SH7785 Datasheet, PDF (521/1692 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

12. DDR2-SDRAM Interface (DBSC2)
Initial
Bit
Bit Name Value
R/W Description
2 to 0 TRCD2 to 001
TRCD0
R/W tRCD (ACT-READ/WRITE period) Setting Bits
These bits set the ACT-READ/WRITE minimum period.
These bits should be set according to the DDR2-
SDRAM specifications. The number of cycles is the
number of DDR clock cycles.
000: Setting prohibit (If specified, correct operation
cannot be guaranteed.)
001: 2 cycles
010: 3 cycles
011: 4 cycles
100: 5 cycles
101: Setting prohibit (If specified, correct operation
cannot be guaranteed.)
:
111: Setting prohibit (If specified, correct operation
cannot be guaranteed.)
Notes: 1. AL (Additive Latency) supported by the DBSC2 is only 0.
2. Writing to this register should be performed only when the following conditions are met.
• When SDRAM access is disabled (when the ACEN bit in the DBEN register is 0.).
• When automatic issue of auto-refresh is disabled (when the ARFEN bit in the
DBRFCNT0 register is cleared to 0.).
Rev.1.00 Jan. 10, 2008 Page 491 of 1658
REJ09B0261-0100