Datasheet

Rev. 3.00, 03/04, page 222 of 830
8.9 Port 9
Port 9 is an 8-bit I/O port. Port 9 pins also function as the bus control I/O pins or the system clock
output pin. Pin functions are switched depending on the operating mode. Port 9 has the following
registers.
• Port 9 data direction register (P9DDR)
• Port 9 data register (P9DR)
8.9.1 Port 9 Data Direction Register (P9DDR)
The individual bits of P9DDR specify input or output for the pins of port 9.
Bit Bit Name Initial Value R/W Description
7 P97DDR 0 W If port 9 pins are specified for use as the general I/O
port, the corresponding port 9 pins are output ports
when the P9DDR bits are set to 1, and input ports
when cleared to 0.
6 P96DDR 0 W When this bit is set to 1, the corresponding port 96 pin
is the system clock output pin (φ), and as a general
input port when cleared to 0.
5 P95DDR 0 W
4 P94DDR 0 W
3 P93DDR 0 W
2 P92DDR 0 W
1 P91DDR 0 W
0 P90DDR 0 W
If port 9 pins are specified for use as the general I/O
port, the corresponding port 9 pins are output ports
when the P9DDR bits are set to 1, and input ports
when cleared to 0.