單片機基礎(chǔ)外文文獻翻譯

SCMdevelopmenthistoryl.ThegeneralsituationoflistslicemachineThesinglechipmicrocomputerreferredtoasSCM,istypicalofembeddedmicro-controller(SCMUnit),thecommonlyusedlettersoftheabbreviationMCUMCU,itwasfirstusedinthefieldofindustrialcontrol.MasterSCMtechnologytoenablemorepeopleintheindustry,students,enthusiasts,productdevelopers,andthequestionaroseduetotheextensiveapplicationofSCMinthefieldofindustrialcontrol,SCMdevelopmentboard,themorefamoussuchase-DZR-01ASCMdevelopmentboard.SCMevolvedbytheonlydedicatedprocessorCPUchip.ThefirstdesignconceptbyalargenumberofperipheralsandCPUintegratedinasinglechip,thecomputersystemissmaller,andmoreeasilyintegratedintocomplexandrequirestrictcontrolequipmentonthevolume.INTELZ80isthefirstprocessordesignedinaccordancewiththisidea,sincethen,thedevelopmentofSCManddedicatedprocessorhasgrownapart.EarlySCMare8or4.OneofthemostsuccessfulistheINTEL8031,becausethesimpleandreliableperformancegoodalotofpraise.Laterin8031onthedevelopmentofMCS51seriesSCMsystem.IsstillinwideuseofSCMsystembasedonthissystemuntilnow.Beganwiththeindustrialcontrolarearequiresimprovementofa16-bitSCM,butnotidealbecausethepricehasnotbeenaverywiderangeofapplications.The1990s,consumerelectronics,SCMtechnologyhasbeenahugeincrease.WiththeINTELThei960series,especiallytheARMseriesofwidelyused32-bitSCMquicklyreplacedthe16-bitsingle-chiphigh-endstatus,andenterthemainstreammarket.Traditional8-bitMCUperformancehasalsobeenarapidincreaseprocessingcapacitythanafewtimesinthe1980s.Atpresent,high-end32-bitSCMclockedmorethan300MHz,performance,catchingupwithadedicatedprocessorinthemid-1990s,whiletheordinarymodelpricesdropto$1,themosthigh-endmodelisonly$10.ContemporarySCMsystemisnolongeronlyinthebaremetalenvironmenttodevelopandusealargenumberofdedicatedembeddedoperatingsystemiswidelyusedinafullrangeofSCM.Ashandheldcomputersandmobilephonescoreprocessinghigh-endSCMcanevenuseadedicatedWindowsandLinuxoperatingsystems.TheSCMismorethanadedicatedprocessorforembeddedsystems,soithasbeenuptotheapplication.InfactSCMistheworld’slargestnumberofcomputer.OfmodernhumanlifeinalmosteveryelectronicandmechanicalproductswillbeintegratedSCM.Mobilephone,telephone,calculator,householdappliances,electronictoys,handheldcomputers,aswellasmouseandothercomputeraccessorieswith1-2MinistriesSCM.ThePCwillhavealargenumberofSCMwork.Generallyequippedwithmorethan40single-chipsinthecar,evenincomplexindustrialcontrolsystemsmayhavehundredsofsinglechipatthesametime!ThenumberofSCMisnotonlyfarmorethanthesumofPCandothercomputingevenmorethanthenumberofhumanbeingsevenmore.Thesingle-chip,alsoknownassingle-chipSCM,itisnotthecompletionofalogicalfunctionofthechip,butacomputersystemintegratedontoonechip.Equivalenttoamini-computerandcomputer,SCMonlythelackofme/Odevices.Speakingingeneralterms:achiphasbecomeacomputer.Itssmallsize,lightweight,inexpensive,andprovidefavorableconditionsforlearning,applicationanddevelopment.Atthesametime,learningtousetheSCMisthebestchoicefortheunderstandingofcomputertheoryandstructure.InternalSCMwithasimilarmoduleandthecomputerfunctions,suchasCPU,memory,parallelbus,thesamememoryandharddiskrole,differentperformanceofthesecomponentsarerelativelyweakalotofourhomecomputer,butthepriceislowgenerallynotmorethan10Yuancanbeuseitforcontrolappliancesofaclassisnotverycomplexworkenough.Weareusinghouseholdappliancesinsideofthedrumfullyautomaticwashingmachine,exhausthood,VCDandsooncanbeseeninitspresence,anditismainlyaspartofthecoreparts.Itisanonlinereal-timecontrolcomputer,on-linesitecontrolneedisastronganti-jammingcapability,lowercost,thisisalsooff-linecomputer(suchashomePC)themaindifference.SCMrelyontheprogramisrunning,andcanbemodified.Differentfunctionsthroughdifferentprograms,especiallythespecialuniquefunction,whichistheotherdevices,requiremuchefforttodo,whileothersmakegreateffortsitisdifficulttodo.Anotverycomplexfunctionsusingpurehardwaretogetthewordsofthe1950sdeveloped74series,or60duringtheCD4000series,thecircuitmustbeabigPCBboard!IfsuccessfulonthemarketintheUnitedStatesinthe1970sseriesofSCM,theresultwillbedifferent!JustbecauseaprogramwrittenbytheMCUthroughyoucanachievehighintelligence,highefficiencyandhighreliability!SCMforcostsensitive,soaccountingforthedominanceofthesoftwareorthelowestlevelassemblylanguage,whichisthelowestlevelthanbinarymachinecodelanguage,sincesuchlow-levelwhyuseit?Alotofhigh-levellanguagehasreachedalevelofvisualprogramming,whynot?Thereasonissimple,istheSCMdoesnothaveahomecomputerastheCPU,alsonotashardasmassstoragedevices.Avisualhigh-levellanguagetowritesmallprogramsinsideevenifthereisonlyonebutton,willreachtensofKofsize!NothingintermsofhomePac’sharddrives,butforSCMintermsofisnotacceptable.SCMintheutilizationofhardwareresourcesmustbehigh,sothecompilationoftheoriginalwhilestillinheavyuse.Thesamereason,ifthecomputergiant'soperatingsystemandapplicationsoftwaretogethomePCrunuptothehomePCcannotafford.Itcanbesaidthatthetwentiethcenturyacrossthethree"power"eraoftheelectricalera,theelectronicageandhasnowenteredthecomputerage.However,suchacomputerusuallyreferstoapersonalcomputer,orPC.Itisbythehost,keyboard,monitor,andsoon.Anothertypeofcomputer,nothowmostpeoplearefamiliarwith.ThiscomputerissmarttogiveavarietyofmechanicalSCM(alsoknownasmicro-controller).Thenamesuggests,thesmallestofthiscomputersystemusingonlyoneICtomakeasimplecalculationandcontrol.Becauseofitssmall