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12.5.3.2.2SynchronousReset
ARMControlofDSPBoot,Clock,andReset
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Inthesynchronousresetstate,theDSP’smoduleresetisassertedanditsmoduleclockisenabled.You
canusethisstatetoresettheDSP.ThefollowingstepsdescribehowtoputtheDSPinthesynchronous
resetstate:
•ARM:NotifytheDSPtoprepareforpower-down.
•DSP:PuttheDSPintheIDLEstate:
1.Setthepower-downcommandregister(PDCCMD)intheDSPpower-downcontroller(PDC)
moduleto00015555h.
Note:PDCCMDcanonlybewrittenwhiletheDSPisinsupervisormode.Seethe
TMS320DM646xDMSoCDSPSubsystemReferenceGuide(SPRUEP8)andthe
TMS320C64x+DSPMegamoduleReferenceGuide(SPRU871)formoreinformationon
thepower-downcontroller(PDC).
2.ExecutetheIDLEinstructioniftheDSPisintheenablestate.IDLEisaprograminstructioninthe
C64x+CPUinstructionset.WhentheCPUexecutesIDLE,thePDCisnotifiedandinitiatesDSP
power-downaccordingtothebitssetinPDCCMD.SeetheTMS320C64x+DSPMegamodule
ReferenceGuide(SPRU871)formoreinformationonthePDCandtheIDLEinstruction.
•ARM:SyncresetDSP:
1.WaitfortheGOSTAT[0]bitinthepowerdomaintransitionstatusregister(PTSTAT)inthePSCto
clearto0.Youmustwaitforthepowerdomaintofinishanypreviouslyinitiatedtransitionsbefore
initiatinganewtransition.
2.SettheNEXTbitinthemodulecontrol1register(MDCTL1)inthePSCto1topreparetheDSP
moduleforasyncresettransition.
3.SettheGO[0]bitinthepowerdomaintransitioncommandregister(PTCMD)inthePSCto1to
initiatethestatetransition.
4.WaitforGOSTAT[0]bitinPTSTATtoclearto0.Thedomainissafelyinthenewstateonlyafter
theGOSTAT[0]bitisclearedto0.
5.WaitfortheSTATEbitinthemodulestatus1register(MDSTAT1)inthePSCtochangeto1.The
moduleissafelyinthenewstateonlyaftertheSTATEbitinMDSTAT1changestoreflectthenew
state.
•ARM:AssertDSPlocalreset.CleartheLRSTbitinthemodulecontrol1register(MDCTL1)inthe
PSCto0.Thisstepisoptional.ThisstepassertstheDSPlocalresetandisincludedheresothatthe
DSPdoesnotstartrunningimmediatelyuponpower-on/enable.Typically,softwaredeassertslocal
resetsometimeafterfinishingtheenablesequence.
ARM-DSPIntegration 132SPRUEP9A–May2008
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