Rainbow Electronics GE863-PY - Manual (Page 55)

GE863 Hardware User Guide
1vv0300783 Rev.0 - 10/06/08
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 55 of 80
8.2 Using a GPIO Pad as INPUT
The GPIO pads, when used as inputs, can be connected to a digital output of another device and
report its status, provided this device has interface levels compatible with the 2.8V CMOS levels of the
GPIO.
If the digital output of the device to be connected with the GPIO input pad has interface levels different
from the 2.8V CMOS, then it can be buffered with an open collector transistor with a 47K pull up to
2.8V.
8.3 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.
8.4 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.
8.5 Using the RFTXMON Output GPIO5
The GPIO5 pin, when configured as RFTXMON Output, is controlled by the GE863 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.