外文以及翻译-基于单片机的电子琴设计.docx
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外文资料原文
Microcontroller-baseddesignandmanufacture
(1)MCU
Amicrocontroller(orMCU)isacomputer-on-a-chip.Itisatypeofmicroprocessoremphasizingself-sufficiencyandcost-effectiveness,incontrasttoageneral-purposemicroprocessor(thekindusedinaPC).
Themajorityofcomputersystemsinusetodayareembeddedinothermachinery,suchastelephones,clocks,appliances,vehicles,andinfrastructure.Anembeddedsystemusuallyhasminimalrequirementsformemoryandprogramlengthandmayrequiresimplebutunusualinput/outputsystems.Forexample,mostembeddedsystemslackkeyboards,screens,disks,printers,orotherrecognizableI/Odevicesofapersonalcomputer.Theymaycontrolelectricmotors,relaysorvoltages,andreadswitches,variableresistorsorotherelectronicdevices.Often,theonlyI/Odevicereadablebyahumanisasinglelight-emittingdiode,andseverecostorpowerconstraintscaneveneliminatethat.
Incontrasttogeneral-purposeCPUs,microcontrollersdonothaveanaddressbusoradatabus,becausetheyintegratealltheRAMandnon-volatilememoryonthesamechipastheCPU.Becausetheyneedfewerpins,thechipcanbeplacedinamuchsmaller,cheaperpackage.
Integratingthememoryandotherperipheralsonasinglechipandtestingthemasaunitincreasesthecostofthatchip,butoftenresultsindecreasednetcostoftheembeddedsystemasawhole.(EvenifthecostofaCPUthathasintegratedperipheralsisslightlymorethanthecostofaCPU+externalperipherals,havingfewerchipstypicallyallowsasmallerandcheapercircuitboard,andreducesthelaborrequiredtoassembleandtestthecircuitboard).Thistrendleadstodesign.
Amicrocontrollerisasingleintegratedcircuit,commonlywiththefollowingfeatures:
centralprocessingunit-rangingfromsmallandsimple4-bitprocessorstosophisticated32-or64-bitprocessors
input/outputinterfacessuchasserialports(UARTs)
otherserialcommunicationsinterfaceslikePC,SerialPeripheralInterfaceandControllerAreaNetworkforsysteminterconnectperipheralssuchastimersandwatchdogRAMfordatastorageROM,EPROM,EEPROMorFlashmemoryforprogramstorageclockgenerator-oftenanoscillatorforaquartztimingcrystal,resonatororRCcircuitmanyincludeanalog-to-digitalconverters.
ThisintegrationdrasticallyreducesthenumberofchipsandtheamountofwiringandPCBspacethatwouldbeneededtoproduceequivalentsystemsusingseparatechipsandhaveprovedtobehighlypopularinembeddedsystemssincetheirintroductioninthe1970s.
SomemicrocontrollerscanaffordtouseaHarvardarchitecture:
separatememorybusesforinstructionsanddata,allowingaccessestotakeplaceconcurrently.
Thedecisionofwhichperipheraltointegrateisoftendifficult.TheMicrocontrollervendorsoftentradeoperatingfrequenciesandsystemdesignflexibilityagainsttime-to-marketrequirementsfromtheircustomersandoveralllowersystemcost.Manufacturershavetobalancetheneedtominimizethechipsizeagainstadditionalfunctionality.
Microcontrollerarchitecturesareavailablefrommanydifferentvendorsinsomanyvarietiesthateachinstructionsetarchitecturecouldrightlybelongtoacategoryoftheirown.Chiefamongthesearethe8051,Z80andARMderivatives.[citationneeded]
Amicrocontroller(alsoMCUorpC)isafunctionalcomputersystem-on-a-chip.Itcontainsaprocessorcore,memory,andprogrammableinput/outputperipherals.
MicrocontrollersincludeanintegratedCPU,memory(asmallamountofRAM,programmemory,orboth)andperipheralscapableofinputandoutput.
Itemphasizeshighintegration,incontrasttoamicroprocessorwhichonlycontainsaCPU(thekindusedinaPC).Inadditiontotheusualarithmeticandlogicelementsofageneralpurposemicroprocessor,themicrocontrollerintegratesadditionalelementssuchasread-writememoryfordatastorage,read-onlymemoryforprogramstorage,Flashmemoryforpermanentdatastorage,peripherals,andinput/outputinterfaces.Atclockspeedsofaslittleas32KHz,microcontrollersoftenoperateatverylowspeedcomparedtomicroprocessors,butthisisadequatefortypicalapplications.Theyconsumerelativelylittlepower(milliwattsorevenmicrowatts),andwillgenerallyhavetheabilitytoretainfunctionalitywhilewaitingforaneventsuchasabuttonpressorinterrupt.Powerconsumptionwhilesleeping(CPUclockandperipheralsdisabled)maybejustnanowatts,makingthemidealforlowpowerandlonglastingbatteryapplications.
Microcontrollersareusedinautomaticallycontrolledproductsanddevices,suchasautomobileenginecontrolsystems,remotecontrols,officemachines,appliances,powertools,andtoys.Byreducingthesize,cost,andpowerconsumptioncomparedtoadesignusingaseparatemicroprocessor,memory,andinput/outputdevices,microcontrollersmakeitec