C52和L298制作的寻迹小车(全英文的)

experiments.BuildasimpletwowheelsrobotwithL293DH-BridgedriverandIRsensors.WriteaCprogramcontrolsrobottrackedwithblacktape.FunwithVing-PeawCompetition2543,courselayout,day-by-daychangedruleandscoringalsoincluded。IntroductionOneofmystudenthasmadeadisgracefulrobotthatusedtwosteppermotorsandwithasimpleIRsensor.Yes,abovepictureiswhatImtalking.Withoutbatterycarrying,alittlebittorqueofthestepperandmisalignmentofdrivingshaft,makesitcrawlingnotwalking,butfirstdemo,showedquiteimpressivetome.HesaidhewroteacoupleofprogramlinesusingC,hisrobotcantracktheblacktape.Ifeeldelightedhisintentionandendeavor.Ithought,"heborrowedmeDS5000,expensiveone,asoftuControllerwithinternalbootloader,whyshouldnttrywithourlearningboardC-52EvaluationBoardinstead".Anotherone,toldmethesameday"IfoundtheL293Push/PullFourChannelDriveratBan-Moah,itcosts1.5US$".Ivebeensearchingthischipforayear.TheMiniBoard,aMotorola68HC11RobotControllerboarddesignedbyFredG.Martin,alsousesthisdriver.Thedayafter,IthendecidedtopreparethepagedescribinghowtouseC-52EVBasarobotcontrollerboard.Iaskedmystudentforcompetition,buildyourselvesrobotthatcantracktheblacktape.Prizeforthewinneris100US$,withabitconditionthatthewinnermustpayforabigpartyatSoiJindasSomtum(PapayaSalad)shop.Andoneofthecompetitorisme.Ithoughttheruleshouldbeconceivedroughlybystudentsandtechnicallybyme.Thepictureonthatdaywillputheresoon.C-52EVBresourcesBeforehand,letlookatavailableresourcesofC-52EVBforrobotexperiments.ActuatorsDCmotorPWMwithtimer2helpsP1.4,P1.5,P1.6,P1.7Sensorsdigital/analogIRdetectorwithcomparatorchip/foranaloginput,seeuseofPIC16C711digitalinput/T0,T1forpulseinputBrainCprogramavailablecodeanddataspaceapprox.32kB8000H-FFFFHProgramDownloaderRunningwithoutmonitorPAULMON2withPAULsstartupheader9600,8n1P3.0(RxD)andP3.1(TxD)DCMotorDriverBasiccircuitofusingL293formsanH-BridgeDriverisshowninFigure1.AsshownforsuchinductiveloadasDCmotor,externaldiodesforsuppressingbackEMFmustbeconnected.TheMiniBoardusesL293Dinstead,theL293Dhasinternaldiodes,howeverprovidingabitlessdrivingcapacity,i.e.,600mA@4.5V-36V.Fromthetruthtable,weseethatdirectionofthemotorcancontrolbypinCandD.VINHenable/disablepowertothemotor,thusforspeedregulation,wethenusethispinforPWMsignaling.Seedetails,L293.pdfdatasheet.Figure1:BasiccircuitofL293formsH-BridgeDriverAcircuitconnectingC-52P1toL293driverchipisshowninFigure2.AsshownEnablepin1connectedtoP1.0isforPWMsignaling.Weuseadditionalinverteratpin7andpin15toprovideproperlogicforeasydirectionalcontrol.Pleasenotethatpin4,5,12,13aretiedtogroundandifheatsinkingneeded,onemethodistomakealargeareaofPCBorsolderingitwithametalsheet,say.Figure2:ConnectingC-52EVBP1.4-P1.7toL293.ExternaldiodesmustbeconnectedforL293(notshownincircuitdiagram).MylatestdesignputadditionalinverterforPWMsignalatpin1andpin9topreventfullpowerdeliveringtoDCmotorswhenresettingthe89C52(i.e.,allbitsofP1islogichigh).CheckthelogicofPWMpinsforanothermicrocontrollers.LineTrackingSensor(IhavetoKUK)SincetheresnoADCfor89C52chip,eachcompetitormaybuildtheirownLineTrackingSensor,somemayuseLM339QUADcomparatorwithIRtransmitterandreceiver,somemayuseLDRasdescribedinLineFollowerRobot.Withanexternalcomparator,itmaynotnecessarytohaveADC,butwithLDR,weneedexternalADC."HavingadditionalADCfor89C52wouldbebetter",Ithought.HowcanweprovideADCfor89C52withacheapmethod?IchosePIC16C711with4-channelADC,and7-pininputport.Interfacingto89C52isdonewithsimplePISOprotocolbyusingRB0forSCLKandRA4forSDA.ThecodeforsuchpurposewaswritteninC,hereisthesourcefile,C52ADC.CandtheHEXcode,C52ADC.HEX.Aftersomeinitialization,the711chipwaitfortriggerreadsignalatpinRB0,i.e.,high-to-lowtransition,thenitresponsesbysending40-bitthroughRA4(SDA)withlow-to-hightransition.40-bitdatastreambeginswithLSBofADC0toMSBofPORTB.ExampleofprogramfrotestingADCisADC.CandthehexfileisADC.HEX.

