
GL865-DUAL V3 Hardware User Guide
1vv0301018 Rev.5 – 2013-08-05
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 52 of 76
Mod. 0805 2011-07 Rev.2
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 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-DUAL V3 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.
11.3.
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.
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 resistor 47K pull up to 2.8V, this pull up must be switched
off when the module is in off condition.
11.5.
Using the RFTXMON Output GPIO5
The GPIO5 pin, when configured as RFTXMON Output, is controlled by the GL865-DUAL
V3 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.