Hitachi H8/3008, Hardware Manual

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3.4.4 Mode 4
Ports 1, 2, and 5 and part of port A function as address pins A
23
to A
0
, permitting access to a
maximum 16-Mbyte address space. The initial bus mode after a reset is 16 bits, with 16-bit access
to all areas. If all areas are designated for 8-bit access in ABWCR, the bus mode switches to
8 bits. A
23
to A
21
are valid when 0 is written in bits 7 to 5 of BRCR. (In this mode A
20
is always
used for address output.)
3.4.5 Modes 5 to 7
These modes cannot be used in the H8/3008. Pin settings must not be made for these modes.
3.5 Pin Functions in Each Operating Mode
The pin functions of ports 1 to 5 and port A vary depending on the operating mode. Table 3.3
indicates their functions in each operating mode.
Table 3.3 Pin Functions in Each Mode
Port Mode 1 Mode 2 Mode 3 Mode 4
Port 1 A
7
to A
0
A
7
to A
0
A
7
to A
0
A
7
to A
0
Port 2 A
15
to A
8
A
15
to A
8
A
15
to A
8
A
15
to A
8
Port 3 D
15
to D
8
D
15
to D
8
D
15
to D
8
D
15
to D
8
Port 4 P4
7
to P4
0
*
1
D
7
to D
0
*
1
P4
7
to P4
0
*
1
D
7
to D
0
*
1
Port 5 A
19
to A
16
A
19
to A
16
A
19
to A
16
A
19
to A
16
Port A PA
7
to PA
4
PA
7
to PA
4
PA
6
to PA
4
, A
20
*
2
PA
6
to PA
4
, A
20
*
2
Notes: 1. Initial state. The bus mode can be switched by settings in ABWCR. These pins function
as P4
7
to P4
0
in 8-bit bus mode, and as D
7
to D
0
in 16-bit bus mode.
2. Initial state. A
20
is always an address output pin. PA
6
to PA
4
are switched over to A
23
to
A
21
output by writing 0 in bits 7 to 5 of BRCR.