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Embedded operating system


Time: 22/12/2021 1329Views

History

Infact,theconceptofembeddedhasexistedalongtimeago.Intermsofcommunications,embeddedsystemswereusedtocontrolelectronicmechanicaltelephoneexchangesinthe1960s,andwerecalled"StoredProgramControl"(StoredProgramControl)atthattime.

Therealdevelopmentofembeddedcomputerswasaftertheadventofmicroprocessors.InNovember1971,Intelsuccessfullyintegratedthearithmeticunitandthecontrollercircuit,andlaunchedthefirstmicroprocessorIntel4004.Sincethen,variousmanufacturershavesuccessivelyintroducedmany8-bitand16-bitmicroprocessors.IncludingIntel8080/8085,8086,Motorola's6800,68000,andZilog'sZ80,Z8000,etc.Thesystemcomposedofthesemicroprocessorsasthecoreiswidelyusedinthefieldsofinstrumentation,medicalequipment,robots,andhouseholdappliances.Theextensiveapplicationofmicroprocessorshasformedabroadembeddedapplicationmarket.ComputermanufacturershavebeguntoprovideuserswithOEMproductsinalargenumberofplug-ins,andthenuserscanchooseasetofsuitableCPUboards,memoryboardsandvarioustypesaccordingtotheirneeds.TheI/Oplug-inboardconstitutesadedicatedembeddedcomputersystemandembedsitinitsownsystemequipment.

Forthesakeofflexibilityandcompatibility,serializedandmodularsingle-boardcomputershaveappeared.Popularsingle-boardcomputersincludeIntel’siSBCseriesandZilog’sMCB.Later,peoplecandesignadedicatedembeddedcomputerwithoutchoosingthechip,butaslongasselectingeachfunctionalmodule,adedicatedcomputersystemcanbebuilt.BothusersanddevelopershopetopurchasethemostsuitableOEMproductsfromdifferentmanufacturersandinsertthemintothepurchasedorself-madechassistoformanewsystem.Inthisway,itishopedthattheplug-insarecompatiblewitheachother,whichleadstotheindustrialcontrolmicrocomputersystembus.Birth.IntelintroducedMultibusin1976andexpandedtoMultibusIIwithabandwidthof40MB/sin1983.ThesimpleSTDbusdesignedbyPrologin1978iswidelyusedinsmallembeddedsystems.

The1980scanbesaidtobeanerawhenallkindsofbusesemergedinanendlessstream.Withtheimprovementofthelevelofmicroelectronicstechnology,integratedcircuitmanufacturersbegantointegratethemicroprocessor,I/Ointerface,A/D,D/Aconversion,serialinterface,RAM,ROMandothercomponentsrequiredinembeddedapplications.IntegrateintoaVLSI,therebymanufacturingamicrocontrollerforI/Odesign,whichiswhatwecommonlycallasingle-chipmicrocomputer,andbecomearookieintheemergenceofembeddedcomputersystems.SubsequentdevelopmentofDSPproductsfurtherimprovedthetechnicallevelofembeddedcomputersystems,andquicklypenetratedintovariousfieldssuchasconsumerelectronics,medicalelectronics,intelligentcontrol,communicationelectronics,instrumentation,andtransportation.

Inthe1990s,drivenbyhugedemandsfordistributedcontrol,flexiblemanufacturing,digitalcommunications,andinformationappliances,embeddedsystemsfurtheracceleratedtheirdevelopment.DSPproductsforreal-timesignalprocessingalgorithmsaredevelopingtowardshighspeed,highprecision,andlowpowerconsumption.Texaslaunchedthethird-generationDSPchipTMS320C30,leadingthedevelopmentofmicrocontrollersto32-bithigh-speedintelligence.Intermsofapplications,handheldcomputers,handheldPCs,andset-topboxesarerelativelymatureanddeveloprapidly.Especiallyhandheldcomputers.In1997,therewereonlyfourorfivebrandsofhandheldcomputersintheUSmarket.Attheendof1998,varioushandheldcomputershavesprungup.Inaddition,Nokialaunchedsmartphones,Siemenslaunchedset-topboxes,Wyselaunchedsmartterminals,andNSlaunchedWebPAD.Thesmallcomputermountedonthecarcannotonlycontrolvariousdevices(suchasaudio,etc.)inthecar,butcanalsobeconnectedtotheGPStoautomaticallycontrolthecar.

The21stcenturyisundoubtedlyaneraofnetworks,andtheapplicationofembeddedcomputersystemstovariousnetworksmustalsobeanimportantdirectionforthedevelopmentofembeddedsystems.

Features

1)Thesystemcoreissmall

Becauseembeddedsystemsaregenerallyusedinsmallelectronicdevices,thesystemresourcesarerelativelylimited,sothecoreismoretraditionalTheoperatingsystemismuchsmaller.Forexample,Enea'sOSEdistributedsystemhasonly5Kcores.

