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8.2.1
Port 1
Port 1 is an 8-bit I/O port. Port 1 pins can also function as the address bus and address-data
multiplex bus pins. The pin functions change according to the operating mode. Port 1 has the
following registers.
• Port 1 data direction register (P1DDR)
• Port 1 data register (P1DR)
• Port 1 pull-up MOS control register (P1PCR)
(1)
Port 1 Data Direction Register (P1DDR)
The individual bits of P1DDR specify input or output for the pins of port 1.
Bit
Bit Name
7
P17DDR
6
P16DDR
5
P15DDR
4
P14DDR
3
P13DDR
2
P12DDR
1
P11DDR
0
P10DDR
Initial Value
R/W Description
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
•
Normal extended mode (ADMXE = 0)
When set to 1, the corresponding pins function as
address output pins; when cleared to 0, function
as input port pins.
•
Address-data multiplex extended mode (ADMXE =
1)
These bits correspond to the AD7 to AD0 pins of
the address-data multiplex bus.
•
Single-chip mode
When set to 1, the corresponding pins function as
output port pins; when cleared to 0, function as
input port pins.
Rev. 1.00 Mar. 12, 2008 Page 275 of 1178
Section 8 I/O Ports
REJ09B0403-0100
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