User's Manual

Table Of Contents

GC864 Hardware User Guide

1vv0300733 Rev.12 – 2009-06-04

11.3. Using a GPIO Pad as OUTPUT

The GPIO pads, when used as outputs, can drive 2.8V CMOS digital devices or

compatible hardware. When set as outputs, the pads have a push-pull output and

therefore the pull-up resistor may be omitted.

The illustration below shows the base circuit of a push-pull stage:

VDD

GPIO7

11.4. Using the RF Transmission Control GPIO4

The GPIO4 pin, when configured as RF Transmission Control Input, permits to disable

the Transmitter when the GPIO is set to Low by the application.

In the design is necessary to add a pull up resistor (47K to VAUX).

11.5. Using the RFTXMON Output GPIO5

The GPIO5 pin, when configured as RFTXMON Output, is controlled by the GC864-

QUAD / PY module and will rise when the transmitter is active and fall after the

transmitter activity is completed.

For example, if a call is started, the line will be HIGH during all the conversation and

it will be again LOW after hanged up.

The line rises up 300ms before first TX burst and will became again LOW from 500ms

to 1sec after last TX burst.