HD6417034B RENESAS [Renesas Technology Corp], HD6417034B Datasheet - Page 143

• Manufacturer Part Number: HD6417034B
• Description: 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

8.2.5
The DRAM area control register (DCR) is a 16-bit read/write register that selects the type of
DRAM control signal, the number of precharge cycles, the burst operation mode, and the use of
address multiplexing. DCR settings are valid only when the DRAME bit in BCR is set to 1. It is
initialized to H'0000 by a power-on reset, but is not initialized by a manual reset or in standby
mode.
Bit 15—Dual-CAS or Dual-WE Select Bit (CW2): When accessing a 16-bit bus width space,
CW2 selects the dual-CAS or the dual-WE method. When cleared to 0, the CASH, CASL, and
WRL signals are valid ; when set to 1, the CASL, WRH, and WRL signals are valid. When
accessing an 8-bit space, only CASL and WRL signals are valid, regardless of the CW2 setting.
Bit 15L: CW2
0
1
Bit 14—RAS Down (RASD): When DRAM access pauses, RASD determines whether to keep
RAS low while waiting for the next DRAM access (RAS down mode) or return it to high (RAS up
mode). When cleared to 0, the RAS signal returns to high; when set to 1, it stays low.
Bit 14: RASD
0
1
Bit
Initial value
Read/Write
Bit
Initial value
Read/Write
DRAM Area Control Register (DCR)
Description
Dual-CAS: CASH, CASL, and WRL signals are valid
Dual-WE: CASL, WRH, and WRL signals are valid
Description
RAS up mode: Return RAS signal to high and wait for the next DRAM access
RAS down mode: Keep RAS signal low and wait for the next DRAM access
CW2
R/W
15
—
—
0
7
0
RASD
R/W
14
—
—
0
6
0
TPC
R/W
13
—
—
0
5
0
R/W
BE
12
—
—
0
4
0
Rev. 7.00 Jan 31, 2006 page 117 of 658
Section 8 Bus State Controller (BSC)
CDTY
R/W
11
—
—
0
3
0
MXE
R/W
10
—
—
0
2
0
REJ09B0272-0700
MXC1
R/W
—
—
9
0
1
0
(Initial value)
(Initial value)
MXC0
R/W
—
—
8
0
0
0