單片機(jī)基礎(chǔ)外文文獻(xiàn)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(jī)基礎(chǔ)單片機(jī)概況單片微型計(jì)算機(jī)簡(jiǎn)稱(chēng)單片機(jī)，是典型的嵌入式微控制器(SCMUnit),常用英文字母的縮寫(xiě)MCU表示單片機(jī)，它最早是被用在工業(yè)控制領(lǐng)域。由于單片機(jī)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(xué)生、愛(ài)好者，產(chǎn)品開(kāi)發(fā)人員掌握單片機(jī)這門(mén)技術(shù)，于是產(chǎn)生單片機(jī)開(kāi)發(fā)板，比較有名的例如電子人DZR-01A單片機(jī)開(kāi)發(fā)板。單片機(jī)由芯片內(nèi)僅有CPU的專(zhuān)用處理器發(fā)展而來(lái)。最早的設(shè)計(jì)理念是通過(guò)將大量外圍設(shè)備和CPU集成在一個(gè)芯片中，使計(jì)算機(jī)系統(tǒng)更小，更容易集成進(jìn)復(fù)雜的而對(duì)體積要求嚴(yán)格的控制設(shè)備當(dāng)中。INTEL的Z80是最早按照這種思想設(shè)計(jì)出的處理器，從此以后，單片機(jī)和專(zhuān)用處理器的發(fā)展便分道揚(yáng)鑣。早期的單片機(jī)都是8位或4位的。其中最成功的是INTEL的8031，因?yàn)楹?jiǎn)單可靠而性能不錯(cuò)獲得了很大的好評(píng)。此后在8031上發(fā)展出了MCS51系列單片機(jī)系統(tǒng)。基于這一系統(tǒng)的單片機(jī)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(kāi)始出現(xiàn)了16位單片機(jī)，但因?yàn)樾詢(xún)r(jià)比不理想并未得到很廣泛的應(yīng)用。90年代后隨著消費(fèi)電子產(chǎn)品大發(fā)展，單片機(jī)技術(shù)得到了巨大提高。隨著INTELi960系列特別是后來(lái)的ARM系列的廣泛應(yīng)用，32位單片機(jī)迅速取代16位單片機(jī)的高端地位，并且進(jìn)入主流市場(chǎng)。而傳統(tǒng)的8位單片機(jī)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(jī)主頻已經(jīng)超過(guò)300MHz，性能直追90年代中期的專(zhuān)用處理器，而普通的型號(hào)出廠價(jià)格跌落至1美元，最高端的型號(hào)也只有10美元。當(dāng)代單片機(jī)系統(tǒng)已經(jīng)不再只在裸機(jī)環(huán)境下開(kāi)發(fā)和使用，大量專(zhuān)用的嵌入式操作系統(tǒng)被廣泛應(yīng)用在全系列的單片機(jī)上。而在作為掌上電腦和手機(jī)核心處理的高端單片機(jī)甚至可以直接使用專(zhuān)用的Windows和Linux操作系統(tǒng)。單片機(jī)比專(zhuān)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(shí)上單片機(jī)是世界上數(shù)量最多的計(jì)算機(jī)?，F(xiàn)代人類(lèi)生活中所用的幾乎每件電子和機(jī)械產(chǎn)品中都會(huì)集成有單片機(jī)。手機(jī)、電話、計(jì)算器、家用電器、電子玩具、掌上電腦以及鼠標(biāo)等電腦配件中都配有1-2部單片機(jī)。而個(gè)人電腦中也會(huì)有為數(shù)不少的單片機(jī)在工作。汽車(chē)上一般配備40多部單片機(jī)，復(fù)雜的工業(yè)控制系統(tǒng)上甚至可能有數(shù)百臺(tái)單片機(jī)在同時(shí)工作！單片機(jī)的數(shù)量不僅遠(yuǎn)超過(guò)PC機(jī)和其他計(jì)算的總和，甚至比人類(lèi)的數(shù)量還要多。單片機(jī)又稱(chēng)單片微控制器，它不是完成某一個(gè)邏輯功能的芯片，而是把一個(gè)計(jì)算機(jī)系統(tǒng)集成到一個(gè)芯片上。相當(dāng)于一個(gè)微型的計(jì)算機(jī)，和計(jì)算機(jī)相比，單片機(jī)只缺少了I/O設(shè)備。概括的講：一塊芯片就成了一臺(tái)計(jì)算機(jī)。它的體積小、質(zhì)量輕、價(jià)格便宜、為學(xué)習(xí)、應(yīng)用和開(kāi)發(fā)提供了便利條件。