SyncMOS Technologies International, Inc.
SM59264
8-Bits Micro-controller
with 128KB flash & 1KB RAM & TWSI & SPWM embedded
1.4 I/O Pin Configuration
The ports 1, 2 and 3 of standard 8051 have internal pull-up resistor, and port 0 has open-drain outputs. Each I/O pin
can be used independently as an input or an output. For I/O ports to be used as an input pin, the port bit latch must
contain a ‘1’ which turns off the output driver FET. Then for port 1, 2 and 3 port pin is pulled high by a weak internal
pull-up, and can be pulled low by an external source. The port 0 has open-drain outputs which means its pull-ups are
not active during normal port operation. Writing ‘1’ to the port 0 bit latch will causing bit floating so that it can be used as
a high-impedance input.
The port 4 used as GPIO will has the same function as port 1, 2 and 3.
Specifications subject to change without notice contact your sales representatives for the most recent information.
Ver 2.1 SM59264 08/2006
11
SYNCMOS [ SYNCMOS TECHNOLOGIES,INC ]
