8.9 Port A
8.9.1 Overview
Port A is a 4-bit I/O port, configured as shown in figure 8-8.
Figure 8-8 Port A Pin Configuration
8.9.2 Register Configuration and Description
Table 8-23 shows the port A register configuration.
Table 8-23
Port A Registers
Name
Abbrev.
R/W
Initial Value
Address
Port data register A
PDRA
R/W
H'F0
H'FFDD
Port control register A
PCRA
W
H'F0
H'FFED
1.
Port data register A (PDRA)
PDRA is an 8-bit register that stores data for port A pins PA
3
to PA
0
. If port A is read while PCRA
bits are set to 1, the values stored in PDRA are read, regardless of the actual pin states. If port A is
read while PCRA bits are cleared to 0, the pin states are read.
Bit
Initial value
Read/Write
7
—
1
—
6
—
1
—
5
—
1
—
4
—
1
—
3
PA
0
R/W
0
PA
0
R/W
2
PA
0
R/W
1
PA
0
R/W
3
2
1
0
PA
3
/COM
4
PA
2
/COM
3
PA
1
/COM
2
PA
0
/COM
1
Port A
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