2)Highspecificity

Embeddedsystemsarehighlypersonalized,andthesoftwaresystemandhardwareareverytightlyintegrated.Generally,thesystemmustbetransplantedtothehardware,eveninTheproductsofthesamebrandandthesameseriesalsoneedtobecontinuouslymodifiedaccordingtothechanges,additionsandreductionsofthesystemhardware.Atthesametime,fordifferenttasks,itisoftennecessarytomakemajorchangestothesystem.Thecompilationanddownloadofprogramsmustbecombinedwiththesystem.Thismodificationandthe"upgrade"ofgeneralsoftwarearecompletelytwoconcepts.

3)Systemsimplification

Embeddedsystemsgenerallydonothaveacleardistinctionbetweensystemsoftwareandapplicationsoftware,anddonotrequiretheirfunctionaldesignandimplementationtobetoocomplicated,whichwillhelpcontrolsystemcostsontheonehand,Butalsoconducivetotherealizationofsystemsecurity.

4)Highreal-timeperformance

Highreal-timesystemsoftware(OS)isthebasicrequirementofembeddedsoftware.Andsoftwarerequiressolid-statestoragetoincreasespeed;softwarecoderequireshighqualityandhighreliability.

5)Multitaskingoperatingsystem

Ifembeddedsoftwaredevelopmentistobestandardized,itmustuseamultitaskingoperatingsystem.Embeddedsystemapplicationscanrundirectlyonthechipwithoutanoperatingsystem;butinordertorationallyschedulemultipletasks,utilizesystemresources,systemfunctions,andinterfacewithspeciallibraryfunctions,usersmustchooseRTOS(Real-TimeOperatingSystem)bythemselvesDevelopmentplatform,soastoensurethereal-timeperformanceandreliabilityofprogramexecution,reducedevelopmenttime,andensuresoftwarequality.

6)Developmenttoolsandenvironmentarerequired

Developmenttoolsandenvironmentarerequiredforembeddedsystemdevelopment.Becauseitdoesnothavetheabilityofindependentdevelopment,usersusuallycannotmodifytheprogramfunctionsevenafterthedesigniscompleted.Asetofdevelopmenttoolsandenvironmentscanbeusedfordevelopment.Thesetoolsandenvironmentsaregenerallybasedonsoftwareandhardwareongeneral-purposecomputers.Equipmentandvariouslogicanalyzers,mixedsignaloscilloscopes,etc.Thereisoftentheconceptofahostandatargetmachineduringdevelopment.Thehostisusedforprogramdevelopment,andthetargetmachineisthefinalexecutionmachine.Thedevelopmentneedstobecombinedalternately.

Core

Thecoreofanembeddedsystemisanembeddedmicroprocessor.Embeddedmicroprocessorsgenerallyhavethefollowingfourcharacteristics:

1)Ithasstrongsupportforreal-timetasks,cancompletemulti-tasksandhasashortinterruptresponsetime,sothattheinternalcodeandreal-timeTheexecutiontimeoftheinnercoreisreducedtoaminimum.

2)Ithasaverypowerfulstorageareaprotectionfunction.Thisisbecausethesoftwarestructureoftheembeddedsystemhasbeenmodularized,andinordertoavoidfalsecross-effectsbetweensoftwaremodules,itisnecessarytodesignapowerfulstorageareaprotectionfunction,whichisalsoconducivetosoftwarediagnosis.

3)Extensibleprocessorstructure,inordertobeabletodevelopthehighestperformanceembeddedmicroprocessorthatmeetstheapplicationmostquickly.

4)Embeddedmicroprocessorsmusthavelowpowerconsumption,especiallyforbattery-poweredembeddedsystemsusedinportablewirelessandmobilecomputingandcommunicationdevices.mWorevenμWlevel.

Classification

Dividedfromhardwareandsoftware.

Basedonhardware

Embeddedmicroprocessor(MicroProcessorUnit,MPU)

EmbeddedmicroprocessorevolvedfromtheCPUingeneral-purposecomputers.Itscharacteristicisthatithasa32-bitormoreprocessor,withhigherperformance,andofcourseitspriceiscorrespondinglyhigher.Butunlikecomputerprocessors,inactualembeddedapplications,onlyfunctionalhardwarecloselyrelatedtoembeddedapplicationsisretained,andotherredundantfunctionalpartsareremoved,sothatembeddedapplicationscanbeimplementedwiththelowestpowerconsumptionandresources.specialrequirements.Comparedwithindustrialcontrolcomputers,embeddedmicroprocessorshavetheadvantagesofsmallsize,lightweight,lowcost,andhighreliability.ThemainembeddedprocessortypesareAm186/88,386EX,SC-400,PowerPC,68000,MIPS,ARM/StrongARMseries,etc.

