User's Manual

HE910 Hardware User Guide

1vv0300925 Rev.9 – 07-02-2012

7.1 Reset signal

Signal

Function

I/O

PAD

RESET*

Phone reset

R13

RESET* is used to reset the HE910. Whenever this signal is pulled low, the HE910 is

reset. When the device is reset it stops any operation. After the release of the reset

HE910 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 HE910. Use the ON/OFF signal to perform this

function or the AT#SHDN command.

Reset Signal Operating levels:

Signal

Min

Max

RESET Input high

1.5V

1.9V

RESET Input low

0.35V

* 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.