single puterThemonolithicintegratedcircuitsaidthatthemonolithicmicrocontroller,itisnotcompletessomelogicalfunctionthechip,butintegratesacomputersystemtoachipon.Summaryspeaking:Achiphaseacomputer.Itsvolumeissmall,thequalityislight,andthepricecheap,forthestudy,theapplicationandthedevelopmenthasprovidedtheconvenientcondition.Atthesametime,thestudyusemonolithicintegratedcircuitisunderstandsthecomputerprincipleandthestructurebestchoice.Themonolithicintegratedcircuitinterioralsouseswiththecomputerfunctionsimilarmodule,forinstanceCPU,memory,parallelmainline,butalsohaswiththeharddiskbehaveidenticallythememorycomponent7whatisdifferentisitsthesepartperformanceisoppositeourhome-usecomputerweakmany,butthepriceisalsolow,generallydoesnotsurpass10YuanthenMadesomecontrolelectricapplianceonekindwithitisnotthe'verycomplexworkfoot,Weusenowthecompleyautomaticdrumwasher,thetoonpetti-coatpipe:VCDandsoonInsidetheelectricalappliancesmayseeitsform!Itismainlytakesthecontrolsectionthecorepart.Itisonekindofonline-likereal-timecontrolcomputer,online-likeisthescenecontrol,needstohavethestrongantijammingability,thelowcost,thisisalsoandtheoff-linetypecomputer(forinstancehomeusePC,)maindifferenceThemonolithicintegratedcircuitisdependingontheprocedure,andmayrevise.Realizesthedifferentfunctionthroughthedifferentprocedure,particularlyspecialuniquesomefunctions,thisisothercomponentneedstotaketheverybigefforttobeabletoachieve,somearethefloweredbigstrengthisalsoverydifficulttoachieve.Oneisnottheverycomplexfunction,ifdevelopsinthe50swiththeUS74series,orthe60s'sCD4000seriesthesepurehardwaredodecides,theelectriccircuitcertainlyarcabigPCBboard!Butif,ifsucceededinthe70swiththeUSputsinthemarkettheseriesmonolithicintegratedcircuit,theresultwillhavethehugedifference.BecauseonlythemonolithicaswellasredundantreliabilityTheCPUisthekeycomponentofadigitalcomputer.Itspurposeistodecodeinstructionreceivedfrommemoryandperformtransfers,arithmetic,logic,andcontroloperationswithdatastoredininternalregisters,memory,orI/Ointerfaceunits.Externally,theCPUprovidesoneormorebusesfortransferringinstructions,data,andcontrolinformationtoandfromcomponentsconnectedtoit.Amicrocontrollerispresentinthekeyboardandinthemonitorinthegenericcomputer;thusthesecomponentsarealsoshaded.Insuchmicrocontrollers,theCPUmaybequitedifferentfromthosediscussedinthischapter.Thewordlengthsmaybeshort,thenumberofregisterssmall,andtheinstructionsetslimited.Performance,relativelyspeaking,ispoor,butadequateforthetask.Mostimportant,thecostofthesemicrocontrollersisverylow,makingtheirusecosteffective.Becausethemonolithicintegratedcircuittothecostissensitive,thereforepresentoccupiesthedominantstatusthesoftwareisthemostpreliminaryassemblylanguage7itwasexceptthebinarymachinecodeabovethemostpreliminarylanguage,sincewhyweresuchpreliminarymustuse?Whyhigh-leveldidthelanguagealreadyachievethevisualizationprogramminglevelnottouse?Thereasonisverysimple,isthemonolithicintegratedcircuitdocsnothavehomecomputersuchCPU,andalsohasnotlookedliketheharddisksuchmassmemoryequipment.Insideevenifavisualizationhigherorderlanguagecompilationscriptonlythenabutton,alsowillachieveseveraldozensKthesizes!DoesnotspeakanythingregardingthehomeusePCharddisk,butsaysregardingthemonolithicintegratedcircuitcannotaccept.Themonolithicintegratedcircuitinthehardwaresourceaspect'struth,ifattains