Getting Started With Arduino and Go by Agus Kurniawan

Copyright

GettingStartedwithArduinoandGo

AgusKurniawan

1stEdition,2015

Copyright2015AgusKurniawan

*CoverphotoiscredittoFajarRamadhany,Bataviasoft,http://bataviasoft.com/.

**Arduinologoistakenfromhttp://www.arduino.cc/.

http://bataviasoft.com/http://www.arduino.cc/

TableofContentsCopyright

Preface

1.PreparingDevelopmentEnvironment

1.1Arduino

1.1.1ArduinoUno

1.1.2ArduinoLeonardo

1.1.3ArduinoMega2560

1.1.4ArduinoDue

1.2ElectronicComponents

1.2.1ArduinoStarterKit

1.2.2Fritzing

1.2.3Cooking-Hacks:ArduinoStarterKit

1.2.4ArduinoSidekickBasickit

1.3Go

1.4ArduinoSoftware

1.5Testing

2.HelloWorld:ArduinoandGo

2.1ArduinoWorld

2.1.1ArduinoHardwareDriveronWindows8/8.1

2.1.2SimpleTesting

2.2ArduinoandGo

2.3TestingSerialPortusingGo

2.4TestingforArduinoandGo

3.ExploringGoPackagesforArduino

3.1GettingStarted

3.2Gobot

3.3go-firmata

3.4ReadingDigitalInput

3.4.1gobot

3.4.2go-firmata

4.AnalogSensor

4.1SensorDevices

4.2ReadingSensor

4.3RunningProgram

5.RGBLED

5.1RGBLED

5.1.1ArduinoAnalogoutput(PWM)

5.1.2ControllingRGBLEDColor

5.2ArduinoImplementation

5.3GoImplementation

SourceCode

Contact

Preface

ThisbookwaswrittentohelpanyonewanttogetstartedwithArduinoandGo.ItdescribesthebasicelementsoftheintegrationofArduinoandGo.

AgusKurniawan

Depok,March2015

1.PreparingDevelopmentEnvironment

1.1Arduino

Arduinoisanopen-sourceelectronicsprototypingplatformbasedonflexible,easy-to-usehardwareandsoftware.ThisboardusesAtmelmicrocontrollerseries.TherearemanyArduinohardwaremodelsthatyoucanuse.FurtherinformationaboutArduinoproducts,youcanvisitonwebsitehttp://arduino.cc/en/.

YoumustoneArduinohardwaretofollowpracticesinthisbook.IrecommendtoobtainoneofthefollowingArduinohardware:

ArduinoUnoArduinoLeonardoArduinoMega2560ArduinoDue

Youcanbuythisproductonyourlocalelectronicstore.Youalsocanorderitbyonline.Finditonhttp://arduino.cc/en/Main/Buy.ThefollowingisthelistofArduinostoreyoucanbuy

Arduinostore,http://store.arduino.cc/Amazon,http://www.amazon.comCooking-hacks,http://www.cooking-hacks.com/index.php/shop/arduino.htmlRSComponents,http://www.rs-components.comElement14,http://www.element14.comEXP-Tech,http://www.exp-tech.de

BecauseArduinoisanopen-sourcehardware,peoplecanbuildit.ItscalledArduinocompatible.Generallyitssoldinlowprices.

1.1.1ArduinoUno

TheArduinoUnoisamicrocontrollerboardbasedontheATmega328.Youcandownloadthedatasheetfile,http://www.atmel.com/dyn/resources/prod_documents/doc8161.pdf.

FurtherinformationaboutArduinoUno,youcanreaditonhttp://arduino.cc/en/Main/ArduinoBoardUno.

http://arduino.cc/en/http://arduino.cc/en/Main/Buyhttp://store.arduino.cc/http://www.amazon.comhttp://www.cooking-hacks.com/index.php/shop/arduino.htmlhttp://www.rs-components.comhttp://www.element14.comhttp://www.exp-tech.dehttp://www.atmel.com/dyn/resources/prod_documents/doc8161.pdfhttp://arduino.cc/en/Main/ArduinoBoardUno

1.1.2ArduinoLeonardo

TheArduinoLeonardoisamicrocontrollerboardbasedontheATmega32u4.Downloaddatasheetforthisproductonhttp://www.atmel.com/dyn/resources/prod_documents/7766S.pdf.

