10 SDRAM CONTROLLER (SDRAMC)
10-6
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
4.2.4 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.)
(3) t
RAS
t
RAS
: ACTIVE to PRECHARGE command period
This timing parameter can be set from 1 to 8 cycles in SDCLK using T60NS[2:0]/SDRAMC_CFG register.
4.2.5
Table 10.
t
RAS
Settings
T60NS[2:0]
t
RAS
0x7
8 cycles
0x6
7 cycles
:
:
0x1
2 cycles
0x0
1 cycle
(Default: 0x0)
(4) t
RP
, t
RCD
t
RP
: PRECHARGE to ACTIVE command period
t
RCD
: ACTIVE to READ/WRITE delay time
These timing parameters can be set from 1 to 4 cycles in SDCLK using T24NS[1:0]/SDRAMC_CFG regis-
ter.
4.2.6
Table 10.
t
RP
and t
RCD
Settings
T24NS[1:0]
t
RP
, t
RCD
0x3
4 cycles
0x2
3 cycles
0x1
2 cycles
0x0
1 cycle
(Default: 0x0)