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12.5.2.2DSPModuleClockOff
12.5.3DSPReset
12.5.3.1DSPLocalReset
ARMControlofDSPBoot,Clock,andReset
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Intheclockdisablestate,theDSP’smoduleclockisdisabledwhiletheDSPmoduleresetremains
deasserted.ThisstateistypicallyusedtodisabletheDSPclocktosavepower.
•ARM:NotifytheDSPtoprepareforpower-down.
•DSP:Prepareforpower-down:
1.Setthepower-downcommandregister(PDCCMD)intheDSPpower-downcontroller(PDC)
moduleto00015555h
Note:PDCCMDcanonlybewrittenwhiletheDSPisinsupervisormode.Seethe
TMS320DM646xDMSoCDSPSubsystemReferenceGuide(SPRUEP8)andthe
TMS320C64x+DSPMegamoduleReferenceGuide(SPRU871)formoreinformationon
thepower-downcontroller(PDC).
2.Enableoneoftheinterrupts:ARM2DSP0,ARM2DSP1,ARM2DSP2,ARM2DSP3,orNMI.This
interruptwakestheDSPintheDSPclock-onsequence.
3.ExecutetheIDLEinstruction.IDLEisaprograminstructionintheC64x+CPUinstructionset.When
theCPUexecutesIDLE,thePDCisnotifiedandinitiatesDSPpower-downaccordingtothebitsset
inPDCCMD.SeetheTMS320C64x+DSPMegamoduleReferenceGuide(SPRU871)formore
informationonthePDCandtheIDLEinstruction.
•ARM:DisabletheDSPclock:
1.WaitfortheGOSTAT[0]bitinthepowerdomaintransitionstatusregister(PTSTAT)inthePSCto
clearto0.Youmustwaitforthepowerdomaintofinishanypreviouslyinitiatedtransitionsbefore
initiatinganewtransition.
2.SettheNEXTbitinthemodulecontrol1register(MDCTL1)inthePSCto2htopreparetheDSP
moduleforadisabletransition.
3.SettheGO[0]bitinthepowerdomaintransitioncommandregister(PTCMD)inthePSCto1to
initiatethestatetransition.
4.WaitfortheGOSTAT[0]bitinPTSTATtoclearto0.Thedomainisonlysafelyinthenewstate
aftertheGOSTAT[0]bitisclearedto0.
5.WaitfortheSTATEbitinthemodulestatus1register(MDSTAT1)inthePSCtochangeto2h.The
moduleisonlysafelyinthenewstateaftertheSTATEbitinMDSTAT1changestoreflectthenew
state.
6.ClockstotheDSParedisabled.
WithaccesstothePSCregisters,theARMcanassertanddeassertDSPlocalresetandDSPmodule
reset.WhenDSPlocalresetisasserted,theDSP’sinternalmemories(L1P,L1D,andL2)arestill
accessible.LocalresetonlyresetstheDSPCPU.LocalresetisusefulwhentheDSPmoduleisinthe
enableordisablestates,sincemoduleresetisassertedintheSyncResetandSwRstDisablestatesand
moduleresetsupersedeslocalreset.TheintentoflocalresetisfortheARMtouselocalresettoresetthe
DSPduringtheDSPbootprocess.TheintentofmoduleresetisforittocompletelyresettheDSP(like
hardreset).FormoreinformationonthePSC,seeChapter6.Formoreinformationonlocalresetandon
modulereset,seeChapter10.ThissectiondescribeshowtoinitiateDSPlocalresetandmodulereset.
Toassert/deassertlocalreset:
1.CleartheLRSTbitinthemodulecontrol1register(MDCTL1)inthePSCto0toassertDSPreset.
2.SettheLRSTbitinMDCTL1to1todeassertDSPreset.
ARM-DSPIntegration 130SPRUEP9A–May2008
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