HD6433044 Datasheet, PDF (260/867 Pages) Hitachi Semiconductor – Hitachi Single-Chip Microcomputer

9.2.2 Register Descriptions
Table 9-2 summarizes the registers of port 1.
Table 9-2 Port 1 Registers
Address* Name
H'FFC0
Port 1 data direction register
H'FFC2
Port 1 data register
Note: * Lower 16 bits of the address.
Abbreviation R/W
P1DDR
W
P1DR
R/W
Initial Value
Modes 1 to 4 Modes 5 to 7
H'FF
H'00
H'00
H'00
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.
Bit
7
6
5
4
3
2
1
0
P1₇DDR P1₆DDR P1₅DDR P1₄DDR P1₃DDR P1₂DDR P1₁DDR P1₀DDR
Modes ^{Initial value 1}
1
1
1
1
1
1
1
1 to 4 _{Read/Write —}
—
—
—
—
—
—
—
Modes ^{Initial value 0}
0
0
0
0
0
0
0
5 to 7 _{Read/Write W}
W
W
W
W
W
W
W
Port 1 data direction 7 to 0
These bits select input or
output for port 1 pins
Modes 1 to 4 (Expanded Modes with On-Chip ROM Disabled): P1DDR values are fixed at 1
and cannot be modified. Port 1 functions as an address bus.
Modes 5 and 6 (Expanded Modes with On-Chip ROM Enabled): 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.
Mode 7 (Single-Chip Mode): 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.
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