Amongthem,Arm/StrongArmisanembeddedmicroprocessorspeciallydevelopedforhandhelddevices,whichisamid-rangeprice.

EmbeddedMicrocontrollerUnit(MCU)

Thetypicalrepresentativeofembeddedmicrocontrolleristhesingle-chipmicrocomputer.Fromtheappearanceofsingle-chipmicrocomputerinthelate1970stotoday,Althoughmorethan30yearshavepassed,this8-bitelectronicdevicestillhasanextremelywiderangeofapplicationsinembeddeddevices.ThemicrocontrollerchipintegratesROM/EPROM,RAM,bus,buslogic,timer/counter,watchdog,I/O,serialport,pulsewidthmodulationoutput,A/D,D/A,FlashRAM,EEPROM,etc.Kindsofnecessaryfunctionsandperipherals.Comparedwithembeddedmicroprocessors,thebiggestfeatureofmicrocontrollersismonolithicandgreatlyreducedvolume,whichreducespowerconsumptionandcost,andimprovesreliability.Theon-chipperipheralresourcesofamicrocontrolleraregenerallyricherandsuitableforcontrol,soitiscalledamicrocontroller.

BecauseofthelowpriceandexcellentfunctionsofMCU,ithasthemostvarietyandquantity.Themorerepresentativeonesinclude8051,MCS-251,MCS-96/196/296,P51XA,C166/167,68KseriesandMCU8XC930/931,C540,C541,andsupportI2C,CAN-Bus,LCDandmanydedicatedMCUandcompatibleseries,MCUaccountedforabout70%ofthemarketshareofembeddedsystems,AvrproducedbyAtmelduetoitsIntegratingFPGAandotherdevices,soithasaveryhighcostperformance,itisboundtopromotethehigherdevelopmentofsingle-chipmicrocomputers.

EmbeddedDigitalSignalProcessor(EDSP)

DSPprocessorisaprocessordedicatedtosignalprocessing.Thesystemstructureandinstructionalgorithmarespeciallydesigned,withhighcompilationefficiencyandinstructionexecutionspeed.DSPhasbeenwidelyusedinvariousinstrumentssuchasdigitalfiltering,FFT,andspectrumanalysis.

ThetheoreticalalgorithmofDSPhasappearedinthe1970s,butsincethespecializedDSPprocessorhasnotyetappeared,thistheoreticalalgorithmcanonlyberealizedbydiscretecomponentssuchasMPU.ThelowerprocessingspeedofMPUcannotmeetthealgorithmrequirementsofDSP,anditsapplicationfieldislimitedtosomecutting-edgehigh-techfields.Withthedevelopmentoflarge-scaleintegratedcircuittechnology,theworld'sfirstDSPchipwasbornin1982.ItscomputingspeedisdozensoftimesfasterthanMPU,andithasbeenwidelyusedinspeechsynthesisandcodecs.Bythemid-1980s,withtheadvancementanddevelopmentofCMOStechnology,thesecondgenerationofDSPchipsbasedonCMOStechnologycameintobeing,andtheirstoragecapacityandcomputingspeedweredoubled,becomingthebasisofvoiceprocessingandimagehardwareprocessingtechnology.Bythelate1980s,thecomputingspeedofDSPwasfurtherimproved,andtheapplicationfieldexpandedfromtheabove-mentionedscopetocommunicationsandcomputers.Afterthe1990s,DSPhasdevelopedtothefifthgenerationofproducts,withhigherintegrationandawiderrangeofapplications.

ThemostwidelyusedisTI’sTMS320C2000/C5000series.Inaddition,Intel’sMCS-296andSiemens’TriCorealsohavetheirownapplicationranges.

EmbeddedSystemOnChip

SoCpursuesthemosttolerantintegrateddevicesintheproductsystemandisoneofthehottopicsintheembeddedapplicationfield.ThebiggestfeatureofSOCisthatithassuccessfullyrealizedtheseamlessintegrationofsoftwareandhardware,anddirectlyembedsthecodemoduleoftheoperatingsystemintheprocessorchip.AndSOChasextremelyhighcomprehensiveness,usingVHDLandotherhardwaredescriptionlanguages​​insideasiliconchiptorealizeacomplexsystem.Usersnolongerneedtodrawhugeandcomplexcircuitboardsandmakealittleconnectionandsolderingliketraditionalsystemdesign.Theyonlyneedtousepreciselanguageandcomprehensivetimingdesigntodirectlycallvariousgeneral-purposeprocessorstandardsinthedevicelibrary,andthenAfterthesimulation,itcanbedirectlydeliveredtothechipmanufacturerforproduction.Sincemostofthesystemcomponentsareinsidethesystem,theentiresystemisparticularlysimple,whichnotonlyreducesthesizeandpowerconsumptionofthesystem,butalsoimprovesthereliabilityofthesystemandimprovesthedesignandproductionefficiency.

