HomeAutomationWithArduinoAutomateYourHomeUsingOpen-SourceHardware

MarcoSchwartz,PhD

ContentsLegalAcknowledgmentsAbouttheauthorAboutthecompanionwebsitePrefacetotheFirstEditionPrefacetotheThirdEditionIntroduction

1 HowistheBookOrganized?2 WhyOpen-Source?3 Whatwillyoulearn?4 Safetyconcerns5 Prerequisites

Chapter1 GettingStarted1.1 TheArduinoPlatform1.2 WhatyouNeedtoKnowAboutElectronics1.3 YourVeryFirstProject:aSimpleAlarmSystem

Chapter2 BuildingaWeatherMeasurementStation2.1 Hardware&SoftwareRequirements2.2 HardwareConfiguration2.3 TestingtheSensors2.4 DisplayingtheDataontheLCDScreen2.5 HowtoGoFurther

Chapter3 BuildingaSmartLamp3.1 Hardware&SoftwareRequirements3.2 HardwareConfiguration3.3 TestingtheRelay3.4 PowerMeasurements&AutomaticLightingControl3.5 HowtoGoFurther

Chapter4 XBeeMotionSensors4.1 Hardware&SoftwareRequirements4.2 BuildinganXBeeMotionSensor4.3 TestingtheMotionSensor4.4 UsingtheXBeeModule4.5 BuildingtheCentralInterface4.6 HowtoGoFurther

Chapter5 BluetoothWeatherStation5.1 Hardware&SoftwareRequirements5.2 BuildingtheBluetoothWeatherStation5.3 PairingtheBluetoothModule5.4 RemoteTemperatureMeasurements5.5 BuildingtheServerInterface5.6 HowtoGoFurther

Chapter6 ControllingLampsviaWiFi6.1 Hardware&SoftwareRequirements6.2 BuildingtheProject6.3 TestingtheWiFiModule6.4 RemoteLampControl6.5 BuildingtheSmartLampInterface6.6 HowtoGoFurther

Chapter7 BuildinganHomeAutomationSystem7.1 Hardware&SoftwareRequirements7.2 BuildingtheProject7.3 TestingtheModules7.4 BuildingtheCentralInterface7.5 HowtoGoFurther

Chapter8 Conclusion8.1 Whatdidyoulearninthisbook?8.2 Howtogofurther?

Chapter9 Resources9.1 GeneralInformationaboutArduino9.2 Components9.3 SuggestedReading

LegalCopyright2014byMarc-OlivierSchwartz

Allrightsreserved. Nopartofthisbookmaybeusedorreproducedinanymannerwhatsoeverwithoutpermissionexceptinthecaseofbriefquotationsembodiedincriticalarticlesorreviews.

ThirdeBookedition:August2014

AcknowledgmentsToallmyfriendswhoencouragedmewhilewritingthisbookandworkingonallmyprojects.

Tomyparentswhosupportedmewhilewritingthisbook,andwhosupportedmeduringalltheotherprojectsImadeinmylife,evenintoughtimes.

TomygirlfriendSylwiaforsupportingmeandencouragingmeineverythingIdo. YouaremysourceofinspirationIneedtogetupeverydayandcontinuetoworkhardtobecomeabetterentrepreneurandabetterperson. Thankyou.

AbouttheauthorIamMarcoSchwartz,andIamanelectricalengineer,entrepreneurandauthor. IhaveaMastersdegreeinElectricalEngineering&ComputerSciencefromoneofthetopElectricalEngineeringschoolinFrance,andaMastersdegreeinMicroEngineeringfromtheEPFLuniversityinSwitzerland.

Ihavemorethan5yearsofexperienceworkinginthedomainofelectricalengineering.Myinterestsgravitatearoundelectronics,homeautomation,theArduinoplatform,open-sourcehardwareprojects,and3Dprinting.

Since2011Ihavebeenworkingfull-timeasanentrepreneur,runningwebsiteswithinformationaboutopen-sourcehardwareandbuildingmyownopen-sourcehardwareproducts.

AboutthecompanionwebsiteThisbookhasacompanionwebsite,OpenHomeAutomation,whichyoucaneasilyfindbygoingathttp://www.openhomeautomation.net. Onthiswebsiteyouwillfindevenmoreprojectsandresourcesaroundhomeautomationandopen-sourcehardware.

Allthecodethatcanbefoundinthisbookcanalsobeaccessedonlineathttps://github.com/openhomeautomation/home-automation-arduino. ThisGitHubrepositoryforthebookcontainsallthelatestup-to-datecodeforalltheprojectsyouwillfindinthisbook.

PrefacetotheFirstEditionIwasintroducedtothefascinatingworldofhomeautomationwhileIwasvisitingthehomeofoneofmyrichfriends. Iwassurprisedbyhoweasyitallseemed:lightswouldactivatethemselvesautomaticallywhenitwasstartingtogetdark,temperatureswereautomaticallymeasuredineveryroomofthehouseandsenttoacentralserver,andthestatusofeveryalarmsensorofthehousecouldbemonitoredfromacellphone. Buttheproblematthattimewashuge:thesolutionsweretailoredforthathousebyprivatecompanies,andthereforeitwasreservedonlytowealthypeople. Andthisisstillanideathatisaroundnowadays:homeautomationcostsalot.

Ipersonallyhaveanotherproblemwithsuchsystems:youdonthaveanycontrolofthem.Youhavetofolloweverythingthemanufacturerhasdecidedforyou:themaincontroller,thesensors,thesoftware. Forexample,ifonesensorisfailinginyoursystem,youhavetoreplaceitwithasensorfromthesamebrand. IrememberwhenIwasusingoneofthesecommercialsystemsatafriendshouse. Ialwayswantedtochangesomething:makeasensoreasiertouse,fixabugintheinterfacebutIcouldnt.

Ofcourse,theideaofbuildingyourownhomeautomationsystemhasalwaysbeenaround. Irememberplayingwithmyfirstmicrocontrollerin2003,anditwasactuallyquiteeasyifyouwereintheengineeringworld. Thesesystemswerequiteclosed,andeachofthemrequiredlearningspecificknowledgeabouttheplatform. Andevaluationkitsforthesemicrocontrollersalsousedtocostalot.

However,thepastfewyearssawtheriseofanewmovement:open-sourcehardware. Asforopen-sourcesoftware,thismeanthathardwaredesignsstartedtobefreelyavailableandcustomizablebyeverybody. Andattheheartofthisopen-sourcehardwaremovement,aplatformwasbornthathadahugeimpactintheworldofelectronics:theArduinoplatform. Arduinoisaniceandfriendlyenvironmentinwhichtoeasilyprogrammicrocontrollers.

Andforme,thischangedeverythingwhenitcomestohomeautomation. Nowitispossiblefornearlyeverybodywithsomeelectronicsandprogrammingexperiencetomaketheirownhomeautomationsystems. Andthisispreciselywhatyouwilllearninthisbook.

PrefacetotheThirdEditionSincethefirstedition,thousandsofpeoplehaveusedtheprinciplespresentedheretobuildtheirownhomeautomationsystems. Ihavealsoreceivedalotofconstructivefeedbackthatallowedmetoimprovethebookandcomeupwithasecondedition.

However,alotofthesecommentsthatIreceivedonthefirsttwoeditionsofthebookalsoconcernedtherelativedifficultyoftheprojectsthatwerepresented. Itwaslessaboutthecontentoftheprojectsthemselves,andmoreaboutthenumberofprogramminglanguagesusedinsomeoftheprojects. Forexample,intheprojectsincludingcommunicationsbetweentheArduinoboardandyourcomputer,IusedacombinationofPython,PHP,HTMLandJavaScript. Youalsohadtoinstallandrunawebserveronyourcomputer,whichaddedanotherlayerofcomplexity.

