NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
- 225 -
Revision V1.30
NUC97
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CHNIC
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[17]
PreActBnk
Pre-active Bank
If this bit is enabled, the SDRAM controller will open request bank early to get better
performance. It means maybe more than one bank active and consumes more power.
There are several bus requests in this chip and the SDRAM controller checks all these
requests simultaneous. If request in queue access bank is different with current bank, the
SDRAM controller will open the new bank early to reduce the access latency to get better
performance.
The mode takes effect for Close-Page mode (OPMode is 0) only. In Open-Page mode,
SDRAM controller always opens bank early.
0 = Disable Pre-Active-Bank mode.
1 = Enable Pre-Active-Bank mode. (Default)
[16]
AutoPDn
Auto Power Down Mode
If this bit is enabled, the SDRAM controller will make SDRAM to enter power down mode (CKE
low) automatically while the memory request is stop. Otherwise, the SDRAM is in IDLE state
(CKE = high).
0 = Disable auto power down mode.
1 = Enable auto power down mode. (Default)
[15:11]
Reserved
Reserved.
[10:8]
RDBUFTH
The AHB Read SDRAM Read Buffer Threshold Control
Due to the SDRAM working clock may be higher than the AHB BUS clock, the SDRAM
controller contains a read buffer for each AHB interface and they are used for data pre-read.
The controller read the data to buffer full or till AHB read request end. When the data buffer
full, the controller stop the read request and to service another AHB request. The RDBUFTH is
used to control the buffer threshold level for the SDRAM re-start the memory request. This
function can minimize the redundant memory read.
[10:8]
RDBUFTH
0,0,0
Reserved
others
Re-start memory read when the data buffer remain data level is
equal to RDBUFTH
[7]
Reserved
Reserved.
[6:5]
SD_TYPE
SDRAM Type
This file indicates which type of SDRAM is used.
The reset value is decided by chip’s system power-on setting.
SD_TYPE[1:0]
SDRAM TYPE
00
SDR SDRAM Type. (Single Data Rate SDRAM)
01
LPDDR SDRAM Type.
10
DDR SDRAM Type. (Double-Data-Rate SDRAM)
11
DDR2 SDRAM Type.