface.Howcanthisbeachieved?HowcanweidentifytheaddressesoftheseI2Cinterface-enableddevicesandcontrolthem?

Chapter3.TheArduinoRaspberryPiInterfaceInthisproject,wewilllookintointerfacingtheRaspberryPitotheArduinomicrocontrollerdevelopmentplatform.Arduino(www.arduino.cc)isapopularmicrocontrollerplatformthatiswidelyusedtoprototypedifferentprojects.WewilldiscussinstallationoftheArduinodevelopmentenvironmentanddiscussanexampleofitsusage.

RaspberryPiandArduinohavebecomepopularplatformsamonghobbyists,anditisbeingwidelyusedbypeoplefromdifferentbackgrounds,includingschoolanduniversitystudents,artists,andengineers.ThisprojectexplainshowtheRaspberryPicanbeusedincombinationwithArduino.

NoteTheRaspberryPicomeswithaGPIOpinsetthatisquitecapableofinterfacingandcontroldevices.WewouldliketodiscusstheArduinoRaspberryPiinterfacebecauseyoumayhaveprojectsthatwereoriginallybuiltusinganArduino,especiallyinscenarioswherearemotefirmwareupdateneedstobeperformedontheArduinoplatformusingtheRaspberryPi.ThisprojectpresentstheoptionsofenhancingthecapabilitiesoftheArduinomicrocontrollerusingaRaspberryPi.

http://www.arduino.cc

MissionbriefingInthefirstpartoftheproject,wewilldiscussprogrammingtheArduinoforthefirsttime,andinthesecondhalf,wewilllookintothecontrolofaWeasleyweatherclock.WewillalsolookintotheRaspberryPiAlaMode,stackableadd-onarduinohardware(http://wyolum.com/projects/alamode/).

http://wyolum.com/projects/alamode/

Whyisitawesome?ArduinoisanopensourcemicrocontrollerdevelopmentplatformbasedontheAtmelseriesofmicrocontrollers.Ithasbroughtengineers,artists,andstudentstothesametable.Theprogramminginterface(programsarewritteninC/C++usually)issosimpleandthiswasthesolereasonthatmadetheplatformsopopular.Hence,itiswidelyusedforprototypinginproductdevelopment.

Overtheyears,therehavebeenseveralhardwareadd-onsthataidedinhardwaredevelopmentusingtheArduino.Someoftheseadd-onscanbestackedontopoftheArduinodevelopmentplatform,andtheyarecommonlyreferredtoasshields.Thereareshieldsformedicaldevices,interfacingsensors,GPSunits,andactuatorssuchassteppermotors,servomotors,andsoon.TheecosystemofthegadgetsthatarebuiltaroundtheArduinoissovastthatthemicrocontrollerplatformwaslaunchedintothestratospherealongwithaheliumballoon.

WherecanyoubuyanArduino?SincetheArduinoisanopensourcemicrocontrollerboard,therearemanyresellersfortheproduct.ThebasicversionoftheArduinoistheArduinoUnoandcostsabout$29.95.Arduino-relatedproductsaresoldatwebsitessuchasSparkfun,Adafruit,andSeeedStudio.

YourHotshotobjectivesInthisproject,wewilldothefollowing:

InstalltheArduinoIDEProgramtheArduinousingtheRaspberryPiRaspberryPiAlaMode(oranyotherArduinodevelopmentboard)IntroductiontoWeasleyWeatherClockandBillofMaterialsControlthestepperusingtheArduinoControltheRGBLEDStripusingtheArduinoI2CCommunicationusingtheArduino(optional)SerialportcommunicationwiththeRaspberryPi

MissionchecklistWeneedaRaspberryPialongwithanSDcardflashedwiththeRaspbianOS,amicroUSBpowercable,displaysetup,andanArduinotogetstarted.Inthelatersectionofthisproject,wewillneedsomeadditionalhardwaresuchasRGBLEDStrips,motors,wires,andsoon.

InstallingtheArduinoIDEInthissection,wewillinstalltheArduinoIDEontheRaspberryPi.

PrepareforliftoffAnArduinomicrocontrollerdevelopmentplatform(anyvariantthatcouldbeprogrammedusingtheArduinoIDEisfine)isabsolutelyessentialforthissectionoftheproject.

