《計算機專業(yè)英語》課件第5章

Unit5EmbeddedSystems教學(xué)目標教學(xué)內(nèi)容教學(xué)目標掌握嵌入式技術(shù)的基本概念了解嵌入式技術(shù)的的發(fā)展簡史掌握嵌入式系統(tǒng)的體系結(jié)構(gòu)了解嵌入式技術(shù)的應(yīng)用情況掌握嵌入式軟件的體系結(jié)構(gòu)教學(xué)內(nèi)容Text1IntroductionofEmbeddedSystemsText2EmbeddedsoftwarearchitecturesText1IntroductionofEmbeddedSystemsMainContentsWordsandExpressionsExercisesAnembeddedsystemisaspecial-purposecomputersystemdesignedtoperformoneorafewdedicatedfunctions,oftenwithreal-timecomputingconstraints.Itisusuallyembeddedaspartofacompletedeviceincludinghardwareandmechanicalparts.Incontrast,ageneral-purposecomputer,suchasapersonalcomputer,candomanydifferenttasksdependingonprogramming.Embeddedsystemscontrolmanyofthecommondevicesinusetoday.Ingeneral,“embeddedsystem”isnotanexactlydefinedterm,asmanysystemshavesomeelementofprogrammability.Forexample,Handheldcomputerssharesomeelementswithembeddedsystems—suchastheoperatingsystemsandmicroprocessorswhichpowerthem—butarenottrulyembeddedsystems,becausetheyallowdifferentapplicationstobeloadedandperipheralstobeconnected.Embeddedsystemsspanallaspectsofmodernlifeandtherearemanyexamplesoftheiruse.Text1IntroductionofEmbeddedSystemsText1IntroductionofEmbeddedSystemsTelecommunicationssystemsemploynumerousembeddedsystemsfromtelephoneswitchesforthenetworktomobilephonesattheend-user.Computernetworkingusesdedicatedroutersandnetworkbridgestoroutedata.Consumerelectronicsincludepersonaldigitalassistants(PDAs),mp3players,mobilephones,videogameconsoles,digitalcameras,DVDplayers,GPSreceivers,andprinters.Manyhouseholdappliances,suchasmicrowaveovens,washingmachinesanddishwashers,areincludingembeddedsystemstoprovideflexibility,efficiencyandfeatures.AdvancedHVACsystemsusenetworkedthermostatstomoreaccuratelyandefficientlycontroltemperaturethatcanchangebytimeofdayandseason.Homeautomationuseswired-andwireless-networkingthatcanbeusedtocontrollights,climate,security,audio/visual,surveillance,etc.,allofwhichuseembeddeddevicesforsensingandcontrolling.Text1IntroductionofEmbeddedSystemsTransportationsystemsfromflighttoautomobilesincreasinglyuseembeddedsystems.NewairplanescontainadvancedavionicssuchasinertialguidancesystemsandGPSreceiversthatalsohaveconsiderablesafetyrequirements.Variouselectricmotors—brushlessDCmotors,inductionmotorsandDCmotors—areusingelectric/electronicmotorcontrollers.Automobiles,electricvehicles,andhybridvehiclesareincreasinglyusingembeddedsystemstomaximizeefficiencyandreducepollution.Otherautomotivesafetysystemssuchasanti-lockbrakingsystem(ABS),ElectronicStabilityControl(ESC/ESP),tractioncontrol(TCS)andautomaticfour-wheeldrive.Medicalequipmentiscontinuingtoadvancewithmoreembeddedsystemsforvitalsignsmonitoring,electronicstethoscopesforamplifyingsounds,andvariousmedicalimaging(PET,SPECT,CT,MRI)fornon-invasiveinternalinspections.Text1IntroductionofEmbeddedSystemsInadditiontocommonlydescribedembeddedsystemsbasedonsmallcomputers,anewclassofminiaturewirelessdevicescalledmotesarequicklygainingpopularityasthefieldofwirelesssensornetworkingrises.Wirelesssensornetworking,WSN,makesuseofminiaturizationmadepossiblebyadvancedICdesigntocouplefullwirelesssubsystemstosophisticatedsensor,enablingpeopleandcompaniestomeasureamyriadofthingsinthephysicalworldandactonthisinformationthroughITmonitoringandcontrolsystems.Thesemotesarecompletelyselfcontained,andwilltypicallyrunoffabatterysourceformanyyearsbeforethebatteriesneedtobechangedorcharged.WordsandExpressionsreliability[ri,lai?'biliti]n.可靠性portable['p?:t?bl]adj.輕便的，手提式的stationary['stei?(?)n?ri]adj.不動的，穩(wěn)定的，靜止的microcontroller

