HW User Guide
1vv0301018 Rev. 15
Page
49
of
72
2019-01-07
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
1.8V 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 1.8V CMOS, then it can be buffered with an open collector
transistor with a 47K pull up to 1.8V.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having
any HIGH logic level signal applied to the digital pins of the GL865 V3/V3.1
when the module is powered OFF or during an ON/OFF transition.
TIP:
The V_AUX / PWRMON pin can be used for input pull up reference or/and
for ON monitoring.
Using a GPIO Pad as OUTPUT
The GPIO pads, when used as outputs, can drive 1.8V 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.
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 resistor 47K pull up to 1.8V, this pull up must be
switched off when the module is in off condition.
Using the RFTXMON Output GPIO5
The GPIO5 pin, when configured as RFTXMON Output, is controlled by the GL865
V3/V3.1 module and will rise when the transmitter is active and fall after the transmitter
activity is completed.
There are 2 different modes for this function:
1. Active during all the Call:
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.
2. Active during all the TX activity:
The GPIO is following the TX bursts
Please refer to the AT User interface manual for additional information on how to enable
this function.
