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102
6.1.4
Register Configuration
Table 6.2 summarizes the bus controller’s registers.
Table 6.2
Bus Controller Registers
Address*
1
Name
Abbreviation
R/W
Initial Value
H'EE020
Bus width control register
ABWCR
R/W
H'FF*
2
H'EE021
Access state control register
ASTCR
R/W
H'FF
H'EE022
Wait control register H
WCRH
R/W
H'FF
H'EE023
Wait control register L
WCRL
R/W
H'FF
H'EE013
Bus release control register
BRCR
R/W
H'FE*
3
H'EE01F
Chip select control register
CSCR
R/W
H'0F
H'EE01E
Address control register
ADRCR
R/W
H'FF
H'EE024
Bus control register
BCR
R/W
H'C6
Notes: 1. Lower 20 bits of the address in advanced mode.
2. In modes 2 and 4, the initial value is H'00.
3. In modes 3 and 4, the initial value is H'EE.
6.2
Register Descriptions
6.2.1
Bus Width Control Register (ABWCR)
ABWCR is an 8-bit readable/writable register that selects 8-bit or 16-bit access for each area.
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
2
ABW2
1
R/W
0
R/W
1
ABW1
1
R/W
0
R/W
0
ABW0
1
R/W
0
R/W
Bit
Modes
1 and 3
Initial value
Read/Write
Initial value
Read/Write
Modes
2 and 4
When ABWCR contains H'FF (selecting 8-bit access for all areas), the chip operates in 8-bit bus
mode: the upper data bus (D
15
to D
8
) is valid, and port 4 is an input/output port. When at least one
bit is cleared to 0 in ABWCR, the chip operates in 16-bit bus mode with a 16-bit data bus (D
15
to
D
0
). In modes 1 and 3, ABWCR is initialized to H'FF by a reset and in hardware standby mode.
In modes 2 and 4, ABWCR is initialized to H'00 by a reset and in hardware standby mode. It is
not initialized in software standby mode.
Summary of Contents for H8/3008
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