puter'sonoperatingsystemandtheapplicationsoftwarehomeusePCtocomeupthemovement,homeusePCcouldalsonotwithstand.Itcanbesaidthatthe20thcenturysurmountedthree"theelectricity"thetime,namelytheelectricaltime,theElectronicAgeandalreadyenteredcomputertime.However,thiskindofcomputer,usuallyreferstothealcomputer,iscalledPCmachine.Itbythemainengine,thekeyboard,themonitorandsooniscomposed.Alsohasakindofcomputer,mostpeopleactuallynothowfamiliar.Thiskindofcomputerisentrustswiththeinligenceeachkindofmechanicalmonolithicintegratedcircuit(alsotocallmicrocontroller),Thiskindofcomputer'ssmallestsystemonlyhasusedasthenamesuggestsapieceofintegratedcircuit,thencarriesonthesimpleoperationandthecontrol.Becauseitsvolumeissmall,usuallyhidesinisaccusedthemachinery"thebelly".Itintheentireinstallment,ysishavinglikethehumanbrainsrole,itwentwrong,theentireinstallmentparalyzed.Now,thiskindofmonolithicintegratedcircuit'susealreadyverywidespread,liketheinligentmeasuringappliance,thesolidworkpaidbytimecontrol,thecommunicationequipment,theguidancesystem,thedomesticelectricappliancesandsoon,Onceeachproductusedthemonolithicintegratedcircuit,couldgetupcausestheeffectwhichtheproductturnedtoanewgeneration,oftenbeforeproductrangecrownbyadjective----‘inligence’,likeinligencewasherandsoon.Nowsomefactory'stechnicalnelorotherextra-curricularelectronicexploiterdocertainproducts,arenottheelectriccircuitaretoocomplex,isthefunctionistoosimple,andisimitatedextremelyeasily.Investigatesitsreason,possiblyoncard,intheproducthasnotusedonthemonolithicintegratedcircuitorotherprogrblelogicalcomponent.SCMisanintegratedcircuitchip,istheuseoflargescaleintegratedcircuittechnologytoadataprocessingcapabilityofCPUCPUrandomaccessmemoryRAM,read-onlymemoryROM,avarietyofI/Oportandinterruptsystem,timers/timerfunctions(whichmayalsoincludedisydrivercircuitry,pulsewidthmodulationcircuit,ogmultiplexer,A/Dconvertercircuit)integratedintoasiliconconstituteasmallandcompletecomputersystems.SCMisalsoknownasmicro-controller(Microcontroller),becauseitisthefirsttobeusedinindustrialcontrol.OnlyasinglechipbytheCPUchipdevelopedfromadedicatedprocessor.ThefirstdesignisbyalargenumberofperipheralsandCPUonachipinthecomputersystem,smaller,moreeasilyintegratedintoacomplexanddemandingonthevolumecontroldevicewhich.TheZ80INisthefirstdesignedinaccordancewiththisideaprocessor,thenonthedevelopmentofmicrocontrolleranddedicatedprocessorswillbepartingways.Are8-bitmicrocontrollerearlyor4bits.OneofthemostsuccessfulistheIN8031,forasimple,reliableandgoodperformancewasalotofpraise.Thendevelopedin8031outofMCS51MCUSystems.SCMsystemsbasedonthissystemuntilnowisstillwidelyused.Withtheincreasedrequirementsofindustrialcontrolfield,begana16-bitmicrocontroller,butnotidealbecausethecosthasnotbeenverywidelyused.After90yearswiththegreatdevelopmentofconsumerelectronics,microcontrollertechnologyhasbeenahugeincrease.WithINi960series,especiallythelaterseriesofwidelyusedARM,32-bitmicrocontrollerquicklyrecehigh-end16-bitMCUstatusandenterthemainstreammarket.Thetraditional8-bitmicrocontrollerperformancehavebeentherapidincreasecapacityincreasecomparedto80thenumberoftimes.Currently,high-end32-bitmicrocontrollerclockedover300MHz,theperformancecatchingthemid-90sdedicatedprocessor,whiletheaveragemodelpricesfalltooneU.S.dollar,themosthigh-endmodelonly10dollars.ModernSCMsystemsarenolongeronlyinthedevelopmentanduseofbaremetalenvironment,alargeofproprietaryembeddedoperatingsystemiswidelyusedinthefullrangeofSCM.Thehandheldcomputersandcellphonesasthecoreprocessingofhigh-endmicrocontrollercanevenuseadedicatedWindowsandLinuxoperatingsystems.SCMismoresuitablethanthespecificprocessorusedinembeddedsystems,soitwasuptotheapplication.InfactthenumberofSCMistheworld'slargestcomputer.Modernhumanlifeusedinalmosteverypieceofelectronicandmechanicalproductswillbeintegratedsinglechip.Phone,ephone,calculator,homeappliances,electronictoys,handheldcomputersandcomputeraccessoriessuchasamousewitha1-2inboththeDepartmentofSCM.alcomputerwillhavealargenumberofSCMinthework.Generalcarwithmorethan40microcontroller,acomplexindustrialcontrolsystemsmayevenhundredsofsinglechipatthesametimework!SCMisnotonlyfarexceedsnumberofPCandothercomputingthesum,orevenmorethanthenumberofhumanSinglechip,alsoknownassingle-chipmicrocontroller,itisnotcompleteacertainlogicchips,buttoacomputersystemintegratedintoachip.Equivalenttoa puter,andcomputerthanjustthelackofamicrocontrollerI/Odevices.Generaltalk:achip esacomputer.Itssmallsize,lightweight,cheap,forthestudy,applicationanddevelopmentoffacilitiesprovided.Atthesametime,learningtousetheMCUistounderstandtheprincipleandstructureofthecomputerthebestoption.Microcontrollerandthecomputerfunctionsinternallywithsimilarmodules,suchasCPU,memory,parallelbus,thesameeffectthere,andharddiskmemorydevice,isitdifferentpropertiesofthesecomponentsarerelativelyweakmanyofourhomecomputer,butthepriceislow,usuallynotmorethan10yuanyoucandowithitsomecontrolforaclassisnotverycomplicatedelectricalworkisenoughof.Weareusingautomaticdrumwashingmachine,smokehood,VCDandsoonapplianceswhichcouldseeitsshadow!Itismainlypartofthecorecomponentsasthecontrol.tisanonlinereal-timecontrolcomputer,on-lineison-sitecontrol,needtohavestronganti-interferenceability,lowcost,andthisis,andoff-linecomputer(suchashomePC),themaindifference.Singlechip.MCUisthroughrunning,andcanbemodified.Throughdifferentprocedurestoachievedifferentfunctions,inparticularspecialuniquefeatures,thisisanotherdevicemucheffortneedstobedone,somearegreateffortsareverydifficulttoachieve.Anotverycomplexfunctionsifthe50'swiththeUnitedStatesdeveloped74series,orthe60'sCD4000seriesofthesepurehardwarebuttoned,thenthecircuitmustbealargePCBboard!ButiftheUnitedStatesifthe70'swithaseriesofsuccessfulSCMmarket,theresultwillbeadrasticchange!Justbecauseyouarepreparedby puterprogramscanachievehighinligence,highefficiencyandhighreliability!Asthemicrocontrolleronthecost-sensitive,sonowthedominantsoftwareorthelowestlevelassemblylanguage,whichisthelowestlevelinadditiontomorethanbinarymachinecodelanguage,andassolowwhyistheuse?Manyhigh-levellanguagehasreachedthelevelofvisualprogrammingWhyisnotit?ThereasonissimplythatthereisnohomecomputerasasinglechipCPU,notashardasamassstoragedevice.Avisualizationofsmallhigh-levellanguageprogramisonlyonebuttononitthough,willreachtensofKinsize!ForthehomePC'sharddriveintermsofnothingbutspeakingfortheMCUisnotacceptable.SCMintheutilizationofhardwareresourcestobeveryhighforthejobsoalthoughtheoriginalisstillinthecompilationofalotofuse.Thesametoken,ifthegiantcomputeroperatingsystemandapplicationsrunupgethomePC,homePC,alsobearnotwork.Canbesaidthatthetwentiethcenturyacrossthethree"power"era,thatis,theageofelectricity,theelectronicageandhasenteredintothecomputerage.However,thiscomputer,usuallyreferstothealcomputer,referredtoasPC.Itconsistsofthehost,keyboard,monitorandothercomponents.Anothertypeofcomputer,mostpeopledonotknowhow.Thiscomputeristogiveallkindsofmachinery,inligentsinglechip(alsoknownasmicro-controller).Asthenamesuggests,thiscomputersystemtookonlyaminimalintegratedcircuit,canbeasimpleoperationandcontrol.Becauseitissmall,usuallyinthechargedwithpossessionofmechanical"stomach"in.Itisinthedevice,likethehumanbrainysarole,itgoeswrong,thewholentwasparalyzed.Now,thismicrocontrollerhasbeenverywidelyusedinthefield,suchassmartmeters,real-timeindustrialcontrol,communicationsequipment,navigationsystems,andhouseholdappliances.OnceallkindsofproductswereusingSCM,canservetoupgradetheeffectivenessofproducts,oftenintheproductnameprecededbytheadjective-"inligent",suchasinligentwashingmachines.Nowsometechnicalneloffactoriesorotheramateurelectronicsdeveloperstoengageinoutofcertainproducts,notthecircuitistoocomplicated,thatfunctionistoosimpleandcaneasilybecopied.Thereasonmaybestuckintheproductdidnotuseamicrocontrollerorotherprogrblelogicdevice.TheAT89C51isalow-power,high-performanceCMOS8-bit puterwith4KbytesofFlashProgrbleandErasableReadOnlyMemory(PEROM)and128bytesRAM.ThedeviceismanufacturedusingAtmel’shighdensitynonvolatilememorytechnologyandiscompatiblewiththeindustrystandardMCS-51?instructionsetandpinout.Thechipcombinesaversatile8-bitCPUwithFlashonamonolithicchip,theAtmelAT89C51isapowerful puterwhichprovidesahighlyflexibleandcosteffectivesolutiontomanyembeddedcontrolapplications.CompatiblewithMCS-51?4KBytesofIn-SystemReprogrbleFlashEndurance:1,000Write/EraseFullyStaticOperation:0Hzto24Three-LevelProgramMemory128x8-BitInternal32ProgrbleI/OTwo16-BitSixInterruptProgrbleSerialLowPowerIdleandPowerDownTheAT89C51providesthefollowingstandardfeatures:4KbytesofFlash,128bytesofRAM,32I/Olines,two16-bittimer/counters,afivevectortwo-levelinterruptarchitecture,afullduplexserialport,on-chiposcillatorandclockcircuitry.Inaddition,theAT89C51isdesignedwithstaticlogicforoperationdowntozerofrequencyandsupportstwosoftwareselectablepowersavingmodes.TheIdleModestopstheCPUwhileallowingtheRAM,timer/counters,serialportandinterruptsystemtocontinuefunctioning.ThePowerDownModesavestheRAMcontentsbutzestheoscillatordisablingallotherchipfunctionsuntilthenexthardwarereset.PinVCCSupplyGNDPortPort0isan8-bitopendrainbidirectionalI/Oport.AsanoutputporteachpincansinkeightTTLinputs.Whenisarewrittentoport0pins,thepinscanbeusedashighimpedanceinputs.Port0mayalsobeconfiguredtobethemultiplexedloworderaddress/databusduringaccessestoexternalprogramanddatamemory.InthismodeP0hasinternalpullups.Port0alsoreceivesthecodebytesduringFlashprogramming,andoutputsthecodebytesduringprogramverification.Externalpullupsarerequiredduringprogramverification.PortPort1isan8-bitbidirectionalI/Oportwithinternalpullups.ThePort1outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort1pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port1pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseoftheinternalpullups.Port1alsoreceivesthelow-orderaddressbytesduringFlashprogrammingandPortPort2isan8-bitbidirectionalI/Oportwithinternalpullups.ThePort2outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort2pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port2pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseoftheinternalpullups.Port2emitsthehigh-orderaddressbyteduringfetchesfromexternalprogrammemoryandduringaccessestoexternaldatamemorythatuse16-bitaddresses(MOVX@DPTR).Inthisapplicationitusesstronginternalpull-upswhenemitting1s.Duringaccessestoexternaldatamemorythatuse8-bitaddresses(MOVX@RI),Port2emitsthecontentsoftheP2SpecialFunctionRegister.Port2alsoreceivesthehigh-orderaddressbitsandsomecontrolsignalsduringFlashprogrammingandverification.PortPort3isan8-bitbidirectionalI/Oportwithinternalpullups.ThePort3outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort3pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port3pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseofthepullups.Port3alsoservesthefunctionsofvariousspecialfeaturesoftheAT89C51aslistedPort