n.微型控制器，微控制器，單片機peripheral[p?'rif?r?l]n.（電腦的）外部設(shè)備；adj.不重要的，外圍的chassis['??si]n.底座，（車身）底盤，enclosure[in'kl?u??]n.附件，圍墻，圍繞，【計】圍封部分programmabilityn.可編程性：減少應(yīng)用方案的開發(fā)時間，降低系統(tǒng)運行和維護成本，提高系統(tǒng)使用效率；handheldadj.手持式，掌上型microprocessor[maikr??'pr??ses?(r)]n.微處理器flashmemory

n.閃存telecommunication[‘telik?mju:ni’kei??n]n.電傳視訊,遠距離通信,電磁通信WordsandExpressionsrouter['ru:t?(r),'ra?-]n.路由程序,路由器PDA個人數(shù)字助理，掌上電腦，是PersonalDigitalAssistant的縮寫GPS

即全球定位系統(tǒng)，GlobalPositioningSystem

HVAC（HeatVentilationAirConditionar）暖通空調(diào)；HeatingVentilatingandAirConditioning制熱、通風(fēng)與空調(diào)控制thermostat['θ?:m?st?t]n.恒溫器，節(jié)溫器surveillance[s?:'veil?ns]n.監(jiān)視,監(jiān)督avionics[,eivi'?niks]n.航空電子學(xué)(航空用電子設(shè)備,控制系統(tǒng))，電子設(shè)備inertialguidancesystems

慣性制導(dǎo)系統(tǒng)considerable[k?n'sid?r?bl]adj.相當(dāng)?shù)?可觀的,重要的hybridvehicle混合驅(qū)動汽車，合成車anti-lockbrakingsystem(ABS)防抱死制動系統(tǒng) WordsandExpressions