Engagethrusters1. TheIDEcouldbeinstalledbyexecutingthefollowingcommandinthecommand

lineterminal:

sudoapt-getinstallarduino

2. MostArduinoproductscomewithaUSBportandareprogrammedviatheUSBport(theArduinoenumeratesasaserialportdevice).IttakesawhiletodownloadandinstalltheArduinoIDE.Oncetheinstallationisfinished,wecantesttheinstallationbyexecutingthefollowingcommand:

arduino

TheArduinoIDEisshowninthefollowingscreenshot:

TheArduinoIDEinterface

Objectivecomplete–minidebriefingNowthatwehaveinstalledtheArduinoIDE,let’smoveontothenextsectionandrunanexampletestusingtheArduinodevelopmentplatform.

ProgrammingtheArduinousingtheRaspberryPiWewillintroduceourselvestotheArduinoIDEwithanLEDblinkingexample.

PrepareforliftoffThereareseveralexamplesfortheArduinoandittakeslessthanaminutetoexecutethefirstprogram.Let’sgetstartedwiththetraditionalLEDblinkingexample.TheLEDblinkingexamplecanbefoundatFile|Examples|01.Basics|Blink.

Engagethrusters1. WegetstartedbyidentifyingtheArduino’sserialportenumeratedontheRaspberry

Pi.2. TheserialportisidentifiedfromTools|SerialPort.Usuallythereisonlyoneserial

portasshowninthefollowingscreenshot.Ifthereismorethanoneserialportdeviceconnected,itisrecommendedthatyouproceedwithcaution.

3. WecanprogramtheArduinobyclickingontheUploadbutton.

TheArduinoIDEinterface

Objectivecomplete–minidebriefingIftheArduinoisconnectedandtheserialportwascorrectlyidentified,theprogramshouldbeuploadedsuccessfully.

SketchuploadedusingtheArduinoIDE

MostArduinoproductscomewithanonboardLEDtotesttheLEDblinkingexample.

RaspberryPiAlaModeInthissection,wewillbrieflydiscusstheRaspberryPiAlaMode’sfeaturesanditssetup.RaspberryPiAlaMode(asshowninthefollowingfigure)isastackableArduinodevelopmentplatformdevelopedspecificallyfortheRaspberryPi.Theboard,whichisreleasedasopensourcehardware,ispricedatabout$45andalsoincludesareal-timeclockandamicroSDcardslotfordatalogging.

RaspberryPiAlaModemodestackedontheRaspberryPi

PrepareforliftoffTheattractivefeatureoftheboardisthatitcouldbeprogrammedviatheRaspberryPi’sUARTpinsandhenceeliminatestheneedforaUSBport.TheboardcouldbeeitherpoweredviatheRaspberryPiorthroughtheMicroBUSBportusingawallwarttransformer.Theproduct’swebpage,http://wyolum.com/projects/alamode/alamode-getting-started/,offersasinglestepprocesstostartusingtheboard.

NoteTheRaspberryPiAlaModemodeisjustoneexampleofthestackableArduinohardware.ThereareprobablyothersimilarstackableArduinohardwareavailableinthemarket.Forexample,https://www.kickstarter.com/projects/raspitv/raspio-duino-affordable-arduino-programming-on-ras.

http://wyolum.com/projects/alamode/alamode-getting-started/https://www.kickstarter.com/projects/raspitv/raspio-duino-affordable-arduino-programming-on-ras

Engagethrusters1. Oncethearchiveisdownloadedfromtheirwebpage,weextractthecontents:

tar–xvzfalamode-setup.tar.gz

2. Oncethefilesareextracted,thesetupisasfollows:

sudo./setup

3. Aftertheinstallationiscomplete,theRaspberryPialamode’sserialportisenumeratedas/dev/ttyS0.

Objectivecomplete–minidebriefingAftertheinstallationiscomplete,weshouldhavetheRaspberryPiAlaModemodeenumeratedandbereadytostartprogrammingthehardwareadd-onboard.