,usuallyhiddeninacontrolledmechanical"stomach”.Throughoutthedevice,itplaysliketheroleofthehumanmind,itiswrong,theentiredevicewasparalyzed.Now,thissinglechipfieldofusehasaverywide,suchassmartmeters,real-timeindustrialcontrol,communicationsequipment,navigationsystems,andhomeappliancesandsoon.AvarietyofproductsusingtheSCM,youcanplaytheeffectofproductupgrades,oftenprecededbyanadjectiveinfrontoftheproductname-"smart”，suchassmartwashingmachines.Somefactoriesorotheramateurelectronicsdeveloperstoengageinoutofcertainproducts,notthecircuitistoocomplicated,toosimpleandcaneasilybeimitation.ThereasonmaybestuckintheproductdoesnotuseaSCMorotherprogrammablelogicdevices.MCUclassificationSCMasanimportantareaofcomputerdevelopment,theapplicationofamorescientificclassification.AccordingtothecurrentdevelopmentsituationfromdifferentanglesSCMcanbedividedintouniversal/specialtype,bus/busandindustrialtype/homeappliancetype.Universal/privatetypeUniversal/privatetypewhichistodistinguishbetweenthescopesofapplicationbySCM.Forexample,80C51isageneral-purposeMCU,itisnotsomekindofpostuse;DedicatedMCUforaproductoraproductdesignedandmanufactured,forexample,inordertomeettherequirementsoftheelectronicthermometerintheintegratedon-chipADCinterfaceandotherfunctionstemperaturemeasurementandcontrolcircuit.Bus/busBus/buswhethertoprovidesingle-chipparallelbustodistinguish.BusSCMisgenerallysetparalleladdressbus,databus,controlbus,thesepinstoextendparallelperipheraldevicescanbeconnectedthroughtheserialportandMCUInaddition,manyoftheSCMhastherequiredperipheraldevicesandperipheralinterfacesintegratedone,soinmanycasesdonotparallelexpansionbus,greatlyreducetheprovinceofpackagecostandchipsize,thetypeofSCMcalledthenon-bus-typeSCM.Controlled/appliancetypeControlled/appliancetypethisdistinctioninaccordancewiththeSCMbroadlyappliedfield.Ingeneral,theindustrial-typeaddressingrange,computingpower;SCMforhomeappliancesandmorespecialtype,usuallythehighintegrationofthesmallpackage,lowprices,peripheraldevices,andperipheralinterfaces.Obviously,thesecategoriesarenottheonlyandstrict.80C51classSCM,forexample,bothgeneral-purposebuses,butalsoforindustrialuse.ThecourseoftheirworkThecourseoftheirworkSCMautomaticallycompletethetasksentrustedtoit,thatis,single-chipimplementationoftheprogramprocess,theprocessofanarticleofinstructionsexecuted,theso-calledinstructionisintheformofsingle-chipimplementationofavarietyofoperatingwiththecommandtowritedown,whichisdesignerassignedtoitbytheinstructionset,aninstructioncorrespondstoabasicoperation;FullinstructionscanbeexecutedbytheSCM,theSCMinstructionset,thedifferenttypesofsingle-chip,anditsinstructionsetisalsodifferent.SothattheSCMcanautomaticallycompleteaspecifictask,theproblemtobesolvedmustbecompiledintoaseriesofinstructions(theseinstructionsmustbeselectedSCMtotheidentificationandimplementationoftheDirective),acollectionofthisseriesofinstructionstobecometheprogram,theprogramneedtopre-storedinthecomponents-memorystoragecapabilities.Memoryiscomposedbyanumberofstorageunits(thesmallestunitofstorage),likealargebuildinghasmanyroomscomposedofthesame,theinstructionsstoredintheseunits,theinstructionfetchunitandperformliketheroomsoflargebuildings,eachassignedtoonlyaroomnumber,eachmemorycellmustbeassignedtoauniqueaddressnumber,theaddressisknownastheaddressofthestorageunit,soaslongasyouknowtheaddressofthestorageunit,youcanfindthestorageunitthatstoresinstructionscanberemoved,andthenbeexecuted.Programsareusuallyexecutedintheorder,instructionprogramisasequentialstorage,single-chipintheimplementationoftheprogramtobeabletoasectionoftheseinstructionsoutandbeimplemented,theremustbeacomponenttotracktheaddressofinstructionwherethisparttheprogramcounterPC(includedintheCPU),thestartofprogramexecution,endowedtheaddresswherethefirstinstructionoftheprogramtothePC,andthenmadeforeachcommandtoexecutethecontentintothePCwillautomaticallyincrease,increasetheamountisdeterminedbytheinstructionlengthofthisarticlemaybe2or3,topointtothestartingaddressofthenextinstructiontoensuretheimplementationoftheinstructionsequence.SCMhistorySCMwasbornin1971,hasgonethroughthreemajorphasesoftheSCM,theMCUSOC.ThebasicstructureoftheSCMThebasicstructureoftheSCMconstitutesthecomputingdevice,controller,memory,inputoutputdevices.ThefirstmodelofSCMSCMstageofthesinglechipmicrocomputer(SingleChipMicrocomputer),seekingamonolithicformofembeddedsystemsarchitecture.Innovativemodeltobesuccessful,andlaidacompletelydifferentpathofdevelopmentoftheSCMandthegeneral-purposecomputer.Independentpathofdevelopmenttocreateanembeddedsystem,Inteldenied.MCUSCM(MicroControllerUnit).Stage,themaindirectionoftechnologydevelopment:expandingavarietyofperipheralcircuitsandinterfacecircuits,embeddedapplicationsaremet,theobjectsystemrequirementsandtohighlighttheintelligentcontrolcapabilitiesofitsobject.Itisinvolvedinthefieldwiththeobjectsystem,therefore,theimportanttaskoftheMCUdevelopmentwillinevitablyfallonelectricalandelectronicsmanufacturers.Fromthisperspective,IntelisgraduallyfadingouttheMCUdevelopmentofobjectivefactors.WhenPhilipsinthedevelopmentofMCU,themostfamousmanufacturers.PhilipsCompanywithitshugeadvantageinembeddedapplications,theMCS51fromthesingle-chipmicrocomputer,therapiddevelopmentofthemicro-controller.Therefore,whenwelookbackatthepathofdevelopmentofembeddedsystems,donotforgetthehistoricalachievementsofIntelandPhilips.EmbeddedsystemsSCMistheroadofindependentdevelopmentofembeddedsystems,animportantfactortotheMCUstagesofdevelopment,isseekingapplicationsonthechiptomaximizethesettlement;dedicatedSCMdevelopmentofnaturalSocktrend.Withthedevelopmentofmicroelectronicstechnology,ICdesign,EDAtools,Sock-basedSCMapplicationsdevelopment.Therefore,understandingoftheSCMfromthesingle-chipmicrocomputersingle-chipSCMextendstothesingle-chipapplications.SCMdevelopmenthistoryIntelCorporationin1971developedtheworld'sfirst4-bitmicroprocessor;HoffofIntelCorporationtodevelopthesuccessoftheworld'sfirst4-bitmicroprocessorchip,theIntel4004,theadventmarksthefirstgenerationofmicroprocessor,themicroprocessorandThecomputererabegan.Theinventionofmicroprocessors,HoughwastheBritish"Economist"magazineasoneofthemostinfluentialsinceWorldWarIIsevenscientists.InNovember1971,IntelintroducedtheMCS-4micro-computersystem(includingthe4001ROMchips,the4002RAMchip,4003shiftregisterchip,and4004microprocessor)ofwhich4004(below)contains2300transistors,sizes3mmx4mm,thecomputationalperformancefarexceedsthatoftheENIAC,wasoriginallypricedat$200.InApril1972,Hough,whodevelopedthefirst8-bitmicroprocessor,theIntel8008.Since8008isaP-channelMOSmicroprocessor,sostillthefirstgenerationofmicroprocessors.IntelCorporationin1973developedthe8-bitmicroprocessor8080;August1973,Hoff,whodevelopedthe8-bitmicroprocessortheIntel8080andreplacedbyaP-channelN-channelMOScircuit,thesecondgenerationofmicroprocessordevicethereonwasborn.Frequency2MHz8080chipcomputationspeed10timesfasterthan8008,youcanaccessthe64KBmemory,using6000transistors,basedona6-microntechnology,processingspeed0.64MIPS(MilliontheInstructionsPerSecond).InApril1975,theMITSreleasedthefirstgeneral-purposetheAltair8800,pricedat$375,with1KBmemory.Thisistheworld'sfirstmicro-computer.IntelCorporationin1976developedtheMCS-48seriesof8-bitSCM,theadventoftheSCM.SiloZ80microprocessordevelopedin1976,iswidelyusedinmicrocomputersandindustrialautomationequipment.Atthattime,thethreepillarsofSilo,MotorolaandIntelinmicroprocessors.Theearly1980s,theIntelCorporationonthebasisoftheMCS-48seriesSCM,theintroductionoftheMCS-51seriesofeighthigh-enddevices.MCS-51seriesMCUon-chipRAMcapacity,I/Oportfunction,thesystemexpansionhasbeengreatlyimproved.HardwarefeaturesAsingle-chipintegrationofhigh.Single-chip,includingCPU,4KBcapacityROM(8031Nil),128B,thecapacityofRAM,16-bitcounter/timers,four8-bitparallelportfull-duplexseriallineport.Thesystemissimple,easytouse,modular;single-chiphighreliability,canworkto10A6-10A7hoursoftrouble-free;Theprocessingfunctionsandspeed.Lowvoltage,lowpowerconsumption,easeofproductionofportableproductsThecontrolfunctionApplicationMCUtoinfiltrateallareasoflife