SinceSOCsareoftendedicated,mostofthemareunknowntousers.AtypicalSOCproductisPhilipsSmartXA.Afewgeneral-purposeseriessuchasTriCoreofSiemens,M-CoreofMotorola,someARMseriesdevices,NeuronchipjointlydevelopedbyEchelonandMotorola,etc.

Itisexpectedthatinthenearfuture,somelargechipcompanieswillrepelcompetitorsinonefellswoopbylaunchingmatureSOCchipsthatcanoccupymostmarkets.SOCchipswillalsoplayanimportantroleinapplicationfieldssuchassound,image,film,networkandsystemlogic.

Basedonsoftware

Fromthesoftwareaspect,itcanbedividedmainlyaccordingtothetypeofoperatingsystem.Therearetwomaintypesofsoftwareforembeddedsystems:real-timesystemsandtime-sharingsystems.Amongthem,real-timesystemsaredividedintotwocategories:hardreal-timesystemsandsoftreal-timesystems.

Thereal-timeembeddedsystemisdesignedtoperformspecificfunctionsandcanperformfunctionsstrictlyaccordingtotimesequence.Itsbiggestfeatureisthattheexecutionoftheprogramisdeterministic.Inareal-timesystem,ifthesystemfailstoachieveacertaintaskwithinaspecifiedtime,itwillleadtoacompletefailureofthesystem,thesystemiscalledahardreal-timesystem.Inasoftreal-timesystem,althoughresponsetimeisequallyimportant,overtimedoesnotcausefatalerrors.Ahardreal-timesystemoftenneedstoaddacontrolchipdedicatedtotimeandprioritymanagementonthehardware,whileasoftreal-timesystemmainlyimplementstimelimitmanagementthroughprogramminginsoftware.Forexample,WindowsCEisamultitaskingtime-sharingsystem,whileUcos-IIisatypicalreal-timeoperatingsystem.

Composition

Hardwarelayer

Thehardwarelayerincludesembeddedmicroprocessor,memory(SDRAM,ROM,Flash,etc.),generalequipmentinterfaceandI/OInterface(A/D,D/A,I/O,etc.).Addingapowersupplycircuit,aclockcircuitandamemorycircuitonthebasisofanembeddedprocessorconstitutesanembeddedcorecontrolmodule.TheoperatingsystemandapplicationprogramscanbesolidifiedinROM.

Embeddedmicroprocessor

Thecoreofthehardwarelayeroftheembeddedsystemistheembeddedmicroprocessor.ThebiggestdifferencebetweentheembeddedmicroprocessorandthegeneralCPUistheembeddedMostoftheembeddedmicroprocessorsworkinsystemsspeciallydesignedforspecificusergroups.Itintegratesmanytaskscompletedbytheboardinthegeneral-purposeCPUinsidethechip,whichisconducivetothetrendofminiaturizationinthedesignofembeddedsystems,anditalsohasVeryhighefficiencyandreliability.

ThearchitectureoftheembeddedmicroprocessorcanadoptthevonNeumannsystemortheHarvardarchitecture;theinstructionsystemcanchoosethereducedinstructionsystem(ReducedInstructionSetComputer,RISC)andthecomplexinstructionsystemCISC(ComplexInstruction)SetComputer,CISC).TheRISCcomputeronlycontainsthemostusefulinstructionsinthechannel,ensuringthatthedatachannelexecuteseachinstructionquickly,therebyimprovingtheexecutionefficiencyandmakingtheCPUhardwarestructuredesignsimpler.

Embeddedmicroprocessorshaveavarietyofdifferentsystems.Eveninthesamesystem,theymayhavedifferentclockfrequenciesanddatabuswidths,orintegratedifferentperipheralsandinterfaces.Accordingtoincompletestatistics,therearemorethan1,000kindsofembeddedmicroprocessorsintheworld,andtherearemorethan30seriesofarchitectures,amongwhichthemainstreamsystemsareARM,MIPS,PowerPC,X86andSH.ButunliketheglobalPCmarket,noembeddedmicroprocessorcandominatethemarket.Intermsof32-bitproductsalone,therearemorethan100embeddedmicroprocessors.Thechoiceofembeddedmicroprocessorisdeterminedaccordingtothespecificapplication.

Memory

Embeddedsystemsneedmemorytostoreandexecutecode.ThememoryoftheembeddedsystemincludesCache,mainmemoryandauxiliarymemory.