Figure3:UsingPIC16C711tobea4-channelADCand7-bitinputportforC-52EVB.SimplePowerSupplyandChargerCircuitsFigure4showsasimplepowersupplycircuit.IhavetestedwithKABO,itworksfine.Forthosewhohaveabigcapacityrechargeablebattery,theresistancevalueofRcanbeselectedforapprox.10%outputchargingcurrent.DCincanbehigherifyourbatteryvoltagehigherthan8.4V,say.ToensuretheoutputcurrentiswithinthevaluecalculatedbyR,measureDCcurrentbefore.ThemaximumsupplyforLM317is~35V.Figure4:CircuitDiagramofbatterysupply+12VAlkalineand+8.4VNiMHwithaconstantcurrentrechargercircuit.For~20mA,useR~60Ohms.S1ismainswitchforCPUandL293circuits.UsingPAULsStartupHeaderfilewithMicro-CBeforewritingPWMgenerationfortestingabovecircuit,letstudyhowtousePaulsheader.WithaPAULsstartupheaderatthebeginningoftheapplicationCprogram,aftersuccessfullydownloadingthehexcode,justpressRESET,the89C52thenwillruntheapplicationinsteadofPAULMON2monitorprogram.AslongastheprogramremaininSRAM,runningtheprogramcanonlybedonewithpressingRESET.ToreturntoPAULMON2prompt,turntheboardpoweroffforawhile,thenbackthepoweronagain.ThisconceptofstartupheaderallowsustouseC-52EVBasadedicatedcontrollerbesideasalearningboard.OriginallyPaulhasmadewithentirelyinAssemblycode.However,IhaveadaptedforMicro-CCompiler.Ihaveputtheheaderforstartupcodeinthestartupandruntimelibraryforsmallmemorymodel.ThefileC52ROBOT.ASM,willcompileandlinktothemain()functionwithS=c52robot.asmwheninvokingcommandcoordinator.Exampleofcommandlineis;c:\mc\cc51%1-ilph=c:\mcm=ss=c52robot.asm%1ishello(.c),sayLettryhello.candcompilewithabovecommandline,downloadthehello.hexintotheC-52board,thenpressRESET,seewhathappen?ManualControlProgramdemonstratesPWMgenerationwithKABOOnemethodofdeliveringDCpowertomotorsistousePWM.ThePWMmethodsupplysDCpulsewithfixedfrequencybutwithadjustabledutycycle.IusedTIMER2inAUTOreloadproducing1000HzPWMfrequency.Eachtimeexecutinghasenteringintoserviceroutine,a16-bitPWM1wasshiftedouttoP1.7andPWM2toP1.6.Mainprogramhasataskthatsetthepowerformotor1andmotor2bywriting16-bitPWMpatternintoPWM1andPWM2formotor1andmortor2respectively.Theserviceroutinefortimer2isputinstartupcode.Seeexampleprogram,KABO1.CandC52ROBOT.ASM,forPWMdemonstrationwithmanualcontrol.Ihavedesignedandbuiltmyownrobotforthecompetitionalso.ItnamesKABOhavingdifferentialdrivemethod.Asshowninright-handside,istherarepartpoweredbyC52-EVB.ThemotordriverchipL293Danda74LS04areputatthesolderingpad.

Ving-PeawCompetitionIsupposethereshouldhavetenrobotstobecompeted.DetailsRuleandScoringwillb