174
2. Port control register A (PCRA)
Bit
Initial value
Read/Write
7
—
1
—
6
—
1
—
5
—
1
—
4
—
1
—
3
PCRA
0
R/W
0
PCRA
0
R/W
2
PCRA
0
R/W
1
PCRA
0
R/W
3
2
1
0
PCRA controls whether each of port A pins PA
3
to PA
0
functions as an input pin or output pin.
Setting a PCRA bit to 1 makes the corresponding pin an output pin, while clearing the bit to 0
makes the pin an input pin.
Upon reset, PCRA is initialized to H'F0.
PCRA is a write-only register, which always reads all 1s.
8.11.3
Pin Functions
Table 8-30 shows the port A pin functions.
Table 8-30 Port A Pin Functions
Pin
Pin Functions and Selection Method
PA
3
to PA
0
The pin function depends on bit PCRA
n
in PCRA.
(n = 3 to 0)
PCRA
n
0
1
Pin function
PA
n
input pin
PA
n
output pin
8.11.4
Pin States
Table 8-31 shows the port A pin states in each operating mode.
Table 8-31 Port A Pin States
Pins
Reset
Sleep
Subsleep
Standby
Watch
Subactive
Active
PA
3
to PA
0
High-
impedance
Retains
previous
state
Retains
previous
state
High-
impedance
Retains
previous
state
Functional
Functional
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