Thiswhyforthisthirdeditionofthebook,Iputtheemphasisonsimplifyingthings. First,Iseparatedthebookintotwoparts. Thefirstpartisaboutbuildingself-containedhomeautomationsystems,withnolinkatallwithacomputeroranotherdevice. Therefore,theseprojectsonlyusetheArduinoprogramminglanguage.

Thesecondpartofthebookuseswhatyouwilllearninthefirstpart,byaddingwirelessmodulestothehomeautomationprojects. Andtobuildtheinterfaceonyourcomputer,Ionlyusedonelanguage:JavaScript. IcompletelyremovedtheneedforotherlanguageslikePythonorPHP.Also,IusedNode.JS,whichallowstoprograminJavaScriptontheserverside. Thisalsoeliminatestheneedtoinstallawebserveronyourcomputer.

Ihopethatyouwilllikethenewpresentationofthebook,andthatyouwillusewhatyouwilllearninthisbooktobuildevenmoreexcitinghomeautomationprojectswithArduino.

Introduction

1 HowistheBookOrganized?

Thisbookisdividedintwomainparts. Thefirstpartofthebookisdedicatedtobuildingself-containedhomeautomationsystemsthatworksontheirown. Forexample,thefirstsystemthatwearegoingtobuildisasimplealarmsystemwithamotionsensor.

Thesecondpartofthebookwillbemoreadvanced,aswearegoingtointerfacehomeautomationprojectswirelesslywithyourcomputer. Forexample,wearegoingtobuildagraphicalinterfacetocontrolalampviaWiFi.

Theentirebookisorganizedaroundprojectsonaspecifictopic,inwhichyouwilllearnaspecificsetofnewskills. Ithinkthisisdefinitelybetterthanaonefits-allsolutionwhereIwouldhavetaughtyouhowtobuildaspecifichomeautomationsystem. Withsmallerprojects,youwilllearnmuchmoreandmuchfaster,andevenmoreimportantlyyouwillhavethesetoftoolstobuildyourownsystemthatistailoredtoyourownhome.Thegoalofthisbookisreallytoinitiateyoutotheworldofhomeautomationusingopen-sourcehardwareandtoshowyouwhatispossible.

Eachchapterwillstartwithverybasicconsiderationsandprojects,andthenwewillbuildontopofthemtoarriveatmorecomplexhomeautomationprojects. Ineverychapterofthebook,youwillfindsectionsthatareorganizedasmini-projects. Inproject,youwillfindalistofwhatyouwillactuallylearnbydoingthistutorial,whathardwareyouwillneed,andastep-by-stepguideonhowtodoit,alongwithscreenshotsandpicturestoguideyoubetterthroughtheprojects.

Asanaid,therewillbelinkstowebsitesforreferencepurposes. Thesearetohelpyoufindhardwarecomponents,andnotethatIhavenocommercialcontractwiththewebsitesthatImentionintheselinks. Also,ineveryprojectIgivesomeadvicetouseequivalentcomponentstotheonesIused,incaseyoualreadyhavesomecomponentsonyourdesk.

Allchaptersincludeadetailedwalkthroughofthecodeusedtobuildthedifferentprojectsinthisbook. Inthesewalkthroughs,Idetailthemostimportantpartssothatyoucanunderstandhoweachhomeautomationprojectworks. However,becauseinsomeprojectsofthisbookthecodeisreallylong,Iwillonlygothroughthemostimportantpiecesofthecode.

Therefore,itisrecommendedthereaderalwaysrefertotheGitHubrepositoryofthisbooktogetthecompletecode. YouwillfindthelinktotheGitHubrepositoryineverychapterofthisbook,orifyouwanttohavealookrightnow,thelinkis:

https://github.com/openhomeautomation/home-automation-arduino

Notethatallchaptersweredesignedtobecompletelyindependentfromeachother,soyoucanstartwithwhateverchapteryoulikeinthebookwithoutbeinglost. However,especiallyifyouareabeginner,itishighlyrecommendedtofollowthechaptersofthisbookinorderfromthestart.

InChapter1,youwilllearnaboutwhattheArduinoplatformreallyis,andwhyitissuchagreatopportunityforhomeautomationsystems. ThechapterwillstartwithageneralintroductiontotheArduinoplatform,andwewilldiveintothethemeofthebookwithafirsthomeautomationproject.

Afterthat,inChapter2,youwillperformyourfirstmeasurementsusingtheopen-sourcehardwareplatformArduino,andyouwilllearnhowtovisualizedataonaLCDscreen.

InChapter3,wewillcontinueourjourneyintohomeautomationsystems. WearegoingtobuildasmartlampwithArduino,thatautomaticallyswitchesonoroffaccordingtotheambientlightlevels.

Chapter4willintroducethesecondpartofthisbook,inwhichwewillbuildwirelesshomeautomationsystems. Forourfirstwirelessproject,wearegoingtobuildXBeemotionsensorsandmanagethemfromyourcomputer.

InChapter5,wearegoingtouseanotherwirelesstechnologywhichisusedinhomeautomation:Bluetooth. Wewillinterfaceatemperature&humiditysensortoArduino,andmeasuredataremotely. Wewillalsobuildaninterfaceonyourcomputertodisplaythedata.

InChapter6,IwillshowyouhowcontrolalampusingWiFi. Notonlywillyoubeabletocontrolthislampfromyourcomputer,butalsofromanydeviceconnectedtoyourlocalWiFinetwork.

Finally,inChapter7,wewillseehowtouseeverythingyouhavelearnedinthisbooktobuildasmallhomeautomationsystemcomposedofmanyelements,allcommunicatingwithacentralinterface.

2 WhyOpen-Source?

Alltheprojectsyouwillfindinsidethebook(andonthecompanionwebsite)arecompletelyopen-source,forbothhardwareandsoftware. Sowhatexactlydoesthismean? Whataretheadvantages? Andwhymakeitanessentialpartofthebook?

Well,letmefirstsayafewwordsabouttheopen-sourcehardwaremovement. Open-sourcesoftwarehasbeenaroundforquiteawhilealready,withtheLinuxoperatingsystemanditsentireecosystem,butopen-sourcehardwareismuchmorerecent. Sohowcanhardwarealsobeopen-source? Well,therearemanyopen-sourcehardwarelicenses,butitbasicallymeansthatwithanopen-sourcehardwaresystem,alltheschematicsandPCBdesignfilescanbefreelyaccessedandmodifiedbyanybody,asyouwoulddownloadandmodifyopen-sourcesoftware. Open-sourcehardwareactuallygoesfurtherthanjustopen-sourceelectronics,asitalsoconcernsopen-sourcedesignsfor3Dprintingforexample,butthisissomethingwewonttouchinthisbook.

Thereareseveraladvantagesofthisopen-sourceapproachforhardwaresystems. Thefirstoneisthatitallowspeopletohavealookintothehardwaresystemsthemselves,andunderstandwhythehardwaresystemtheyareusingisworkingalongwiththeopen-sourcesoftwarethatusuallycomeswithit. Butthemainadvantageformeisthatitallowspeopletomodifythehardwaresystemsandthensharethemagainwiththecommunity. Thisproducesamuchfasterdevelopmentprocessforhardwareproductsasitreallyengagestheusersandcreatescommunitiesaroundagivenhardwareproduct.

AndthisispreciselywhyIputopen-sourceatthecoreofthisbookandofthecompanionwebsite:becauseyoucanaccessthesourcesofalltheprojectsfoundinthisbook,youwillbeabletounderstandthemdeeply,modifythem,makethembetter,andthensharethemagainwiththecommunity. WhatIreallydidntwantwastospeakabouthomeautomationbyjustpreachingmyownvision;Iwanttoengageyouasmuchaspossibletogobeyondthisbookandmakeyourownsystemswithwhatyouaregoingtolearninthebook.