同時(shí)，學(xué)習(xí)使用單片機(jī)是了解計(jì)算機(jī)原理與結(jié)構(gòu)的最佳選擇。單片機(jī)內(nèi)部也用和電腦功能類(lèi)似的模塊，比如CPU，內(nèi)存，并行總線，還有和硬盤(pán)作用相同的存儲(chǔ)器件，不同的是它的這些部件性能都相對(duì)我們的家用電腦弱很多，不過(guò)價(jià)錢(qián)也是低的，一般不超過(guò)10元即可，用它來(lái)做一些控制電器一類(lèi)不是很復(fù)雜的工作足矣了。我們現(xiàn)在用的全自動(dòng)滾筒洗衣機(jī)、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(shí)時(shí)控制計(jì)算機(jī)，在線式就是現(xiàn)場(chǎng)控制，需要的是有較強(qiáng)的抗干擾能力，較低的成本，這也是和離線式計(jì)算機(jī)的（比如家用PC）的主要區(qū)別。單片機(jī)是靠程序運(yùn)行的，并且可以修改。通過(guò)不同的程序?qū)崿F(xiàn)不同的功能，尤其是特殊的獨(dú)特的一些功能，這是別的器件需要費(fèi)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(gè)不是很復(fù)雜的功能要是用美國(guó)50年代開(kāi)發(fā)的74系列，或者60年代的CD4000系列這些純硬件來(lái)搞定的話，電路一定是一塊大PCB板！但是如果要是用美國(guó)70年代成功投放市場(chǎng)的系列單片機(jī)，結(jié)果就會(huì)有天壤之別！只因?yàn)閱纹瑱C(jī)的通過(guò)你編寫(xiě)的程序可以實(shí)現(xiàn)高智能，高效率，以及高可靠性！由于單片機(jī)對(duì)成本是敏感的，所以目前占統(tǒng)治地位的軟件還是最低級(jí)匯編語(yǔ)言，它是除了二進(jìn)制機(jī)器碼以上最低級(jí)的語(yǔ)言了，既然這么低級(jí)為什么還要用呢？很多高級(jí)的語(yǔ)言已經(jīng)達(dá)到了可視化編程的水平為什么不用呢？原因很簡(jiǎn)單，就是單片機(jī)沒(méi)有家用計(jì)算機(jī)那樣的CPU，也沒(méi)有像硬盤(pán)那樣的海量存儲(chǔ)設(shè)備。一個(gè)可視化高級(jí)語(yǔ)言編寫(xiě)的小程序里面即使只有一個(gè)按鈕，也會(huì)達(dá)到幾十K的尺寸！對(duì)于家用PC的硬盤(pán)來(lái)講沒(méi)什么，可是對(duì)于單片機(jī)來(lái)講是不能接受的。單片機(jī)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(jì)算機(jī)上的操作系統(tǒng)和應(yīng)用軟件拿到家用PC上來(lái)運(yùn)行，家用PC的也是承受不了的?？梢哉f(shuō)，二十世紀(jì)跨越了三個(gè)“電”的時(shí)代，即電氣時(shí)代、電子時(shí)代和現(xiàn)已進(jìn)入的電腦時(shí)代。不過(guò)，這種電腦，通常是指?jìng)€(gè)人計(jì)算機(jī)，簡(jiǎn)稱(chēng)PC機(jī)。它由主機(jī)、鍵盤(pán)、顯示器等組成。還有一類(lèi)計(jì)算機(jī)，大多數(shù)人卻不怎么熟悉。這種計(jì)算機(jī)就是把智能賦予各種機(jī)械的單片機(jī)（亦稱(chēng)微控制器）。顧名思義，這種計(jì)算機(jī)的最小系統(tǒng)只用了一片集成電路，即可進(jìn)行簡(jiǎn)單運(yùn)算和控制。因?yàn)樗w積小，通常都藏在被控機(jī)械的“肚子”里。它在整個(gè)裝置中，起著有如人類(lèi)頭腦的作用，它出了毛病，整個(gè)裝置就癱瘓了?，F(xiàn)在，這種單片機(jī)的使用領(lǐng)域已十分廣泛，如智能儀表、實(shí)時(shí)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(jī)，就能起到使產(chǎn)品升級(jí)換代的功效，常在產(chǎn)品名稱(chēng)前冠以形容詞——“智能型”，如智能型洗衣機(jī)等?，F(xiàn)在有些工廠的技術(shù)人員或其它業(yè)余電子開(kāi)發(fā)者搞出來(lái)的某些產(chǎn)品，不是電路太復(fù)雜，就是功能太簡(jiǎn)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(jī)或其它可編程邏輯器件上單片機(jī)的分類(lèi)單片機(jī)作為計(jì)算機(jī)發(fā)展的一個(gè)重要領(lǐng)域，應(yīng)用一個(gè)較科學(xué)的分類(lèi)方法。