User's Guide

UL865 Hardware User Guide
1VV0301050 Rev 2 – 2013-10-09
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 UL865 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.
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.