Rainbow Electronics GM862-QUAD-PY - Manual (Page 59)

GM862-QUAD / PY Hardware User Guide
1vv0300748 Rev. 5 - 20/09/07
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 59 of 68
10.2 Using a GPIO pin as INPUT
The GPIO pins, 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 pin has interface levels different
from the 2.8V CMOS, then it can be connected to GPIO1 or can be buffered with an open collector
transistor, provided a 47KΩ pull-up to 2.8V.
10.3 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.
10.4 Using the RFTXMON Output GPIO5
The GPIO5 pin, when configured as RFTXMON Output, is controlled by the GM862-QUAD/PY module
and will rise when the transmitter is active and fall after the transmitter activity is completed.
For example, if a call is started, the line will be HIGH during all the conversation and it will be again
LOW after hanged up.
The line rises up 300ms before first TX burst and will became again LOW from 500ms to 1sec after
last TX burst.
10.5 Using the Alarm Output GPIO6
The GPIO6 pin, when configured as Alarm Output, is controlled by the GM862-QUAD / PY module
and will rise when the alarm starts and fall after the issue of a dedicated AT command.
This output can be used to power up the GM862-QUAD / PY controlling microcontroller or application
at the alarm time, giving you the possibility to program a timely system wake-up to achieve some
periodic actions and completely turn off either the application and the GM862-QUAD / PY during sleep
periods, dramatically reducing the sleep consumption to few μA.
In battery powered devices this feature will greatly improve the autonomy of the device.
NOTE: During RESET the line is set to HIGH logic level.