User's Manual

UE910 3G HARDWARE USER GUIDE 1vv0301171 Rev.3 • 2015-04-17 47 of 78

Using a GPIO 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 UE910 when the

module is powered off or during an ON/OFF transition.

Using a GPIO 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.