Visitthisproducttogetthefurtherinformationonhttp://arduino.cc/en/Main/ArduinoBoardLeonardo.

1.1.3ArduinoMega2560

TheArduinoMega2560isamicrocontrollerboardbasedontheATmega2560.Youcandownloadthedatasheetfileonhttp://www.atmel.com/dyn/resources/prod_documents/doc2549.PDF.

FurtherinformationaboutArduinoMega2560,youcanvisiton

http://www.atmel.com/dyn/resources/prod_documents/7766S.pdfhttp://arduino.cc/en/Main/ArduinoBoardLeonardohttp://www.atmel.com/dyn/resources/prod_documents/doc2549.PDF

http://arduino.cc/en/Main/ArduinoBoardMega2560.

1.1.4ArduinoDue

TheArduinoDueisamicrocontrollerboardbasedontheAtmelSAM3X8EARMCortex-M3CPU.Youcandownloadthedatasheet,http://www.atmel.com/Images/doc11057.pdf.

IfyouwanttoknowaboutArduinoDue,Irecommendtovisitthiswebsite,http://arduino.cc/en/Main/ArduinoBoardDue.

http://arduino.cc/en/Main/ArduinoBoardMega2560http://www.atmel.com/Images/doc11057.pdfhttp://arduino.cc/en/Main/ArduinoBoardDue

1.2ElectronicComponents

Weneedelectroniccomponentstobuildourtesting,forinstance,Resistor,LED,sensordevicesandetc.Irecommendyoucanbuyelectroniccomponentkit.

1.2.1ArduinoStarterKit

Storewebsite:http://arduino.cc/en/Main/ArduinoStarterKit

1.2.2Fritzing

Storewebsite:http://shop.fritzing.org/.

YoucanbuyFritzingStarterKitwithArduinoUNOorFritzingStarterKitwithArduinoMega.

http://arduino.cc/en/Main/ArduinoStarterKithttp://shop.fritzing.org/

1.2.3Cooking-Hacks:ArduinoStarterKit

Storewebsite:http://www.cooking-hacks.com/index.php/shop/arduino/starter-kits/arduino-starter-kit.html

http://www.cooking-hacks.com/index.php/shop/arduino/starter-kits/arduino-starter-kit.html

1.2.4ArduinoSidekickBasickit

Storewebsite:http://www.seeedstudio.com/depot/arduino-sidekick-basic-kit-p-775.html

Alternativeonlinestore

http://www.amazon.com/Arduino-Sidekick-Basic-Kit-Version/dp/B007B14HM8/

http://www.exp-tech.de/Zubehoer/Arduino-Sidekick-Basic-Kit.html

http://www.seeedstudio.com/depot/arduino-sidekick-basic-kit-p-775.htmlhttp://www.amazon.com/Arduino-Sidekick-Basic-Kit-Version/dp/B007B14HM8/http://www.exp-tech.de/Zubehoer/Arduino-Sidekick-Basic-Kit.html

1.3Go

TheofficialwebofGocouldbefoundonhttps://golang.org/.WhatisGo?Basedoninformationfromwebsite,wecouldknowwhatitis.Goisanopensourceprogramminglanguagethatmakesiteasytobuildsimple,reliable,andefficientsoftware.

InstallationofGoapplicationiseasy.ForWindowsandMacPlatform,youdownloadsetupfilefromGowebsite,http://golang.org/doc/install.Runitandfollowinstallationcommands.

ThenextstepistoconfigureGOROOTpath.ForWindowsplatform,youcanaddGOROOTvariableonEnvironmentVariables.ForMac/Linux,youcanitonyourbashprofile.

https://golang.org/.http://golang.org/doc/install

ForWindowsplatform,youcanaddGOinstallationpath,forinstancemyGoinstallationpathisc:/go/bin,intoPATHvariableonEnvironmentVariables.

Afterconfigured,youcanverifyGoversionbytypingthiscommandonyourTerminalorCMDforWindows.

