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Port Data Register 4 (PDR4)
Bit
Initial value
Read/Write
PDR4 is an 8-bit register that stores data for port 4 pins P4
bits are set to 1, the values stored in PDR4 are read, regardless of the actual pin states. If port 4 is
read while PCR4 bits are cleared to 0, the pin states are read.
The pin state is always read from bit 3 (P4
Upon reset, PDR4 is initialized to H'F8.
Port Control Register 4 (PCR4)
Bit
Initial value
Read/Write
PCR4 controls whether each of the port 4 pins P4
Setting a PCR4 bit to 1 makes the corresponding pin an output pin, while clearing the bit to 0
makes the pin an input pin. The settings in PCR4 and in PDR4 are valid only when the
corresponding pin is designated in SCR3 as a general I/O pin.
Upon reset, PCR4 is initialized to H'F8.
PCR4 is a write-only register. All bits are read as 1.
7
6
5
⎯
⎯
⎯
1
1
1
⎯
⎯
⎯
7
6
5
⎯
⎯
⎯
1
1
1
⎯
⎯
⎯
4
3
⎯
P4
1
Undefined
⎯
R
to P4
2
).
3
4
3
⎯
⎯
1
1
⎯
⎯
to P4
functions as an input pin or output pin.
2
0
Rev.3.00 Jul. 19, 2007 page 195 of 532
2
1
P4
P4
3
2
1
0
0
R/W
R/W
. If port 4 is read while PCR4
0
2
1
PCR4
PCR4
2
0
0
W
W
REJ09B0397-0300
8. I/O Ports
0
P4
0
0
R/W
0
PCR4
1
0
0
W
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