3 Whatwillyoulearn?

Beforedivingintotheheartofthisbook,andbuildingyourfirsthomeautomationproject,Iwantedtospendafewmomentstoexplainwhatisyouwillactuallylearninthisbook.

Ofcourse,youwilllearnabouthomeautomation. Youwilllearnhowmostcommonhomeautomationsystemsworkbybuildingyourownsystem,forexamplesimplymeasuringthetemperatureinyourhomeanddisplayingitonyourcomputer. Youwillalsolearnaboutthebasicsofalarmsystems,andhowtocontrolthelightsinyourhomesotheycanadapttoyourcommandsortotheambientluminosity.

Butyouwilllearnmorethanthat. YouwilllearnaboutwhatIconsidertobeoneofthemostimportantplatformsatthemomentwhenitcomestodo-it-yourselfelectronicsprojects:theArduinoplatform. Whatyouwilllearnaboutthisplatformcanthenbeusedagaininmanyotherprojects.

Youwillalsolearnaboutelectronicsingeneral. Fromthemostbasicthing,likehowtoconnectamotionsensortotheArduinoboard,tohowtoconnectadigitalsensor,wewillcoveralotinthedomainofelectronics,andtheknowledgeyouwillacquirecanalsobeusedinseveraldomainsoutsideofhomeautomation.

Finally,youwillalsolearnaboutsoftwaredevelopment. WewillfirstprogramtheArduinoboardusingtheArduinoIDE,whichisbasedonC/C++. IwillalsointroduceabitofHTMLandJavascripttomakeremotemeasurementspossible,andtocontrolhomeautomationsystemsfromyourcomputer. Sowithalltheswitchingbetweenprojectsandlanguages,youwillalsoacquireasolidbackgroundinsoftwaredevelopment.

4 Safetyconcerns

Mostoftheprojectsyouwillfindinthisbookuselow-voltagedevices,whicharecompletelyharmless. However,becauseinagoodhomeautomationsystemwewanttocommandsome110or230Vdeviceslikelamps,someprojectswillmakeuseofsuchvoltagesourcesandcanbedangerousifcertainprecautionsarenottaken.

Dontworry. Youcanlearnabouthomeautomation&Arduinoandcompletealloftheprojectsfoundinthisbookwithouteverconnectingyoursystemstothepowerpluginyourwall,butifyouactuallywanttoinstallsomeofthesedevicesinyourhomeIreallyadvisereadingthissectioncarefully.

Itisusuallyacceptedthatanythingabove50Visdangerous,and25Visusuallytakenasasafevalue.

Forus,itmeansthatmostcircuitswillbesafe(Arduinooperatesat5Vor3.3V),theonlythingwherewewillhavetobecarefuliswhenconnectingsomepartofyourcircuittothemainselectricity(whichisat110VintheUSor230VinEurope,forexample).

Therisksofbeingindirectcontactwithavoltageabove50Vareveryhigh,andtheconsequencesincludeventricularfibrillation,cardiacarrest,respiratoryarrest,andseriousburns,allpossiblyleadingtodeath.

Itisactuallynotthatdifficulttoavoidriskswhenworkingwithhighvoltages. Thefirstone,whichseemsquiteevident,istoalwaysworkwiththecircuitbeingoff,andtobefarfromitwhenthecircuitisinoperation. Alsokeepinmindthatsomethinginsidethecircuitcouldhavebrokendownandtouchedthecaseofyourdevice,sodonttouchanythingwhenthecircuitisinoperation.

Alsomakesurethatthecircuitisde-energizedbeforetouchingit. Indeed,somehigh-voltagecircuitscancontaincomponentslikecapacitorsthatstoreenergyevenifthepowerhasbeenshutdown. However,youwontfindsuchcircuitsinthisbook.

5 Prerequisites

Firstofall,youcouldjustreadthisbookfromstarttofinishwithoutactuallydoinganyoftheprojects,andstilllearnalotaboutelectronics,programmingandofcoursehomeautomation. However,Ireallyrecommendspendingtimedoingtheprojectsyourself. Youwilllearnsomuchmorebydoingso.

Nowfortheprerequisites. Youactuallydonotneedtoknowmuch,butapreviousexperiencewiththeworldofelectronicsandprogrammingwillbeusefulandwillallowyoutogetthroughtheprojectsfaster. Theprojectscanberunfromanycomputer,butIwillfocusonusingtheOSXandLinuxoperatingsystems. However,theArduinosoftwarealsoperfectlyrunsonWindowsandalltutorialswillworkunderthisoperatingsystem.

Fortheprogrammingside,IwilluselanguageslikeC/C++,HTML,andJavascript. IwillnotmakeafullintroductionoftheselanguageswhenIusethem,butIwilldetaileveryoneofthefunctionsIuseandpointtoareferenceifIamusingmorecomplexfunctionsinoneoftheselanguages. Butoverall,wewillkeepitsimple.

Fortheelectronicspart,Iwillintroducethefunctionofeverynewcomponent. Also,foreverycomponentusedintheprojectsinthisbook,Iwillincludeusefullinksinthesupportpagessothatyoucaneasilyfindandbuythesecomponentsontheweb. Alloftheprojectswilluseabreadboardforrapidprototypingsoyoudonthavetosolderanything.Again,thegoalofthisbookistoteachyouabouthomeautomationusingtheArduinoplatformsoyoucanbuildyourownsystemslater.

Mostofthehardwareandthesoftwarerequiredforthisbookarespecifictoeverychapter.However,thereareafewthingsyouwillneedthroughoutthebookandthosewewillinstallrightnow.

ThefirstthingistheArduinoIDE(IDEmeanIntegratedDevelopmentEnvironment). YoucangrabitontheofficialArduinowebsiteatthefollowingaddress:

http://arduino.cc/en/Main/Software

Inthesecondpartofthebook,wearegoingtoconnectourprojectswirelesslytoyourcomputer. Tousetheserver-sidecode,youaregoingtoneedtohaveNode.jsinstalledonyourcomputer. Node.jsissoftwarethatallowstheconstructionofserver-sidecodeusingJavascript,andwewilluseittobuildinterfacesforourhomeautomationprojects. You

cangrabitatthefollowingaddress:

http://nodejs.org/download/

Itisalsoavailableforallplatforms,andeasytoinstall. ToinstallitunderWindowsorOSX,simplydownloadtheinstallerfile,andfollowtheinstructionsgivenbytheinstallsoftware.

IfyouareunderWindows,inorderforNode.jstoworkcorrectlyyoualsoneedtocreateafoldercallednpminsidethisfolder:

C:\Users\yourUserName\AppData\Roaming\

IfyouarerunningunderUbuntuorotherLinuxdistributions,youhavetheenterthefollowingcommandsinaterminal:

sudoapt-getinstallpython-software-propertiessudoapt-add-repositoryppa:chris-lea/node.jssudoapt-getupdate

Then,enterthefollowingcommandtoinstallNode.js:

sudoapt-getinstallnodejs

NotethatunderLinux,Node.jsissometimesdenotedasnodejsandnotnodelikefortheotheroperatingsystems.

IfyouareusingaRaspberryPi,firstenterthiscommandinaterminal:

sudowgethttp://node-arm.herokuapp.com/node_latest_armhf.deb

Then,installNode.jsbytyping:

sudodpkg-inode_latest_armhf.deb

Chapter1

GettingStarted

1.1 TheArduinoPlatform

Youarejustminutesawayfromactuallydoingyourfirstopenhomeautomationproject.Beforethat,however,Iwanttointroducetheplatformthatwewillbeusinginthiswholebook:theArduino.