$goversion

AsampleoutputcanbeseeninFigurebelow,Macplatform.

TheoutputofprogramonWindowsplatform.

Inthisbook,IdontexploreallprogramminglanguageforGo.Youcanreaditonseveralbookorwebsite.IhavealreadywrittenabookaboutGoProgrammingbyExample.Youcangetthisbookonthislink,http://blog.aguskurniawan.net/post/Go-Programming-by-Example.aspx.

http://blog.aguskurniawan.net/post/Go-Programming-by-Example.aspx

1.4ArduinoSoftware

TodevelopapplicationbasedonArduinoboard,weneedArduinosoftware.Youcanobtainitonhttp://arduino.cc/en/Main/Software.Pleaseinstallbasedonyourplatform.

IfyourplatformisUbuntu,youcaninstallbywritingthisscriptsudoapt-getinstallarduino

ForWindowsplatform,youcandownloadsetupfileandinstallit.

ThefollowingisascreenshotofArduinosoftwareonUbuntuplatform.

HereisArduinosoftwareonWindows8platform.

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

IfyourunArduinosoftwareonWindowsplatform,youshouldconfigurearduino.exerunningasAdministrator.Youcanchangeitbyeditingfileproperty.ClickCompatibilityandthencheckedRunthisprogramasanadministrator.

1.5Testing

Fortesting,IusedArduinoUnoR3andArduinoMega2560onUbuntuandWindows8.1platforms.

IalsousedArduinoSidekickBasickitforelectroniccomponents.

2.HelloWorld:ArduinoandGo

ThischapterexplainshowtoworkwithArduinoandGoforgettingstarted.

2.1ArduinoWorld

AfteryouinstalledArduinosoftware,youcanpluginArduinohardwareintocomputerviaUSB.

ThenyouexecuteArduinosoftware.IngeneralitwilldetectArduinohardwareincludeArduinotypeandmodel.

2.1.1ArduinoHardwareDriveronWindows8/8.1

OnWindowsplatform,youmaygetaproblemaboutArduinohardwaredriver.ItdoesntberecognizedonWindowsDeviceManagerasbelow.

YoucanupdatethisdevicedriverbynavigatinghardwaredriveronthedriverfolderofArduinosoftwareinstallationfolder,forinstanceE:\arduino-1.0.2\drivers.

Sometimeyoumaygetaproblemespeciallyforx64editionaboutdigitalsignatureofArduinodriver,showninFigurebelow.

ConfiguretoignorethedigitalsignaturesettingsonyourWindows.NormallyyoucandoitbypressingF8keyonrestartingWindows.ThenchooseDisableDriversignatureEnforcement.

ForWindows8,youcandobyclickingRestartmenuandpressingSHIFTkey.SelectTroubleshoot.ThenselectAdvancedoptions.

OnAdvancedoptionsdisplay,selectStartupsettings,showninFigurebelow.

ClickRestartbutton.ThenWindows8willrestart.Afterthat,selectDisabledriversignatureenforcement.

NowyoucaninstallArduinodriveronyourWindows.

Ifsuccess,youcanseeArduinohardwareonTheDeviceManagerasbelow.

YoucanseeyourArduinohardwarerunningonCOM8.

2.1.2SimpleTesting

Nowyourereadytogetstarted.Forillustration,IusethesamplecodefromArduino,Blink.Youcanvisitonhttp://arduino.cc/en/Tutorial/Blinkforconfiguration.

Forthisscenario,youneedLEDandresistor.Attachresistortopin13.NegativepinofLEDisattachedtopinGND.Youcanseethehardwareconfigurationasbelow.

http://arduino.cc/en/Tutorial/Blink

OnArduinosoftware,ClickFile->Examples->01.Basics->Blink.

ThenyouwillgetasamplecodeofBlinkapp.

NowtrytoconnectyourArduinointocomputer.

CompileanduploadBlinkapptoArduinohardware.Ifsuccess,youcanseetheLEDwillbeon/offeverysecond.

2.2ArduinoandGo

TocommunicatebetweenArduinoandcomputer,wecanuseaserialcommunication.ItmeansGogivescommandandreceivesdataviaserialport.