alternate rxd(serialinput txd(serialoutput ^int0(external ^int1(external t0(timer0external t1(timer1external ^WR(externaldatamemorywrite ^rd(externaldatamemoryreadPort3alsoreceivessomecontrolsignalsforFlashprogrammingandResetinput.AhighonthispinfortwomachinecycleswhiletheoscillatorisrunningresetstheAddressLatchEnableoutputpulseforlatchingthelowbyteoftheaddressduringaccessestoexternalmemory.Thispinisalsotheprogrampulseinput(PROG)duringFlashprogramming.InnormaloperationALEisemittedataconstantrateof1/6theoscillatorfrequency,andmaybeusedforexternaltimingorclockingpurposes.Note,however,thatoneALEpulseisskippedduringeachaccesstoexternalDataMemory.Ifdesired,ALEoperationcanbedisabledbysettingbit0ofSFRlocation8EH.Withthebitset,ALEisactiveonlyduringaMOVXorMOVCinstruction.Otherwise,thepinisweaklypulledhigh.SettingtheALE-disablebithasnoeffectifthemicrocontrollerisinexternalexecutionmode.ProgramStoreEnableisthereadstrobetoexternalprogramWhentheAT89C51isexecutingcodefromexternalprogrammemory,PSENisactivatedtwiceeachmachinecycle,exceptthattwoPSENactivationsareskippedduringeachaccesstoexternaldataExternalAccessEnable.EAmustbestrappedtoGNDinordertoenablethedevicetofetchcodefromexternalprogrammemorylocationsstartingat0000HuptoFFFFH.Note,however,thatiflockbit1isprogrammed,EAwillbeinternallylatchedonreset.EAshouldbestrappedtoVCCforinternalprogramThispinalsoreceivesthe12-voltprogrammingenablevoltage(VPP)duringFlashprogramming,forpartsthatrequire12-voltVPP.InputtotheinvertingoscillatoramplifierandinputtotheinternalclockoperatingOutputfromtheinvertingoscillatorOscillatorXTAL1andXTAL2aretheinputandoutput,respectively,ofaninvertingamplifierwhichcanbeconfiguredforuseasanon-chiposcillator,asshowninFigure1.Eitheraquartzcrystalorceramicresonatormaybeused.Todrivethedevicefromanexternalclocksource,XTAL2shouldbeleftunconnectedwhileXTAL1isdrivenasshowninFigure2.Therearenorequirementsonthedutycycleoftheexternalclocksignal,sincetheinputtotheinternalclockingcircuitryisthroughadivide-by-twoflip-flop,butminimumandumvoltagehighandlowtimespecificationsmustbeobserved.IdleInidlemode,theCPUputsitselftosleepwhilealltheonchipperipheralsremainactive.Themodeisinvokedbysoftware.Thecontentoftheon-chipRAMandallthespecialfunctionsregistersremainunchangedduringthismode.Theidlemodecanbeterminatedbyanyenabledinterruptorbyahardwarereset.Itshouldbenotedthatwhenidleisterminatedbyahardwarereset,thedevicenormallyresumesprogramexecution,fromwhereitleftoff,uptotwomachinecyclesbeforetheinternalresetalgorithmtakescontrol.On-chiphardwareinhibitsaccesstointernalRAMinthisevent,butaccesstotheportpinsisnotinhibited.ToeliminatethepossibilityofanunexpectedwritetoaportpinwhenIdleisterminatedbyreset,theinstructionfollowingtheonethatinvokesIdleshouldnotbeonethatwritestoaportpinortoexternalmemory.算機系統(tǒng)集成到一 上概括的講一 就成了一臺計算機它的體積小10元即可，用它來做一些控制電器一類不是很復(fù)雜的工作足矣了。我們現(xiàn)在用的全自動滾筒洗農(nóng)機、排煙罩、VCD等等的家，它是一種存線式實時控