,almostdifficulttofindwhichareasoftheSCMtrail.Navigationdeviceofthemissile,aircraft,variousinstrumentcontrol,computernetworkcommunicationsanddatatransmission,industrialautomationandprocessreal-timecontrolanddataprocessing,widelyusedsmartcardIC,civilluxurycarsecuritysystem,VCR,cameras,thecontrolofautomaticwashingmachines,andprogram-controlledtoys,electronicpets,etc.,whichareinseparablefromtheSCM.Nottomentionthefieldofautomaticcontrol,robotics,intelligentinstruments,medicalequipmentandavarietyofintelligentmechanical.Therefore,thelearning,developmentandapplicationoftheSCMwillcreateanumberofcomputerapplicationsandintelligentcontrolofthescientists,engineers.TheSCMiswidelyusedinthefieldofinstrumentation,homeappliances,medicalequipment,aerospace,equipmentfortheintelligentmanagementandprocesscontrol,generallycanbedividedintothefollowingcategories:8.1.OnsmartinstrumentationTheSCMhasasmallsize,lowpowerconsumption,andcontrolfunctions,andexpansionoftheadvantagesofflexibility,miniaturizationandeasytouse,widelyusedininstrumentation,combinedwithdifferenttypesofsensorscanberealizedsuchasvoltage,power,frequency,humidity,temperature,flow,speed,thickness,angle,length,hardness,elements,pressureandotherphysicalmeasurement.SCMmakesthedigitalinstrumentation,intelligent,miniaturizationandmorepowerfulfunctionthantheuseofelectronicordigitalcircuits.Suchasprecisionmeasuringequipment(powermeter,oscilloscope,analyzer).InindustrialcontrolapplicationsMCUcanconstitutevariousformsofcontrolsystems,dataacquisitionsystems.Suchasfactoryassemblylineofintelligentpipechip,liftintelligentcontrol,andvariousalarmsystems,andcomputernetworkingconstitutethetwocontrolsystems.InHouseholdAppliancesItcanbesaidthatthehouseholdappliancesisbasicallyusingtheMCUcontrol,fromricecookers,washingmachines,refrigerators,airconditioners,colorTVs,audioandvideoequipmenttotheelectronicweighingequipment,multifarious,ubiquitous.InthefieldofcomputernetworksandcommunicationModernSCMwithuniversalcommunicationinterfacecanbeeasilyandcomputerdatacommunications,providesexcellentmaterialforuseincomputernetworksandcommunicationdevices,communicationequipmentbasicallytotheMCUintelligentcontrolfromthemobilephones,telephones,smallprogram-controlledswitchboards,buildingautomatedcommunicationscallsystems,trainradiocommunications,andthentotheubiquitousmobilephonesintheirdailywork,truckingmobilecommunicationradios.ChipinthefieldofmedicalequipmentTheSCMusesinmedicaldevicesisalsoquiteextensive,suchasmedicalventilator,avarietyofanalyzers,monitors,ultrasounddiagnosticequipmentandhospitalbedscallsystemandsoon.ModularapplicationsinavarietyoflargeappliancesSomededicatedSCMdesignedforspecificfunctions,modularapplicationsinavarietyofcircuit,withoutrequiringtheuseofpersonneltounderstanditsinternalstructure.Integratedsingle-chip,suchasmusic,seeminglysimplefunction,miniaturepureelectronicchip(asopposedtotheprincipleofthetapedrive),youneedacomplexsimilartotheprincipleofthecomputer.Suchas:themusicsignalindigitalforminmemory(similartotheROM),readbytheSCMintoanalogmusicsignal(similartothesoundcard).Inlargecircuits,thismodularapplicationgreatlyreducethesize,simplifyingthecircuit,reducingthedamage,errorrate,isalsoconvenienttoreplace.ChipinthefieldofautomotiveequipmentTheSCMiswidelyusedinautomotiveelectronics,suchasautomotiveenginecontrollers,intelligentelectroniccontrollerbasedonCANbusautomotiveengine,GPSnavigationsystem,absanti-locksystems,brakingsystems,etc.MCUbasis[Revision][seriesoftextbooksSCMandembeddedsystems.]單片機基礎(chǔ)單片機概況單片微型計算機簡稱單片機，是典型的嵌入式微控制器(SCMUnit),常用英文字母的縮寫MCU表示單片機，它最早是被用在工業(yè)控制領(lǐng)域。由于單片機在工業(yè)控制領(lǐng)域的廣泛應(yīng)用，為使更多的業(yè)內(nèi)人士、學生、愛好者，產(chǎn)品開發(fā)人員掌握單片機這門技術(shù)，于是產(chǎn)生單片機開發(fā)板，比較有名的例如電子人DZR-01A單片機開發(fā)板。單片機由芯片內(nèi)僅有CPU的專用處理器發(fā)展而來。最早的設(shè)計理念是通過將大量外圍設(shè)備和CPU集成在一個芯片中，使計算機系統(tǒng)更小，更容易集成進復(fù)雜的而對體積要求嚴格的控制設(shè)備當中。INTEL的Z80是最早按照這種思想設(shè)計出的處理器，從此以后，單片機和專用處理器的發(fā)展便分道揚鑣。早期的單片機都是8位或4位的。其中最成功的是INTEL的8031，因為簡單可靠而性能不錯獲得了很大的好評。此后在8031上發(fā)展出了MCS51系列單片機系統(tǒng)?；谶@一系統(tǒng)的單片機系統(tǒng)直到現(xiàn)在還在廣泛使用。隨著工業(yè)控制領(lǐng)域要求的提高，開始出現(xiàn)了16位單片機，但因為性價比不理想并未得到很廣泛的應(yīng)用。90年代后隨著消費電子產(chǎn)品大發(fā)展，單片機技術(shù)得到了巨大提高。隨著INTELi960系列特別是后來的ARM系列的廣泛應(yīng)用，32位單片機迅速取代16位單片機的高端地位，并且進入主流市場。而傳統(tǒng)的8位單片機的性能也得到了飛速提高，處理能力比起80年代提高了數(shù)百倍。目前，高端的32位單片機主頻已經(jīng)超過300MHz，性能直追90年代中期的專用處理器，而普通的型號出廠價格跌落至1美元，最高端的型號也只有10美元。當代單片機系統(tǒng)已經(jīng)不再只在裸機環(huán)境下開發(fā)和使用，大量專用的嵌入式操作系統(tǒng)被廣泛應(yīng)用在全系列的單片機上。而在作為掌上電腦和手機核心處理的高端單片機甚至可以直接使用專用的Windows和Linux操作系統(tǒng)。單片機比專用處理器更適合應(yīng)用于嵌入式系統(tǒng)，因此它得到了最多的應(yīng)用。事實上單片機是世界上數(shù)量最多的計算機。現(xiàn)代人類生活中所用的幾乎每件電子和機械產(chǎn)品中都會集成有單片機。手機、電話、計算器、家用電器、電子玩具、掌上電腦以及鼠標等電腦配件中都配有1-2部單片機。而個人電腦中也會有為數(shù)不少的單片機在工作。汽車上一般配備40多部單片機，復(fù)雜的工業(yè)控制系統(tǒng)上甚至可能有數(shù)百臺單片機在同時工作！單片機的數(shù)量不僅遠超過PC機和其他計算的總和，甚至比人類的數(shù)量還要多。單片機又稱單片微控制器，它不是完成某一個邏輯功能的芯片，而是把一個計算機系統(tǒng)集成到一個芯片上。相當于一個微型的計算機，和計算機相比，單片機只缺少了I/O設(shè)備。概括的講：一塊芯片就成了一臺計算機。它的體積小、質(zhì)量輕、價格便宜、為學習、應(yīng)用和開發(fā)提供了便利條件。同時，學習使用單片機是了解計算機原理與結(jié)構(gòu)的最佳選擇。單片機內(nèi)部也用和電腦功能類似的模塊，比如CPU，內(nèi)存，并行總線，還有和硬盤作用相同的存儲器件，不同的是它的這些部件性能都相對我們的家用電腦弱很多，不過價錢也是低的，一般不超過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衣機、排煙罩、VCD等等的家電里面都可以看到它的身影，它主要是作為控制部分的核心部件。它是一種在線式實時控制計算機，在線式就是現(xiàn)場控制，需要的是有較強的抗干擾能力，較低的成本，這也是和離線式計算機的（比如家用PC）的主要區(qū)別。單片機是靠程序運行的，并且可以修改。通過不同的程序?qū)崿F(xiàn)不同的功能，尤其是特殊的獨特的一些功能，這是別的器件需要費很大力氣才能做到的，有些則是花大力氣也很難做到的。