OnGo,wecanuseseveralGopackages.ThefollowingisalistofGopackageforcommunicatingwithserialport:

GoSerial,https://code.google.com/p/goserial/go-serial,https://github.com/jacobsa/go-serial

Inthissection,IjustshowyouhowtouseGoSerialtocommunicatewithserialport.

https://code.google.com/p/goserial/https://github.com/jacobsa/go-serial

2.3TestingSerialPortusingGo

NowyoucanconnectyourArduinotocomputer.ForWindowsplatform,youcanverifybyopeningDeviceManagerandexpandPorts(COM&LPT).YoucanseeCOMyourArduinoused.

ForDebian/Ubuntu/Mac,youcancheckitbytypingonterminalls/dev/ttyACM*

YoucanseeArduinoserialport.Hereisasampleoutput./dev/ttyACM0

Nowwecreateprojectcalledserialtestbycreatingafolder,serialtest.$mkdirserialtest

$cdserialtest

Createafile,calledmain.go.Writethefollowingcode.packagemain

import("github.com/tarm/goserial""fmt")

funcmain(){c:=&serial.Config{Name:"COM6",Baud:9600}s,err:=serial.OpenPort(c)iferr!=nil{panic(err)}defers.Close()fmt.Println("connected")}

Note:changeyourserialport.Inthissection,myArduinoisconnectedtoCOM6inWindowsplatform.

BecauseweuseexternalpackagefromGithub,youmustinstallgitruntime.

ToinstallGolibraryfromGithub,youmustinstalgit,http://git-scm.com/.Downloaditbasedonyourplatform.IfyouuseWindowsplatform,dontforgettosetitonPATHonEnvironmentVariables.

http://git-scm.com/

ThenextstepistoconfigureGOPATH.Itrepresentsourworkspacepath,forinstance,myworkspacepathisD:\PE_PRESS\eBook\arduino_go\codes.InLinux/Mac,youcandefineyourownworkspacepathinunderyouraccounthomepath,forinstance.Furtherinformation,youcanreaditonhttps://golang.org/doc/code.html.

IfyouuseLinux/Mac,youcandefineGOPATHusingexportcommandoryouadditonyourprofilefile.

$mkdir$HOME/go$exportGOPATH=$HOME/go

IfyouuseWindowsplatform,youopenEnvironmentVariables.YoucanopenitfromAdvancedsystemsettings.Then,clickEnvironmentVariablesbutton.AddGOPATHonyouruserandSystemvariables.

https://golang.org/doc/code.html

NowwecaninstallgoseriallibraryfromGithub.Typethefollowingcommand.$gogetgithub.com/tarm/goserial

Savethiscodeonmain.gofile.

Nowyoucanbuildandrunthisprogram.DontforgettoconnectyourArduinointoPCviaUSB.

$gobuild$gorunmain.go

AprogramoutputcanbeseeninFigurebelow.

2.4TestingforArduinoandGo

NowwetestforcommunicatingbetweenArduinoandGo.Inthisscenario,webuildArduinoapptosenddatatoserialport.Then,Goappwillreceivethismessagebylisteningonserialport.

ThefirststepistocreateArduinoapp.FromBlinkArduinoapp,youcanmodifythiscode.Writethiscode:

intled=13;

voidsetup(){pinMode(led,OUTPUT);Serial.begin(9600);}

voidloop(){digitalWrite(led,HIGH);Serial.write("LEADisHIGH\n");delay(1000);digitalWrite(led,LOW);Serial.write("LEADisLOW\n");delay(1000);}

Explanation

Onsetup(),weactivateserialporton9600baudrateandLEDonpin13Onloop(),wewriteHIGHonpin13andthensendamessageLEADisHIGH\ntoserialportWealsodoitagain.ItwritesLOWvalueandsendsamessageLEADisLOW\ntoserialport

Savethiscodeasblinked.CompileanduploadthiscodetoArduinohardware.

MakesureyoualreadyconfigureArduinoboardandserialportofArduinoboard.

YoucancompilebyclickingiconcheckedanddeploytoArduinobyclickingiconarrow.

YoucanchecktheserialportresponseusingSerialMonitor.ClickmenuTools->SerialMonitor.YouwillseemessagesfromArduinohardware.

