h8s-2646 Renesas Electronics Corporation., h8s-2646 Datasheet - Page 168

• Manufacturer Part Number: h8s-2646
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

Section 7 Bus Controller
7.2
7.2.1
Bit
Modes 5 to 7
Initial value :
RW
Mode 4
Initial value :
RW
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.
After a reset and in hardware standby mode, ABWCR is initialized to H'FF in modes 5, 6, 7, and
to H'00 in mode 4. It is not initialized 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.
Rev. 5.00 Sep 22, 2005 page 142 of 1136
REJ09B0257-0500
Bit n
ABWn
0
1
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
ABW3
R/W
R/W
3
1
0
ABW2
R/W
R/W
2
1
0
ABW1
R/W
R/W
1
1
0
ABW0
(n = 7 to 0)
R/W
R/W
0
1
0