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6.3.3LocalReset
6.4ExecutingStateTransitions
6.4.1PowerDomainStateTransitions
6.4.2ModuleStateTransitions
ExecutingStateTransitions
Inadditiontomodulereset(describedinSection6.3.2),theDSPCPUcanberesetusingaspeciallocal
reset.WhenDSPlocalresetisasserted,theDSPsinternalmemories(L1P,L1D,andL2)arestill
accessible.ThelocalresetonlyresetstheDSPCPUcore,nottherestoftheDSPsubsystem,astheDSP
moduleresetwould.
ModuleresettakesprecedenceoverLocalReset;therefore,LocalResetisnotusefulwhentheDSPisin
SyncResetorSwRstDisablestate.
SeeChapter10formoreinformationonlocalresetandscenarioswherethiscanbeused.
Theproceduresforassertingandde-assertingDSPlocalresetareasfollows:
1.CleartheLRSTbitinMDCTL39to0(asserttheDSPlocalreset).
2.SettheLRSTbitinMDCTL39to1(de-assertDSPlocalreset).IftheDSPisintheenablestate,it
immediatelyexecutesprograminstructionsafterresetisde-asserted.
Thissectiondescribeshowtoexecutestatetransitionsfordevicemodules.
TheDM643xDMPconsistsofonlyonepowerdomain--theAlwaysOnpowerdomain.ThisAlwaysOn
PowerDomainisalwaysintheONstatewhenthechipispowered-on.Youarenotallowedtochangethis
powerdomainstatetoOFF.
Thissectiondescribestheprocedurefortransitioningthemodulestate.AllDM643xDMPmodulesareon
theAlwaysOndomain(PowerDomain0).
Notethatsomeperipheralshavespecialprogrammingrequirementsandstepsyoumusttakebeforeyou
caninvokethePSCmodulestatetransition.Refertotheindividualperipheralreferenceguideformore
details.Forexample,theDDR2memorycontrollerrequiresthatyoufirstplacetheDDRmemoryin
self-refreshmodebeforeyouinvokethePSCmodulestatetransition,ifyouwanttomaintainthememory
content.
Note:Thefollowingprocedureisdirectlyapplicableforallmodules,exceptfortheDSPinthe
DM643xDMP.TotransitiontheDSPmodulestate,youmustbeawareofseveralsystem
considerations.
Theprocedureformodulestatetransitionsisasfollows(wherencorrespondstothemodule):
1.WaitfortheGOSTAT[0]bitinPTSTATtoclearto0.Youmustwaitforanypreviouslyinitiated
transitionstofinishbeforeinitiatinganewtransition.
2.SettheNEXTbitinMDCTLntoSwRstDisable(0),SyncReset(1),Disable(2h),orEnable(3h).
Note:YoumaysettransitionsinmultipleNEXTbitsinMDCTLninthisstep.Transitionsdonot
actuallytakeplaceuntilyousettheGO[0]bitinPTCMDinalaterstep.
3.SettheGO[0]bitinPTCMDto1toinitiatethetransition(s).
4.WaitfortheGOSTAT[0]bitinPTSTATtoclearto0.Themodulesaresafelyinthenewstatesonly
aftertheGOSTAT[0]bitinPTSTATisclearedto0.
SPRU978E–March2008PowerandSleepController65
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