8.5
Port 4
8.5.1
Overview
Port 4 is a 3-bit I/O port and 1-bit input port, configured as shown in figure 8-4.
P43 /IRQ0
P42 /TXD32
Port 4
P41 /RXD32
P40 /SCK32
Figure 8-4 Port 4 Pin Configuration
8.5.2
Register Configuration and Description
Table 8-11 shows the port 4 register configuration.
Table 8-11 Port 4 Registers
Name
Abbrev.
PDR4
R/W
R/W
W
Initial Value
H'F8
Address
H'FFD7
H'FFE7
Port data register 4
Port control register 4
PCR4
H'F8
1. Port data register 4 (PDR4)
Bit
7
—
1
6
—
1
5
—
1
4
—
1
3
P43
1
2
1
0
P42
0
P41
0
P4 0
0
Initial value
Read/Write
—
—
—
—
R
R/W
R/W
R/W
PDR4 is an 8-bit register that stores data for port 4 pins P42 to P40. If port 4 is read while PCR4
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.
Upon reset, PDR4 is initialized to H'F8.
152
ETC [ ETC ]