Onthenextstep,wecreateGoapp.BasicallywecreateaGoapptolistenincomingmessagesfromserialport.Createaproject,calledserialdemo,bycreatingfolder,serialdemo.

$mkdirserialdemo$cdserialdemo


import("github.com/tarm/goserial""fmt""strings")

funcmain(){//openserialportArduino//changeportvaluebasedonyourplatformc:=&serial.Config{Name:"COM6",Baud:9600}s,err:=serial.OpenPort(c)iferr!=nil{panic(err)}defers.Close()

//readdatainbackgroundgofunc(){buf:=make([]byte,128)str:=""for{n,err:=s.Read(buf)iferr!=nil{panic(err)}str=fmt.Sprintf("%s%s",str,string(buf[:n]))ifstrings.Index(str,"\n")>=0{ind:=strings.Index(str,"\n")temp:=str[:ind+1]str=fmt.Sprintf("%s",str[ind+1:])fmt.Printf("%s",temp)}

}}()

//pressENTERtoexitfmt.Println("pressEntertoexit..")varinputstringfmt.Scanln(&input)fmt.Println("done")

}

Note:changeyourArduinoserialport.

Savethiscodeonmain.gofile.



Hereisasampleofprogramoutput.

YoucanseetheincomingmessagefromserialportofArduino.Toexitfromprogram,youpressENTERfromyourPCkeyboard.

3.ExploringGoPackagesforArduino

InthischapterImgoingtoexplainhowtouseexternalGopackagestoaccessArduinodirectly.

3.1GettingStarted

ToaccessArduino,wecandoinmanyways.OneofthemistouseFirmataprotocol,http://firmata.org/.YoufindmanyGopackageswhichimplementFirmataprotocol.ThefollowingisalistofGopackagetoimplementFirmataprotocol.

Gobot,http://gobot.io/go-firmata,https://github.com/kraman/go-firmatagofirmata,https://github.com/choffee/gofirmata

TouseArduinowithFirmataprotocolonArduino,wemustloadFirmataprotocolmoduleonArduino.FirstlywemustloadFirmataprotocolonyourArduinoboard.OpenArduinosoftwareandclickmenuFile->Examples->Firmata->StandardFirmata.

http://firmata.org/http://gobot.io/https://github.com/kraman/go-firmatahttps://github.com/choffee/gofirmata

ThenyouobtainFirmatacodes.

NowyoucancompileanddeployFirmataProtocolcodeintoyourArduinoboard.DontforgettoselectyourArduinoboardmodelandserialport.

Thenextstepistobuildasimpleapp,blinkingled,usingGowithGobotandgo-firmatapackages.

3.2Gobot

Gobotisaframeworkforrobotics,physicalcomputing,andtheInternetofThings,writtenintheGoprogramminglanguage.Furtherinformationaboutgobot,youcanvisittheofficialwebsiteonhttp://gobot.io/.

Inthissection,wetrytoaccessArduinoviagobot.Toinstallgobotpackage,youmustinstallthefollowingruntime:

git,http://git-scm.com/mercurial,http://mercurial.selenic.com/wiki/Download

Nowyoucaninstallgobotpackagewiththefollowingcommand$goget-d-ugithub.com/hybridgroup/gobot/...

YoualsoinstallFirmataforGobotpackage.Typethiscommand.$gogetgithub.com/hybridgroup/gobot&&goinstallgithub.com/hybridgroup/gobot/platforms/firmata

http://gobot.io/http://git-scm.com/http://mercurial.selenic.com/wiki/Download

Forillustration,webuildasimpleapp,blinkingled.WeuseLEDontheboard,LEDonpin13.

Nowwecreateprojectcalledledgobotbycreatingafolder,ledgobot.$mkdirledgobot$cdledgobot


import("fmt""time""github.com/hybridgroup/gobot""github.com/hybridgroup/gobot/platforms/firmata""github.com/hybridgroup/gobot/platforms/gpio")

funcmain(){gbot:=gobot.NewGobot()

//changeArduinoport,windowsCOMx.Linux/dev/ttyACMxfirmataAdaptor:=firmata.NewFirmataAdaptor("arduino","COM6")led:=gpio.NewLedDriver(firmataAdaptor,"led","13")

//functiontorunledblinkingwork:=func(){gobot.Every(1*time.Second,func(){fmt.Println("ledtoggling..")led.Toggle()})}

gbot.AddRobot(gobot.NewRobot("bot",[]gobot.Connection{firmataAdaptor},[]gobot.Device{led},work,))

gbot.Start()}

Savethiscodeandrunit.


