車輛電子控制技術(shù)：LIN總線

LIN總線技術(shù)LIN(LocalInterconnectNetwork)局部互連網(wǎng)絡(luò)是一種將開關(guān)、顯示器、傳感器及執(zhí)行器等簡單控制設(shè)備連接起來的串行通信網(wǎng)絡(luò),主要用于實(shí)現(xiàn)汽車中的分布式電子系統(tǒng)控制。LIN總線的特點(diǎn)1、單主機(jī),多從機(jī)結(jié)構(gòu)(沒有總線仲裁);2、基于普通UART/SCI接口的低成本硬件、低成本軟件或作為純狀態(tài)機(jī);3、帶時(shí)間同步的多點(diǎn)廣播接收,從節(jié)點(diǎn)無需石英或陶瓷振蕩器:4、確定性的信號(hào)傳輸;5、低成本的單線實(shí)現(xiàn);6、速率可達(dá)20kbps;7、總線長度≤40m;8、保證信號(hào)傳輸?shù)难舆t時(shí)間;9、可選的數(shù)據(jù)場長度:0～8byte;10、配置的靈活性;11、數(shù)據(jù)校驗(yàn)和的安全性和錯(cuò)誤檢測;12、網(wǎng)絡(luò)中故障節(jié)點(diǎn)的檢測;13、使用最小成本的半導(dǎo)體元件(小尺寸,單芯片系統(tǒng));14、不需改變LIN從節(jié)點(diǎn)的硬件和軟件即可在網(wǎng)絡(luò)上增加節(jié)點(diǎn);15、通常一個(gè)LIN網(wǎng)絡(luò)節(jié)點(diǎn)數(shù)小于16個(gè);16、汽車電池供電。

CAN總線和LIN總線對(duì)比表WhyuseLIN?HeavyadoptionbyEuropeanOEMsIncreasedinterestfromUSOEMs,SAEOpenstandardnetworking(e.g.-LIN)means:Off-the-shelftools&componentsavailableNoneedforcustomtraining/supportofproprietaryprotocolsIncreasedinteroperabilityopensmarketopportunitiesStandardizationofInterfacesandComponentsFasterintroductionofnewtechnologiesGatewayCentralModuleMirrorX/YmovementHeaterDoorLockSuperLockLockSwitchPanalContactMonitorsWindowLiftMotor318PuddleLamp117StallDetection62PuddleFlasherECFoldMemory186843ComplexHarness(ManyVariations)Driver’sDoor(TraditionalWiring)μCμCSMALLGatewayCentralModuleMirrorPuddleFlasherECFoldMemoryX/YmovementHeaterDoorLockSuperLockLockPuddleLampSwitchPanalContactMonitorsWindowLiftMotorStallDetection33333DrasticHarnessSavings(onlyoneGatewaymoduleneeded)μCμCMechatronicPlug&PlayoptionDriver’sDoorwithLINLINHistory1998:FirstIdeas:LocalInterconnectNetworkaslowcostNetworkforin-Vehiclecommunicationwithlimitedrequirements,wellsuitedforMechatronicApplications.Smallteamofcompanies:VCT,Volvo,BMW,Volkswagen,Audi,DaimlerChryslerandMotorolaFastdecisionmaking,protocolbasedonexistingtechnology2000:LINConsortiumformedandofficiallyannounced2002:FirstCarswithLINentertheroad(DaimlerBenzSL,DaimlerBenzE-Class)September2002:1stInternationalLINConferenceSeptember2003:ReleaseofLIN2.0FirstexperiencewithLINflowsintonewSpecificationMainfocus:ReconfigurationofOff-The-ShelfnodesFebruary2004:LINSpecialMagazineMay2004:ConformanceTestforLIN2.0TheLINSpecificationSimpleCommunicationProtocolSignals(”publish/subscribe”Concept)nointerferenceinapplicationarchitecture

Efficient(lowProductionCost)RAM,CPUruntime,bandwidth

(inthisorder)SimpleIntegrationConfigurabilityIntegratedSignalGatewaybetweendifferentBusesReliabilityandTestabilityErrorsarenottolerablePredictabilityCostFactorsReducenumberofcablesSimpleandreliablephysicallayerSimpleandlowcostclockgenerationSimplicityofprotocolIndependenceofhardwareplatformUseofexistingcomponentsLowrequirementsforcommunicationspeedImplementationasstate-machine(inASIC‘s)ReducedrequireddieareaLINSpecification1.3UBPshistoricallyonlydefinetheprotocolandphysicallayerdetails.