TheWeasleyweatherclockWewillbuildaWeasleyweatherclockinthisprojectusinganArduinomicrocontrollerboardandtheRaspberryPi.TheWeasleyWeatherclockisinspiredbytheWeasleyclockseenintheHarryPotterseriesofmovies.AWeasleyclockisusedtoidentifythecurrentlocationofafamilymemberoftheWeasleys(forexample,work,school,andsoon)andalsothesafetyofthefamilymember.Mrs.MollyWeasley(thematriarchoftheWeasleys)usedtheWeasleyclocktokeeptabsonherfamilyandthisclockhashaditsvariantsovertheyears.Thisprojecthappenstobeoneofthem!

TheWeasleyweatherclockisonethatdisplaysthecurrentoutdoortemperatureandtheforecast.Italsowarnsusaboutimpendingdangersduetoconditionssuchastornadoes,blizzards,andsoon.

AWeasleyweatherclockbuiltusingtheArduinoandtheRaspberryPi

PrepareforliftoffThefollowingitems(alongwiththeirapproximatecost)arerequiredtobuildourWeasleyclock:

Item Price

RaspberryPimodelB*1 US$35

ArduinoUno/RaspberryPiAlaModemode(http://wyolum.com/projects/alamode/)*1 US$30/45

AcrylicSheet24inchesx20inches*0.093inchthick*1 US$10

Woodsheet1ftx1/2ftx0.25inchthick*1 US$5

5VDCSteppermotorfromAdafruit*1(http://www.adafruit.com/product/858) US$5

RGBLEDStrip1m*1(analogones(http://www.adafruit.com/products/1004)) US$15

NPNtransistors*2(BC547orNP2222) US$1

PowerDarlingtonStepperDriver(ULN2003A) US$2

Cablesforconnection US$4

7-SegmentBackpack(http://www.adafruit.com/product/879) US$10

A8x8LEDMatrixbackpack(optional(http://www.adafruit.com/product/871)) US$10

BlinkM(optional) US$13

12V,1ADCwalltransformer(optional(https://www.sparkfun.com/products/8579)) US$8

Totalcost US$122approx.

http://wyolum.com/projects/alamode/http://www.adafruit.com/product/858http://www.adafruit.com/products/1004http://www.adafruit.com/product/879http://www.adafruit.com/product/871https://www.sparkfun.com/products/8579

Engagethrusters1. TheWeasleyclockcouldbeeasilyassembledwithpartsmachinedwithalasercutter.

Lasercuttingisaprocesswherepartsaremachined/engraved/cutusingahigh-powerlaserbeaminacontrolledenvironment.Thelasercutteriswidelyusedforprototypingpurposes.Thedesignfilesforlasercuttingareavailablealongwiththisbookcodebundle.Inthisexample,thedialoftheweatherclockiscutfromtheacrylicandthedesignincludesmountingholesfortheclockaswellasthesteppermotor.Theweatherkeywordsareengravedandmachinedusingwoodsheets.Theassemblyofthekeywordsandthedialareshowninthefollowingfigure:

PartialassemblyoftheWeasleyClock

Objectivecomplete–minidebriefingTheassemblyshownintheimageissufficienttotestthisexample.Youcanaddmorefeaturestothedesign.Forexample,youcanaddslotsontheacrylicboardtoembeda7-Segmentdisplay,8x8LEDmatrix,oraBlinkMRGBLEDtothedesign.

Inthisexample,theArduinoisthelow-levelcontroller,whichdrivestheRGBLEDstrip,steppermotor,andsoon,whiletheweatherdataisobtainedfromtheInternetusingtheRaspberryPi.WewilldiscusstheArduinocodeinthefirstpartofourtask.

FlowofdataandcontrolinthisWeasleyClockproject

ControllingthestepperusingtheArduinoThepartnumberofthesteppermotorusedinthisexampleis28BJY-48(http://www.adafruit.com/product/858).Asteppermotorisatypeofmotorthatisoperatedbyenergizingitscoilsinseveralsteps.Thecoilenergizationinseveralstepsenablesthesteppertorotateinpreciseangularsteps.Thisprecisemovementaidstheuseofasteppermotorinopenloopsystems.Sincetheworkingprincipleofasteppermotorisbeyondthescopeofthebook,let’sdiscussitscontroltechnique.

http://www.adafruit.com/product/858

PrepareforliftoffThesteppermotorispoweredbyacommonleadconnectedtothepowersupplyandtheotherendisconnectedtoatransistor.Sincetransistorscanbeusedasswitches,theleadsofthecoilcanbegroundedalternatively.Thisalternativesequencecausesthesteppermotortorotateandthespeedofrotationiscontrolledbyintroducingadelayinbetweenthecoilenergization.Theminimumdelayrequiredbetweeneachenergizationsteptomakethestepperrotateproperlyandavoidmissstepsis2milliseconds.Thisisduetothedesignlimitationsofthesteppermotor.

Thefollowingtableshowsthecoilenergizationsequenceforthesteppermotorinaclockwisedirection(borrowedfromthedatasheet).Theenergizationsequenceshownherewouldmakethestepperrotateinahalfstepperactuation,thatis,thestepperwouldrotate2.8125degreesforeveryactuationsequence.

NoteItisassumedthatyouarefamiliarwithsteppermotorsandtheircontroltheory.

Asteppermotorenergizationsequencefrom28BJY-48’sdatasheet

Engagethrusters1. Eachcolumnintheprecedingdiagramindicatestheleadthatneedstobeenergizedto

rotateasinglestep.2. Forexample,inthecaseofclockwiserotation,Lead4isenergizedandallotherleads

areturnedoff.Thedatasheetexplainsthatthesteppermotorrotatesapproximately5.625degreesperstep.

3. Hence,64actuationstepsarerequired(64*5.626=360degrees)tomakeonecompleterotation.Thesteppermotorisinterfacedtoagearboxof1:64ratio,andeachrotationtakesabout4096steps.

4. Let’sreviewthecoderequiredfortheenergizationsequence(codeborrowedfromtheArduinoforumshttp://forum.arduino.cc/index.php?topic=85335.0):

//Step1digitalWrite(motorPin4,HIGH);digitalWrite(motorPin3,LOW);digitalWrite(motorPin2,LOW);digitalWrite(motorPin1,LOW);delay(motorSpeed);//Step2digitalWrite(motorPin4,HIGH);digitalWrite(motorPin3,HIGH);digitalWrite(motorPin2,LOW);digitalWrite(motorPin1,LOW);delay(motorSpeed);//Step3digitalWrite(motorPin4,LOW);digitalWrite(motorPin3,HIGH);digitalWrite(motorPin2,LOW);digitalWrite(motorPin1,LOW);delay(motorSpeed);//Step4digitalWrite(motorPin4,LOW);digitalWrite(motorPin3,HIGH);digitalWrite(motorPin2,HIGH);digitalWrite(motorPin1,LOW);delay(motorSpeed);//Step5digitalWrite(motorPin4,LOW);digitalWrite(motorPin3,LOW);digitalWrite(motorPin2,HIGH);digitalWrite(motorPin1,LOW);delay(motorSpeed);//Step6digitalWrite(motorPin4,LOW);digitalWrite(motorPin3,LOW);digitalWrite(motorPin2,HIGH);digitalWrite(motorPin1,HIGH);delay(motorSpeed);//Step7digitalWrite(motorPin4,LOW);digitalWrite(motorPin3,LOW);digitalWrite(motorPin2,LOW);

http://forum.arduino.cc/index.php?topic=85335.0

digitalWrite(motorPin1,HIGH);delay(motorSpeed);//Step8digitalWrite(motorPin4,HIGH);digitalWrite(motorPin3,LOW);digitalWrite(motorPin2,LOW);digitalWrite(motorPin1,HIGH);delay(motorSpeed);}

5. Let’sdiscussthefirststepinthesteppermotorenergizationsequence:

//Step1digitalWrite(motorPin4,HIGH);digitalWrite(motorPin3,LOW);digitalWrite(motorPin2,LOW);digitalWrite(motorPin1,LOW);delay(motorSpeed);

6. Intheprecedinglinesofcode,themotorPin4pinissettoHigh,whiletheotherpinsaresettoLow.Asshowninthefollowingfigure,thepinsmotorPin1throughmotorPin4areconnectedtoapowerDarlingtoncircuit.YoucanfindareferencetothePowerDarlingtoncircuitathttps://coefs.uncc.edu/dlsharer/files/2012/04/F5.pdf.

AnArduinosteppermotorinterface

7. Whenmotorpin4(theD11pinoftheArduinoisconnectedtothebasepinofthepowerDarlingtonpair)issettohigh,thetransistor(whichactsaswitch)connectstheorangeleadtothegroundandenergizesthecoilandtherebythesteppermovesbyasinglestep.

8. Similarly,thesteppermotor’scoilsareenergizedinthesequenceshowninthetable.Forexample,instep2,thecoils4and3areenergizedbysettingmotorPin4andmotorPin3toHighandotherpinstoLow.

Counterclockwiserotationofthesteppermotor

https://coefs.uncc.edu/dlsharer/files/2012/04/F5.pdf

1. Thecounterclockwiserotationisachievedbyreversingtheorderofenergization.Inthefirststep,Lead1isenergized,whichisfollowedbyLeads1and2.Thetableforcounterclockwiserotationisshownasfollows:

LeadWireColorCCWDirection

1 2 3 4 5 6 7 8

1BLU - -

2PIK - - -

3YEL - - -

4ORG - - -

2. Hence,thecodeforthefirststepwillbeasfollows:

digitalWrite(motorPin1,HIGH);digitalWrite(motorPin2,LOW);digitalWrite(motorPin3,LOW);digitalWrite(motorPin4,LOW);delay(motorSpeed);

Objectivecomplete–minidebriefingNoteIfyouarenotfamiliarwithsteppermotorsandtheircontroltechniques,thereareabundantresourcesandonesuchresourceishttp://www.societyofrobots.com/member_tutorials/node/314.

WediscussedthesteppermotorcontroltechniqueusingtheArduinomicrocontroller.Oncewehavediscussedtheprerequisites,wewilltakethiscodesampleandbuildthingsaroundit.

http://www.societyofrobots.com/member_tutorials/node/314

ControllingtheRGBLEDStripusingtheArduinoWedepictthemoodoftheweatherforecastbyusingRGBLEDlighting.Weindicatecoldweatherindicationswithbluecolorlighting,fairweatherconditionswithgreenlighting,andwarm/dangerousweatherconditionsusingredlighting.Inthissection,wewilllookintocontrollinganRGBLEDusingtheArduino.

TheRGBLEDstripsoldbyAdafruitindustries(http://www.adafruit.com/products/1004)consumesabout60mApersegment.ItisbestrecommendedtodrivetheRGBLEDstripusingatransistorswitchingcircuit.Weneedtousethreetransistorsforthethreecolorsanditispossibletocontroleachcolorindividuallyanditisalsopossibletoobtainacombinationofcolours.

NoteItispossibletoproduceasecondarycolorusingtheRGBcombinations.ThiscanbeachievedbyturningontheRGBsegmentsatthesametimeandvaryingthebrightnessoftheprimarycolors.TherearevastresourcesavailableforsuchtipsandtricksontheInternetandanexplanationofthisisbeyondthescopeofthisbook.

http://www.adafruit.com/products/1004

PrepareforliftoffTheAdafruitlearningwebsiteprovidesexamplesforcontrollingtheRGBLEDusingapulsewidthmodulationtechnique.TheschematicfortheAnalogRGBstripisshowninthefollowingdiagram:

RGBLEDstripschematic(borrowedfromAdafruit)

SincetheRGBstriprequires12V,wemustuseatransistorswitchingcircuittocontroltheLEDs.ThetransistorswitchingcircuitforcontrollingtheRed,Green,andBluechannelsoftheLEDstripisshowninthefollowingdiagram:

TheArduinoRGBswitchingcircuit

TheRGBchannelsareconnectedtotheNPNtransistorsthatactasswitches.ThebaseofthetransistorisconnectedtothePWM(PulseWidthModulation)outputoftheArduino.ThisenablesyoutoadjustthebrightnessoftheRGBchannels,andconsequently,producedifferentcolors.

Engagethrusters1. AdafruithasprovidedanexampleforadjustingthebrightnessoftheLEDsand

producingdifferentcolorsfromthecombinationofprimarycolors.Let’sconsiderthefollowingpieceofcode:

//fadefrombluetovioletfor(r=0;r<256;r++){analogWrite(REDPIN,r);delay(FADESPEED);}//fadefromviolettoredfor(b=255;b>0;b--){analogWrite(BLUEPIN,b);delay(FADESPEED);}

2. Inthiscode,thered,greenandbluesegmentsoftheRGBLEDstripareconnectedtotheD3,D5,andD6oftheArduino,respectively.

ThevaluewrittentothepinsusingtheanalogWritefunctionsetsthebrightnessvalueofeachcolor.TheanalogWritefunctionvariesthedutycycleofthePWMchannelandacceptsvaluesbetween0and255.Thevalue0indicatesa0percentdutycycleand255indicatesa100percentdutycycle.ThedutycycledeterminesthecurrentthatflowsthroughtheLED,andinturn,controlsthebrightnessandcolor.

