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单片机温度控制系统外文翻译外文文献英文文献中英翻译

DesignoftheTemperatureControlSystemBasedonAT89C51

ABSTRACT

TheprincipleandfunctionsofthetemperaturecontrolsystembasedonmicrocontrollerAT89C51arestudied,andthetemperaturemeasurementunitconsistsofthe1-WirebusdigitaltemperaturesensorDS18B20。

Thesystemcanbeexpectedtodetectthepresettemperature,displaytimeandsavemonitoringdata。

Analarmwillbegivenbysystemifthetemperatureexceedstheupperandlowerlimitvalueofthetemperaturewhichcanbesetdiscretionarilyandthenautomaticcontrolisachieved,thusthetemperatureisachievedmonitoringintelligentlywithinacertainrange。

Basingonprincipleofthesystem,itiseasytomakeavarietyofothernon-linearcontrolsystemssolongasthesoftwaredesignisreasonablychanged。

Thesystemhasbeenprovedtobeaccurate,reliableandsatisfiedthroughfieldpractice。

KEYWORDS:

AT89C51;microcontroller;DS18B20;temperature

1INTRODUCTION

Temperatureisaveryimportantparameterinhumanlife。

Inthemodernsociety,temperaturecontrol(TC)isnotonlyusedinindustrialproduction,butalsowidelyusedinotherfields.Withtheimprovementofthelifequality,wecanfindtheTCapplianceinhotels,factoriesandhomeaswell.AndthetrendthatTCwillbetterservethewholesociety,soitisofgreatsignificancetomeasureandcontrolthetemperature.BasedontheAT89C51andtemperaturesensorDS18B20,thissystemcontrolstheconditiontemperatureintelligently。

Thetemperaturecanbesetdiscretionarilywithinacertainrange.ThesystemcanshowthetimeonLCD,andsavemonitoringdata;andautomaticallycontrolthetemperaturewhentheconditiontemperatureexceedstheupperandlowerlimitvalue.Bydoingsoitistokeepthetemperatureunchanged。

Thesystemisofhighanti-jamming,highcontrolprecisionandflexibledesign;italsofitstheruggedenvironment。

Itismainlyusedinpeople’slifetoimprovethequalityoftheworkandlife.Itisalsoversatile,sothatitcanbeconvenienttoextendtheuseofthesystem。

Sothedesignisofprofoundimportance.Thegeneraldesign,hardwaredesignandsoftwaredesignofthesystemarecovered.

1。

1Introduction

The8-bitAT89C51CHMOSmicrocontrollersaredesignedtohandlehigh—speedcalculationsandfastinput/outputoperations.MCS51microcontrollersaretypicallyusedforhigh—speedeventcontrolsystems.Commercialapplicationsincludemodems,motor—controlsystems,printers,photocopiers,airconditionercontrolsystems,diskdrives,andmedicalinstruments。

TheautomotiveindustryuseMCS51microcontrollersinengine—controlsystems,airbags,suspensionsystems,andantilockbrakingsystems(ABS)。

TheAT89C51isespeciallywellsuitedtoapplicationsthatbenefitfromitsprocessingspeedandenhancedon-chipperipheralfunctionsset,suchasautomotivepower-traincontrol,vehicledynamicsuspension,antilockbraking,andstabilitycontrolapplications.Becauseofthesecriticalapplications,themarketrequiresareliablecost—effectivecontrollerwithalowinterruptlatencyresponse,abilitytoservicethehighnumberoftimeandeventdrivenintegratedperipheralsneededinrealtimeapplications,andaCPUwithaboveaverageprocessingpowerinasinglepackage。

Thefinancialandlegalriskofhavingdevicesthatoperateunpredictablyisveryhigh.Onceinthemarket,particularlyinmissioncriticalapplicationssuchasanautopilotoranti-lockbrakingsystem,mistakesarefinanciallyprohibitive。

Redesigncostscanrunashighasa$500K,muchmoreifthefixmeans2backannotatingitacrossaproductfamilythatsharethesamecoreand/orperipheraldesignflaw。

Inaddition,fieldreplacementsofcomponentsisextremelyexpensive,asthedevicesaretypicallysealedinmoduleswithatotalvalueseveraltimesthatofthecomponent。

Tomitigatetheseproblems,itisessentialthatcomprehensivetestingofthecontrollersbecarriedoutatboththecomponentlevelandsystemlevelunderworstcaseenvironmentalandvoltageconditions。

Thiscompleteandthoroughvalidationnecessitatesnotonlyawell—definedprocessbutalsoaproperenvironmentandtoolstofacilitateandexecutethemissionsuccessfully。

IntelChandlerPlatformEngineeringgroupprovidespostsiliconsystemvalidation(SV)ofvariousmicro—controllersandprocessors。

Thesystemvalidationprocesscanbebrokenintothreemajorparts。

Thetypeofthedeviceanditsapplicationrequirementsdeterminewhichtypesoftestingareperformedonthedevice。