-APIApplicationProgrammingInterface(SoftwareRec.Practice)

-CLDConfigurationLanguageDescription(ToolsInterfacing)

-PSProtocolSpecification+PhysicalLayerProtocolSoftwareTools

SAEJ2602andLINSpecification2.0

-PHYPhysicalLayerSpecificationSAEJ2602influenced

LIN2.0

-DIAGSIMPLIFIEDby

SAEJ2602:DIAGNOSTICS

areOPTIONALCONFIGURATIONisSIMPLER

-NCLNodeCapabilityLanguageSpecificationNO

SIGNIFICANT

CHANGES

-CLSConfigurationLanguageSpecificationNO

SIGNIFICANT

CHANGES

-APIApplicationProgrammingInterfaceNO

SIGNIFICANT

CHANGES

-PROTProtocolSpecificationNO

SIGNIFICANT

CHANGESSoftwareLayerHardwareLayerToolsECUOperatingSystemBusTransceiverApplicationCommunicationManagerVehiclePhysicalNetwork(thewire)LINAPISpecificationLINProtocolSpecificationLINPhysicalLayerSpec.DesignToolSuiteLINConfiguration

LanguageSignalDatabaseManager(SDM/L)BusAnalyzer(LINSpector)NetworkConfigurationGenerator(LCFG)LINPhysicalLayerSpec.LINConfigurationLanguageLINConformanceTestSpecificationLINSpecificationforDiagnosticsLINSystemDesignGuide(inPreparation)LINStandard-OverviewLIN1.2LIN1.1PL/PCLDLIN1.3LIN2.0RPAPILegend:PL/P –PhysicalLayer/ProtocolCLD –ConfigurationLanguageDescriptionRP –RecommendedPracticeAPI –ApplicationProgrammer’sInterfaceCT –ConformanceTestDC –DiagnosticsandConfigurationNCLD –NodeCapabilityLanguageDescriptionPL/PCLDRPAPIPL/PCLDRPAPIPLCLDAPICTNCLDApr.2000Nov.2000

Nov.2002

Sept.2003

CTProtocolnewmodDCnewnewLINSpecificationHistoryLIN-ProtocolSpecificationTheLINProtocolSpecificationdescribesthelogicaltransportofdatainaLINSystem.Thisincludes:FormatofdataframesHeaderDataChecksumSignalsandSignalTypesTypeofFramesSchedulingStatusManagementLIN-PhysicalLayerSpecificationTheLINPhysicalLayerSpecificationdescribestheelectricalrepresentationofthesignalsonthewire.Thisincludes:SignalshapeSignalvoltagesPhysicalpropertiesoftheelectricalinterfacesofthenodesAdditionallythePLSpecificationalsodescribestheclockrequirements.LINPhysicalLayerSingleWireConnection(GroundisReturnConductor)OpenDrain(WiredAND),ApprovedDominant/RecessiveConceptBasedonVbatt(noVoltageRegulatorrequired)VBAT8...18VGNDUART/SCIorSLICRxTxMaster: 1k

Slave: 30kLINBusControlledSlopeLINPhysicalLayerVBAT8...18VGNDRcessiveLogic‘1’DominantLogic‘0’60%40%BusVoltageTimeSCI/UARTorSLICRxTxElectronicControlUnitmaster:1k

slave:30kBuscontrolledslopeMaster: 2.2nFSlave: 220pFNote:TheLINspecificationreferstoVBATattheECUconnector.LINPhysicalInterfaceinPracticeEmbeddedLINNode(ECU)VSUPVSUPVBATRxTx30K1KGNDGNDLINInMasteronlyTransceiverICmaster:1k

slave:30k實(shí)例LINHeaderLINDatafield13bitBreak&delimiter0x55SynchMsgIDCloseupofAutomaticHeaderHandlingFrameSynchronizationand