ThehistoryofArduinobeganin2005,whenthefoundersMassimoBanziandDavidCuartielleswantedtomakeadevicethatwouldbeeasytoprogrambynon-experts,sothattheirstudentsindesigncouldbuildprojectsthatusedmicrocontrollers. TheArduinoplatformwascreatedtobenotonlyabouttheboardsandthemicrocontrollers,butalsoasacompletehardwareandsoftwareecosystemthatmadethelifeoftheusermuchsimplercomparedtoothermicrocontrollersolutions.

Onthehardwareside,Arduinoisasingle-boardmicrocontrollersystem,usuallyequippedwithan8-bitAtmelAVRmicrocontroller,althoughnewmodelsliketheArduinoDuehavea32-bitARMprocessor. Forourprojects,wedontneedthatmuchpower,andwewillonlyusethemostcommonArduinoboard:theArduinoUno.

OnecharacteristicofArduinoboardsisthattheirpinsarealwaysexposedinasimilarfashion,whichmeansthatitisveryeasytopluginextensions,calledshields,directlyintotheboards. Theseshieldscanaddvariousfunctionalitiestotheboard,liketheabilitytocontrolDCmotorsforroboticsapplications,ortoconnectwirelesslytoyourphoneviaBluetooth.

Butforme,itsreallythesoftwarepartthatmakestheArduinoplatformsopowerful. ToprogramanArduinoboard,youcanusetheofficialArduinosoftware(whichistotallyfreetodownload)andthenusealanguageclosetoC++toactuallywritethecodethatyouwilluploadtotheboard. Comparedtoothermicrocontrollers,believeme,itisveryeasytoprogramtheboardtomakeitdowhatwewant. Forexample,asimpleinstructionlikemakinganLEDlightuponlytakesasinglelineofcodewithanArduinoboard,whereasitwouldtakemanylineswithothermicrocontrollers.

AnotherimportantpointisthatthereisalsoahugecommunityaroundtheArduinoplatform. ThismeansthateveryfunctionuseisreallywelldocumentedontheofficialArduinowebsite(www.arduino.cc). Youwillalsofindtutorialsformostofthecommonlyusedfunctionsoftheboard.

Iwillnowgiveyouabitmoredetailabouttheboardthatwewillbeusinginthisbook:theArduinoUno. HereisapictureoftheboardIpersonallyusedforalltheprojectsin

thisbook:

Theboarditselfisverytiny. WhatyoucanseeonthelowerrightportionofthepictureisanAtmelmicrocontroller,thebrainoftheboard. Itreceivesthesoftwarewhichwewilldevelopforourhomeautomationprojects. Onthetopandonthebottomoftheboard,youwillseetworowsofconnectors. Wewillusethesetoconnecttheinputandoutputsignalssuchastheanaloginputs,thedigitalinputsandoutputs,andreferencevoltageslikethegroundand5V.Finally,youcanseetheUSBconnectorontheleftuppercorner. Thiswillconnecttheboardtothehostcomputer.

1.2 WhatyouNeedtoKnowAboutElectronics

Thisisnotabookaboutgeneralelectronics;therearemuchbetterbooksforthat. Thisbookwillteachyouhowtobuildhomeautomationsystems. Itwillcoachyouhowtoconnectdifferentcomponents,sensorsandotherdevicestotheArduinoplatform.

However,inordertounderstandhowthesecomponentswork,youneedtounderstandseveralbasicelectronicprinciples. Thissectionwillgiveyouaquickintroductionoftheprinciplesusedintheprojectsfoundinthisbook.

Mainvariablesusedinelectronics

Tocharacterizeacircuit,manyvariablesareused,butwearejustgoingtolookatthemostimportantones.

ImaginethatanelectricalcircuitislikewaterflowingfrompointAtopointB.Forwatertoflownaturallyintothecircuit,weneedadifferenceofheightbetweenAandB.Andinelectricalcircuits,thisdifferenceiscalledthevoltage,usuallynotedasV.

WecanalsodefinetheequivalentflowofwaterbetweenAandBastheflowofelectrons,whichisthecaseinanelectricalcircuit. ThiselectronflowiscalledtheelectricalcurrentandwillberepresentedbytheletterI.

WecanalsoexpressthepowerPdissipatedbyagivencomponent,inWatts,bymultiplyingthevoltagebythecurrent:P=V*I.

Basiccircuitrepresentation

Inordertorepresentelectricalcircuits,anormalizedsetofsymbolsisused. Here,forexample,isasimplecircuitwithavoltagesourceVCC,aresistorR1,anLEDcalledLED1,andagroundGND.

Lateron,wewillseemoredetailsaboutsomeofthesecomponents,butfornow,letsjustidentifythecomponentswhichareusuallyfoundinmanycircuits.

Whenreadingacircuit,youshouldfirstlocatethepowerandgroundpins. Here,thepowerisrepresentedbytheVCCpin,whichwillusuallybeequalto5Vintheprojectsfoundinthisbook. ThegroundpinhereisrepresentedbyGND.

AfterVCCandGND,youcanlookforthecomponents. Here,wesimplyhavearesistorandanLED.

Powersources

Inthefirstcircuitofthissection,thepowersourcewasapinnamedVCC. Thissourcecanbeliterallyanything,butbyconvention,VCCwilldenoteapositive,low-voltagepowersource(usually3.3,5or12V).

Topowertheprojectsthatyouwillfindinthisbook,theUSBportoftheArduinoboardwillusuallybeused. However,youcanalsopowerupyourArduinoboardfromotherpowersourceslikeregulatedpowersupplieswhichcanbedirectlypluggedintothewallsocket(bewarenottoexceedthemaximumvoltageacceptedbyyourArduinoboard)orontobatteries.

Resistors

Resistorsarekeycomponentsofmostelectricalcircuits. Takingagainourpreviousanalogywithwater,aresistorwillactuallylimittheflowofwater(orelectrons)inagivenbranchofthecircuit.

Toquantifyhowmuchtheresistorislimitingthecurrentinacircuit,wecanintroduceanewvariablecalledR,resistancewhichismeasuredinOhms. Foraresistor,theformulathatlinksvoltage,currentandresistanceiscalledOhmslaw:V=R*I.

LEDs

LEDs,shortforLightEmittingDiodes,arethemostcommonlyusedcomponentsforsignalingandtestinginacircuit. Whencurrent(usuallyabout20mA)isgoingthroughanLED,theyemitlight,whichcanbered,blue,greenorevenwhite,dependingontheLED.

OntheArduinoboardforexample,LEDsareusedtomakesuretheboardison,toindicatethataserialcommunicationisactuallyhappeningorasatestcomponentforsoftware(onpinnumber13).

Asshowninthefirstcircuitofthissection,LEDsareusuallyassociatedwithresistorstolimitthecurrentthatflowsthroughthem. Beware,thepinsofanLEDarenotequalthepositivepowersupply(forexample,VCC)hastogoontheleftsideoftheLEDcalledtheanode,andtheotherpin,calledthecathode,hastobeconnectedtotheground. Youcaneasilyidentifythecathodeasittheonewiththeshorterlead.

Relays

Inhomeautomation,wewanttoswitchthingslikelampsonandoffasyouwoulddowhenyoupressalightswitchonthewall. Thisisdoneusingrelays,whichbasicallyareelectromechanicalswitches.

Therearetwoprimarypartsinarelay. Theleftpartofthesymbolisthecoil,andisthecontrolpartoftherelay. Whenavoltage(usually5Vforrelaysusedinthisbook)isappliedtothecoil,theotherpartoftherelaywillswitchitsstate,goingfromaclosedstatetoanopenstate,forexample.

