《电子信息类专业英语》课件-第11章

Unit11SingleChipComputer网络实用知识(二)——英文网站注册申请表的填写

SingleChipMicrocomputerisalsonamedMicrocontrollerUnitorEmbeddedController.Amicrocontroller(orMCU)isacomputer-on-a-chip.Itisatypeofmicroprocessoremphasizingself-sufficiencyandcost-effectivenessincontrasttoageneral-purposemicroprocessor(thekindusedinaPC).Inadditiontoallarithmeticandlogicelementsofageneralpurposemicroprocessor,themicrocontrollerusuallyalsointegratesadditionalelementssuchasread-onlyandread-writememory,andinput/outputinterfaces.

Microcontrollersarefrequentlyusedinautomaticallycontrolledproductsanddevices,suchasautomobileenginecontrolsystems,officemachines,appliances,powertools,andtoys.Byreducingthesize,cost,andpowerconsumptioncomparedtoadesignusingaseparatemicroprocessor,memory,andinput/outputdevices,microcontrollersmakeiteconomicaltoelectronicallycontrolmanymoreprocesses.

Themajorityofcomputersystemsinusetodayareembeddedinothermachinery,suchastelephones,clocks,appliances,andvehicles.Anembeddedsystemmayhaveminimalrequirementsformemoryandprogramlength.Inputandoutputdevicesmaybediscreteswitches,relays,orsolenoids.Anembeddedcontrollermaylackanyhuman-readableinterfacedevicesatall.Forexample,embeddedsystemsusuallydon’thavekeyboards,screens,disks,printers,orotherrecognizableI/Odevicesofapersonalcomputer.Microcontrollersmaycontrolelectricmotors,relaysorvoltages,andmayreadswitches,variableresistorsorotherelectronicdevices.

Incontrasttogeneral-purposeCPUs,microcontrollersmaynotimplementanexternaladdressordatabus,becausetheyintegrateRAMandnon-volatilememoryonthesamechipastheCPU.Becausetheyneedfewerpins,thechipcanbeplacedinamuchsmaller,cheaperpackage.

Amicrocontrollerisasingleintegratedcircuit,commonlywiththefollowingfeatures:

·centralprocessingunit—rangingfromsmallandsimple4-bitprocessorstocomplex32-or64-bitprocessors.

·discreteinputandoutputbits,allowingcontrolordetectionofthelogicstateofanindividualpackagepin.

·serialinput/outputsuchasserialports(UARTs).

·otherserialcommunicationsinterfaceslikeI2C,SerialPeripheralInterfaceandControllerAreaNetworkforsysteminterconnect.

·peripheralssuchastimersandwatchdog.

·volatilememory(RAM)fordatastorage.

·ROM,EPROM,EEPROMorFlashmemoryforprogramandoperatingparameterstorage.

·clockgenerator—oftenanoscillatorforaquartztimingcrystal,resonatororRCcircuit.

·manyincludeanalog-to-digitalconverters.

Thisintegrationdrasticallyreducesthenumberofchips，theamountofwiringandPCBspacethatwouldbeneededtoproduceequivalentsystemsusingseparatechips.

Microcontrollerarchitecturesvarywidely.Somedesignsincludegeneral-purposemicroprocessorcores,withoneormoreROM,RAM,orI/Ofunctionsintegratedontothepackage.Otherdesignsarepurposebuiltforcontrolapplications.Amicrocontrollerinstructionsetusuallyhasmanyinstructionsintendedforbit-wiseoperationstomakecontrolprogramsmorecompact.Forexample,ageneralpurposeprocessormightrequireseveralinstructionstotestabitinaregisterandbranchifthebitisset,whereamicrocontrollercouldhaveasingleinstructionth