1)Cache

Cacheisasmall-capacity,fast-speedmemoryarray.Itislocatedbetweenthemainmemoryandtheembeddedmicroprocessorcore.Whendatareadoperationsarerequired,ThemicroprocessorreadsdatafromtheCacheasmuchaspossible,ratherthanfromthemainmemory,whichgreatlyimprovestheperformanceofthesystemandincreasesthedatatransferratebetweenthemicroprocessorandthemainmemory.ThemaingoalofCacheistoreducethememoryaccessbottleneckcausedbythememory(suchasmainmemoryandauxiliarymemory)tothemicroprocessorcore,sothattheprocessingspeedisfasterandthereal-timeperformanceisstronger.

Intheembeddedsystem,Cacheisallintegratedintheembeddedmicroprocessor,andcanbedividedintodataCache,instructionCacheorhybridCache.ThesizeofCachedependsondifferentprocessors.Cacheisgenerallyintegratedintohigh-endembeddedmicroprocessors.

2)Mainmemory

Themainmemoryisaregisterthattheembeddedmicroprocessorcandirectlyaccess,usedtostoresystemanduserprogramsanddata.Itcanbelocatedinsideoroutsidethemicroprocessor,anditscapacityis256KB~1GB,dependingonthespecificapplication.Generally,theon-chipmemoryhasasmallcapacity,highspeed,andalargeoff-chipmemory.

Thememoriescommonlyusedasmainmemoryare:

ROMtypeNORFlash,EPROMandPROM,etc.

RAMtypeSRAM,DRAMandSDRAM,etc.

Amongthem,NORFlashhasbeenwidelyusedintheembeddedfieldduetoitsadvantagessuchasmanyerasingtimes,faststoragespeed,largestoragecapacity,andlowprice.

3)Auxiliarymemory

Auxiliarymemoryisusedtostoreprogramcodesorinformationwithalargeamountofdata.Ithasalargecapacity,butitsreadingspeedismuchslowerthanthatofmainmemory.,Usedforlong-termpreservationofuserinformation.Commonlyusedexternalstorageinembeddedsystemsare:harddisk,NANDFlash,CFcard,MMCandSDcard,etc.

UniversaldeviceinterfaceandI/Ointerface

Interactionbetweenembeddedsystemandtheoutsideworldrequiresacertainformofuniversaldeviceinterface,suchasA/D,D/A.I/O,etc.Peripheralsrealizetheinput/outputfunctionofthemicroprocessorthroughtheconnectionwithotherdevicesorsensorsoutsidethechip.Eachperipheralusuallyhasonlyasinglefunction,anditcanbeoutsidethechiporbuiltintothechip.Therearemanytypesofperipherals,rangingfromasimpleserialcommunicationdevicetoaverycomplex802.11wirelessdevice.

CommondeviceinterfacescommonlyusedinembeddedsystemsincludeA/D(analog/digitalconversioninterface),D/A(digital/analogconversioninterface),andI/OinterfaceshaveRS-232interfaces(serialLinecommunicationinterface),Ethernet(Ethernetinterface),USB(universalserialbusinterface),audiointerface,VGAvideooutputinterface,I2C(fieldbus),SPI(serialperipheralinterface)andIrDA(infraredinterface),etc..

Intermediatelayer

Thereisanintermediatelayerbetweenthehardwarelayerandthesoftwarelayer,alsoknownastheHardwareAbstractLayer(HAL)orBoardSupportPackage(BoardSupportPackage,BSP),whichseparatestheupper-layersoftware(application)ofthesystemfromthelower-layerhardware,sothatthelower-layerdriverofthesystemhasnothingtodowiththeupperlayer.Theupper-layersoftwaredevelopersdonotneedtocareaboutthespecificconditionsoftheunderlyinghardware,andcanproceedaccordingtotheinterfaceprovidedbytheBSPlayer.Development.Thislayergenerallyincludestheinitializationofrelatedunderlyinghardware,datainput/outputoperations,andhardwaredeviceconfigurationfunctions.BSPhasthefollowingtwocharacteristics.

Hardwarerelevance:Becausethehardwareenvironmentofembeddedreal-timesystemshasapplicationrelevance,asaninterfacebetweenupper-levelsoftwareandhardwareplatforms,BSPneedstoprovideoperatingsystemswithmethodstooperateandcontrolspecifichardware.

Operatingsystemrelevance:Differentoperatingsystemshavetheirownsoftwarehierarchicalstructure,therefore,differentoperatingsystemshavespecifichardwareinterfaceforms.

Actually,BSPisasoftwarelevelbetweentheoperatingsystemandtheunderlyinghardware,includingmostofthesoftwaremodulesinthesystemthatarecloselyrelatedtothehardware.DesigningacompleteBSPneedstocompletetwoparts:thehardwareinitializationoftheembeddedsystemandtheBSPfunction,andthedesignofhardware-relateddevicedrivers.