BitRateSynchronizationFrameSynchronization(1)–NominalCaseApriori: +/-14%OscillatorDifferencefromthenominalfrequencyRecognitionofSynch-BreaksStopBitStartBitTotalLengthofaSCI/UARTFrames(10bittimes)Max.LengthofadominantPeriod

ofanormalUARTFrame(9bittimes)LengthofastandardUARTBREAKSymbol(10bittimes)Bydefinition,aUARTbreaksymbolisaminimumof10dominantbittimes.ItisseenbyareceivingUARTasa0x00datacharacterwithaframingerror.FrameSynchronisation(2)–FastSlaveClockApriori: +/-14%OscillatorDifferencefromthenominalfrequencyRecognitionofSynch-BreaksStopBitStartBitTotalLengthofaUARTFramesMax.LengthofadominantPeriod

ofanormalUARTFrame10TbitfromthevantagepointofaSlavewhichis14%fasterthanthenominalClockFrequency11-BitLimit(fastSlave)FrameSynchronisation(3)–SlowSlaveClock121111013Apriori: +/-14%OscillatorDifferencefromthenominalfrequencyRecognitionofSynch-BreaksStart-BitTotalLengthofaUARTFrameMax.LengthofadominantPeriod

ofanormalUARTFrameLengthofastandardUARTBREAKSignalBitRateSynchronizationSynchronizingisnecessaryinordertoensuredatatransfer.BitSamplingSynchronizingisnecessaryinordertoensuredatatransfer:StopBitStartBitDataaresampledintheexpectedmiddleofdatabit:UARTSampleClock(e.g.-StartBit)BitSampling–StandardUARTBitSampling(1)–ValiddetectionofSTOPStopBitStartBitSampleClockAfterrecognitionofLowlevelatthestartbit,thesamplecounterisstarted.Samplingtakesplaceattheparticular(subjective)middleofthebit.Importantisthatitissampledinavalidareaatthelastbitofabyte(stopbit).BitSampling(2)–EffectsonSlaveOscillatorAccuracyThevalidsampleareafortheSTOPbitisbetween138and152sampleclocks(with16oversampleclocks).Thiscorrelateswithamaximumalloweddifferenceofapproximately4%betweentransmitterandreceiver.Withinthistolerancerange,aSTOPbitwillalwaysbeproperlydetected.Thedifferencecanarisefromthetotaleffectsofclocktolerance,sampleerrorsandphysicallayererrorduetogroundshift.YoucanONLYproperlycommunicateifyoucancorrectlysampletheSTOPbitofeachbyteThereforethemaximumtolerancefortheclocksis+/-2%

(4%totaldifference)LINBaudRateRequirementsSync.StatusRequirementAccuracyConditionBeforesynchronizationBreakrecognition±14%(1)Masterclockaccuracyassumedtobewithin±0.5%ofnominalAftersynchronization(master-slave)LINmessagingwiththemaster±2%Relativetothemaster’sclockAftersynchronization(inc.slave-slave)LINmessagingwiththemasterandotherslaves±1%TheLINMessageFrameLINMessageFrame1to8datafieldschecksumMessageResponsesynchbreak13bitsynchfieldidentifierMessageHeaderFrame-

SynchronizationBit-time

SynchronizationMessageDescriptorMessageContentsLINMessageFrameSlaveMasterSYNCIDENTDATA1DATA2DATA1DATA2DATA3DATA4DATA1DATA2DATA3DATA8...CHECKSUMCHECKSUMCHECKSUMHeaderIn-FrameResponseSpaceResponseBREAKBreakFieldBREAKFieldBitTimeSYNC-DelimiterTSYNDELBREAKTSYNBRKSYNCFieldMessageResponseMessageHeaderSynchronizationFieldStopBitIdentifierSYNCFieldStartBit01234567MessageResponseMessageHeaderIdentifierFieldIdentifierBitsIdentifierFieldParityBitsMessageResponseMessageHeaderStartBitID00ID11ID22ID33ID44ID55P06P17StopbitIdentifierTheIdentifierlogicallydescribesthemeaningofthemessage.TheIdentifierisprotectedwith2Paritybits.Thereareupto64differentIdentifiersinaLINsystem.

60ofthemarefreelyavailabletoasystemdesigner.synchbreak13bitsynchfieldidentifiermessageheaderDataFieldInter-FrameSpaceIn-FrameResponseSpaceInterbyteSpaceSlaveResponseDataFieldsDataBytenChecksumFieldMessageResponseMessageHeaderDataByte0DataByte1…DataByteDataFieldByteField8DataBitsMessageResponseMessageHeaderStopBitStartBit0LSB1234567MSBChecksumFieldChecksumFieldMessageResponseMessageHeaderStopBitStartBit0LSB1234567MSB8ChecksumBitsLINSystemMessages

&SpecialFrames

CommandFrame8datafieldsClassicchecksumMessageResponsesynchbreak13bitsynchfieldidentifier$3CMessageHeaderExtendedFrame1tondatafieldsClassicchecksumMessageResponsesynchbreak13bitsynchfieldidentifier$3EMessageHeaderWake-UpFrameTWUSIGWAKE-UPSIGNALFRAMEoftheSlaveTaskWAKE-UPDelimiterBusinSleepModeSignalisIdleSYNCBREAKoftheMasterTaskLINMessageFrameTypes

