HD6435348R Hitachi Semiconductor, HD6435348R Datasheet - Page 172

• Manufacturer Part Number: HD6435348R
• Description: Single-Chip Microcomputer
• Manufacturer: Hitachi Semiconductor

2. Port 3 Data Register (P3DR)—H'FE86
Bit
Initial value
Read/Write
P3DR is an 8-bit register containing the data for pins P3
At a reset and in the hardware standby mode, P3DR is initialized to H'00.
When the CPU reads P3DR, for output pins it reads the value in the P3DR latch, but for input
pins, it obtains the pin status directly.
9.4.3 Pin Functions in Each Mode
Port 3 has different functions in the expanded modes (modes 1, 2, 3, 4) and the single-chip mode
(mode 7). Separate descriptions are given below.
Pin Functions in Expanded Modes: In the expanded modes (modes 1, 2, 3, and 4), port 3 is
automatically used as the data bus and P3DDR is ignored. Figure 9-6 shows the pin functions for
the expanded modes.
R/W
P3
7
0
7
Figure 9-6 Port 3 Pin Functions in Expanded Modes
Port
3
R/W
P3
6
0
6
R/W
P3
5
0
5
D
D
D
D
D
D
D
D
7
6
5
4
3
2
1
0
155
(input/output)
(input/output)
(input/output)
(input/output)
(input/output)
(input/output)
(input/output)
(input/output)
R/W
P3
4
0
4
7
to P3
R/W
P3
3
0
3
0
.
R/W
P3
2
0
2
R/W
P3
1
0
1
R/W
P3
0
0
0