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8. I/O Ports
Port Data Register 9 (PDR9)
Bit
P9
Initial value
Read/Write
R/W
PDR9 is an 8-bit register that stores data for port 9 pins P9
bits are set to 1, the values stored in PDR9 are read. If port 9 is read while PCR9 bits are cleared to
0, the pin states are read.
Upon reset, PDR9 is initialized to H'00.
Port Control Register 9 (PCR9)
Bit
PCR9
Initial value
Read/Write
PCR9 is an 8-bit register for controlling whether each of the port 9 pins P9
input or output pin. Setting a PCR9 bit to 1 makes the corresponding pin an output pin, while
clearing the bit to 0 makes the pin an input pin.
Upon reset, PCR9 is initialized to H'00.
PCR9 is a write-only register. All bits are read as 1.
8.7.3
Pin Functions
Table 8.18 shows the port 9 pin functions.
Table 8.18 Port 9 Pin Functions
Pin
Pin Functions and Selection Method
P9
to P9
The pin function depends on the corresponding bit in PCR9.
7
0
PCR9
Pin function
Note: n = 7 to 0
Rev.3.00 Jul. 19, 2007 page 202 of 532
REJ09B0397-0300
7
6
5
P9
P9
7
6
0
0
0
R/W
R/W
7
6
5
PCR9
PCR9
7
6
0
0
0
W
W
W
n
4
3
P9
P9
5
4
3
0
0
R/W
R/W
to P9
7
4
3
PCR9
PCR9
5
4
0
0
W
W
0
P9
input pin
n
2
1
P9
P9
2
1
0
0
R/W
R/W
. If port 9 is read while PCR9
0
2
1
PCR9
PCR9
3
2
0
0
W
W
to P9
functions as an
7
0
1
P9
output pin
n
0
P9
0
0
R/W
0
PCR9
1
0
0
W
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