Datasheet

Section 8 I/O Ports
Rev. 6.00 Aug 04, 2006 page 220 of 680
REJ09B0145-0600
1. Port Data Register 3 (PDR3)
Bit
Initial value
Read/Write
7
P3
0
R/W
6
P3
0
R/W
5
P3
0
R/W
4
P3
0
R/W
3
P3
0
R/W
0
P3
0
R/W
2
P3
0
R/W
1
P3
0
R/W
2105476 3
PDR3 is an 8-bit register that stores data for port 3 pins P3
7
to P3
0
. If port 3 is read while PCR3
bits are set to 1, the values stored in PDR3 are read, regardless of the actual pin states. If port 3 is
read while PCR3 bits are cleared to 0, the pin states are read.
Upon reset, PDR3 is initialized to H'00.
2. Port Control Register 3 (PCR3)
Bit
Initial value
Read/Write
7
PCR3
0
W
6
PCR3
0
W
5
PCR3
0
W
4
PCR3
0
W
3
PCR3
0
W
0
PCR3
0
W
2
PCR3
0
W
1
PCR3
0
W
21054376
PCR3 is an 8-bit register for controlling whether each of the port 3 pins P3
7
to P3
0
functions as an
input pin or output pin. Setting a PCR3 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 PCR3 and in PDR3 are valid only
when the corresponding pin is designated in PMR3 as a general I/O pin.
Upon reset, PCR3 is initialized to H'00.
PCR3 is a write-only register, which is always read as all 1s.
3. Port Pull-up Control Register 3 (PUCR3)
Bit
Initial value
Read/Write
7
PUCR3
0
R/W
6
PUCR3
0
R/W
5
PUCR3
0
R/W
4
PUCR3
0
R/W
3
PUCR3
0
R/W
0
PUCR3
0
R/W
2
PUCR3
0
R/W
1
PUCR3
0
R/W
2
10
5
4376
PUCR3 controls whether the MOS pull-up of each of the port 3 pins P3
7
to P3
0
is on or off. When
a PCR3 bit is cleared to 0, setting the corresponding PUCR3 bit to 1 turns on the MOS pull-up for
the corresponding pin, while clearing the bit to 0 turns off the MOS pull-up.
Upon reset, PUCR3 is initialized to H'00.