DDR2 DRAM Controller (ADSP-2146x)
3-80
ADSP-214xx SHARC Processor Hardware Reference
is currently underway. The DDR2 remains in self-refresh mode for at least
t
RAS
and until an internal access (read/write) to DDR2 space occurs.
The self-refresh entry command does automatically disable the
DDR2 memory DLL. Therefore its release command (exit)
requires additional stall cycles until the DLL has re-locked.
Self-refresh exit.
When any DDR2 access occurs, the DDR2C asserts
DDR2CKE
high which causes the DDR2 to exit from self-refresh mode. The
controller waits to meet the t
XSNR
specification (exit with no read com-
mand) or the t
XSRD
specification (exit with read command). Here is a
significant difference; releasing with a read command requires 200 DDR2
cycles (since the memory DLL needs to re read memory).
System clock during self-refresh mode.
Note that the
DDR2CLK
is not dis-
abled by the controller during self-refresh mode. However, software may
disable the clocks by setting the
DIS_DDR2CTL
bit in the
DDR2CTL0
register.
Programs should ensure that all applicable clock timing specifications are
met before the transfer to DDR2 address space (which causes the control-
ler to exit the self-refresh mode). If a transfer occurs to DDR2 address
space when the
DIS_DDR2CTL
bit is cleared, an internal bus error is gener-
ated, and the access does not occur externally, leaving the DDR2 in
self-refresh mode.
The following steps are required when using self-refresh mode.
1. Set the
DDR2SRF
bit to enter self-refresh mode.
2. Poll the
DDR2SRA
bit in the DDR2 status register (
DDR2STAT
) to
determine if the DDR2 has already entered self-refresh mode.
3. Optionally: set the
DIS_DDR2CTL
bit to freeze
DDR2_CLK
.
4. Optionally: clear the
DIS_DDR2CTL
bit to re-enable
DDR2_CLK.
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Содержание SHARC ADSP-214 Series
Страница 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...