$gobuild

$gorunmain.go

Onconsole,youcanseetheoutputasbelow.

Then,youcanseeLEDisblinkingontheArduinoboard.

3.3go-firmata

ThesecondFirmatapackageforGoisgo-firmata.Youcanreaditonhttps://github.com/kraman/go-firmata.Youcaninstallthispackagebytypingthiscommand.

$gogetgithub.com/kraman/go-firmata

Forillustration,webuildasimpleapp,blinkingled.WeuseLEDontheboard,LEDonpin13.

Nowwecreateprojectcalledfirmataclientbycreatingafolder,firmataclient.$mkdirfirmataclient$cdfirmataclient


import("fmt""time""github.com/kraman/go-firmata"

)

funcmain(){board,err:=firmata.NewClient("COM6",57600)iferr!=nil{panic(err)}deferboard.Close()fmt.Println("SetPinMode")board.SetPinMode(13,firmata.Output)

gofunc(){fmt.Println("gorun")for{fmt.Println("LEDON")board.DigitalWrite(13,true)time.Sleep(1*time.Second)fmt.Println("LEDOFF")board.DigitalWrite(13,false)time.Sleep(1*time.Second)}}()

//pressENTERtoexitfmt.Println("pressEntertoexit..")

https://github.com/kraman/go-firmata

varinputstringfmt.Scanln(&input)fmt.Println("done")}





3.4ReadingDigitalInput

Aftercreatedablinkingled,wecancontinuetobuildappwhichreadsdigitalinput.Weneedaswitch/buttonandaLED.ConnectyourdigitalswitchonArduinodigitalpin6andLEDonArduinodigital9.

3.4.1gobot

Youcreateprojectcalledgobuttonbycreatingafolder,gobutton.$mkdirgobutton$cdgobutton


import("fmt""time""github.com/hybridgroup/gobot""github.com/hybridgroup/gobot/platforms/firmata""github.com/hybridgroup/gobot/platforms/gpio")

funcmain(){

gbot:=gobot.NewGobot()

//changeArduinoport,windowsCOMx.Linux/dev/ttyACMxfirmataAdaptor:=firmata.NewFirmataAdaptor("myFirmata","COM6")

//createabuttonondigitalpin6andaledondigitalpin9button:=gpio.NewButtonDriver(firmataAdaptor,"myButton","6")led:=gpio.NewLedDriver(firmataAdaptor,"led","9")

work:=func(){gobot.On(button.Event("push"),func(datainterface{}){fmt.Println("buttonispressed")led.On()})gobot.On(button.Event("release"),func(datainterface{}){fmt.Println("buttonisreleased")led.Off()})}

gbot.AddRobot(gobot.NewRobot("bot",

[]gobot.Connection{firmataAdaptor},[]gobot.Device{button,led},work,))

gbot.Start()

}




PressthebuttonsoyoucanseeLEDisON.


Asampleoutputonhardwareschema.

3.4.2go-firmata

Createprojectcalledfirmatabuttonbycreatingafolder,firmatabutton.$mkdirfirmatabutton$cdfirmatabutton


import("fmt""time""github.com/kraman/go-firmata"

)

funcmain(){board,err:=firmata.NewClient("COM6",57600)iferr!=nil{panic(err)}deferboard.Close()//LEDondigitalpin9board.SetPinMode(9,firmata.Output)//buttonondigitalpin6board.SetPinMode(6,firmata.Input)board.EnableDigitalInput(6,true)

gofunc(){

forbuttonVal:=rangeboard.GetValues(){_,val,_:=firmata.FirmataValue(buttonVal).GetDigitalValue()

ifval[6]==true{fmt.Println("LEDON")board.DigitalWrite(9,true)}else{fmt.Println("LEDOFF")board.DigitalWrite(9,false)}

time.Sleep(700*time.Millisecond)}

}()

//pressENTERtoexitfmt.Println("pressEntertoexit..")varinputstringfmt.Scanln(&input)fmt.Println("done")}



$gobuild

$gorunmain.go

PressthebuttonsoyoucanseeLEDisON.


