GE865 Hardware User Guide
1vv0300799 Rev.9 – 27-07-2009
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page 49 of 70
11.2 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.
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.
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 PWRMON);
11.5 Using the RFTXMON Output GPIO5
The GPIO5 pin, when configured as RFTXMON Output, is controlled by the GE865
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 1s after last TX burst.
