User's Manual

GE864
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-DUAL V2 Hardware User Guide
DUAL V2 Hardware User GuideDUAL V2 Hardware User Guide
DUAL V2 Hardware User Guide
1vv0300875 Rev.1 – 2010-03-29
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved. Page 51 of 73
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 2.8V 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 2.8V CMOS, then it can be buffered with an open
collector transistor with a 47K pull up to 2.8V, this pull up must be switched off when
the module is in off condition.
11.3. Using a GPIO Pad as OUTPUT
The GPIO pads, when used as outputs, can drive 2.8V 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.
The illustration below shows the base circuit of a push-pull stage:
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.
Q1
Q2
VDD
GPIO7