Thecoolthingisthatthissecondpartoftherelaycanhandlemuchhighervoltages(upto300Vfortheonesusedinthisbook)comparedtowhattheArduinoboardcouldhandle.ThisallowsanArduinoboardtocontroldevicesthatusepowerdirectlyfromthemainselectricity,likelamps.

Goingfurther

Thissectionisclearlyjustanintroductiontoelectronicsandtothecomponentsthatwearegoingtousethemostinthisbook.

Togofurtherandlearnmoreaboutelectronics,thereareseveralthingsthatyoucando.

Ofcourse,justbrowsingtheInternetisanoption. Youwillfindmanyresourcesbyusingthisway. YoucanalsohavealookinsidetheResourceschapterofthisbooktofindseveralbookrecommendationsaboutArduino&electronics.

1.3 YourVeryFirstProject:aSimpleAlarmSystem

Toendthischapter,wearegoingtobuildourveryfirsthomeautomationproject:asimplealarmsystem. WearegoingtointerfaceaPIRmotionsensorwithArduino. Ifmotionisdetected,wewillflashanLEDandmakesomesoundwithasmallpiezobuzzer. ThissimpleprojectwillgiveyouthebasicsofhomeautomationwithArduino.

Hereisthelistofcomponentsyouwillneedforthisproject:

ArduinoUno(http://www.adafruit.com/product/50)PIRmotionsensor(http://www.adafruit.com/product/189)LED(https://www.sparkfun.com/products/9590)330Ohmresistor(https://www.sparkfun.com/products/8377)Piezobuzzer(http://www.adafruit.com/product/160)Breadboard(http://www.adafruit.com/product/64)Jumperwires(http://www.adafruit.com/product/758)

Wecannowstartassemblingtheproject. Tohelpyouout,theschematicbelowsummarizesthehardwareconnections:

ThisimagewascreatedwithFritzing(http://fritzing.org/).

First,placeallthecomponentsonthebreadboard. Afterthat,positionthebreadboardnexttotheArduinoboard. Then,connectthePIRmotionsensortothebreadboard. ConnecttheGNDpinoftheArduinoboardtothebluerailofthebreadboardaswewillneedtoconnectalldevicestothesameground.

FortheLED,connecttheresistorinserieswiththeLEDanodeonthebreadboard(theanodeisthelongestpinontheLED). Then,connecttheotherpinoftheresistortoArduinopin5. TheothersideoftheLEDmustbeconnectedtotheArduinoground.

ForthePIRmotionsensor,connecttheGNDpintotheArduinoground,VCCtotheArduino5Vpin,andSIGpintoArduinopin7.

ForthePiezobuzzer,connectthepositivepin(markedwitha+)toArduinopin8,andtheotherpintotheArduinoground.

Thisisapictureofthefullyassembledproject:

Nowthatthehardwareisassembled,wecanstartwritingtheArduinosketchforoursimplealarmsystem. Thisisthecompletecodeforthispart:

//Codeforthesimplealarmsystem

//Pins

constintalarm_pin=8;constintled_pin=5;constintmotion_pin=7;

//Alarmbooleanalarm_mode=false;

//VariablesfortheflashingLDEDintledState=LOW;longpreviousMillis=0;longinterval=100;//Intervalatwhichtoblink(milliseconds)

voidsetup(){//SetpinstooutputpinMode(led_pin,OUTPUT);pinMode(alarm_pin,OUTPUT);//Waitbeforestartingthealarmdelay(5000);}

voidloop(){//Motiondetected?if(digitalRead(motion_pin)){alarm_mode=true;}

//Ifalarmmodeison,flashtheLEDandmakethealarmringif(alarm_mode){unsignedlongcurrentMillis=millis();if(currentMillis-previousMillis>interval){previousMillis=currentMillis;if(ledState==LOW)ledState=HIGH;elseledState=LOW;//SwitchtheLEDdigitalWrite(led_pin,ledState);}tone(alarm_pin,1000);}}

Letsnowseethedetailsofthiscode. Itstartsbydeclaringthepinstowhichthedifferentcomponentsareconnectedto:

constintalarm_pin=8;constintled_pin=5;constintmotion_pin=7;

Wewillstorethefactthatthealarmisonornotinsideavariable:

booleanalarm_mode=false;

WewillalsohaveavariabletomaketheLEDflashwhenthealarmison:

intledState=LOW;longpreviousMillis=0;longinterval=100;//Intervalatwhichtoblink(milliseconds)

Now,insidethesetup()functionofthesketch,weneedtosetthepinsfortheLEDandthePiezoasoutputs:

pinMode(led_pin,OUTPUT);pinMode(alarm_pin,OUTPUT);

Wealsowaitfor5seconds,sothealarmdoesntturnonrightaway:

delay(5000);

Intheloop()functionofthesketch,wecontinuouslycheckthestateofthePIRmotionsensor. Ifsomemotionhasbeendetected,wesetthealarmvariabletotrue:

if(digitalRead(motion_pin)){alarm_mode=true;}

Now,ifthealarmison,wedotwothings:continuouslyflashtheLEDandinitiatethePiezobuzzertomakesomenoise. Thisisdonebythefollowingpieceofcode:

if(alarm_mode){unsignedlongcurrentMillis=millis();if(currentMillis-previousMillis>interval){previousMillis=currentMillis;if(ledState==LOW)ledState=HIGH;elseledState=LOW;//SwitchtheLEDdigitalWrite(led_pin,ledState);}tone(alarm_pin,1000);}

NotethatallthecodesforthisfirstprojectcanbefoundontheGitHubrepositoryofthebook:

https://github.com/openhomeautomation/home-automation-arduino/

Youcannowtestthisfirstprojectofthebook. UploadthecodetotheArduinoboardusingtheArduinoIDE.Trywavingyourhandinfrontofthesensoraftertheinitial5secondsdelayhaspassed. YoushouldhearthealarmturnonandseetheLEDflashingcontinuously. Toturnitoffagain,simplypresstheredresetbuttonontheArduinoboard.

Incaseitisnotworkingatthispoint,thereareseveralthingswhichyoucancheck. First,makesurethatallthehardwareconnectionsarecorrectbydoingthehardwareconfigurationpartagain. Also,makesurethatyouhavecorrectlyuploadedthelatestversionofthecodethatyoucanfindinsidetheGitHubrepositoryofthebook.

IhopethissimpleprojectgaveyouanideaofwhatyoucandowithArduinoforhomeautomationapplications. Inthenextchapterofthebook,wearegoingtousetheArduinoplatformtobuildevenmoreexcitinghomeautomationapplications!

Chapter2

BuildingaWeatherMeasurementStationInthepreviouschapter,whichreallyintroducedyoutotheworldofopen-sourcehomeautomation,youlearnedhowtointerfaceamotionsensorwithArduinotocreateasimplealarmsystem.

Inthisproject,Iwillshowyouhowtomonitorthetemperature,humidityandlightlevelofaroomusingArduino,atemperature&humiditysensor,aphotocell,andaLCDscreen. WearegoingtocontinuouslydisplayallthisdataontheLCDscreen.

Thisprojectperfectlyrespectsthefoundationsofthisbookasitusesonlyopen-sourcecomponents. Youcanseeitasthefoundationofamorecomplexsystemtoremotelymonitorinformationaboutyourhome.

2.1 Hardware&SoftwareRequirements

Forthisproject,youwill,ofcourse,needanArduinoUnoboard. YoucanalsouseotherArduinoboardslikeanArduinoMegaorLeonardoastheywillworkjustfinetoo.

Fortemperatureandhumiditymeasurements,youwillalsoneedaDHT11sensor,alongwitha4.7Kresistor. YoucanalsouseaDHT22sensorwhichismoreprecise,onlyyouwillhavetochangeonelineofcode.

Forlightlevelsmeasurements,Iusedaphotocellwitha10KOhmresistor. Thiswillreturnasignalwhichisproportionaltotheincominglightlevel.

YouwillalsoneedanLCDscreentodisplaythemeasurements. Iuseda4x20characterLCDsoIcandisplayuptofourdifferentmeasurementsatthesametime. Youcan,ofcourse,useasmallerLCDscreen,butyouwillonlybeabletodisplaythetemperatureandhumidityatthesametime,forexample.

ThescreenIusedforthisprojectusesanI2CinterfacetocommunicatewiththeArduinoboard. IstronglyrecommendusingascreenwiththisinterfaceasthereareonlytwodatapinsneededtoconnecttotheArduinoboard.

Finally,Iusedabreadboardandsomemale-malejumperwirestomakethedifferentelectricalconnections.

Hereisalistofallcomponentsusedinthisprojectalongwithlinkswhereyoucouldpurchasethemonline:

ArduinoUno(http://www.adafruit.com/product/50)DHT11sensor+4.7kOhmresistor(http://www.adafruit.com/product/386)Photocell(http://www.adafruit.com/product/161)10kOhmresistor(https://www.sparkfun.com/products/8374)LCDdisplay(http://www.robotshop.com/en/dfrobot-i2c-twi-lcd-module.html)Breadboard(http://www.adafruit.com/product/64)Jumperwires(http://www.adafruit.com/product/758)

YouwillalsoneedthelibraryfortheDHTsensor:

https://github.com/adafruit/DHT-sensor-library

AndtheLiquidCrystallibraryfortheLCDscreen:

https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads

Toinstallalibrary,simplyputthefolderinthe/libraries/folderofyourmainArduinofolder.

2.2 HardwareConfiguration

Thehardwareconnectionsforthisprojectarequitesimple:wehavetoconnecttheDHT11sensor,theLCDscreenandthepartresponsibleforthelightlevelmeasurementwiththephotocell. Tohelpyouout,thefollowingpicturesummarizesthehardwareconnections:

ThisimagewascreatedwithFritzing(http://fritzing.org/).

First,connecttheArduinoUno+5Vpintotheredrailonthebreadboard,andthegroundpintothebluerail.

ToknowwhichpintoconnectfortheDHT11sensor,refertothepicturebelow:

Then,connectpinnumber1oftheDHT11sensor(VCC)totheredrailonthebreadboard,andpinnumber4(GND)thebluerail. Also,connectpinnumber2ofthesensortopinnumber7oftheArduinoboard. TofinishupwiththeDHT11sensor,connectthe4.7kOhmbetweenpinnumber1and2ofthesensor.

Forthephotocell,placethecellinserieswiththe10kOhmresistoronthebreadboardfirst. Next,connecttheotherendofthephotocelltotheredrailonthebreadboard,andtheotherendoftheresistortothebluerail(ground). Finally,connectthecommonpinbetweenthephotocellandtheresistortotheArduinoUnoanalogpinA0.

Now,wearegoingtoconnecttheLCDscreen. SinceweareusinganLCDwithanI2Cinterface,therewillonlybetwowiresneededtoconnectforthesignal,andtwoforthepower. ConnecttheLCDpincalledVCCtotheredrailonthebreadboard,andtheGNDpintothebluerailonthebreadboard. Then,connecttheLCDpinSDAtotheArduinopinA4,andtheSCLpintotheArduinopinA5.

Hereisapictureofthefullyassembledprojectsoyoucanhaveanideaonhowthecompleteprojectlookslike:

2.3 TestingtheSensors

Nowthatthehardwareoftheprojectisfullyassembled,wearegoingtotestthedifferentsensorsontheboard. Todoso,wearegoingtowriteasimpleArduinosketch. WewillsimplyreadoutdatafromthesensorsandprintthesedataontheSerialport. Thisisthecompletecodeforthispart:

//CodetomeasuredataandprintitontheSerialmonitor

//Libraries#include"DHT.h"

//DHTsensor#defineDHTPIN7#defineDHTTYPEDHT11

//DHTinstanceDHTdht(DHTPIN,DHTTYPE);

voidsetup(){//InitializetheSerialportSerial.begin(9600);//InitDHTdht.begin();}

voidloop(){//MeasurefromDHTfloattemperature=dht.readTemperature();floathumidity=dht.readHumidity();//Measurelightlevelfloatsensor_reading=analogRead(A0);floatlight=sensor_reading/1024*100;//DisplaytemperatureSerial.print("Temperature:");Serial.print((int)temperature);Serial.println("C");//DisplayhumiditySerial.print("Humidity:");Serial.print(humidity);Serial.println("%");//DisplaylightlevelSerial.print("Light:");Serial.print(light);Serial.println("%");Serial.println("");//Wait500msdelay(500);}

ItstartsbyimportingthelibraryfortheDHTsensor:

#include"DHT.h"

AndcreateaDHTinstance:

DHTdht(DHTPIN,DHTTYPE);

Inthesetup()functionofthesketch,wehavetoinitializethesensor:

dht.begin();

AndtheSerialport:

Serial.begin(9600);

Intheloop()function,wearegoingtocontinuouslyreaddatafromthesensorsandprintthemtotheSerialport. Westartbygettingdatafromthetemperatureandhumiditysensor:

floattemperature=dht.readTemperature();floathumidity=dht.readHumidity();

Forthephotocell,wefirstreaddatafromtheanalogpinA0,whichreturnsavaluefrom0to1023astheresolutionoftheAnalog-To-DigitalconverteroftheArduinoUnoboardis10bitsor1024values. Then,wedividethisvalueby1024andmultiplyitby100tohavethelightlevelasapercentage:

floatsensor_reading=analogRead(A0);floatlight=sensor_reading/1024*100;

Next,weprintthesedifferentmeasurementstotheSerialport. First,thetemperature:

Serial.print("Temperature:");Serial.print((int)temperature);Serial.println("C");

Printinghumidityissimilartothelightlevel:

Serial.print("Light:");Serial.print(light);Serial.println("%");

Finally,weintroduceadelayof500msbetweeneachnewsetofmeasurements:

delay(500);

NotethatthecompletecodeforthischaptercanbefoundonthecorrespondingfolderinsidetheGitHubrepositoryofthebook:

https://github.com/openhomeautomation/home-automation-arduino

ItsnowtimetotestthisfirstArduinosketch. UploadthecodetotheArduinoboardand

opentheSerialmonitorinsidetheArduinoIDE(makingsuretheSerialspeedissetto9600). Thisiswhatyoushouldsee:

Temperature:25CHumidity:36.00%Light:83.79%

Ifthatworks,congratulations,yoursensorsareworkingcorrectly! Youcantry,forexample,topassyourhandinfrontofthephotocell,andyoushouldseethatthelightlevelchangesinstantly.

Incaseitisnotworkingatthispoint,thereareseveralthingsthatyoucancheck. First,makesurethatthesensorsandtheLCDscreenarecorrectlyconnectedtotheArduinoboard. Also,makesurethatyouhavecorrectlydownloadedandinstalledthelibrariesfortheDHTsensorandtheLCDscreen.

2.4 DisplayingtheDataontheLCDScreen

Wearenowgoingtoputthingstogether,andusewhatwealreadydidtofinishourproject. Wewillthereforekeepthemeasurementpartofthesketchwejustwrote,anddisplaytheresultsontheLCDscreen.