根據(jù)目前發(fā)展情況，從不同角度單片機(jī)大致可以分為通用型/專(zhuān)用型、總線型/非總線型及工控型/家電型。通用型/專(zhuān)用型這是按單片機(jī)適用范圍來(lái)區(qū)分的。例如，80C51是通用型單片機(jī)，它不是為某種專(zhuān)用途設(shè)計(jì)的；專(zhuān)用型單片機(jī)是針對(duì)一類(lèi)產(chǎn)品甚至某一個(gè)產(chǎn)品設(shè)計(jì)生產(chǎn)的，例如為了滿足電子體溫計(jì)的要求，在片內(nèi)集成ADC接口等功能的溫度測(cè)量控制電路。總線型/非總線型這是按單片機(jī)是否提供并行總線來(lái)區(qū)分的?？偩€型單片機(jī)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(kuò)展并行外圍器件都可通過(guò)串行口與單片機(jī)連接，另外，許多單片機(jī)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(kuò)展總線，大大減省封裝成本和芯片體積，這類(lèi)單片機(jī)稱(chēng)為非總線型單片機(jī)?？刂菩?家電型這是按照單片機(jī)大致應(yīng)用的領(lǐng)域進(jìn)行區(qū)分的。一般而言，工控型尋址范圍大，運(yùn)算能力強(qiáng)；用于家電的單片機(jī)多為專(zhuān)用型，通常是小封裝、低價(jià)格，外圍器件和外設(shè)接口集成度高。顯然，上述分類(lèi)并不是惟一的和嚴(yán)格的。例如，80C51類(lèi)單片機(jī)既是通用型又是總線型，還可以作工控用。工作過(guò)程單片機(jī)自動(dòng)完成賦予它的任務(wù)的過(guò)程，也就是單片機(jī)執(zhí)行程序的過(guò)程，即一條條執(zhí)行的指令的過(guò)程，所謂指令就是把要求單片機(jī)執(zhí)行的各種操作用的命令的形式寫(xiě)下來(lái)，這是在設(shè)計(jì)人員賦予它的指令系統(tǒng)所決定的，一條指令對(duì)應(yīng)著一種基本操作；單片機(jī)所能執(zhí)行的全部指令，就是該單片機(jī)的指令系統(tǒng)，不同種類(lèi)的單片機(jī)，其指令系統(tǒng)亦不同。為使單片機(jī)能自動(dòng)完成某一特定任務(wù)，必須把要解決的問(wèn)題編成一系列指令（這些指令必須是選定單片機(jī)能識(shí)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(chǔ)功能的部件——存儲(chǔ)器中。存儲(chǔ)器由許多存儲(chǔ)單元（最小的存儲(chǔ)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(gè)房間的被分配到了唯一一個(gè)房間號(hào)一樣，每一個(gè)存儲(chǔ)單元也必須被分配到唯一的地址號(hào)，該地址號(hào)稱(chēng)為存儲(chǔ)單元的地址，這樣只要知道了存儲(chǔ)單元的地址，就可以找到這個(gè)存儲(chǔ)單元，其中存儲(chǔ)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(jī)在執(zhí)行程序時(shí)要能把這些指令一條條取出并加以執(zhí)行，必須有一個(gè)部件能追蹤指令所在的地址，這一部件就是程序計(jì)數(shù)器PC(包含在CPU中)，在開(kāi)始執(zhí)行程序時(shí)，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(huì)自動(dòng)增加，增加量由本條指令長(zhǎng)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(jī)歷史單片機(jī)誕生于1971年，經(jīng)歷了SCM、MCU、SOC三大階段。單片機(jī)的基本結(jié)構(gòu)單片機(jī)由運(yùn)算器、控制器、存儲(chǔ)器、輸入輸出設(shè)備構(gòu)成。起初模型1.SCM即單片微型計(jì)算機(jī)(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(jì)算機(jī)完全不同的發(fā)展道路。在開(kāi)創(chuàng)嵌入式系統(tǒng)獨(dú)立發(fā)展道路上，Intel公司功不可沒(méi)。MCU即微控制器(MicroControllerUnit)階段，主要的技術(shù)發(fā)展方向是：不斷擴(kuò)展?jié)M足嵌入