了解Microchip的CAN模块的位定时

TheControllerAreaNetwork(CAN)protocolisan

asynchronousserialbuswithNon-ReturntoZero

(NRZ)bitcodingdesignedforfast,robustcommunica-

tionsinharshenvironments,suchasautomotiveand

industrialapplications.TheCANprotocolallowsthe

usertoprogramthebitrate,thesamplepointofthebit,

andthenumberoftimesthebitissampled.Withthese

features,thenetworkcanbeoptimizedforagiven

application.

Therearerelationshipsbetweenbittimingparameters,

thephysicalbuspropagationdelays,andtheoscillator

tolerancesthroughoutthesystem.Thisapplication

noteinvestigatestheserelationshipsastheypertainto

Microchip’sCANmoduleandassistsinoptimizingthe

bittimingforgivenphysicalsystemattributes.MAN754UnderstandingMicrochip’sCANModuleBitTimingAuthor:PatRichardsNominalBitTimeMicrochipTechnologyInc.TheNominalBitTime(NBT),ortbit,ismadeupofnon-overlappingsegments(Figure1),therefore,theNBTisINTRODUCTIONthesummationofthefollowingsegments:TheControllerAreaNetwork(CAN)protocolisantbit=tSyncSeg+tPropSeg+tPS1+tPS2asynchronousserialbuswithNon-ReturntoZero(NRZ)bitcodin