Asmostofthecodeisthesamecomparedtotheprevioussketch,IwillonlydetailthepartsthatwereaddedforthedisplayontheLCDscreen. Ofcourse,youcanfindallthecodeontheGitHubrepositoryofthebook. Thisisthecompletecodeforthispart:

//Codetomeasuredata&displayitontheLCDscreen

//Libraries#include#include#include"DHT.h"

//DHTsensor#defineDHTPIN7#defineDHTTYPEDHT11

//LCDdisplayinstanceLiquidCrystal_I2Clcd(0x27,20,4);

//DHTinstanceDHTdht(DHTPIN,DHTTYPE);

voidsetup(){//Initializethelcdlcd.init();//PrintamessagetotheLCD.lcd.backlight();lcd.setCursor(1,0);lcd.print("Hello!");lcd.setCursor(1,1);lcd.print("Initializing");//InitDHTdht.begin();//ClearLCDdelay(2000);lcd.clear();}

voidloop(){//MeasurefromDHTfloattemperature=dht.readTemperature();floathumidity=dht.readHumidity();//Measurelightlevelfloatsensor_reading=analogRead(A0);floatlight=sensor_reading/1024*100;//Displaytemperaturelcd.setCursor(1,0);lcd.print("Temperature:");lcd.print((int)temperature);lcd.print((char)223);lcd.print("C");//Displayhumidity

lcd.setCursor(1,1);lcd.print("Humidity:");lcd.print(humidity);lcd.print("%");//Displaylightlevellcd.setCursor(1,2);lcd.print("Light:");lcd.print(light);lcd.print("%");//Wait100msdelay(100);}

ItstartsbyincludingtherequiredlibrariesfortheLCDscreenandtheDHTsensor:

#include#include#include"DHT.h"

Then,wecancreatetheinstanceoftheLCDscreen. Ifyouareusingotherscreensizes,forexampleswithtwolinesonly,thisisthetimetochangeit:

LiquidCrystal_I2Clcd(0x27,20,4);

Inthesetup()functionofthesketch,weneedtoinitializetheLCDscreen:

lcd.init();

Stillinthisfunction,weputthebacklightoftheLCDon,andprintawelcomemessage:

lcd.backlight();lcd.setCursor(1,0);lcd.print("Hello!");lcd.setCursor(1,1);lcd.print("Initializing");

Aftertwoseconds,wesimplycleardownthescreenbeforedoingmeasurements:

delay(2000);lcd.clear();

Now,intheloop()functionofthesketch,afterthedifferentmeasurements,weprintoutthetemperatureonthefirstlineoftheLCDscreen:

lcd.setCursor(1,0);lcd.print("Temperature:");lcd.print((int)temperature);lcd.print((char)223);lcd.print("C");

Wethenprintthehumidityonthesecondline:

lcd.setCursor(1,1);lcd.print("Humidity:");lcd.print(humidity);lcd.print("%");

Now,ifyouhaveathirdlineavailable,likeonthescreenIused,youcandirectlyprintthelightlevelaswellonthethirdline:

lcd.setCursor(1,2);lcd.print("Light:");lcd.print(light);lcd.print("%");

IfyoudonthaveathirdlineavailableonyourLCDscreen,youhaveseveraloptions. Forexample,youcanjustintroducesomedelay,clearthescreenagain,andprintoutthelightlevelonthefirstline.

Wealsointroducea100msdelaybetweeneachsetofmeasurementsandrefreshoftheLCDscreen:

delay(100);

NotethatthecompletecodeforthischaptercanbefoundinsidetheGitHubrepositoryofthebook:

https://github.com/openhomeautomation/home-automation-arduino

Itsnowtimetotesttheproject. UploadthecodeagaintoyourArduinoboardandwaitforsometime. YoushouldbeabletoseetheLCDprintingthewelcomemessagebeforemovingontodisplaythemeasurements. Hereisapictureoftheprojectinaction:

Ifitdoesntwork,thereareseveralthingsthatyoucancheck. Thefirstonetocheckisthatthecodetotestthedifferentsensorsisworkingcorrectly. So,donothesitatetogobacktotheprevioussectionsifnecessary. Also,makesurethatyourLCDscreeniscorrectlywired. Finally,makesurethatyouareusingthecorrectLCDlibraryforthescreenyouareusing.

2.5 HowtoGoFurther

Inthischapter,webuiltasimplehomeautomationproject:anLCDweatherstationbasedonArduino. WeinterfacedseveralsensorswithArduinolikedigitalhumidityandtemperaturesensors. Then,wedisplayedthesedataonanLCDscreen,whichisalsocontrolledbytheArduinoboard.

Thereareseveralwaystousewhatyouhavelearnedinthischaptertobuildevenmoreexcitingprojects. YoucanconnectmoresensorstotheprojectsanddisplaytheirmeasurementsontheLCDscreen. Forexample,youcanconnectabarometricpressuresensortotheproject. YoucanalsokeepthesamesensorsandgraphicallydisplaytheirmeasureddataonanOLEDscreen.

Chapter3

BuildingaSmartLampInthisproject,wearegoingtobuildaverycommonhomeautomationsystem:asmartlamp. Andbysmart,Imeanalampthatautomaticallyswitchesonwhentheambientlightlevelislow,andswitchesoffagainwhenthelightlevelrises. Todoso,wewillusearelaymoduletocontrolthelamp,andaphotocelltomeasuretheambientlightlevel.SincewewillusetheArduinoplatformtodoso,wearegoingtointroducesomeextrafeatures.

First,wewilladdacurrentsensortotheproject,sowecanknowhowmuchcurrentandenergythelampisconsumingatagivenmoment. WewillalsoaddanLCDscreentotheproject,soyoucaninstantlycheckthestateoftherelay,theenergyconsumptionofthelamp,andthevalueoftheambientlightlevel. Asforthelampitself,wearesimplygoingtouseasimpledesklamp,however,theprinciplesofthisprojectshouldworkwithanylamp.

3.1 Hardware&SoftwareRequirements

Forthisproject,youwill,ofcourse,needanArduinoUnoorasimilarboard.

Fortherelaymodule,Iuseda5VrelaymodulefromPololu,whichnicelyintegratesarelayonaboard,alongwithalltherequiredcomponentstotheArduinoboard. HereisapictureoftherelaymoduleIused:

Tomeasurethecurrentflowingthroughthelamp,IusedaboardbasedontheAC712sensorfromITeadStudio. ThissensorisreallyeasytousewithArduino,asitreturnsavoltagethatisproportionaltothemeasuredcurrent. Withthecorrectformula,wewilltheninferthecurrentflowingthroughthelampfromthevoltagemeasuredbytheArduinoboard. Ofcourse,youcanuseotherboardsbasedonthesamesensor. Hereisapictureofthecurrent-measuringboardIusedforthisproject:

Forlightlevelsmeasurements,Iusedaphotocellwitha10KOhmresistor. Thiswillreturnasignalwhichisproportionaltotheincominglightlevel.

YouwillalsoneedanLCDscreentodisplaythestateoftherelay,thepowerconsumptionofthedevice,andthelightlevel. Iuseda4x20charactersLCDsothatIcandisplayuptofourlinesatthesametime. Youcan,ofcourse,useasmallerLCDscreen,butyouwillonlybeabletodisplaythestateoftherelayandthecurrentconsumptionatthesametime,forexample.

ThescreenIusedforthisprojectusesanI2CinterfacetocommunicatewiththeArduinoboard. IrecommendusingascreenwiththisinterfaceasthereareonlytwodatapinsneededtoconnecttotheArduinoboard.

Toconnectthelamptotheproject,Iusedastandardpairofpowerplugswithbarecablesattheend,withonefemalesocket(toplugthelampin)andonemalesocket(toplugitintothepowersocketinthewall). HereisapictureofthecablesIused:

Becarefulinworkingonthecablesasthisisahigh-voltageproject.

