Datasheet

Section 8 I/O Ports
Rev. 2.00 Aug. 20, 2008 Page 277 of 1198
REJ09B0403-0200
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 Initial Value R/W Description
7 P17DDR 0 W
6 P16DDR 0 W
5 P15DDR 0 W
4 P14DDR 0 W
3 P13DDR 0 W
2 P12DDR 0 W
1 P11DDR 0 W
0 P10DDR 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.