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10.4DSPReset
10.4.1DSPLocalReset
10.4.2DSPModuleReset
10.4.2.1SoftwareResetDisable(SwRstDisable)
DSPReset
Note:TheeffectsofDSPlocalresetandDSPmoduleresethavenotbeenfullyvalidated;
therefore,theseresetsarenotsupportedandshouldnotbeused.Instead,thePORor
RESETpinsshouldbeusedtoresettheentireDSP.
Withaccesstothepowerandsleepcontroller(PSC)registers,theexternalhost(forexample,PCIorHPI)
canassertandde-assertDSPlocalresetandDSPmodulereset.WhenDSPlocalresetisasserted,the
DSP’sinternalmemories(L1P,L1D,andL2)arestillaccessible.LocalresetonlyresetstheDSPCPU.
LocalresetisusefulwhentheDSPmoduleisintheenableordisablestates,sincemoduleresetis
assertedintheSyncResetandSwRstDisablestatesandmoduleresetsupersedeslocalreset.Theintent
ofDSPmoduleresetisfortheexternalhosttocompletelyresettheDSP.TheintentofDSPlocalresetis
toallowtheexternalhosttoholdtheCPUinresetwhilethehostisloadingcodeintotheDSPinternal
memory—thisstepcanbeusefulafterthehostputstheDSPinmoduleresetandthensubsequently
enablestheDSP.FormoreinformationonthePSC,seeChapter6.Thissectiondescribeshowtoinitiate
DSPlocalresetandmodulereset.
Thefollowingstepsdescribehowanexternalhostcanassert/de-assertlocalresettotheDSP:
1.CleartheLRSTbitinMDCTL39to0toassertDSPreset.
2.SettheLRSTbitinMDCTL39to1tode-assertDSPreset.
TheexternalhostmayprogramthePSCtoassertDSPmoduleresetbyplacingtheDSPineither
SoftwareResetDisable(SwRstDisable)stateorSynchronousReset(SyncReset)state.SeeChapter6for
descriptionsofthesePSCstates.
Inthesoftwareresetdisable(SwRstDisable)state,theDSP’smoduleresetisassertedanditsmodule
clockisturnedoff.YoucanusethisstatetoresettheDSP.Thefollowingstepsdescribehowtoputthe
DSPinthesoftwareresetdisablestate:
•Host:NotifytheDSPtoprepareforpower-down.
•DSP:PuttheDSPintheIDLEstate.
–SetPDCCMDto00015555h.PDCMDisacontrolregisterintheDSPpower-downcontroller
module.
Note:ThisregistercanonlybewrittenwhiletheDSPisinitssupervisormode.
–ExecutetheIDLEinstructioniftheDSPisintheenablestate.IDLEisaprograminstructioninthe
C64x+CPUinstructionset.WhentheCPUexecutesIDLE,thePDCisnotifiedandwillinitiatethe
DSPpower-downaccordingtothebitsthatyousetinthePDCCMD(01810000h)register.Seethe
TMS320C64x+DSPMegamoduleReferenceGuide(SPRU871)formoreinformationonthePDC
andtheIDLEinstruction.
•Host:SoftwareresetdisableDSP.
–WaitfortheGOSTAT[0]bitinPTSTATtoclearto0.Youmustwaitforthepowerdomaintofinish
anypreviouslyinitiatedtransitionsbeforeinitiatinganewtransition.
–CleartheNEXTbitinMDCTL39to0topreparetheDSPmoduleforaSwRstDisabletransition.
–SettheGO[0]bitinPTCMDto1toinitiatethestatetransition.
–WaitforGOSTAT[0]bitinPTSTATtoclearto0.Themoduleissafelyinthenewstateonlyafter
theGOSTAT[0]bitisclearedto0.
SPRU978E–March2008Reset93
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