Embeddedsystemhardwareinitialization

Thesysteminitializationprocesscanbedividedinto3mainlinks,whichareinorderfrombottomtotop,fromhardwaretosoftware.:Chip-levelinitialization,board-levelinitializationandsystem-levelinitialization.

Chip-levelinitialization

Completetheinitializationoftheembeddedmicroprocessor,includingsettingthecoreregisterandcontrolregisteroftheembeddedmicroprocessor,thecoreworkingmodeoftheembeddedmicroprocessorandtheembeddedmicroprocessorLocalbusmodeandsoon.Chip-levelinitializationgraduallysetstheembeddedmicroprocessorfromthedefaultstatewhenitispoweredontotheworkingstaterequiredbythesystem.Thisisapurehardwareinitializationprocess.

Board-levelinitialization

Completetheinitializationofhardwaredevicesotherthanembeddedmicroprocessors.Inaddition,somesoftwaredatastructuresandparametersneedtobesettoestablishahardwareandsoftwareenvironmentforsubsequentsystem-levelinitializationandapplicationprogramoperation.Thisisaninitializationprocessthatincludesbothsoftwareandhardware.

Systeminitialization

Theinitializationprocessismainlysoftwareinitialization,mainlyfortheinitializationoftheoperatingsystem.TheBSPtransfersthecontroloftheembeddedmicroprocessortotheembeddedoperatingsystem,andtheoperatingsystemcompletestheremaininginitializationoperations,includingloadingandinitializingdevicedriversthathavenothingtodowithhardware,establishingasystemmemoryarea,loadingandinitializingothersystemsoftwaremodules,Suchasnetworksystems,filesystems,etc.Finally,theoperatingsystemcreatestheapplicationenvironmentandpassescontroltotheentranceoftheapplication.

Hardware-relateddevicesDrivers

AnothermainfunctionofBSPishardware-relateddevicedrivers.Theinitializationofhardware-relateddevicedriversisusuallyaprocessfromhightolow.AlthoughtheBSPcontainshardware-relateddevicedrivers,thesedevicedriversareusuallynotdirectlyusedbytheBSP.Instead,theBSPassociatesthemwiththegeneraldevicedriversintheoperatingsystemduringthesysteminitializationprocess,andthenlaterTheapplicationiscalledbythegeneraldevicedrivertorealizetheoperationofthehardwaredevice.DriversrelatedtohardwareareanotherverycriticallinkinBSPdesignanddevelopment.

SystemSoftwareLayer

ThesystemsoftwarelayerconsistsofReal-timeOperationSystem(RTOS),filesystem,GraphicUserInterface(GUI),Networksystemandcommoncomponentmodules.RTOSisthefoundationanddevelopmentplatformofembeddedapplicationsoftware.

EmbeddedOperatingSystem

EmbeddedOperationSystem(EOS)isawide-rangingsystemsoftware.Inthepast,itwasmainlyusedinThefieldofindustrialcontrolanddefensesystems.EOSisresponsiblefortheallocationofallsoftwareandhardwareresourcesembeddedinthesystem,taskscheduling,andcontrolandcoordinationofconcurrentactivities.Itmustreflectthecharacteristicsofthesysteminwhichitislocated,andbeabletoachievetherequiredfunctionsofthesystembyloadingandunloadingcertainmodules.SomeEOSproductserieswithrelativelysuccessfulapplicationshavebeenlaunched.WiththedevelopmentofInternettechnology,thepopularizationandapplicationofinformationappliances,andtheminiaturizationandspecializationofEOS,EOShasbeguntodevelopfromasingleweakfunctiontoahighlyspecializedandstrongfunction.Theembeddedoperatingsystemhasmoreprominentfeaturesinthereal-timeefficiencyofthesystem,thedependencyofthehardware,thesolidificationofthesoftware,andthespecificityoftheapplication.EOSisrelativetothegeneraloperatingsystem.Inadditiontothemostbasicfunctionsofthegeneraloperatingsystem,EOSalsohasthefollowingfunctions:suchastaskscheduling,synchronizationmechanism,interruptprocessing,fileprocessing,etc.

Applications

IndustrialControl

Industrialautomationequipmentbasedonembeddedchipswillmakegreatprogress.Therearealreadyalargenumberof8,16,32-bitembeddedmicrocomputers.Intheapplicationofcontrollers,networkingisthemainwaytoimproveproductionefficiency,productquality,andreducehumanresources,suchasindustrialprocesscontrol,digitalmachinetools,powersystems,powergridsecurity,powergridequipmentmonitoring,andpetrochemicalsystems.Asfarastraditionalindustrialcontrolproductsareconcerned,thelow-endmodelsoftenuse8-bitmicrocontrollers.However,withthedevelopmentoftechnology,32-bitand64-bitprocessorshavegraduallybecomethecoreofindustrialcontrolequipment,andtheywillsurelyachieveconsiderabledevelopmentinthenextfewyears.

