HD6412240 RENESAS [Renesas Technology Corp], HD6412240 Datasheet - Page 177

• Manufacturer Part Number: HD6412240
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family / H8S/2200 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

6.2
6.2.1
ABWCR is an 8-bit readable/writable register that designates each area for either 8-bit access or
16-bit access.
ABWCR sets the data bus width for the external memory space. The bus width for on-chip
memory and internal I/O registers is fixed regardless of the settings in ABWCR.
In normal mode, the settings of bits ABW7 to ABW1 have no effect on operation.
After a power-on reset and in hardware standby mode, ABWCR is initialized to H'FF in modes 1,
2, 3, and 5, 6, 7, and to H'00 in mode 4. It is not initialized by a manual reset or in software
standby mode.
Bits 7 to 0—Area 7 to 0 Bus Width Control (ABW7 to ABW0): These bits select whether the
corresponding area is to be designated for 8-bit access or 16-bit access. In normal mode, only part
of area 0 is enabled, and the ABW0 bit selects whether external space is to be designated for 8-bit
access or 16-bit access.
Note: n = 7 to 0
Bit n
ABWn
0
1
Bit
Modes 1, 2, 3, 5, 6, 7
Initial value
R/W
Mode 4
Initial value
R/W
Register Descriptions
Bus Width Control Register (ABWCR)
Description
Area n is designated for 16-bit access
Area n is designated for 8-bit access
:
:
:
:
:
ABW7
R/W
R/W
7
1
0
ABW6
R/W
R/W
6
1
0
ABW5
R/W
R/W
5
1
0
ABW4
R/W
R/W
4
1
0
Rev.3.00 Mar. 26, 2007 Page 135 of 772
ABW3
R/W
R/W
3
1
0
ABW2
R/W
R/W
Section 6 Bus Controller
2
1
0
REJ09B0355-0300
ABW1
R/W
R/W
1
1
0
ABW0
R/W
R/W
0
1
0