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Mode 1: Address output or generic input can be selected for each pin in port 1. A pin becomes an
address output pin if the corresponding P1DDR bit is set to 1, and a generic input pin if this bit is
cleared to 0. Following a reset, all pins are input pins. To use a pin for address output, its P1DDR
bit must be set to 1. Figure 7-2 shows the pin functions in mode 1.
Port 1
Figure 7-2 Pin Functions in Mode 1 (Port 1)
Modes 2 and 3 (Single-Chip Modes): Input or output can be selected separately for each pin in
port 1. A pin becomes an output pin if the corresponding P1DDR bit is set to 1, and an input pin if
this bit is cleared to 0. Figure 7-3 shows the pin functions in modes 2 and 3.
Figure 7-3 Pin Functions in Modes 2 and 3 (Port 1)
When P1DDR = 1
When P1DDR = 0
A (output)
P1 (input)
7
A (output)
P1 (input)
6
A (output)
P1 (input)
5
A (output)
P1 (input)
4
A (output)
P1 (input)
3
A (output)
P1 (input)
2
A (output)
P1 (input)
1
A (output)
P1 (input)
0
P1 (input/output)
7
P1 (input/output)
6
P1 (input/output)
5
P1 (input/output)
4
Port 1
P1 (input/output)
3
P1 (input/output)
2
P1 (input/output)
1
P1 (input/output)
0
125
7
6
5
4
3
2
1
0
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