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8.4
Port 3
8.4.1
Overview
Port 3 is an 8-bit input/output port with the pin configuration shown in figure 8.3. Port 3 is a data
bus in modes 1 to 5 (expanded modes) and a generic input/output port in mode 6, 7 (single-chip
mode).
Pins in port 3 can drive one TTL load and a 90-pF capacitive load. They can also drive a
darlington transistor pair.
Port 3
8.4.2
Register Descriptions
Table 8.5 summarizes the registers of port 3.
Table 8.5
Port 3 Registers
Address*
Name
H'EE002
Port 3 data direction register
H'FFFD2
Port 3 data register
Note: * Lower 20 bits of the address in advanced mode.
Port 3 pins
Modes 1 to 5
P3 /D
D
7
15
15
P3 /D
D
6
14
14
P3 /D
D
5
13
13
P3 /D
D
4
12
12
P3 /D
D
3
11
11
P3 /D
D
2
10
10
P3 /D
D
1
9
9
P3 /D
D
0
8
8
Figure 8.3 Port 3 Pin Configuration
Mode 6 and 7
(input/output)
P3 (input/output)
(input/output)
P3 (input/output)
(input/output)
P3 (input/output)
(input/output)
P3 (input/output)
(input/output)
P3 (input/output)
(input/output)
P3 (input/output)
(input/output)
P3 (input/output)
(input/output)
P3 (input/output)
Abbreviation
R/W
P3DDR
W
P3DR
R/W
Rev. 4.00 Jan 26, 2006 page 279 of 938
Section 8 I/O Ports
7
6
5
4
3
2
1
0
Initial Value
H'00
H'00
REJ09B0276-0400
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