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8.2.2
Register Descriptions
Table 8.2 summarizes the registers of port 1.
Table 8.2
Port 1 Registers
Address*
Name
H'EE000
Port 1 data direction register P1DDR
H'FFFD0
Port 1 data register
Note: * Lower 20 bits of the address in advanced mode.
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
P1 DDR
Initial value
Modes
1 to 4
Read/Write
Initial value
Modes
5 to 7
Read/Write
Modes 1 to 4 (Expanded Modes with On-Chip ROM Disabled): P1DDR values are fixed at 1.
Port 1 functions as an address bus.
Modes 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.
Mode 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.
Abbreviation R/W
P1DR
7
6
5
P1 DDR
P1 DDR
7
6
5
1
1
1
0
0
0
W
W
W
Modes 1 to 4
W
H'FF
R/W
H'00
4
3
P1 DDR
P1 DDR
4
3
1
1
0
0
W
W
Port 1 data direction 7 to 0
These bits select input or
output for port 1 pins
Rev. 4.00 Jan 26, 2006 page 273 of 938
Section 8 I/O Ports
Initial Value
Modes 5 to 7
H'00
H'00
2
1
P1 DDR
P1 DDR
P1 DDR
2
1
1
1
0
0
W
W
REJ09B0276-0400
0
0
1
0
W
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