
Rev. 3.0, 10/02, page 102 of 686
ABWCR sets the data bus width for the external memory space. The bus width for on-chip
memory and internal I/O registers except for the on-chip USB is fixed regardless of the settings in
ABWCR.
Bit
Bit Name
Initial Value
R/W
Description
7
6
5
4
3
2
1
0
ABW7
ABW6
*
2
ABW5
ABW4
ABW3
ABW2
ABW1
ABW0
1/0
*
1
1/0
*
1
1/0
*
1
1/0
*
1
1/0
*
1
1/0
*
1
1/0
*
1
1/0
*
1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Area 7 to 0 Bus Width Controls:
These bits select whether the corresponding area is to
be designated for 8-bit access or 16-bit access.
0: Area n is designated for 16-bit access
1: Area n is designated for 8-bit access
Legend
n = 7 to 0
Notes:
*
1 In modes 5 to 7, initial value of each bit is 1. In mode 4, initial value of each bit is 0.
*
2 The on-chip USB is allocated to area 6. Therefore this bit should be set to 1.
6.3.2
Access State Control Register (ASTCR)
ASTCR designates each area as either a 2-state access space or a 3-state access space.
ASTCR sets the number of access states for the external memory space. The number of access
states for on-chip memory and internal I/O registers except for the on-chip USB is fixed regardless
of the settings in ASTCR.
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 Controls:
These bits select whether the corresponding area is to
be designated as a 2-state access space or a 3-state
access space. Wait state insertion is enabled or disabled
at the same time.
0: Area n is designated for 2-state access
Wait state insertion in area n external space is
disabled
1: Area n is designated for 3-state access
Wait state insertion in area n external space is
enabled
Legend
n = 7 to 0
Note:
*
The on-chip USB is allocated to area 6. Therefore this bit should be set to 1.
Summary of Contents for H8S/2215 Series
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