User's Manual

UC864-G Hardware User Guide

DRAFT

- 29/10/07

12 General Purpose I/O

The general-purpose I/O pads can be configured to act in three different ways:

• Input

• Output

• Alternate function (internally controlled)

Input pads can only be read and report the digital value (high or low) present on the pad at the read

time; output pads can only be written or queried and set the value of the pad output; an alternate

function pad is internally controlled by the UC864-G firmware and acts depending on the function

implemented.

Not all GPIO pads support all these three modes:

• GPIO5 supports all three modes and can be input, output, RFTX monitor output (Alternate

function)

• GPIO6 supports all three modes and can be input, output, alarm output (Alternate function)

• GPIO7 supports all three modes and can be input, output, buzzer output (Alternate function)

Some alternate functions for UC864-G may be added later on