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Section 8 I/O Ports
8.11
Port A
8.11.1
Overview
Port A is a 4-bit I/O port, configured as shown in figure 8.10.
8.11.2
Register Configuration and Description
Table 8.29 shows the port A register configuration.
Table 8.29 Port A Registers
Name
Port data register A
Port control register A
1. Port Data Register A (PDRA)
Bit
7
—
Initial value
1
Read/Write
—
PDRA is an 8-bit register that stores data for port A pins PA
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.
Upon reset, PDRA is initialized to H'F0.
Rev. 6.00 Aug 04, 2006 page 248 of 680
REJ09B0145-0600
Port A
Figure 8.10 Port A Pin Configuration
Abbr.
R/W
PDRA
R/W
PCRA
W
6
5
—
—
1
1
—
—
PA
/COM
3
4
PA
/COM
2
3
PA
/COM
1
2
PA
/COM
0
1
Initial Value
H'F0
H'F0
4
3
2
—
PA
PA
3
1
0
0
—
R/W
R/W
to PA
. If port A is read while
3
0
Address
H'FFDD
H'FFED
1
0
PA
PA
2
1
0
0
0
R/W
R/W
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