Trafficmanagement

Intheaspectsofvehiclenavigation,flowcontrol,informationmonitoringandcarservices,embeddedsystemtechnologyhasbeenwidelyused.EmbeddedGPSmodule,GSMmodulemobilePositioningterminalshavebeensuccessfullyusedinvarioustransportationindustries.GPSequipmenthasenteredthehomesofordinarypeoplefromcutting-edgeproducts,andyoucanfindyourlocationanytimeandanywherewithonlyafewthousandyuan.

Informationappliances

Thiswillbecalledthelargestapplicationfieldofembeddedsystems.Thenetworkingandintelligenceofrefrigeratorsandairconditionerswillleadpeople'slivesintoabrandnewspace.Evenifyouarenotathome,youcanremotelycontrolitviatelephonelineandinternet.Inthesedevices,embeddedsystemswillbeveryuseful.

Smarthomemanagement

Remoteautomaticmeterreadingofwater,electricity,andgasmeters,safetyfireprevention,anti-theftsystem,andadedicatedcontrolchipembeddedinitwillreplacethetraditionalmanualinspection,andAchievehigher,moreaccurateandsaferperformance.Intheservicearea,suchasremoteorderingdevices,theadvantagesofembeddedsystemshavebeenembodied.

POSnetwork

Publictransportationcontactlesssmartcard(ContactlessSmartcard,CSC)issuancesystem,publictelephonecardissuancesystem,automaticvendingmachines,varioussmartATMterminalswillbefullyintegratedintopeople’sLife,whenyouholdacard,youcantravelallovertheworld.

EnvironmentalEngineeringandNature

Real-timemonitoringofhydrologicaldata,floodcontrolsystemandwaterandsoilqualitymonitoring,damsafety,earthquakemonitoringnetwork,real-timeweatherinformationnetwork,watersourceandairpollutionmonitoring.Inmanyareaswithharshenvironmentsandcomplexterrain,embeddedsystemswillrealizeunmannedmonitoring.

Robots

Thedevelopmentofembeddedchipswillmakerobotsmoreobviousinminiaturizationandhighintelligence.Atthesametime,theywillgreatlyreducethepriceofrobots,makingthemmoresuitableforindustrialapplicationsandservices.Thefieldhasbeenwidelyused.

Intheseapplications,youcanfocusontheapplicationofcontrol.Asfarasremotehomeappliancecontrolisconcerned,inadditiontodevelopingembeddedsystemsthatsupportTCP/IP,homeapplianceproductcontrolprotocolsalsoneedtobeformulatedandunified,whichrequireshomeappliancemanufacturerstodo.Inthesameway,allnetwork-basedremotecontroldevicesneedtorealizeaninterfacewiththeembeddedsystem,andthentheembeddedsystemcontrolsandrealizescontrolthroughthenetwork.Therefore,itisveryimportanttodevelopanddiscussembeddedsystems.

Applicationofelectromechanicalproducts

Comparedwithotherfields,electromechanicalproductscanbesaidtobeoneofthemosttypicalandbroadestapplicationsofembeddedsystems.Therearehugemarketsforsingle-chipmicrocomputers,industrialcomputers,andSOCsinvariouselectromechanicalproducts.

MobileInternetfield

ManymobileInternetfieldsalsorequireembeddeddevelopmenttechnology

Trends

EmbeddedTheembeddedoperatingsystemwillbeanindispensablecomponentinthefutureembeddedsystem.Itsfuturedevelopmenttrendsinclude:

1.Customization:Theembeddedoperatingsystemwillprovideasimplifiedsystemcallinterfaceforspecificapplications.Supportoneoronetypeofembeddedapplications.Theembeddedoperatingsystemwillalsohaveascalableandscalablesystemarchitecture,providingamulti-levelsystemarchitecture.Theembeddedoperatingsystemwillincludevariousplug-and-playdevicedriverinterfaces;

2.Energysaving:Theembeddedoperatingsystemwillcontinuetousemicrokerneltechnologytoachievesmallsize,lowpowerconsumption,andlowcost.Supportsmallelectronicdevices.Atthesametime,improvethereliabilityandmaintainabilityoftheproduct.Embeddedoperatingsystemwillformaminimumcoreprocessingset,reducesystemoverhead,improveoperatingefficiency,andcanbeusedinvariousnon-computerequipment;

3,humanization:embeddedoperatingsystemwillprovidesophisticatedmultimediaHuman-machineinterfacetomeettheever-increasingneedsofusers;

4.Security:Theembeddedoperatingsystemshouldbeabletoprovideasecurityguaranteemechanism,andthereliabilityofthesourcecodeisgettinghigherandhigher;

