NE866B1_Hardware_Design_Guide
1VV0301354 Rev. 6
Page
43
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70
2018-02-28
5.6.1.
Using a GPIO as an 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 VAUX.
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
NB866B1 when the module is powered off or during a
powerup/reboot transition.
Using bidirectional level translators which do not support High Z
mode during power off is not recommended.
The VAUX /PWRMON pin can be used for input pull up reference.
5.6.2.
Using a GPIO as an 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.