electronicstethoscope電子聽診器amplify['?mpli,fai]v.擴大，詳述，使...增幅，放大，加強non-invasiveadj.非侵入，非損傷inspection[in'spek??n]n.檢查,視察miniature['minj?t??]n.縮圖,小畫像；adj.小規(guī)模的,纖小的mote[m?ut]n.微塵(塵埃,瑕疵)，導(dǎo)火線wirelesssensor無線傳感器miniaturization[,mini?t??rai'zei??n]n.小型化，微型化sophisticated[s?'fistikeitid]adj.高級的,先進的,復(fù)雜的myriad['miri?d]adj.無數(shù)的n.極大數(shù)量ExercisesI.Trueorfalse?Ifcorrect,writeTinparentheses;Otherwise,writeF.（）1.Anembeddedsystemisaspecial-purposecomputersystemdesignedtoperformonlyonededicatedfunctions,oftenwithreal-timecomputingconstraints.（）2.Ageneral-purposecomputer,suchasapersonalcomputer,candomanydifferenttasksdependingonprogramming.（）3.Sincetheembeddedsystemisdedicatedtospecifictasks,designengineerscanoptimizeit,increasingthesizeandcostoftheproduct,orreducingthereliabilityandperformance.（）4.Ingeneral,“embeddedsystem”isanexactlydefinedterm,asmanysystemshavesomeelementofprogrammability.（）5.Handheldcomputerssharesomeelementswithembeddedsystems—suchastheoperatingsystemsandmicroprocessorswhichpowerthem—butarenottrulyembeddedsystems,becausetheyallowsimilarapplicationstobeloadedandperipheralstobeconnected.（）6.Transportationsystemsfromflighttoautomobilesincreasinglyuseembeddedsystems.NewairplanescontainadvancedavionicssuchasinertialguidancesystemsandPDAsthatalsohaveconsiderablesafetyrequirements.（）7.Homeautomationonlyuseswired-networkingthatcanbeusedtocontrollights,climate,security,audio/visual,surveillance,etc.,allofwhichuseembeddeddevicesforsensingandcontrolling.ExercisesII.Fillintheblankswithproperwords.Anembeddedsystemisa_________computersystemdesignedtoperformoneorafewdedicatedfunctions,oftenwithreal-timecomputingconstraints.2.Physically,embeddedsystemsrangefrom_____devicessuchasdigitalwatchesandMP4players,tolargestationaryinstallationsliketrafficlights,factorycontrollers,orthesystemscontrollingnuclearpowerplants.3.Newairplanescontainadvanced_____suchasinertialguidancesystemsandGPSreceiversthatalsohaveconsiderablesafetyrequirements.4.Automobiles,electricvehicles,andhybridvehiclesareincreasinglyusingembeddedsystemsto_____efficiencyandreducepollution.Text2EmbeddedsoftwarearchitecturesMainContentsWordsandExpressionsExercisesThereareseveraldifferenttypesofsoftwarearchitectureincommonuse.SimplecontrolloopInthisdesign,thesoftwaresimplyhasaloop.Theloopcallssubroutines,eachofwhichmanagesapartofthehardwareorsoftware.InterruptcontrolledsystemSomeembeddedsystemsarepredominantlyinterruptcontrolled.Thismeansthattasksperformedbythesystemaretriggeredbydifferentkindsofevents.Aninterruptcouldbegeneratedforexamplebyatimerinapredefinedfrequency,orbyaserialportcontrollerreceivingabyte.Text2EmbeddedsoftwarearchitecturesText2EmbeddedsoftwarearchitecturesThesekindsofsystemsareusedifeventhandlersneedlowlatencyandtheeventhandlersareshortandsimple.Usuallythesekindsofsystemsrunasimpletaskinamainloopalso,butthistaskisnotverysensitivetounexpecteddelays.Sometimestheinterrupthandlerwilladdlongertaskstoaqueuestructure.Later,aftertheinterrupthandlerhasfinished,thesetasksareexecutedbythemainloop.Thismethodbringsthesystemclosetoamultitaskingkernelwithdiscreteprocesses.CooperativemultitaskingAnonpreemptivemultitaskingsystemisverysimilartothesimplecontrolloopscheme,exceptthattheloopishiddeninanAPI.Theprogrammerdefinesaseriesoftasks,andeachtaskgetsitsownenvironmentto“run”in.Whenataskisidle,itcallsanidleroutine,usuallycalled“pause”,“wait”,“yield”,“nop”(standsfornooperation),etc.Text2EmbeddedsoftwarearchitecturesTheadvantagesanddisadvantagesareverysimilartothecontrolloop,exceptthataddingnewsoftwareiseasier,bysimplywritinganewtask,oraddingtothequeue-interpreter.Preemptivemultitaskingormulti-threadingInthistypeofsystem,alow-levelpieceofcodeswitchesbetweentasksorthreadsbasedonatimer(connectedtoaninterrupt).Thisisthelevelatwhichthesystemisgenerallyconsideredtohavean“operatingsystem”kernel.Dependingonhowmuchfunctionalityisrequired,itintroducesmoreorlessofthecomplexitiesofmanagingmultipletasksrunningconceptuallyinparallel.Asanycodecanpotentiallydamagethedataofanothertask(exceptinlargersystemsusinganMMU)programsmustbecarefullydesignedandtested