一個不是很復(fù)雜的功能要是用美國50年代開發(fā)的74系列，或者60年代的CD4000系列這些純硬件來搞定的話，電路一定是一塊大PCB板！但是如果要是用美國70年代成功投放市場的系列單片機，結(jié)果就會有天壤之別！只因為單片機的通過你編寫的程序可以實現(xiàn)高智能，高效率，以及高可靠性！由于單片機對成本是敏感的，所以目前占統(tǒng)治地位的軟件還是最低級匯編語言，它是除了二進制機器碼以上最低級的語言了，既然這么低級為什么還要用呢？很多高級的語言已經(jīng)達到了可視化編程的水平為什么不用呢？原因很簡單，就是單片機沒有家用計算機那樣的CPU，也沒有像硬盤那樣的海量存儲設(shè)備。一個可視化高級語言編寫的小程序里面即使只有一個按鈕，也會達到幾十K的尺寸！對于家用PC的硬盤來講沒什么，可是對于單片機來講是不能接受的。單片機在硬件資源方面的利用率必須很高才行，所以匯編雖然原始卻還是在大量使用。一樣的道理，如果把巨型計算機上的操作系統(tǒng)和應(yīng)用軟件拿到家用PC上來運行，家用PC的也是承受不了的。可以說，二十世紀跨越了三個“電”的時代，即電氣時代、電子時代和現(xiàn)已進入的電腦時代。不過，這種電腦，通常是指個人計算機，簡稱PC機。它由主機、鍵盤、顯示器等組成。還有一類計算機，大多數(shù)人卻不怎么熟悉。這種計算機就是把智能賦予各種機械的單片機（亦稱微控制器）。顧名思義，這種計算機的最小系統(tǒng)只用了一片集成電路，即可進行簡單運算和控制。因為它體積小，通常都藏在被控機械的“肚子”里。它在整個裝置中，起著有如人類頭腦的作用，它出了毛病，整個裝置就癱瘓了。現(xiàn)在，這種單片機的使用領(lǐng)域已十分廣泛，如智能儀表、實時工控、通訊設(shè)備、導(dǎo)航系統(tǒng)、家用電器等。各種產(chǎn)品一旦用上了單片機，就能起到使產(chǎn)品升級換代的功效，常在產(chǎn)品名稱前冠以形容詞——“智能型”，如智能型洗衣機等?，F(xiàn)在有些工廠的技術(shù)人員或其它業(yè)余電子開發(fā)者搞出來的某些產(chǎn)品，不是電路太復(fù)雜，就是功能太簡單且極易被仿制。究其原因，可能就卡在產(chǎn)品未使用單片機或其它可編程邏輯器件上單片機的分類單片機作為計算機發(fā)展的一個重要領(lǐng)域，應(yīng)用一個較科學的分類方法。根據(jù)目前發(fā)展情況，從不同角度單片機大致可以分為通用型/專用型、總線型/非總線型及工控型/家電型。通用型/專用型這是按單片機適用范圍來區(qū)分的。例如，80C51是通用型單片機，它不是為某種專用途設(shè)計的；專用型單片機是針對一類產(chǎn)品甚至某一個產(chǎn)品設(shè)計生產(chǎn)的，例如為了滿足電子體溫計的要求，在片內(nèi)集成ADC接口等功能的溫度測量控制電路。總線型/非總線型這是按單片機是否提供并行總線來區(qū)分的。總線型單片機普遍設(shè)置有并行地址總線、數(shù)據(jù)總線、控制總線，這些引腳用以擴展并行外圍器件都可通過串行口與單片機連接，另外，許多單片機已把所需要的外圍器件及外設(shè)接口集成一片內(nèi)，因此在許多情況下可以不要并行擴展總線，大大減省封裝成本和芯片體積，這類單片機稱為非總線型單片機?？刂菩?家電型這是按照單片機大致應(yīng)用的領(lǐng)域進行區(qū)分的。一般而言，工控型尋址范圍大，運算能力強；用于家電的單片機多為專用型，通常是小封裝、低價格，外圍器件和外設(shè)接口集成度高。顯然，上述分類并不是惟一的和嚴格的。例如，80C51類單片機既是通用型又是總線型，還可以作工控用。工作過程單片機自動完成賦予它的任務(wù)的過程，也就是單片機執(zhí)行程序的過程，即一條條執(zhí)行的指令的過程，所謂指令就是把要求單片機執(zhí)行的各種操作用的命令的形式寫下來，這是在設(shè)計人員賦予它的指令系統(tǒng)所決定的，一條指令對應(yīng)著一種基本操作；單片機所能執(zhí)行的全部指令，就是該單片機的指令系統(tǒng)，不同種類的單片機，其指令系統(tǒng)亦不同。為使單片機能自動完成某一特定任務(wù)，必須把要解決的問題編成一系列指令（這些指令必須是選定單片機能識別和執(zhí)行的指令），這一系列指令的集合就成為程序，程序需要預(yù)先存放在具有存儲功能的部件——存儲器中。存儲器由許多存儲單元（最小的存儲單位）組成，就像大樓房有許多房間組成一樣，指令就存放在這些單元里，單元里的指令取出并執(zhí)行就像大樓房的每個房間的被分配到了唯一一個房間號一樣，每一個存儲單元也必須被分配到唯一的地址號，該地址號稱為存儲單元的地址，這樣只要知道了存儲單元的地址，就可以找到這個存儲單元，其中存儲的指令就可以被取出，然后再被執(zhí)行。程序通常是順序執(zhí)行的，所以程序中的指令也是一條條順序存放的，單片機在執(zhí)行程序時要能把這些指令一條條取出并加以執(zhí)行，必須有一個部件能追蹤指令所在的地址，這一部件就是程序計數(shù)器PC(包含在CPU中)，在開始執(zhí)行程序時，給PC賦以程序中第一條指令所在的地址，然后取得每一條要執(zhí)行的命令，PC之中的內(nèi)容就會自動增加，增加量由本條指令長度決定，可能是1、2或3,以指向下一條指令的起始地址，保證指令順序執(zhí)行。單片機歷史單片機誕生于1971年，經(jīng)歷了SCM、MCU、SOC三大階段。單片機的基本結(jié)構(gòu)單片機由運算器、控制器、存儲器、輸入輸出設(shè)備構(gòu)成。起初模型1.SCM即單片微型計算機(SingleChipMicrocomputer)階段，主要是尋求最佳的單片形態(tài)嵌入式系統(tǒng)的最佳體系結(jié)構(gòu)?！皠?chuàng)新模式”獲得成功，奠定了SCM與通用計算機完全不同的發(fā)展道路。在開創(chuàng)嵌入式系統(tǒng)獨立發(fā)展道路上，Intel公司功不可沒。MCU即微控制器(MicroControllerUnit)階段，主要的技術(shù)發(fā)展方向是：不斷擴展?jié)M足嵌入