Section 8 I/O Ports
Rev. 7.00 Mar 10, 2005 page 209 of 652
REJ09B0042-0700
8.4 Port 4
8.4.1 Overview
Port 4 is a 3-bit I/O port and 1-bit input port, configured as shown in figure 8.3.
P4
P4
P4
P4
/IRQ
0
/TXD
32
/RXD
32
/SCK
32
3
2
1
0
Port 4
Figure 8.3 Port 4 Pin Configuration
8.4.2 Register Configuration and Description
Table 8.8 shows the port 4 register configuration.
Table 8.8 Port 4 Registers
Name Abbr. R/W Initial Value Address
Port data register 4 PDR4 R/W H'F8 H'FFD7
Port control register 4 PCR4 W H'F8 H'FFE7
Port mode register 2 PMR2 R/W H'D8 H'FFC9
Port Data Register 4 (PDR4)
Bit
Initial value
Read/Write
7
—
1
—
6
—
1
—
5
—
1
—
4
—
1
—
3
P4
1
R
0
P4
0
R/W
2
P4
0
R/W
1
P4
0
R/W
3210
PDR4 is an 8-bit register that stores data for port 4 pins P4
2
to P4
0
. 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.
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