Datasheet

Section 7 Bus Controller
Page 176 of 1434 R01UH0166EJ0600 Rev. 6.00
Mar 02, 2011
H8S/2633 Group, H8S/2633 F-ZTAT
TM
,
H8S/2633R F-ZTAT
TM
, H8S/2695
7.2 Register Descriptions
7.2.1 Bus Width Control Register (ABWCR)
7
ABW7
1
R/W
0
R/W
6
ABW6
1
R/W
0
R/W
5
ABW5
1
R/W
0
R/W
4
ABW4
1
R/W
0
R/W
3
ABW3
1
R/W
0
R/W
0
ABW0
1
R/W
0
R/W
2
ABW2
1
R/W
0
R/W
1
ABW1
1
R/W
0
R/W
Bit :
Initial value
:
Modes 5 to 7
Mode 4
:R/W
Initial value
:
:R/W
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 5
to 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.
Bit n
ABWn Description
0 Area n is designated for 16-bit access
1 Area n is designated for 8-bit access
(n = 7 to 0)