UnconditionalFramesUnconditionalFramesarethestandardframesofaLINSystem.Withunconditionalframesanykindofdatacanbetransported.Unconditionalframeshaveanidentifierintherangeof0..0x3B.Theheaderisalwayssentbythemaster(mastertask)Publisherofanunconditionalframeshallalwaysprovidetheresponsetotheheader.Allsubscribertoanunconditionalframeshallreceivetheunconditionalframeandmakeitscontentsavailabletotheapplication.BasicLINCommunications–MASTERtoSLAVESlaveNodeSlaveNodeSlaveNodeSlaveNode(MastersendsDatatooneSlave)synchfieldidentifiersynchbreakdatabytedatabytechecksumMasterNodequartzIDRecognizedIDNOTrecognizedLINMasterTaskSlaveTask(transmitting)IgnoresdataReceivesdatasynchfieldidentifiersynchbreakBasicLINCommunications–MASTERtoSLAVESlaveNodeSlaveNodeSlaveNodeSlaveNode(Sendingmulticastmessages)databytedatabytechecksumMasterNodequartzLINMasterTaskSlaveTask(transmitting)IDRecognizedIDRecognizedReceivesdataReceivesdatadatabytedatabytechecksumsynchfieldidentifiersynchbreaksynchfieldidentifiersynchbreakdatabytedatabytechecksumBasicLINCommunications–SLAVEtoMASTER(PollingSLAVESfordata)SlaveNodeSlaveNodeSlaveNodeSlaveNodeMasterNodequartzIDRecognizedSlaverespondsaccordinglyIDNOTRecognizedNoresponseIDRecognizedSlaverespondsaccordinglyIDNOTRecognizedNoresponseLINMasterTaskSlaveTask(receiving)LINCommunication-DatafromSlavetoSlaveSlaveNodeASlaveTaskTransmissionSlaveTaskReceivingSlaveNodeBSlaveTaskTransmissionSlaveTaskReceivingMasterNodeLINMasterTaskSlaveTaskTransmissionSlaveTaskReceivingquartzEventTriggeredFrameInordertominimizetimeforinterrogatingeventsensors,amethodforinterrogatingmultiplenodeshasbeendeveloped:Themastersendsoutaheader,andaresponseisplacedonthebusonlyifachangeinthestate(event)hashappened.Threecasescantakeplace:Noeventtookplace:Noresponse1Nodesignalschange:ResponseMorethanoneNodesignalchange:CollisionSpecialLINCommunications–EventTriggeredFramesCASE1–NORESPONSE(PollingSLAVESfordata)synchfieldidentifiersynchbreakSlaveNodeSlaveNodeSlaveNodeSlaveNodeMasterNodequartzIDRecognizedNoEvent

→NoresponseLINMasterTaskIDRecognizedNoEvent

→NoresponseSpecialLINCommunications–EventTriggeredFrames

CASE2–SINGLENODERESPONSE(PollingSLAVESfordata)databytedatabytechecksumsynchfieldidentifiersynchbreakSlaveNodeSlaveNodeSlaveNodeSlaveNodeMasterNodequartzLINMasterTaskSlaveTask(receiving)IDRecognizedNoEvent

→NoresponseIDRecognizedEventoccured

→ResponseSpecialLINCommunications–EventTriggeredFrames

CASE3–MULTIPLENODERESPONSE(PollingSLAVESfordata)SlaveNodeSlaveNodeSlaveNodeSlaveNodeMasterNodequartzIDRecognizedSlaverespondsaccordinglyLINMasterTaskSlaveTask(receiving)databytedatabytechecksumdatabytedatabytechecksumsynchfieldidentifiersynchbreakIDRecognizedEventoccured

