AT89S52单片机 外文文献 英文文献 外文翻译中英对照.docx

AT89S52单片机 外文文献 英文文献 外文翻译中英对照.docx

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AT89S52

Features

•CompatiblewithMCS-51Products

•8KBytesofIn-SystemProgrammable（ISP）FlashMemory一Endurance:

10,000Write/EraseCycles

•4.0Vto5.5VOperatingRange

•FullyStaticOperation:

0Hzto33MHz

•Three-levelProgramMemoryLock

•256x8-bitInternalRAM

•32ProgrammableI/OLines

•Three16-bitTimer/Counters

•EightInterruptSources

•FullDuplexUARTSerialChannel

•Low-powerIdleandPower-downModes

•InterruptRecoveryfromPower-downMode

•WatchdogTimer•DualDataPointer

•Power-offFlag•FastProgrammingTime

•FlexibleISPProgramming（ByteandPageMode）

•Green（Pb/Halide-free）PackagingOption

1.Description

TheAT89S52isalow-power,high-performanceCMOS8-bitmicrocontrollerwith8Kbytesofin-systemprogrammableFlashmemory.ThedeviceismanufacturedusingAtmeFshigh-densitynonvolatilememorytechnologyandiscompatiblewiththeindus-try-standard80C51instructionsetandpinout.Theon-chipFlashallowstheprogrammemorytobereprogrammedin-systemorbyaconventionalnonvolatilememorypro-grammer.Bycombiningaversatile8-bitCPUwithin-systemprogrammableFlashonamonolithicchip,theAtmelAT89S52isapowerfulmicrocontrollerwhichprovidesahighly-flexibleandcost-effectivesolutiontomanyembeddedcontrolapplications.

TheAT89S52providesthefollowingstandardfeatures:

8KbytesofFlash,256bytesofRAM,32I/Olines,Watchdogtimer,twodatapointers,three16-bittimer/counters,asix-vectortwo-levelinterruptarchitecture,afullduplexserialport,on-chiposcillator,andclockcircuitry.Inaddition,theAT89S52isdesignedwithstaticlogicforoperationdowntozerofrequencyandsupportstwosoftwareselectablepowersavingmodes.TheIdleModestopstheCPUwhileallowingtheRAM,timer/counters,serialport,andinterruptsystemtocontinuefunctioning.ThePower-downmodesavestheRAMcon-tentsbutfreezestheoscillator,disablingallotherchipfunctionsuntilthenextinterruptorhardwarereset.

2.PinDescription

VCC:

Supplyvoltage.

GND:

Ground.

Port0：

Port0isan8-bitopendrainbidirectionalI/Oport.Asanoutputport,eachpincansinkeightTTLinputs.WhenIsarewrittentoport0pins,thepinscanbeusedashigh-impedanceinputs.Port0canalsobeconfiguredtobethemultiplexedlow-orderaddress/databusduringaccessestoexternalprogramanddatamemory.Inthismode,P0hasinternalpull-ups.Port0alsoreceivesthecodebytesduringFlashprogrammingandoutputsthecodebytesdur-ingprogramverification.Externalpull-upsarerequiredduringprogramverification.

Port1：

Port1isan8-bitbidirectionalI/Oportwithinternalpull-ups.ThePort1outputbufferscansink/sourcefourTTLinputs.WhenIsarewrittentoPort1pins,theyarepulledhighbytheinter-nalpull-upsandcanbeusedasinputs.Asinputs,Port1pinsthatareexternallybeingpulledlowwillsourcecurrent（IIL）becauseoftheinternalpull-ups.Inaddition,P1.0andPl.lcanbeconfiguredtobethetimer/counter2externalcountinput（P1.0/T2）andthetimer/counter2triggerinput（P1.1/T2EX）,respectively,asshowninthefollow-ingtable.

Port1alsoreceivesthelow-orderaddressbytesduringFlashprogrammingandverification.

Tablel

PortPin

AlternateFunctions

Pl.0

T2（externalcountinputtoTimer/Counter2）,clock-out

Pl.l

T2EX（Timer/Counter2capture/reloadtriggeranddirectioncontrol）

Pl.5

MOSI（usedforIn-SystemProgramming）

Pl.6

MISO（usedforIn-SystemProgramming）

Pl.7

SCK（usedforIn-SystemProgramming）

Port2：

Port2isan8-bitbidirectionalI/Oportwithinternalpull-ups.ThePort2outputbufferscansink/sourcefourTTLinputs.WhenIsarewrittentoPort2pins,theyarepulledhighbytheinter-nalpull-upsandcanbeusedasinputs.Asinputs,Port2pinsthatareexternallybeingpulledlowwillsourcecurrent（IIL）becauseoftheinternalpull-ups.Port2emitsthehigh-orderaddressbyteduringfetchesfromexternalprogrammemoryanddur-ingaccessestoexternaldatamemorythatuse16-bitaddresses（MOVX@DPTR）.Inthisapplication,Port2usesstronginternalpull-upswhenemittingIs.Duringaccessestoexternaldatamemorythatuse8-bitaddresses（MOVX@RI）,Port2emitsthecontentsoftheP2SpecialFunctionRegister.Port2alsoreceivesthehigh-orderaddressbitsandsomecontrolsignalsduringFlashprogram-mingandverification.

Port3：

Port3isan8-bitbidirectionalI/Oportwithinternalpull-ups.ThePort3outputbufferscansink/sourcefourTTLinputs.WhenIsarewrittentoPort3pins,theyarepulledhighbytheinter-nalpull-upsandcanbeusedasinputs.Asinputs,Port3pinsthatareexternallybeingpulledlowwillsourcecurrent（IIL）becauseofthepull-ups.Port3receivessomecontrolsignalsforFlashprogrammingandverification.Port3alsoservesthefunctionsofvariousspecialfeaturesoftheAT89S52,asshowninthefol-lowingtable.

