Datasheet

Section 6 Bus Controller (BSC)
Page 158 of 1408 R01UH0309EJ0500 Rev. 5.00
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
6.3.1 Bus Width Control Register (ABWCR)
ABWCR designates each area in the external address space as either 8-bit access space or 16-bit
access space.
Bit Bit Name Initial Value
*
R/W Description
7
6
5
4
3
2
1
0
ABW7
ABW6
ABW5
ABW4
ABW3
ABW2
ABW1
ABW0
1/0
1/0
1/0
1/0
1/0
1/0
1/0
1/0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Area 7 to 0 Bus Width Control
These bits select whether the corresponding
area is to be designated as 8-bit access space
or 16-bit access space.
0: Area n is designated as 16-bit access space
1: Area n is designated as 8-bit access space
(n = 7 to 0)
Note: * In modes 2 and 4, ABWCR is initialized to 1. In modes 1 and 7, ABWCR is initialized to
0.
6.3.2 Access State Control Register (ASTCR)
ASTCR designates each area in the external address space as either 2-state access space or 3-state
access space.
Bit Bit Name Initial Value R/W Description
7
6
5
4
3
2
1
0
AST7
AST6
AST5
AST4
AST3
AST2
AST1
AST0
1
1
1
1
1
1
1
1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Area 7 to 0 Access State Control
These bits select whether the corresponding
area is to be designated as 2-state access
space or 3-state access space. Wait state
insertion is enabled or disabled at the same
time.
0: Area n is designated as 2-state access
space
Wait state insertion in area n access is
disabled
1: Area n is designated as 3-state access
space
Wait state insertion in area n access is
enabled
(n = 7 to 0)