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4.3SDRAMConfigurationRegister(SDCFG)
DDR2MemoryControllerRegisters
TheSDRAMconfigurationregister(SDCFG)containsfieldsthatprogramtheDDR2memorycontrollerto
meetthespecificationoftheDDR2memory.ThesefieldsconfiguretheDDR2memorycontrollertomatch
thedatabuswidth,CASlatency,numberofinternalbanks,andpagesizeoftheexternalDDR2memory.
Bits0-14oftheSDCFGregisterareonlywriteablewhentheTIMUNLOCKbitissetto0(unlocked).See
Section2.11.1formoreinformationoninitializingtheconfigurationregistersoftheDDR2memory
controller.TheSDCFGisshowninFigure22anddescribedinTable20.
Figure22.SDRAMConfigurationRegister(SDCFG)
3124
Reserved
R-0x0
232219181716
BOOT_
ReservedDDR_DRIVEReserved
UNLOCK
R/W-0R/W-0xAR-0R-0x3
151413121198
TIMUNLOCKNMReservedCLReserved
R/W-0R/W-0R-0x0R/W-0x5R-0x0
764320
ReservedIBANKReservedPAGESIZE
R-0x0R/W-0x2R-0x0R/W-0x0
LEGEND:R/W=Read/Write;R=Readonly;-n=valueafterreset
Table20.SDRAMConfigurationRegister(SDCFG)FieldDescriptions
BitFieldValueDescription
31-24ReservedReserved.Writestothisregistermustkeepthesebitsattheirdefaultvalues.
23BOOT_UNLOCKBootunlockbit.Controlswriteaccesstobits16through22ofthisregister.
0Writestobits22:16ofthisregisterarenotpermitted
1Writestobits22:16ofthisregisterareallowed
22-19ReservedReserved.Writestothisregistermustkeepthesebitsattheirdefaultvalue.
18DDR_DRIVEDDR2SDRAMdrivestrength.ThisbitisusedtoselectthedrivestrengthusedbytheDDR2
SDRAM.ThisbitiswriteableonlywhenBOOT_UNLOCKisunlocked(setto1).
0Normaldrivestrength
1Weak(60%)drivestrength
17-16ReservedReserved.Writestothisregistermustkeepthesebitsattheirdefaultvalue.
15TIMUNLOCKTimingunlockbit.ControlswriteaccessfortheSDRAMTimingRegister(SDTIM1)andSDRAM
TimingRegister2(SDTIM2).AwritetothisbitwillcausetheDDR2MemoryControllertostartthe
SDRAMinitializationsequence.
0RegisterfieldsintheSDTIM1andSDTIM2registersmaynotbechanged.
1RegisterfieldsintheSDTIM1andSDTIM2registersmaybechanged.
14NMDDR2databuswidth.AwritetothisbitwillcausetheDDR2MemoryControllertostarttheSDRAM
initializationsequence.
032-bitbuswidth.
116-bitbuswidth
13-12ReservedReserved.Thereservedbitlocationisalwaysreadas0.Avaluewrittentothisfieldhasnoeffect.
38DSPDDR2MemoryControllerSPRUEK5A–October2007
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