1.2TheAT89C51providesthefollowingstandardfeatures

4KbytesofFlash,128bytesofRAM,32I/Olines,two16-bittimer/counters,afivevectortwo-levelinterruptarchitecture,afulldupleser—ialport,on—chiposcillatorandclockcircuitry.Inaddition,theAT89C51isdesignedwithstaticlogicforoperationdowntozerofrequencyandsupportstwosoftwareselectablepowersavingmodes.TheIdleModestopstheCPUwhileallowingtheRAM,timer/counters,serialportandinterruptsys—temtocontinuefunctioning。

ThePower—downModesavestheRAMcontentsbutfreezestheoscil–latordisablingallotherchipfunctionsuntilthenexthardwarereset。

1.3PinDescription

VCCSupplyvoltage。

GNDGround。

Port0:

Port0isan8-bitopen—drainbi—directionalI/Oport.Asanoutputport,eachpincansinkeightTTLinputs.When1sarewrittentoport0pins,thepinscanbeusedashighimpedanceinputs.Port0mayalsobeconfiguredtobethemultiplexedloworderaddress/databusduringaccessestoexternalprogramanddatamemory.InthismodeP0hasinternalpullups.Port0alsoreceivesthecodebytesduringFlashprogramming,andoutputsthecodebytesduringprogramverification。

Externalpullupsarerequiredduringprogramverification.

Port1:

Port1isan8-bitbi-directionalI/Oportwithinternalpullups.ThePort1outputbufferscansink/so-urcefourTTLinputs.When1sarewrittentoPort1pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs。

Asinputs,Port1pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseoftheinternalpullups。

Port1alsoreceivesthelow-orderaddressbytesduringFlashprogrammingandverification.

Port2:

Port2isan8-bitbi-directionalI/Oportwithinternalpullups.ThePort2outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort2pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port2pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseoftheinternalpullups.Port2emitsthehigh—orderaddressbyteduringfetchesfromexternalprogrammemoryandduringaccessestoPort2pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseoftheinternalpullups.Port2emitsthehigh—orderaddressbyteduringfetchesfromexternalprogrammemoryandduringaccessestoexternaldatamemorythatuse16—bitaddresses(MOVX@DPTR).Inthisapplication,itusesstronginternalpull-upswhenemitting1s。

Duringaccessestoexternaldatamemorythatuse8-bitaddresses(MOVX@RI),Port2emitsthecontentsoftheP2SpecialFunctionRegister。

Port2alsoreceivesthehigh-orderaddressbitsandsomecontrolsignalsdurinFlashprogrammingandverification.

Port3:

Port3isan8—bitbi—directionalI/Oportwithinternalpullups。

ThePort3outputbufferscansink/sou—rcefourTTLinputs.When1sarewrittentoPort3pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs。

Asinputs,Port3pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseofthepullups。

Port3alsoservesthefunctionsofvariousspecialfeaturesoftheAT89C51aslistedbelow:

RST:

Resetinput.Ahighonthispinfortwomachinecycleswhiletheoscillatorisrunningresetsthedevice.

ALE/PROG:

AddressLatchEnableoutputpulseforlatchingthelowbyteoftheaddressduringaccessestoexternalmemory。

Thispinisalsotheprogrampulseinput(PROG)duringFlashprogramming。

InnormaloperationALEisemittedataconstantrateof1/6theoscillatorfrequency,andmaybeusedforexternaltimingorclockingpurposes.Note,however,thatoneALEpulseisskippedduri-ngeachaccesstoexternalDataMemory。

Ifdesired,ALEoperationcanbedisabledbysettingbit0ofSFRlocation8EH。

Withthebitset,ALEisactiveonlyduringaMOVXorMOVCinstruction.Otherwise,thepinisweaklypulledhigh。

SettingtheALE—disablebithasnoeffectifthemicrocontrollerisinexternalexecutionmode.

PSEN:

ProgramStoreEnableisthereadstrobetoexternalprogrammemory.WhentheAT89C51isexecutingcodefromexternalprogrammemory,PSENisactivatedtwiceeachmachinecycle,exceptthattwoPSENactivationsareskippedduringeachaccesstoexternaldatamemory.

EA/VPP:

ExternalAccessEnable。

EAmustbestrappedtoGNDinordertoenablethedevicetofetchcodefromexternalprogrammemorylocationsstartingat0000HuptoFFFFH.Note,however,thatiflockbit1isprogrammed,EAwillbeinternallylatchedonreset。

EAshouldbestrappedtoVCCforinternalprogramexecutions.Thispinalsreceivesthe12—voltprogrammingenablevoltage(VPP)duringFlashprogramming,forpartsthatrequire12-voltVPP。

XTAL1:

Inputtotheinvertingoscillatoramplifierandinputtotheinternalclockoperatingcircuit。

XTAL2:

Outputfromtheinvertingoscillatoramplifier.OscillatorCharacteristicsXTAL1andXTAL2aretheinputandoutput,respectively,ofaninvertingamplifierwhichcanbeconfiguredforuseasanon-chiposcillator,asshowninFigure1.Eitheraquartzcrystalorceramicresonatormaybeused。

Todrivethedevicefromanexternalclocksource,XTAL2shouldbeleftunconnectedwhileXTAL1isdrivenasshowninFigure2.Therearenorequirementsonthed

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