10 SDRAM CONTROLLER (SDRAMC)
10-18
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
7.5 t
Table 10.
RC
, t
RFC
, and t
XSR
Settings
T80NS[3:0]
t
RC
, t
RFC
, t
XSR
0xf
16 cycles
0xe
15 cycles
0xd
14 cycles
0xc
*
13 cycles
0xb
12 cycles
0xa
11 cycles
0x9
10 cycles
0x8
*
9 cycles
0x7
8 cycles
0x6
7 cycles
0x5
6 cycles
0x4
*
5 cycles
0x3
4 cycles
0x2
3 cycles
0x1
2 cycles
0x0
*
1 cycle
(Default: 0xe)
*
Recommended settings (For more information, see “(2) External
SRAM access rate while the SDRAM is in self-refresh status” in Sec-
tion 3.8.)
D3
Reserved
D[2:0]
ADDRC[2:0]: SDRAM Address Configuration Bits
Selects SDRAM size and chip configuration. This selection also sets up the bank size, column address
size (page size), and row address size.
7.6 SDRAM Size Selections
Table 10.
ADDRC[2:0]
Number of banks
Row size
Column size
SDRAM chip configuration Memory size
0x7
4
8K
1K
32M
×
16 bits
×
1
64M bytes
0x6
4
4K
1K
16M
×
8 bits
×
2
32M bytes
0x5
4
4K
512
8M
×
8 bits
×
2
16M bytes
0x4
Reserved (Do not set ADDRC[2:0] to 0x4.)
0x3
4
8K
512
16M
×
16 bits
×
1
32M bytes
0x2
4
4K
512
8M
×
16 bits
×
1
16M bytes
0x1
4
4K
256
4M
×
16 bits
×
1
8M bytes
0x0
2
2K
256
1M
×
16 bits
×
1
2M bytes
(Default: 0x0)
SDRAM Refresh Register (SDRAMC_REF)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
SDRAM
Refresh Control
Register
(SDRAMC_REF)
0x302208
(32 bits)
D31–26 –
reserved
–
–
–
0 when being read.
D25
SREFDO
SDRAM self-refresh status
1 Finished
0 Busy
0
R
D24
SCKON
SDRAM clock during self-refresh
1 Enable
0 Disable
0
R/W
D23
SELEN
SDRAM self-refresh enable
1 Enable
0 Disable
0
R/W
D22–16 SELCO[6:0] SDRAM self-refresh counter
0x0 to 0x7f
0x7f R/W
D15–12 –
reserved
–
–
–
0 when being read.
D11–0 AURCO[11:0] SDRAM auto-refresh counter
0x0 to 0xfff
0x8c R/W
D[31:26] Reserved
D25
SREFDO: SDRAM Self-Refresh Status Bit
Indicates the SDRAM self-refresh status.
1 (R):
Self-refresh has finished
0 (R):
Self-refresh mode (default)
SREFDO is set to 0 while the SDRAM is placed into self-refresh mode. Otherwise, SREFDO is set to 1.
Before entering the SLEEP mode, always be sure to read this bit using a program stored elsewhere (i.e., not
in the SDRAM) to confirm that the SDRAM is in self-refresh mode.