Finally,Iusedabreadboardandsomejumperwirestomakethedifferentelectricalconnections.

Hereisalistofallcomponentsusedinthisproject,alongwiththelinkswhereyoucanpurchasethemonline:

ArduinoUno(http://www.adafruit.com/product/50)Relaymodule(http://www.pololu.com/product/2480)Currentsensor(http://imall.iteadstudio.com/im120710011.html)Photocell(http://www.adafruit.com/product/161)10kOhmresistor(https://www.sparkfun.com/products/8374)LCDdisplay(http://www.robotshop.com/en/dfrobot-i2c-twi-lcd-module.html)Breadboard(http://www.adafruit.com/product/64)Jumperwires(http://www.adafruit.com/product/758)

Forthelampitself,Iusedastandarddesklamp(30W)forthisproject.*However,therelaymoduleIusedcansupportupto1200W,soyoucanpluginmorepowerfullampsordevicesifyouwish.

Onthesoftwareside,allyouneedistheArduinoIDE,andtheLiquidCrystallibraryfortheLCDscreen:

https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads

Toinstallalibrary,simplyputthefolderinyour/libraries/folderofyourmainArduinofolder.

*Note:InUSAandCanadawhere110VACisused,standardwattageis60W.

3.2 HardwareConfiguration

Letsnowassemblethehardwareforthisproject. Wewilldosointwoparts. WewillfirstconnectthedifferentcomponentsliketherelaymoduletotheArduinoboard,andthenwewillconnectthelamptotheproject.

Thehardwareconnectionsforthefirstpartareactuallyquitesimple:wehavetoconnecttherelaymodule,thecurrentsensorandthephotocell. First,connecttheArduinoUno+5Vpintotheredrailonthebreadboard,andthegroundpintothebluerail.

Forthephotocell,placethecellinserieswiththe10kOhmresistoronthebreadboardfirst. Then,connecttheotherendofthephotocelltotheredrailonthebreadboard,andtheotherendoftheresistortothebluerail(ground). Finally,connectthecommonpinbetweenthephotocellandtheresistortotheArduinoUnoanalogpinA0.

Fortherelaymodule,therearethreepinsyouneedtoconnect:VCC,GNDandasignalpin,usuallydenotedasSIG.VCCneedstogototheArduino5Vpin,soconnectittotheredpowerrail. GNDgoestotheArduinogroundpin,soconnectittothebluepowerrail.Finally,connecttheSIGpintopinnumber8oftheArduinoboard.

Inasimilarway,connectthecurrentsensormodule. Ithasthreepins:VCC,GND,andOUT.Asfortherelay,VCCneedstogototheArduino5Vpin,soconnectittotheredpowerrail. GNDgoestotheArduinogroundpin,soconnectittothebluepowerrail.Then,connecttheOUTpintotheanalogpinA1oftheArduinoboard.

Now,wearegoingtoconnecttheLCDscreen. SinceweareusinganLCDwithanI2Cinterface,therewillonlybetwowirestoconnectforthesignal,andtwoforthepower.ConnecttheLCDpincalledVCCtotheredrailonthebreadboard,andtheGNDpintothebluerailonthebreadboard. Then,connecttheLCDpinSDAtotheArduinopinA4,andtheSCLpintoArduinopinA5.

Hereisapictureofthefullyassembledproject,withoutthelampconnectedyet:

Wearenowgoingtoconnectthelamptothehardwarewealreadyassembled. Basically,theideaistohavethemainpowersupply(comingfromthepowersocketinthewall)gototherelay,thentothecurrentsensor,andfinallytothelamp. Followthisschematictomaketherequiredconnections:

Asitimpliesdangerousvoltagelevels(110vor230vdependingonwhereyouareintheworld),youshouldtakesomeprecautionsatthispoint. Youcanfindthemintheintroductionofthisbook. Notethatyoucantestthisprojectwithouthavinganydeviceconnectedtotherelay&thecurrentsensor.

3.3 TestingtheRelay

Itisnowtimetotesttheproject. Asthemostimportantpartoftheprojectistherelaycontrollingthelamp,wearegoingtotestthere. Wearesimplygoingtoswitchtherelayonandoffcontinuouslyevery5secondsjusttocheckthattherelayisworkingandthattheconnectionswiththelampwerecorrectlymade. Hereisthecompletecodeforthispart:

//Simplesketchtotesttherelay//Relaypinconstintrelay_pin=8;

voidsetup(){pinMode(relay_pin,OUTPUT);}

voidloop(){//ActivaterelaydigitalWrite(relay_pin,HIGH);//Waitfor5secondsdelay(5000);//DeactivaterelaydigitalWrite(relay_pin,LOW);//Waitfor5secondsdelay(5000);}

Itstartsbydeclaringonwhichpintherelayisconnectedto:

constintrelay_pin=8;

Inthesetup()functionofthesketch,wesetthispinasanoutput:

pinMode(relay_pin,OUTPUT);

Then,intheloop()functionofthesketch,wesetthispintoaHIGHstate,switchingontherelay:

digitalWrite(relay_pin,HIGH);

Waitfor5seconds:

delay(5000);

Wethenswitchtherelayoffagain:

digitalWrite(relay_pin,LOW);

Andwaitfor5secondsbeforerepeatingtheloop():

delay(5000);

NotethatthecompletecodeforthischaptercanbefoundonthecorrespondingfolderinsidetheGitHubrepositoryofthebook:

https://github.com/openhomeautomation/home-automation-arduino

Itsnowtimetotestthesketch. Makesurethatthelampiscorrectlyconnectedtotheproject,andthatthemaleplugispluggedintothepowersocketinthewall. Then,uploadtheArduinosketchtotheboard. Youshouldseethatevery5seconds,therelayisswitching,turningthelamponandoff.

Besuretofixtherelayinapositionsuchthatitcannotbetouchedbyaccident.

3.4 PowerMeasurements&AutomaticLightingControl

Letsnowmovetothemainpartoftheproject:buildingtheArduinosketchforoursmartlamp. Webasicallyneedtocontinuouslymeasurethelightlevelandthecurrentconsumptionofthelamp,printthisdataontheLCDscreen,andchangethestateoftherelayaccordingly. Hereisthecompletecodeforthispart:

//Codeforthesmartlampproject

//Libraries#include#include

//Relaystateconstintrelay_pin=8;booleanrelay_state=false;

//LCDdisplayinstanceLiquidCrystal_I2Clcd(0x27,20,4);

//Definemeasurementvariablesfloatamplitude_current;floateffective_value;floateffective_voltage=230;//Setvoltageto230V(Europe)or110V(US)floateffective_power;floatzero_sensor;

voidsetup(){//Initializethelcdlcd.init();//PrintamessagetotheLCD.lcd.backlight();lcd.setCursor(1,0);lcd.print("Hello!");lcd.setCursor(1,1);lcd.print("Initializing");//SetrelaypintooutputpinMode(relay_pin,OUTPUT);//Calibratesensorwithnullcurrentzero_sensor=getSensorValue(A1);//ClearLCDdelay(2000);lcd.clear();}

voidloop(){//Measurelightlevelfloatsensor_reading=analogRead(A0);floatlight=(sensor_reading/1024*100);//Performpowermeasurementfloatsensor_value=getSensorValue(A1);//Converttocurrentamplitude_current=(float)(sensor_value-zero_sensor)/1024*5/185*1000000;effective_value=amplitude_current/1.414;effective_power=abs(effective_value*effective_voltage/1000);

//Switchrelayaccordingly//Ifthelightlevelismorethan75%,switchthelightsoffif(light>75){digitalWrite(relay_pin,LOW);relay_state=false;}//Ifthelightlevelislessthan50%,switchthelightsoffif(light