Table2

PortPin

AlternateFunctions

P3.0

RXD（serialinputport）

P3.1

TXD（serialoutputport）

P3.2

INTO（externalinterrupt0）

P3.3

INTI（externalinterrupt1）

P3.4

TO（timer0externalinput）

P3.5

T1（timer1externalinput）

P3.6

WR（externaldatamemorywritestrobe）

P3.7

RD（externaldatamemoryreadstrobe）

RST:

Resetinput.Ahighonthispinfortwomachinecycleswhiletheoscillatorisrunningresetsthedevice.Thispindriveshighfor98oscillatorperiodsaftertheWatchdogtimesout.TheDISRTObitinSFRAUXR（address8EH）canbeusedtodisablethisfeature.InthedefaultstateofbitDISRTO,theRESETHIGHoutfeatureisenabled.

ALE/PROG:

AddressLatchEnable（ALE）isanoutputpulseforlatchingthelowbyteoftheaddressduringaccessestoexternalmemory.Thispinisalsotheprogrampulseinput（PROG）duringFlashprogramming.Innormaloperation,ALEisemittedataconstantrateof1/6theoscillatorfrequencyandmaybeusedforexternaltimingorclockingpurposes.Note,however,thatoneALEpulseisskippeddur-ingeachaccesstoexternaldatamemory.Ifdesired,ALEoperationcanbedisabledbysettingbit0ofSFRlocation8EH.Withthebitset,ALEisactiveonlyduringaMOVXorMOVCinstruction.Otherwise,thepinisweaklypulledhigh.SettingtheALE-disablebithasnoeffectifthemicrocontrollerisinexternalexecutionmode.

PSEN:

ProgramStoreEnable（PSEN）isthereadstrobetoexternalprogrammemory.

WhentheAT89S52isexecutingcodefromexternalprogrammemory,PSENisactivatedtwiceeachmachinecycle,exceptthattwoPSENactivationsareskippedduringeachaccesstoexter-naldatamemory.

EA/VPP：

ExternalAccessEnable.EAmustbestrappedtoGNDinordertoenablethedevicetofetchcodefromexternalprogrammemorylocationsstartingat0000HuptoFFFFH.Note,however,thatiflockbit1isprogrammed,EAwillbeinternallylatchedonreset.EAshouldbestrappedtoVCCforinternalprogramexecutions.Thispinalsoreceivesthe12-voltprogrammingenablevoltage（VPP）duringFlashprogramming.

XTAL1：

Inputtotheinvertingoscillatoramplifierandinputtotheinternalclockoperatingcircuit.

XTAL2：

Outputfromtheinvertingoscillatoramplifier.

3.MemoryOrganization

MCS-51deviceshaveaseparateaddressspaceforProgramandDataMemory.Upto64KbyteseachofexternalProgramandDataMemorycanbeaddressed.

3.1ProgramMemory

IftheEApinisconnectedtoGND,allprogramfetchesaredirectedtoexternalmemory.OntheAT89S52,ifEAisconnectedtoVCC,programfetchestoaddresses0000Hthrough1FFFHaredirectedtointernalmemoryandfetchestoaddresses2000HthroughFFFFHaretoexternalmemory.

3.2DataMemory

TheAT89S52implements256bytesofon-chipRAM.Theupper128bytesoccupyaparalleladdressspacetotheSpecialFunctionRegisters.Thismeansthattheupper128byteshavethesameaddressesastheSFRspacebutarephysicallyseparatefromSFRspace.Whenaninstructionaccessesaninternallocationaboveaddress7FH,theaddressmodeusedintheinstructionspecifieswhethertheCPUaccessestheupper128bytesofRAMortheSFRspace.InstructionswhichusedirectaddressingaccesstheSFRspace.Forexample,thefollowingdirectaddressinginstructionaccessestheSFRatlocationOAOH（whichisP2）.

MOVOAOH,#data

Instructionsthatuseindirectaddressingaccesstheupper128bytesofRAM.Forexample,thefollowingindirectaddressinginstruction,whereROcontainsOAOH,accessesthedatabyteataddressOAOH,ratherthanP2（whoseaddressisOAOH）.

MOV@R0,#data

Notethatstackoperationsareexamplesofindirectaddressing,sotheupper128bytesofdataRAMareavailableasstackspace.

4.WatchdogTimer（One-timeEnabledwithReset-out）

TheWDTisintendedasarecoverymethodinsituationswheretheCPUmaybesubjectedtosoftwareupsets.TheWDTconsistsofa14-bitcounterandtheWatchdogTimerReset（WDTRST）SFR.TheWDTisdefaultedtodisablefromexitingreset.ToenabletheWDT,ausermustwrite01EHand0E1HinsequencetotheWDTRSTregister（SFRlocation0A6H）.WhentheWDTisenabled,itwillincrementeverymachinecyclewhiletheoscillatorisrunning.TheWDTtimeoutperiodisdependentontheexternalclockfrequency.ThereisnowaytodisabletheWDTexceptthroughreset（eitherhardwareresetorWDToverflowreset）.WhenWDTover-flows,itwilldriveanoutputRESETHIGHpulseattheRSTpin.

4.1UsingtheWDT

ToenabletheWDT,ausermustwrite01EHand0E1HinsequencetotheWDTRSTregister（SFRlocation0A6H）.WhentheWDTisenabled,theuserneedstoserviceitbywriting01EHand0E1HtoWDTRSTtoavoidaWDToverflow.The14-bitcounteroverflowswhenitreaches16383（3FFFH）,andthiswillresetthedevice.WhentheWDTisenabled,itwillincrementeverymachinecyclewhiletheoscillatorisrunning.T