3 MEMORY MAP
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
3-7
(Note)
*
1: Interval between #CE access cycles will be increased.
*
2: When SDON = 1 (SDRAMC enabled) and SELEN = 1 (self-refresh enabled), the SRAM setup cycle will be shorter
than the CE
x
SETUP[1:0] set value. Determine the setup time according to the characteristics of the device con-
nected.
*
3: When SDON = 1 (SDRAMC enabled) and SELEN = 1 (self-refresh enabled), the SRAM setup cycle will be longer
than the CE
x
SETUP[1:0] set value. Determine the setup time according to the characteristics of the device con-
nected.
(3) SDRAM access rate
8.3 SDRAM Access Cycle
Table 3.
SDRAM access cycle
Number of access cycles
Byte/half-word
Word
4-word burst read
8-word burst read
CPU/DMAC/GE
single random write
5 + T24NS
×
2
6 + T24NS
×
2
–
–
CPU/DMAC/GE
single random read
6 + T24NS
×
2 + CAS 6 + T24NS
×
2 + CAS
–
–
CPU/DMAC/GE
bulk read
6 + CAS
6 + CAS
–
–
Cache burst read (
*
1)
–
–
11 + T24NS
×
2 + CAS
–
DMAC burst read (
*
2)
–
–
11 + T24NS
×
2 + CAS
–
LCDC burst read (
*
3)
–
–
–
19 + T24NS
×
2 + CAS
T24NS: Value set in T24NS[1:0]/SDRAMC_CFG register CAS: CAS latency set in CAS[1:0]/SDRAMC_APP register
The values in the table do NOT take the following conditions into consideration:
• When the SDRAM is in auto-refresh or self-refresh status
• When SDRAM addresses across the 512-byte boundary are accessed
(Note)
*
1: When the CPU accesses an external SDRAM with caching enabled (CCU module)
*
2: When the DMA control table is located in an external SDRAM and the SDRAMC loads the control table during
DMA transfer
*
3: When the LCDC loads display data stored in an external SDRAM (VRAM) to the FIFO
Note that the factor when the LCDC accesses the external SDRAM across the boundary between the main and
sub-window areas (located in the same SDRAM) are not taken into consideration.