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II CORE BLOCK: BCU (Bus Control Unit)
S1C33210 FUNCTION PART EPSON B-II-4-43
CRAS: Successive RAS mode (D8) / DRAM timing set-up register (0x48130)
Set the successive RAS mode.
Write "1": Successive RAS mode
Write "0": Normal mode
Read: Valid
In systems using DRAM, the successive RAS mode is entered by writing "1" to CRAS. In this mode, read/write
operations can be performed in page mode even when DRAM accesses do not occur back-to-back.
When using the successive RAS mode, be sure to use #DRD for the read signal and #DWE for the write signal for
low-byte.
When CRAS = "0", random read/write cycles are used for non-successive DRAM accesses.
The contents set here are applied to all of areas 14, 13, 8, and 7 that are set for DRAM.
At cold start, CRAS is set to "0" (normal mode). At hot start, CRAS retains its status before being initialized.
RPRC1–RPRC0: Number of RAS precharge cycles (D[7:6]) / DRAM timing set-up register (0x48130)
Select the number of precharge cycles during a DRAM access.
Table 4.26 Number of RAS Precharge Cycles
RPRC1 RPRC0 Number of cycles
1 1 4 cycles
1 0 3 cycles
0 1 2 cycles
0 0 1 cycle
The contents set here are applied to all of areas 14, 13, 8, and 7 that are set for DRAM.
At cold start, RPRC is set to "0" (1 cycle). At hot start, RPRC retains its status before being initialized.
CASC1–CASC0: Number of CAS cycles (D[4:3]) / DRAM timing set-up register (0x48130)
Select the number of CAS cycles during a DRAM access.
Table 4.27 Number of CAS Cycles
CASC1 CASC0 Number of cycles
1 1 4 cycles
1 0 3 cycles
0 1 2 cycles
0 0 1 cycle
The contents set here are applied to all of areas 14, 13, 8, and 7 that are set for DRAM.
At cold start, CASC is set to "0" (1 cycle). At hot start, CASC retains its status before being initialized.
RASC1–RASC0: Number of RAS cycles (D[1:0]) / DRAM timing set-up register (0x48130)
Select the number of RAS cycles during a DRAM access.
Table 4.28 Number of RAS Cycles
RASC1 RASC0 Number of cycles
1 1 4 cycles
1 0 3 cycles
0 1 2 cycles
0 0 1 cycle
The contents set here are applied to all of areas 14, 13, 8, and 7 that are set for DRAM.
At cold start, RASC is set to "0" (1 cycle). At hot start, RASC retains its status before being initialized.