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7.4EnhancedDirectMemoryAccess(EDMA3)Controller
SM320C6455-EP
FIXED-POINTDIGITALSIGNALPROCESSOR
SPRS462B–SEPTEMBER2007–REVISEDJANUARY2008
TheprimarypurposeoftheEDMA3istoserviceuser-programmeddatatransfersbetweentwo
memory-mappedslaveendpointsonthedevice.TheEDMA3servicessoftware-drivenpagingtransfers
(e.g.,datamovementbetweenexternalmemoryandinternalmemory),performssortingorsubframe
extractionofvariousdatastructures,serviceseventdrivenperipheralssuchasaMcBSPortheUTOPIA
port,andoffloadsdatatransfersfromthedeviceCPU.
TheEDMA3includesthefollowingfeatures:
•Fullyorthogonaltransferdescription
–Threetransferdimensions:array(multiplebytes),frame(multiplearrays),andblock(multiple
frames)
–Singleeventcantriggertransferofarray,frame,orentireblock
–Independentindexesonsourceanddestination
•Flexibletransferdefinition:
–IncrementorFIFOtransferaddressingmodes
–Linkingmechanismallowsforping-pongbuffering,circularbuffering,andrepetitive/continuous
transfers,allwithnoCPUintervention
–Chainingallowsmultipletransferstoexecutewithoneevent
•256PaRAMentries
–Usedtodefinetransfercontextforchannels
–EachPaRAMentrycanbeusedasaDMAentry,QDMAentry,orlinkentry
•64DMAchannels
–Manuallytriggered(CPUwritestochannelcontrollerregister),externaleventtriggered,andchain
triggered(completionofonetransfertriggersanother)
•FourQuickDMA(QDMA)channels
–Usedforsoftware-driventransfers
–TriggereduponwritingtoasinglePaRAMsetentry
•Fourtransfercontrollers/eventqueueswithprogrammablesystem-levelpriority
•Interruptgenerationfortransfercompletionanderrorconditions
•Memoryprotectionsupport
–ActivememoryprotectionforaccessestoPaRAMandregisters
•Debugvisibility
–Queuewatermarking/thresholdallowsdetectionofmaximumusageofeventqueues
–Errorandstatusrecordingtofacilitatedebug
Eachofthetransfercontrollershasadirectconnectiontotheswitchedcentralresource(SCR).
NOTE
AlthoughthetransfercontrollersaredirectlyconnectedtotheSCR,theycanaccessonly
certaindeviceresources.Forexample,onlytransfercontroller1(TC1)canaccessthe
McBSPs.Table4-1liststhedeviceresourcesthatcanbeaccessedbyeachofthe
transfercontrollers.
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