CAN通讯协议介绍

IntrepidControlSystems,Inc.:[phone]Email:[e-mail]s,Inc.LearnthebasicsoftheCANprotocolUnderstandwhatmakesupaCANnetworkUnderstandwhatmakesupaCANnodeLearnhowCANcomparestocompetitiveprotocolsLearnhowtouseaCANtesttoolandaCANDatabase(DBC)filetomonitorandtransmitCANmessagesandsignalsIntrepidControlSystems,Inc.Part1:LearnthehighlevelCANfeaturesPart2:UnderstandtheCANmessagePart3:UnderstandhowmessagesarecommunicatedbetweenCANnodesIntrepidControlSystems,Inc.Standsfor:Controller–AreaNetworkDevelopmentoftheCAN-busstartedoriginallyin1983atRobertBoschGmbHTheprotocolwasofficiallyreleasedin1986attheSocietyofAutomotiveEngineers(SAE)congressinDetroitIntrepidControlSystems,Inc.•Speedupto1Mbps•Non-destructivemessagearbitration•Allnodesreceiveallmessages•NoguaranteedmessagelatencyIntrepidControlSystems,Inc.[bps]20K1M10M25MIntrepidControlSystems,Inc.•CANismuchfaster:upto1Mbps•LINoffersatimedeterministicmodel•CANoffersamorepowerfulchecksum•UsesLDFinsteadofDBCfilesfordatabasesIntrepidControlSystems,Inc.•FlexRaynetworkstartupmorecomplicated•FlexRayofferstimedeterministiccommunications•FlexRayoffersfaulttoleranceusingvariousmechanisms•FlexRayofferslargerdataframes•UsesFIBEXinsteadofDBCfilesIntrepidControlSystems,Inc.•MOSTistargetedatinfotainmentapplications•MOSToffersdedicatedtransfersinaringnetworkat25MbpsOptical,50MbCopper,and150MbpsopticalphysicallayersIntrepidControlSystems,Inc.•Moderatecostsiliconimplementation•RequireshardwareCANcontrollerandCANtransceiver•RequireshardwareCANtransceiverMicroprocessorCANTransceiverCANControllerCANHighCANLowGroundIntrepidControlSystems,Inc.(TrueorFalse)‏2.CANrequireshardwarecontrollers.(TrueorFalse)‏3.CANissimilartoLIN:bothhaveverydefinedmessagestructure.(TrueorFalse)‏4.WhatisthemaximumnumberofbytescanbeinaCANmessage?IntrepidControlSystems,Inc.•HighSpeedCAN:upto1Mbps•LowSpeedFaultTolerantCAN:upto125kbps•SingleWireCAN:upto83.3kbpsIntrepidControlSystems,Inc.•SingleWirePlusGround•Two120Ohmterminationresistors•Buslengthto40meters@1Mbps,•Slower=longer.SWPhysicalLayerIntrepidControlSystems,Inc.•TwistedPair(CANH/CANL)plusGround•Two120Ohmterminationresistors•Buslengthto40meters@1Mbps,•Slower=longer.IntrepidControlSystems,Inc.•MultipleversionsofCANaresupportedinValueCANandneoVIFIRE:HighSpeedCAN,LSFTCAN,SingleWireCAN•VehicleSpyprovidesfullCANsupport:CANmessageandsignaldecoding,logging,CANnodesimulationIntrepidControlSystems,Inc.•GetfamiliarwithIntrepidCAN/LINboard•FindUSBpowerconnector•FindCANandneoVIpowerconnector•LocateLINandCANtransceiversontheboard•ConnectUSBandpowercables•ConnectneoVItotheboardIntrepidControlSystems,Inc.•TwoidenticalconnectedCANnodes•PowerissuppliedthroughUSB•CANconnectorsforneoVIandValueCAN•PowerconnectorforneoVIIntrepidControlSystems,Inc.•TwoCANtransceiverswithtestpoints•TworesetbuttonsIntrepidControlSystems,Inc.(TrueorFalse)‏2.CANrequiresthreelines:CANlow,CANHighandground(TrueorFalse)‏3.SinglewireCANisingeneraltheslowestCANtype.(TrueorFalse)‏IntrepidControlSystems,Inc.•TypicalCANmessageiscalleddataframe•Numberofdatabytes:0-8CANDataFrameProtocolOverheadDataBytesProtocolOverheadIntrepidControlSystems,Inc.•ArbitrationfieldrepresentsframeID•Controlfieldhasdefinesframelength•CRCstandsforCyclicRedundancyCheck:thisisCANframechecksum•ACKisacknowledgefield:confirmsframereceptionCANDataFrameDataBytesArbitrationFieldControlFieldCRCACKIntrepidControlSystems,Inc.•Identifierassigns11bitIDtoCANframes•RemoteTransmitRequest(RTR)bit•CANnodesendsCANframewithrecessiveRTRbit(logical1)whenthenoderequestsdatafromothernodesDataBytesControlFieldIdentifierRTR111ArbitrationFieldCRCACKIntrepidControlSystems,Inc.•IdenticaltotheDataFrame,exceptthereisnodatabytes•RTRbitisrecessive(logical1)‏ControlFieldCRCACKArbitrationFieldIntrepidControlSystems,Inc.•DLCspecifiesnumberofdatabytes:0-8•RB0bitissettological0andreservedfo