Datasheet

Section 8 I/O Ports
Rev. 6.00 Aug 04, 2006 page 227 of 680
REJ09B0145-0600
2. Port Control Register 4 (PCR4)
Bit
Initial value
Read/Write
7
—
1
—
6
—
1
—
5
—
1
—
4
—
1
—
3
—
1
—
0
PCR4
0
W
2
PCR4
0
W
1
PCR4
0
W
210
PCR4 is an 8-bit register for controlling whether each of port 4 pins P4
2
to P4
0
functions as an
input pin or output pin. 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. PCR4 and PDR4 settings are valid when the
corresponding pins are designated for general-purpose input/output by SCR3-2.
Upon reset, PCR4 is initialized to H'F8.
PCR4 is a write-only register, which always reads all 1s.