4.AnalogSensor

InthischapterImgoingtoexplainhowtoaccesssensordataonArduinowithsensordevice.Inthissection,Iusego-firmata,https://github.com/kraman/go-firmatatodevelopGoapplicationtoaccesssensordeviceonArduino.


4.1SensorDevices

Arduinocanbeinterfacedwithsensordevices.Youcanseethelistofsensorinterfaceonhttp://playground.arduino.cc/Main/InterfacingWithHardware.

Inthisscenario,weusecheapsensordevices,ThemistorsandLDR(LightDependentResistors).ThermistorcanbeusedtomeasuretemperatureandLDRcanbeusedtomeasurelightanddarkbasedonillumination.

IhaveThermistor503andLDRfromArduinoSidekickBasickit.

Forbuildingsensorhardware,weneed2resistors,50kohmand10kohm.Ifyourthermistoris10kohm,youshouldusearesistorwith10kohm.

ThefollowingisacircuitschemaforThermistorandLDRsensors.

http://playground.arduino.cc/Main/InterfacingWithHardware

Oneofsensorpinisconnectedto5VArduinopin.Weuseadividerapproach.Thermistor503isattachedtotheAnalogInofArduino,A0.Otherwise,LDRisattachedtoA2.

YoumayattachLEDastheindicatorforsensorreadingstate.Youcanuseasolutiononchapter2,Blinkapp.

Hereisasampleofhardwareimplementation.

YoualsocanuseArduinoshieldwhichsensordevicesarebeconnected,forinstance,IuseLinkerkitfromhttp://store.linksprite.com/linker-kit/withthefollowingsensoritems:

LDR,http://store.linksprite.com/ldr-ambient-light-module-of-linker-kit-for-pcduino-arduino/Temperaturesensor,http://store.linksprite.com/thermal-module-of-linker-kit-for-pcduino-arduino/

HardwareimplementationcanbeseeninFigurebelow.

http://store.linksprite.com/linker-kit/http://store.linksprite.com/ldr-ambient-light-module-of-linker-kit-for-pcduino-arduino/http://store.linksprite.com/thermal-module-of-linker-kit-for-pcduino-arduino/

4.2ReadingSensor

HowtoreadthesensordatafromArduino?.Weusego-firmata,https://github.com/kraman/go-firmata.ToaccessArduinoAnalogfromFirmata,wecanconvertthefollowingpin:

ArduinoanalogA0>Firmatapin14ArduinoanalogA1>Firmatapin15ArduinoanalogA2>Firmatapin16ArduinoanalogA3>Firmatapin17

Firstly,wecreateprojectcalledsensordemobycreatingafolder,sensordemo.$mkdirsensordemo$cdsensordemo


import("fmt""math""time"arduino"github.com/kraman/go-firmata"

)

funcmain(){board,err:=arduino.NewClient("COM6",57600)iferr!=nil{panic(err)}deferboard.Close()

//LDRonA0=Pin14err1:=board.EnableAnalogInput(14,true)iferr1!=nil{panic(err1)}//TemperatureonA2=Pin16err2:=board.EnableAnalogInput(16,true)iferr2!=nil{panic(err2)}gofunc(){

for{


forsensorVal:=rangeboard.GetValues(){pin,val,_:=arduino.FirmataValue(sensorVal).GetAnalogValue()fmt.Println(pin,":",val)

ifpin==16{//linkerkittemperatureC:=CalculateTempLinkerKit(float64(val))//Thermistor//temperatureC:=CalculateThermistor(float64(val))fmt.Println("Temperature:",temperatureC,"degreesC"}

ifpin==14{

//ifyouuseLDR//ldr:=val//ifyouuseLDRfromlinkerkitldr:=CalculateLDR(float64(val))ifldr

Getting Started With Arduino and Go by Agus Kurniawan

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