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3.11.4ARMBootModeConfiguration
3.11.5AEMIFConfiguration
3.12DeviceBootModes
TMS320DM355
DigitalMediaSystem-on-Chip(DMSoC)
SPRS463A–SEPTEMBER2007–REVISEDSEPTEMBER2007
Table3-16.ModuleConfiguration(continued)
DefaultStates
31ARMAlwaysOnONEnable
32BUSAlwaysOnONEnable
33BUSAlwaysOnONEnable
34BUSAlwaysOnONEnable
35BUSAlwaysOnONEnable
36BUSAlwaysOnONEnable
37BUSAlwaysOnONEnable
38BUSAlwaysOnONEnable
39ReservedReservedReservedReserved
40VPSSDACAlwaysOnONSyncRst
TheinputpinsBTSEL[1:0]determinewhethertheARMwillbootfromitsROMorfromtheAsynchronous
EMIF(AEMIF).WhenROMbootisselected(BTSEL[1:0]=00,10,or11),ajumptothestartofinternal
ROM(address0x0000:8000)isforcedintothefirstfetchedinstructionword.TheembeddedROMboot
loadercode(RBL)thenperformscertainconfigurationsteps,readstheBOOTCFGregistertodetermine
thedesiredbootmethod,andbranchestotheappropriatebootroutine(i.e.,aNAND,MMC/SD,orUART
loaderroutine).
IfAEMIFbootisselected(BTSEL[1:0]=01),ajumptothestartofAEMIF(address0x0200:0000)is
forcedintothefirstfetchedinstructionword.TheARMthencontinuesexecutingfromexternal
asynchronousmemoryusingthedefaultAEMIFtimingsuntilmodifiedbysoftware.
NOTE
ForAEMIFboot,theOneNANDmustbeconnectedtothefirstAEMIFchipselectspace
(EM_CE0).Also,theAEMIFdoesnotsupportdirectexecutionfromNANDFlash.
BootmodesarefurtherdescribedinSection3.12.
3.11.5.1AEMIFPinConfiguration
TheinputpinsAECFG[3:0]determinetheAEMIFconfigurationimmediatelyafterreset.UseAECFG[3:0]
toproperlyconfigurethepinsoftheAEMIF.RefertothesectiononpinmultiplexinginSection3.9.
Also,seetheAsynchronousExternalMemoryInterface(AEMIF)PeripheralReferenceGuide(SPRUEE8)
formoreinformationontheAEMIF.
3.11.5.2AEMIFTimingConfiguration
WhenAEMIFisenabled,thewaitstateregistersareresettotheslowestpossibleconfiguration,whichis
88cyclesperaccess(16cyclesofsetup,64cyclesofstrobe,and8cyclesofhold).Thus,witha24MHz
clockatMXI,theAEMIFisconfiguredtorunat6MHz/88whichequalsapproximately68kHzbydefault.
SeetheAsynchronousExternalMemoryInterface(AEMIF)PeripheralReferenceGuideformore
informationontheAEMIF.
TheDM355ARMcanbootfromeitherAsyncEMIF(AEMIF/OneNand)orfromARMROM,asdetermined
bythesettingofthedeviceconfigurationpinsBTSEL[1:0].TheBTSEL[1:0]pinscandefinetheROMboot
modefurtheraswell.
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