,andaccesstoshareddatamustbecontrolledbysomesynchronizationstrategy,suchasmessagequeues,semaphoresoranon-blockingsynchronizationscheme.Text2EmbeddedsoftwarearchitecturesBecauseofthesecomplexities,itiscommonfororganizationstobuyareal-timeoperatingsystem,allowingtheapplicationprogrammerstoconcentrateondevicefunctionalityratherthanoperatingsystemservices,atleastforlargesystems;smallersystemsoftencannotaffordtheoverheadassociatedwithagenericrealtimesystem,duetolimitationsregardingmemorysize,performance,and/orbatterylife.Amicrokernelisalogicalstepupfromareal-timeOS.TheusualarrangementisthattheoperatingsystemkernelallocatesmemoryandswitchestheCPUtodifferentthreadsofexecution.Usermodeprocessesimplementmajorfunctionssuchasfilesystems,networkinterfaces,etc.Ingeneral,microkernelssucceedwhenthetaskswitchingandintertaskcommunicationisfast,andfailwhentheyareslow.Exokernelscommunicateefficientlybynormalsubroutinecalls.Thehardware,andallthesoftwareinthesystemareavailableto,andextensiblebyapplicationprogrammers.MicrokernelsandexokernelsMonolithickernelsInthiscase,arelativelylargekernelwithsophisticatedcapabilitiesisadaptedtosuitanembeddedenvironment.ThisgivesprogrammersanenvironmentsimilartoadesktopoperatingsystemlikeLinuxorMicrosoftWindows,andisthereforeveryproductivefordevelopment;onthedownside,itrequiresconsiderablymorehardwareresources,isoftenmoreexpensive,andbecauseofthecomplexityofthesekernelscanbelesspredictableandreliable.CommonexamplesofembeddedmonolithickernelsareEmbeddedLinuxandWindowsCE.Despitetheincreasedcostinhardware,thistypeofembeddedsystemisincreasinginpopularity,especiallyonthemorepowerfulembeddeddevicessuchasWirelessRoutersandGPSNavigationSystems.Herearesomeofthereasons:Portstocommonembeddedchipsetsareavailable.MonolithickernelsTheypermitre-useofpubliclyavailablecodeforDeviceDrivers,WebServers,Firewalls,andothercode.Developmentsystemscanstartoutwithbroadfeature-sets,andthenthedistributioncanbeconfiguredtoexcludeunneededfunctionality,andsavetheexpenseofthememorythatitwouldconsume.Manyengineersbelievethatrunningapplicationcodeinusermodeismorereliable,easiertodebugandthatthereforethedevelopmentprocessiseasierandthecodemoreportable.Manyembeddedsystemslackthetightrealtimerequirementsofacontrolsystem.AsystemsuchasEmbeddedLinuxhasfastenoughresponseformanyapplications.Featuresrequiringfasterresponsethancanbeguaranteedcanoftenbeplacedinhardware.ManyRTOSsystemshaveaper-unitcost.Whenusedonaproductthatisorwillbecomeacommodity,thatcostissignificant.ExoticcustomoperatingsystemsAsmallfractionofembeddedsystemsrequiresafe,timely,reliableorefficientbehaviorunobtainablewiththeoneoftheabovearchitectures.Inthiscaseanorganizationbuildsasystemtosuit.Insomecases,thesystemmaybepartitionedintoa“mechanismcontroller”usingspecialtechniques,anda“displaycontroller”withaconventionaloperatingsystem.Acommunicationsystempassesdatabetweenthetwo.AdditionalsoftwarecomponentsInadditiontothecoreoperatingsystem,manyembeddedsystemshaveadditionalupper-layersoftwarecomponents.ThesecomponentsconsistofnetworkingprotocolstackslikeCAN,TCP/IP,FTP,HTTP,andHTTPS,andalsoincludedstoragecapabilitieslikeFATandFlashmemorymanagementsystems.Iftheembeddeddeviceshasaudioandvideocapabilities,thentheappropriatedriversandcodeswillbepresentinthesystem.Inthecaseofthemonolithickernels,manyofthesesoftwarelayersareincluded.IntheRTOScategory,theavailabilityoftheadditionalsoftwarecomponentsdependsuponthecommercialoffering.WordsandExpressionspredominantly[,pri'd?min?nt]adj.占優(yōu)勢的，支配其他的，優(yōu)越的，突出的，最顯著的，主要的subroutine[,s?bru:'ti:n]n.子程序，【計算機】=subprogram21世紀大英漢詞典》triggered['triɡ?d]adj.有觸發(fā)器的，觸發(fā)器啟動的，有扳機的frequency['fri:kw?nsi]n.頻繁，頻率handler['h?ndl?]n.處理程序21世紀大英漢詞典》latency['leit?nsi]n.潛伏，潛在，等待時間queue[kju:]n.【計算機】等候行列，排隊nonpreemptiveadj.非搶占式scheme[ski:m]n.方案,計劃,陰謀；v.計畫,設(shè)計,體系，結(jié)構(gòu),圖謀idle['aidl]adj.【機械學(xué)】空轉(zhuǎn)的；慢轉(zhuǎn)的；怠速的；【電子學(xué)】空載的；無功的routine[ru:'ti:n]n.【計算機】程序；例行程序Interpretern.【計算機】翻譯器，譯印機，解釋程序，翻譯程序functionality[,f??k???'n?liti]n.函數(shù)性(泛函性,官能度),功能（尤指軟件、硬件的功能）21世紀大英漢詞典》WordsandExpressionsconceptually[k?n'septju?li]adv.概念地21世紀大英漢詞典》

