Sony Ericsson TT4031 (SE-GM29) 3.Operation, 3.1Switching On the Modem, 3.2Switching Off the Modem, 3.3Resetting the Modem, assert HR_IN high for > 3.5 s, either use the AT+CFUN command;

3.Operation

3.1Switching On the Modem

There are two ways to switch on the modem, once power is applied.

either assert TO_IN high for > 0.2 s;

or activate the RS232 control line DTR, high for > 0.2 s.

The modem is fully operational after 4 seconds. Logging onto a network may take longer than this and is outside the control of the modem.

The modem can be configured to start up at the time power is applied by permanently tying power connector signals TO_IN (pin 4) and VCC (pin 1) together. In this case DTR must be used to switch the modem on again after it has been switched off or reset, while power is still applied.

3.2Switching Off the Modem

There are two ways to switch off (power down) the modem as described below:

either use the AT+CFUN command;

or assert HR_IN high for 1 - 2 seconds. A delay of up to 10 s is experienced as the modem logs off the network.

Note!_ The DTR line must be deactivated prior to switching off the modem to ensure the unit switches off correctly.

3.3Resetting the Modem

A full system reset, independent of the status of the software, may be applied to the modem as follows:

assert HR_IN high for > 3.5 s.

Owner’s Manual Rev 1.0 Page 37 of 37