HD64F3028F25 Datasheet, PDF (283/925 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

8.2.2 Register Descriptions
Table 8.2 summarizes the registers of port 1.
Table 8.2 Port 1 Registers
Address^* Name
Abbreviation R/W
H'EE000 Port 1 data direction register P1DDR
W
H'FFFD0 Port 1 data register
P1DR
R/W
Note: * Lower 20 bits of the address in advanced mode.
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.
Port 1 functions as an address bus.
Mode 5 (Expanded Modes with On-Chip ROM Enabled): After a reset, port 1 functions as an
input port. 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 6 and 7 (Single-Chip Mode): Port 1 functions as an input/output port. A pin in port 1
becomes an output port if the corresponding P1DDR bit is set to 1, and an input port if this bit is
cleared to 0.
In modes 1 to 4, P1DDR bits are always read as 1, and cannot be modified.
In modes 5 to 7, P1DDR is a write-only register. Its value cannot be read. All bits return 1 when
read.
Rev. 2.00, 09/03, page 251 of 890