HD643303x Hitachi, HD643303x Datasheet - Page 138

• Manufacturer Part Number: HD643303x
• Description: Hitachi Microcomputer
• Manufacturer: Hitachi

7.2.2 Register Descriptions
Table 7-2 summarizes the registers of port 1.
Table 7-2 Port 1 Registers
Address*
H'FFC0
H'FFC2
Note: * Lower 16 bits of the address.
Port 1 Data Direction Register (P1DDR): P1DDR is an 8-bit write-only register that can select
input or output for each pin in port 1.
Mode 1: A pin in port 1 becomes an address output pin if the corresponding P1DDR bit is set to 1,
and a generic input pin if this bit is cleared to 0.
Modes 2 and 3 (Single-Chip Modes): Port 1 functions as an input/output port. A pin in port 1
becomes an output pin if the corresponding P1DDR bit is set to 1, and an input pin if this bit is
cleared to 0.
P1DDR is a write-only register. Its value cannot be read. All bits return 1 when read.
P1DDR is initialized to H'00 by a reset and in hardware standby mode. In software standby mode it
retains its previous setting. If a P1DDR bit is set to 1, the corresponding pin maintains its output
state in software standby mode.
Bit
Initial value
Read/Write
Name
Port 1 data direction register
Port 1 data register
P1 DDR
7
W
7
0
P1 DDR
6
W
6
0
P1 DDR
5
W
5
0
Port 1 data direction 7 to 0
These bits select input or
output for port 1 pins
P1 DDR
123
Abbreviation
P1DDR
P1DR
4
W
4
0
P1 DDR
3
W
3
0
P1 DDR
R/W
W
R/W
2
W
2
0
P1 DDR
Initial Value
H'00
H'00
1
W
1
0
P1 DDR
0
W
0
0