Rev. 2.00, 09/03, page 174 of 690
Bit
Bit
Name
Initial
Value
R/W
Description
6, 5
0
R
Reserved
These bits are always read as 0. The write value should
always be 0.
4
3
TRWL1
TRWL0
0
0
R/W
R/W
Number of Cycles from WRITA/WRIT Command to Auto-
precharge/PRE Command
Specifies the number of cycles from issuing WRITA/WRIT
command to the start of auto-precharge or to issuing PRE
command. The setting for areas 2 and 3 is common.
00: 0 cycle
01: 1 cycle
10: 2 cycles
11: Setting prohibited
2
0
R
Reserved
This bit is always read as 0. The write value should always be
0.
1
0
TRC1
TRC0
0
0
R/W
R/W
Number of Cycles from REF Command/Self-refresh Release
to ACTV Command
Specify the number of cycles from issuing the REF command
or releasing self-refresh to issuing the ACTV command. The
setting for areas 2 and 3 is common.
00: 3 cycles
01: 4 cycles
10: 6 cycles
11: 9 cycles
Note:
*
Specify area 3 as SDRAM when only one area is connected with SDRAM. In this case,
specify area 2 as normal space.
7.4.4
SDRAM Control Register (SDCR)
SDCR specifies the method to refresh and access SDRAM, and the types of SDRAMs to be
connected.
The bits other than RFSH and RMODE should be written in the initialization after a power-on
reset and should not be modified after the initialization. When modifying these bits RFSH and
RMODE, do not change the values of other bits and write the previous values. Do not access area
2 or 3 until the SDCR register setting is complete when using synchronous DRAM.
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