5.Networking:Forthenetworkandforspecificapplications,theembeddedoperatingsystemrequiresastandardnetworkcommunicationinterface.Thedevelopmentofembeddedoperatingsystemswillbecomeeasiertotransplantandnetwork.Theembeddedoperatingsystemwillhavenetworkaccessfunctions,provideTCP/UDP/IP/PPPprotocolsupportandaunifiedMACaccesslayerinterface,andreserveinterfacesforvariousmobilecomputingdevices;

6.Standardization:Withthedevelopmentofthewidespreadapplicationofembeddedoperatingsystems,theemergenceofproblemssuchasinformationexchangeandresourcesharingopportunities,itisnecessarytoestablishcorrespondingstandardstoregulateitsapplications.

Embeddedoperatingsystemshavecertainreal-timeperformance,easytocutandscale,andcanbesuitableforvariousARMCPUandvariousgradesofapplicationsfromARM7toXscale.EmbeddedoperatingsystemscanusethewidelypopularARMDevelopmenttools,suchasSDT/ADSandRealViewofARM,canalsousedevelopmentsoftware,suchasGCC/GDB,KDEorEclipedevelopmentenvironment.Therearealsodedicateddevelopmenttoolsonthemarket,suchasTornado,μC/View,μC/KA,CODE/Lab,Metroworks,etc.

NewproductsfromMicrosoft

MicrosoftplanstolaunchtheWindowsEmbedded8embeddedoperatingsysteminMarch2013,whichisthepuzzleformofWindows8.TheWindowsEmbedded8StandardoperatingsystemisamodularTheversionofWindows,whichrunssimilartoLinux-stylecustomization,allowsmanufacturerstomodifyandcustomizeit,andnewtouchandgesture-basedinterfaceswillbeappliedonthisembeddedoperatingsystem.

PeoplearealreadyfamiliarwithdeviceswithembeddedoperatingsystemssuchasVOIPphones,DVDplayers,GPSreceivers,andprinters.Asmoreandmoredevicesareaddedtocomputerchipsusingembeddedoperatingsystems,ithasbecomeanever-increasingdemandtomanagethesedevicesthroughsoftware.Inthepast,thebarebonesversionofLINUXwasanoptionforembeddedoperatingsystems,thankstoitslowsystemrequirementsandeasycustomization.Moreandmorehouseholditemsareenteringthefieldofintelligenceanddigital,arousingpeople'sinterestinthe"InternetofThings",andthisnetworkcanconnectallthecomputerizeditemsinyourhome,makingthemeasyfortheirownerstocontrolandsearch.Thingsareassimpleasfindingfilesonacomputer.

WindowsEmbedded8maybejustonestepinMicrosoft'srevivalplan.ThisplanwilltransformMicrosoftfromasoftwarecompanyintoacompanyof"devicesandservices".TheMicrosoftfolksareseekingtoreleaseanembeddedroadmap,mostlikelytoshowstockholdersthattheyarenotbulkydinosaursthatwillbedestroyedbythecomingwaveofmobile.Infact,theWindowsembeddedoperatingsystemhasexistedforsometime,andtheearliestWin3.xhasanembeddedversionthatcanrunonPOSterminals.ButtherealWindowsembeddeddevicewasbuiltin1999calledWindowsNTEmbedded.TheWindowsXPcodewasusedtocreate"XPembedded"atthattime.FollowingitspaceisWindowsEmbeddedcompact,somepeopleareveryunfamiliarwiththisname,butyoumusthaveheardofitsotherwell-knownname,WindowsCE.Thisproductismoreusedinset-topboxes,especiallyafteritisusedintheSegaill-fatedDreamcastconsole,itiswidelyknown.

In2009,WindowsXPEmbeddedwasupgradedtoWindowsEmbeddedStandard.ItprovidesacompleteWin32API,butunlikeWindowsCE,itcanrunonARM,MIPSandSuperHprocessors.WindowsEmbeddedStandardCanonlyrunonx86.Itisfullycompatiblewith"standard"projects,suchasNETframework,IE7,WindowsMediaPlayer,Silverlight,etc.WindowsEmbeddedStandardallowsmanufacturerstocustomizethesystem,deleteunnecessaryparts,whileretainingthecorefunctionsofthesystem.AndthisfeaturehasbeenusedbysomesmartpeopleinthepastforWindowson-siteCDSproductionsuchasBartPE.

Commonsystem

μTenux

uC/OSII

RT-thread

uCLinux

FreeRTOS

RTX

Arm-Linux

VxWorks

RTEMS

pSOS

Nucleus

PalmOS

WindowsCE

WindowsXPEmbedded

WindowsVistaEmbedded

EmbeddedLinux

ECOS

QNX

Lynx

Symbian

HOPENOS

Android

Maemo

Meego

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