→ResponseSpecialLINCommunications–EventTriggeredFrames

CASE3–RESOLVINGMULTIPLENODERESPONSES(PollingSLAVESfordata)SlaveNodeSlaveNodeSlaveNodeSlaveNodeMasterNodequartzIDRecognizedSlaverespondsaccordinglyIDNOTRecognizedNoresponseIDRecognizedSlaverespondsaccordinglyIDNOTRecognizedNoresponseLINMasterTaskSlaveTask(receiving)databytedatabytechecksumdatabytedatabytechecksumsynchfieldidentifiersynchbreaksynchfieldidentifiersynchbreakLINIdentifierUsageMapSimpletabletoshowIDassignments:0x00-0x3B -Userspace0x3C -CommandMessage0x3D -ResponseMessage0x3E -UserDefinedsystemmessages0x3F -ReservedforfutureLINusage–mustnotbeused!InLIN1.xonlyclassicalchecksumisused(Checksumoverdatabytesonly).InLIN2.0messageswithIDsfrom0x00to0x3BarealwaysassociatedwiththeenhancedChecksum(Checksumoveridentifieranddatabytes).MessageswithIdentifiers0x3Ctrough0x3EalwaysusetheclassicalChecksum.DiagnosticFramesInLIN1.3norestrictionsfordiagnosticandconfigurationmessageshavebeendefined.

Theusageisopenforusers.InLIN2.0DiagnosticandConfigurationmessagesmakeuseof0x3Cand0x3Dmessages.Configurationmessages:LIN2.0defines(re-)configurationmessages,whichusethediagnosticmessageframeswiththeIDs0x3C(forcommandmessages)and0x3D(forresponsemessages).ThediagnosticmessageframeformatarederivedfromISO15675StandardDiagnosticFrameFormatNADPCISIDD1D2D3D4D5NADPCIRSIDD1D2D3D4D5TheDiagnosticFrameFormatisbasedonISO15765.Thedatastructureisasfollows(DataBytes1..8oftheLINFrame):Request(ID=0x3C):Response(ID=0x3D):ADiagnosticFrameisalwaysassociatedwiththeclassicchecksum

(checksumoverthedatafieldsonly).NAD–NodeAddress–physicalidentificationofanodeinthesystemPCI–ProtocolControlInformationSID–ServiceIdentifier–specifiesthecontentsoftherequestRSID–ResponseServiceIdentifier–specifiesthecontentsoftheresponseUserDefined&ReservedFramesUserDefinedMessages(ID=0x3E):Userdefinedframescancarryanykindofinformation.Theformatandlengthisdefinedbytheuser.Thistypeofframemaybeusede.g.fordownloadofdataoruploadofdiagnosticinformation.Reservedframes(ID=0x3F)ReservedframesmustnotbeusedinaLIN2.0cluster.Theidentifierisreservedforfutureuse.AslavenodecomplianttoLIN2.0mustremainsilentuponreceptionoftheIdentifier0x3F

LINMessageFrameBudgetInordertoensurethatsignalsarriveattheirdestinationwithintheirtimelimit,thebehaviorofthesystemmustbepredictable.Thereforethemessageframeshavetobecompletedwithinaspecifictimeframe.LINdefines“messageslots“inwhicheachmessageistransported.Thisallowstopredictwhenamessageisbeingsent.Themessageslothasadefinedminimumlengthof140%ofthetheoreticalminimumlengthoftheframe.Theslotlengthcalculatesasfollows:(lHeader+nData*lByte+lChksum)*140%=(44+nData*10)*1.4TBitExample:A2-bytemessageslothasaminimumlengthof90bit-times.

An8-bytemessageslothasaminimumlengthof174bit-timesProtocolSoftwareTools

SAEJ2602andLINSpecification2.0

-PHYPhysicalLayerSpecificationSAEJ2602influenced

LIN2.0

-DIAGSIMPLIFIEDby

SAEJ2602:DIAGNOSTICS

areOPTIONALCONFIGURATIONisSIMPLER

-NCLNodeCapabilityLanguageSpecification

-CLSConfigurationLanguageSpecification

-APIApplicationProgrammingInterface

-PROTProtocolSpecificationLIN-ConfigurationLanguageDescriptionTheLINConfigurationFilecontainsallimportantinformationfortheoperationofthenetwork:Signals,LatencyTimes,CycleTimes,Nodes…Servesasdevelopmentinterfacebetweenthesinglenodes.InputFilefor:LINApplicationGeneratorLINEmulatorLINAnalyzerLINdescriptionfile

LIN_description_file; //example:mirrornetworkLIN_protocol_version= "1.1";LIN_language_version= "1.1";LIN_speed= 9.6kbps;Nodes {Master:CBCM,timebase5ms,jitter0.1ms; Slave: MR_DR,MR_PS,MR_RF;}Frames {frame_name,frame_id,published_by{

{signal_name,signaloffset}}Signals {signal_name:signal_size,init_value, published_by,subscribed_by}Schedule_tables {schedule_table_name{ frame_namedelayframe_time}Signal_grou