HE910 Hardware User Guide
1VV0300925 Rev. 32 Page 87 of 111 2019-11-25
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
HE910 when the module is powered off or during an ON/OFF
transition.
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.
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