User guide

UC864-E/G/WD/WDU Hardware User Guide

1vv0300766a Rev.4

- 03/02/09

7.1. Reset Signal

Signal Function I/O PIN Number

RESET Phone reset I 54

RESET is used to reset the UC864-E/G/WD/WDU module. Whenever this signal is

pulled low, UC864-E/G/WD/WDU is reset. When the device is reset it stops all

operations. After the release of the reset UC864-E/G/WD/WDU 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.

Reset Signal Operating levels:

Signal Min Max

RESET Input high 2.0V* 2.6V

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:

Do not use this signal to power off UC864-E/G/WD/WDU. Use the ON/OFF signal to

perform this function or the AT#SHDN command(To turn off UC864-E, first of all, you

MUST cut off supplying power to the USB_VBUS, or the module does not turn off).