User's Manual
HC864-AUTO Hardware User Guide
1vv0300946 Rev.4 – 2012-12-27
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Reserved. Page 41 of 77
7.1. Reset Signal
Signal Function I/O PIN Number
RESET Phone reset I 54
RESET is used to reset the HC864-AUTO module. Whenever this signal is pulled low
HC864-AUTO is reset. When the device is reset it stops all operations. After the release of the
reset HC864-AUTO is unconditionally shut down, without doing any detach operations from
the network where it is registered. This behavior is not a proper shutdown because the device
is requested to issue a detach request on turn off. For this reason, the Reset signal must not be
used for 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. There is 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 HC864-AUTO. 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* 2.1V
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, it must always be connected with an
open collector transistor to permit the internal circuitry the power on reset and under voltage
lockout functions.
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 module when is powered OFF or during an
ON/OFF transition.