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3.12.1BootModesOverview
TMS320DM355
DigitalMediaSystem-on-Chip(DMSoC)
SPRS463A–SEPTEMBER2007–REVISEDSEPTEMBER2007
Thebootselectionpins(BTSEL[1:0])determinetheARMbootprocess.Afterreset(POR,warmreset,or
maxreset),ARMprogramexecutionbeginsinARMROMat0x0000:8000,exceptwhenBTSEL[1:0]=01,
indicatingAEMIF(AEMIF/OneNand)boot.SeeSection3.11.1forinformationonthebootselectionpins.
DM355’sARMROMbootloader(RBL)executeswhentheBOOTSEL[1:0]pinsindicateaconditionother
thanthenormalARMEMIFboot.
•IfBTSEL[1:0]=01-AsynchronousEMIF(AEMIF)boot.Thismodeishandledbyhardwarecontroland
doesnotinvolvetheROM.InthecaseofOneNAND,theuserisresponsibleforputtinganynecessary
bootcodeintheOneNAND'sbootpage.ThiscodeshallconfiguretheAEMIFmoduleforthe
OneNANDdevice.AftertheAEMIFmoduleisconfigured,bootingwillcontinueimmediatelyafterthe
OneNAND’sbootpagewiththeAEMIFmodulemanagingpagesthereafter.Furthermore,incaseof
FastBootfromAEMIF/OneNAND,theuserisresponsibleforcheckingthestateoftheFASTBOOTbit
intheBOOTCFGregisterintheSystemModuleinordertorespondproperlybyexecutinganyrequired
deviceinit,bringingmDDRoutofself-refresh,andbranchingtouserentrypointinmDDR.
•TheRBLsupports3distinctbootmodes:
–BTSEL[1:0]=00-ARMNANDBoot
–BTSEL[1:0]=10-ARMMMC/SDBoot
–BTSEL[1:0]=11-ARMUARTBoot
•IfNANDbootfails,thenMMC/SDmodeistried.
•IfMMC/SDbootfails,thenMMC/SDbootistriedagain.
•IfUARTbootfails,thenUARTbootistriedagain.
•RBLusesGIO61toindicatebootstatus(canusetoblinkLED):
–Afterreset,GIO61isinitiallydrivenlow(e.gLEDoff)
–IfNANDbootfailsandthenMMC/SDbootfails,thenGIO61shalltoggleat4HzwhileMMC/SD
bootisretried.
–IfMMC/SDbootfails,thenGIO61shalltoggleat4HzwhileMMC/SDbootisretried
–IfUARTbootfails,thenGIO61shalltoggleat2HzwhileUARTbootisretried
–Whenbootissuccessful,justbeforeprogramcontrolisgiventoUBL,GIO61isdrivenhigh(e.g.
LEDon)
–DM355Timer0shallbeusedtoaccuratelytoggleGIO61at4Hzand2Hz
•ARMROMBoot-NANDMode
–Nosupportforafullfirmwareboot.Instead,copiesasecondstageuserbootloader(UBL)from
NANDflashtoARMinternalRAM(AIM)andtransferscontroltotheuser-definedUBL.
–SupportforNANDwithpagesizesupto2048bytes.
–Supportformagicnumbererrordetectionandretry(upto24times)whenloadingUBL
–Supportforupto30KBUBL(32KBIRAM-~2KBforRBLstack)
–Optional,user-selectable,supportforuseofDMAandI-cacheduringRBLexecution(i.e.,while
loadingUBL)
–Supportsbootingfrom8-bitNANDdevices(16-bitNANDdevicesarenotsupported)
–Supports4-bitECC(1-bitECCisnotsupported)
–SupportsNANDflashthatrequireschipselecttostaylowduringthetRreadtime
–SupportsFastBootoption,whichallowsyoutoquicklybootandrecoverfromalowpowermode
•ARMROMBoot-MMC/SDMode
–Nosupportforafullfirmwareboot.Instead,copiesasecondstageUwerBootLoader(UBL)from
MMC/SDtoARmInternalRAM(AIM)andtransferscontroltotheusersoftware.
–SupportforMMC/SDNativeprotocol(MMC/SDSPIprotocolisnotsupported)
–Supportfordescriptorerrordetectionandretry(upto24times)whenloadingUBL
–Supportforupto30KBUBL(32KB-~2KBforRBLstack)
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