HD6433044 Hitachi Semiconductor, HD6433044 Datasheet - Page 269

• Manufacturer Part Number: HD6433044
• Description: (HD64 Series) Hitachi Single-Chip Microcomputer
• Manufacturer: Hitachi Semiconductor

9.5.2 Register Descriptions
Table 9-6 summarizes the registers of port 4.
Table 9-6 Port 4 Registers
Address*
H'FFC5
H'FFC7
H'FFDA
Note: * Lower 16 bits of the address.
Port 4 Data Direction Register (P4DDR): P4DDR is an 8-bit write-only register that can select
input or output for each pin in port 4.
Modes 1 to 6 (Expanded Modes): When all areas are designated as 8-bit-access areas, selecting
8-bit bus mode, port 4 functions as a generic input/output port. A pin in port 4 becomes an output
port if the corresponding P4DDR bit is set to 1, and an input port if this bit is cleared to 0.
When at least one area is designated as a 16-bit-access area, selecting 16-bit bus mode, port 4
functions as part of the data bus.
Mode 7 (Single-Chip Mode): Port 4 functions as an input/output port. A pin in port 4 becomes an
output port if the corresponding P4DDR bit is set to 1, and an input port if this bit is cleared to 0.
P4DDR is a write-only register. Its value cannot be read. All bits return 1 when read.
P4DDR is initialized to H'00 by a reset and in hardware standby mode. In software standby mode
it retains its previous setting.
Bit
Initial value
Read/Write
Name
Port 4 data direction register
Port 4 data register
Port 4 input pull-up MOS
control register
P4 DDR
7
W
7
0
P4 DDR
6
W
6
0
P4 DDR
5
W
5
0
Port 4 data direction 7 to 0
These bits select input or output for port 4 pins
P4 DDR
256
4
W
4
0
Abbreviation
P4DDR
P4DR
P4PCR
P4 DDR
3
W
3
0
P4 DDR
2
W
2
0
R/W
W
R/W
R/W
P4 DDR
1
W
1
0
Initial Value
H'00
H'00
H'00
P4 DDR
0
W
0
0