GL865 Hardware User Guide
1vv0300910 Rev.1 – 2011-07-22
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page 57 of 79
Input high level
2.1V
3.1V
Input low level
0V
0.5V
Output high
level
2.2V
3.1V
Output low level
0V
0.35V
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.
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 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/OFF monitoring.
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 RFTXMON Output GPIO5
The GPIO5 pin, when configured as RFTXMON Output, is controlled
by the GL865 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: