GE866-QUAD Hardware User Guide
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Page 57 of 82
Mod. 0805 2011-07 Rev.2
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 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 GE866-QUAD 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.
11.3.
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.
11.4.
Using the RF Transmission Control GPIO4
The GPIO4 pin, when configured as RF Transmission Control Input, permits to disable
the Transmitter when the GPIO is set to Low by the application.
In the design is necessary to add a resistor 47K pull up to 2.8V, this pull up must be
switched off when the module is in off condition.