parallel['p?r?lel]adj.【電子學(xué)、計算機】并聯(lián)的；n.【電子學(xué)、計算機】并聯(lián)的potentially[p?'ten??li]adv.潛在地，假定地.MMUabbr.MemoryManagerUnit內(nèi)存管理單元synchronization[,si?kr?nai'zei??n]n.同步化21世紀大英漢詞典》

semaphore

['sem?f?:]n.信號燈,旗語non-blockingadj.非阻塞microkernel微核Shelln.命令解譯程序（連接并解譯用戶命令，調(diào)用并執(zhí)行存儲器中的程序）allocate['?l?ukeit]vi.&vt.【計算機】分配，指定，保留extensible[ik‘stens?bl]adj.可展開的，可伸展的，可延續(xù)的；可擴大的，可擴展的；可延伸的WordsandExpressionsdownside['daun,said]n.消極面,負面navigation[,n?vi'gei??n]n.航行,航海guarantee[,g?r?n'ti:]v.&n.保證,擔(dān)保；vt.保證RTOSabbr.RealTimeOperatingSystems實時操作系統(tǒng)exotic[,iɡ'z?tik]adj.1.外來的，非本地的；2.【核物理學(xué)】異的；極不穩(wěn)定的unobtainable['?n?b'tein?bl]adj.無法得到的,難獲得的partition[pɑ:'ti??n]n.分割,隔離物,隔墻;v.區(qū)分,隔開,分割mechanism['mek?niz?m]n.機械,機構(gòu),結(jié)構(gòu),機制，原理upper-layeradj.上層的category['k?tig?ri]n.種類,類別availability[?,veil?'bil?ti]n.有效性；可用性，可得性，利用(或獲得)的可能性ExercisesI.Trueorfalse?Ifcorrect,writeTinparentheses;Otherwise,writeF.（）1.Theloopcallssubroutines,eachofwhichmanagesallofthehardwareorsoftware.（）2.Thisgivesprogrammersanenvironmentdifferenttoa