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1. Port data register 9 (PDR9)
Bit
Initial value
Read/Write
7
—
0
—
6
—
0
—
5
—
0
—
4
—
0
—
3
P9
3
0
R/W
0
P9
0
0
R/W
2
P9
2
0
R/W
1
P9
1
0
R/W
PDR9 is an 8-bit register that stores data for port 9 pins P9
3
to P9
0
. If port 9 is read while PCR9
bits are set to 1, the values stored in PDR9 are read, regardless of the actual pin states. If port 9 is
read while PCR9 bits are cleared to 0, the pin states are read.
Upon reset, PDR9 is initialized to H'F0.
2. Port control register 9 (PCR9)
Bit
Initial value
Read/Write
7
—
1
—
6
—
1
—
5
—
1
—
4
—
1
—
3
PCR9
3
0
W
0
PCR9
0
0
W
2
PCR9
2
0
W
1
PCR9
1
0
W
PCR9 is an 8-bit register for controlling whether each of the port 9 pins P9
3
to P9
0
functions as an
input pin 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'F0.
PCR9 is a write-only register, which is always read as all 1s.
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