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7.2
Port 1
7.2.1
Overview
Port 1 is an 8-bit input/output port also used for address output, with the pin configuration shown
in figure 7.1. The pin functions differ according to the operating mode. In modes 1 to 4 (expanded
modes with on-chip ROM disabled), they are address bus output pins (A
In mode 5 (expanded modes with on-chip ROM enabled), settings in the port 1 data direction
register (P1DDR) can designate pins for address bus output (A
and 7 (single-chip mode), port 1 is a generic input/output port.
Pins in port 1 can drive one TTL load and a 90-pF capacitive load. They can also drive an LED or
a darlington transistor pair.
Port 1 pins
Port 1
7.2.2
Register Descriptions
Table 7.2 summarizes the registers of port 1.
Table 7.2
Port 1 Registers
Address *
Name
H'EE000
Port 1 data direction register P1DDR
H'FFFD0
Port 1 data register
Note: * Lower 20 bits of the address in advanced mode
Modes 1 to 4
P1 /A
A (output)
7
7
7
P1 /A
A (output)
6
6
6
P1 /A
A (output)
5
5
5
P1 /A
A (output)
4
4
4
P1 /A
A (output)
3
3
3
P1 /A
A (output)
2
2
2
P1 /A
A (output)
1
1
1
P1 /A
A (output)
0
0
0
Figure 7.1 Port 1 Pin Configuration
Abbreviation R/W
P1DR
7
to A
) or generic input. In modes 6
7
0
Mode 5
P1 (input)/A (output)
7
7
P1 (input)/A (output)
6
6
P1 (input)/A (output)
5
5
P1 (input)/A (output)
4
4
P1 (input)/A (output)
3
3
P1 (input)/A (output)
2
2
P1 (input)/A (output)
1
1
P1 (input)/A (output)
0
0
Modes 1 to 4
W
H'FF
R/W
H'00
to A
).
0
Modes 6 and 7
P1 (input/output)
7
P1 (input/output)
6
P1 (input/output)
5
P1 (input/output)
4
P1 (input/output)
3
P1 (input/output)
2
P1 (input/output)
1
P1 (input/output)
0
Initial Value
Modes 5 to 7
H'00
H'00
169
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