Objectivecomplete–minidebriefingWediscussedadjustingthebrightnessoftheRGBLEDstripusingthePulseWidthModulationTechniqueandanArduinomicrocontroller-baseddevelopmentplatform.

I2CCommunicationusingtheArduino(optional)Inthisproject,thereisa7-Segmentdisplay,8x8LEDmatrix,proximitysensor(todeterminethehomeposition),andaBlinkMRGBLEDthatcommunicatesviatheI2Cinterface.Wewilldiscusstheapplicationofeachcomponentinthisproject.

PrepareforliftoffThemainrequirementforthissectionisthenecessaryI2Cdevicerequiredtointerfacewiththeweatherclock.

EngagethrustersLetusreviewaboutthe7-Segmentdisplay.

tentacle.netprophet/raspberrypi/Raspberry...Table of Contents Raspberry Pi Mechatronics Projects...

Documents

Transcript of tentacle.netprophet/raspberrypi/Raspberry...Table of Contents Raspberry Pi Mechatronics Projects...

STANDARDS FOR INTERAGENCY HOTSHOT … Standards for Interagency Hotshot Crew Operations provides the ... in accordance with the Standards for Interagency Hotshot Crew ... Squad Leader

Power Ground Control GPIO Raspberry Pi Zero v1.3 Raspberry ...

Hotshot 102

Hotshot Magazine | Fall 2014

Developer Study Guide - How to Deploy BlueZ on a Raspberry ... · • Raspberry Pi 2B • Raspberry Pi 3B • Raspberry Pi 3B+ • Raspberry Pi 4B If you have one of above-verified

Programming the Raspberry Pi - tentacle.netprophet/raspberrypi/Raspberry Pi/0071807837 {F30082C2... · When Raspberry Pi boots up, you get the Linux desktop shown in Figure 1-2. This

Raspberry Pi Mechatronics Projects HOTSHOT - … Related/PDFs and Books...Operating systems on the Raspberry Pi Getting started with Raspbian Downloading Raspbian Flashing image on

StandardS For Interagency HotSHot crew operatIonS

Setting up your Raspberry Pi | Raspberry Pi Projects2/13/2019 Setting up your Raspberry Pi | Raspberry Pi Projects 2/18

Raspberry Pi - Lecture 5 Python for Raspberry Pi

WHAT IS THE BEST RASPBERRY KETONE SUPPLEMEN T?. Which produces better weight loss results: Raspberry Ketone Plus, Raspberry Ketone Pure, or Raspberry.

Motion Imaging Corporation introduces the HotShot e64 · manufacturing, research, design & test, production and veterinary / human biomechanics analysis, to name a few. The HotShot

TIF Labs Private Limited · RASPBERRY PI Raspberry Pi Pico - Latest Raspberry Pi Raspberry Pi Pico with Headers and Micro USB Cable Raspberry Pi 400 Official Kit Raspberry Pi 4 Model

Raspberry Pi - Lecture 6 Working on Raspberry Pi

Raspberry Pi Compute Module (CM1) Raspberry Pi Compute ...

E T RASPBERRY PI3-MOD B + SD8G * 1,330.- RASPBERRY-MOD … Pi 3.pdf · Raspberry Pi 3 Raspberry Pi 3 Raspberry Pi PRODUCT CATALOG 2018 1 Electronics Technology Team RASPBERRY-MOD

HotShot LS 2100 - BarcodesInc · HotShot ™ LS 2100 Excellent Performance and Superior Ergonomics at an Affordable Price The ergonomically designed HotShot LS 2100 Series of scanners

Raspberry pi projects: 1079 raspberry-pi projects

HSITriFoldOutside2015 - Hotshot Imaging

From Hotshot to the Top- Sandra Hoskins