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ID:35656517
大小:89.81 KB
页数:14页
时间:2019-04-05
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1、TheIntroductionofAT89C51DescriptionTheAT89C51isalow-power,high-performanceCMOS8-bitmicrocomputerwith4KbytesofFlashprogrammableanderasablereadonlymemory(PEROM).ThedeviceismanufacturedusingAtmel’shigh-densitynonvolatilememorytechnologyandiscompatiblewiththei
2、ndustry-standardMCS-51instructionset.Theon-chipFlashallowstheprogrammemorytobereprogrammedin-systemorbyaconventionalnonvolatilememoryprogrammer.Bycombiningaversatile8-bitCPUwithFlashonamonolithicchip,theAtmelAT89C51isapowerfulmicrocomputerwhichprovidesahig
3、hly-flexibleandcost-effectivesolutiontomanyembeddedcontrolapplications.FunctioncharacteristicTheAT89C51providesthefollowingstandardfeatures:4KbytesofFlash,128bytesofRAM,32I/Olines,two16-bittimer/counters,one5vectortwo-levelinterruptarchitecture,afullduplex
4、serialport,one-chiposcillatorandclockcircuitry.Inaddition,theAT89C51isdesignedwithstaticlogicforoperationdowntozerofrequencyandsupportstwosoftwareselectablepowersavingmodes.TheIdleModestopstheCPUwhileallowingtheRAM,timer/counters,serialportandinterruptsyst
5、emtocontinuefunctioning.ThePower-downModesavestheRAMcontentsbutfreezestheoscillatordisablingallotherchipfunctionsuntilthenexthardwarereset.PinDescriptionVCC:Supplyvoltage.GND:Ground.Port0Port0isan8-bitopen-drainbi-directionalI/Oport.Asanoutputport,eachpinc
6、ansinkeightTTLinputs.When1sarewrittentoport0pins,thepinscanbeusedashigh-impedanceinputs.Port0mayalsobeconfiguredtobethemultiplexedaddress/databusduringaccessestoexternalprogramanddatamemory.InthismodeP0hasinternalPull-upresistor.Port0alsoreceivesthecodebyt
7、esduringFlashprogramming,andoutputsthecodebytesduringProgramverification.ExternalPull-upresistorsarerequiredduringProgramverification.Port1Port1isan8-bitbi-directionalI/OportwithinternalPull-upresistors.ThePort1outputbufferscansink/sourcefourTTLinputs.When
8、1sarewrittentoPort1pinstheyarepulledhighbytheinternalPull-upresistorsandcanbeusedasinputs.Asinputs,Port1pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseoftheinternalPull-upresistors.Port1alsor
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