10 SDRAM CONTROLLER (SDRAMC)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
10-15
6.1 Correspondence between DQB Status and Bus Operation
Table 10.
Bus operation
DQB status
CPU instruction fetch
Enabled
CPU vector fetch
Enabled
CPU data read
Enabled
CPU data write
Disabled
CPU stack read
Enabled
CPU stack write
Disabled
DMAC data read
Enabled
DMAC data write
Disabled
If the CPU executes writing to the address of data buffered in the DQB, the buffered data concerned are flushed.
Initial resetting also resets and empty the DQB.
Control Register Details
10.7
7.1 List of SDRAMC Registers
Table 10.
Address
Register name
Function
0x302200 SDRAMC_INIT
SDRAM Initialization Register
Enable SDRAMC and control SDRAM initialization
0x302204 SDRAMC_CFG
SDRAM Configuration Register
Set SDRAM size and timing parameters
0x302208 SDRAMC_REF
SDRAM Refresh Control Register
Control SDRAM refresh
0x302210 SDRAMC_APP
SDRAM Application Configuration Register
Set CAS latency and double frequency mode
The following describes each SDRAMC register. These are all 32-bit registers.
Note: When data is written to the registers, the “Reserved” bits must always be written as 0 and not 1.
SDRAM Initialization Register (SDRAMC_INIT)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
SDRAM
Initialization
Register
(SDRAMC_INIT)
0x302200
(32 bits)
D31–5 –
reserved
–
–
–
0 when being read.
D4
SDON
SDRAM controller enable
1 Enable
0 Disable
0
R/W
D3
INIDO
SDRAM initialization status
1 Finished
0 Busy
0
R
D2
INIMRS
MRS command enable for init.
1 Enable
0 Disable
0
R/W
D1
INIPRE
PALL command enable for init.
1 Enable
0 Disable
0
R/W
D0
INIREF
REF command enable for init.
1 Enable
0 Disable
0
R/W
D[31:5] Reserved
D4
SDON: SDRAM Controller Enable Bit
Enables the SDRAM controller.
1 (R/W): Enabled
0 (R/W): Disabled (default)
When SDON is set to 1, the SDRAM controller activates and outputs the SDRAM clock from the SD-
CLK pin. Before setting SDON to 1, be sure to start SDRAMC clock supply to the SDRAM controller.
Note: Be sure to avoid setting SDON to 0 (SDRAMC disabled) during self-refreshing. Before dis-
abling the SDRAMC, always make sure the SDRAMC is not in self-refresh mode.
D3
INIDO: SDRAM Initialization Status Bit
Indicates that the SDRAM has finished initialization (Mode Register Set).
1 (R):
Initialization finished
0 (R):
Before initialization (default)
INIDO is set to 1 when the initialization sequence is completed. Make sure that INIDO is set to 1 be-
fore the SDRAM is accessed.
D2
INIMRS: MRS Command Enable for Initialization Bit
Enables to output the MRS (Mode Register Set) command for initializing the SDRAM.
1 (R/W): Enabled
0 (R/W): Disabled (default)