Rainbow Electronics GM862-GPS - Manual (Page 18)

GM862-GPS Hardware User Guide
1vv0300728 Rev. 8 - 20/09/07
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 18 of 73
4.5.1 Reset signal
Signal Function I/O Pin
RESET Phone reset I 23 (connector SO301)
RESET is used to reset the GM862-GPS modules . Whenever this signal is pulled low, the GM862 is
reset. When the device is reset it stops any operation. After the release of the reset GM862-GPS is
unconditionally shut down, without doing any detach operation from the network where it is registered.
This behaviour is not a proper shut down because any GSM device is requested to issue a detach
request on turn off. For this reason the Reset signal must not be used to normally shutting down the
device, but only as an emergency exit in the rare case the device remains stuck waiting for some
network response.
The RESET is internally controlled on start-up to achieve always a proper power-on reset sequence,
so there's no need to control this pin on start-up. It may only be used to reset a device already on that
is not responding to any command.
NOTE: do not use this signal to power off the
GM862 . Use the ON/OFF signal (Pin 17 of SO301) to
perform this function or the AT#SHDN command.
Reset Signal Operating levels:
Signal Min Max
RESET Input high 2.0V* 2.2V
RESET Input low 0V 0.2V
* this signal is internally pulled up so the pin can be left floating if not used.
If unused, this signal may be left unconnected. If used, then it must always be connected with an
open collector transistor
, to permit to the internal circuitry the power on reset and under voltage
lockout functions.