Sony Ericsson GM29, Integrator'S Manual, Page: 36 / 264

GM29 INTEGRATOR’S MANUAL
36
LZT 123 7361 R1B
3. Operation
3.1 Switching On the Modem
There are two ways to switch on the modem, once power is applied.
• either assert TO_IN high for > 0.2s;
• or activate the RS232 control line DTR, high for > 0.2s.
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.
Note!
DTR must be cycled from low to high.
3.2 Switching Off the Modem
There are three 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 10s is
experienced as the modem logs off the network
• or assert TO_IN low to high for 1 - 2 seconds.
Note!
The DTR line must be deactivated prior to switching off the modem to
ensure the unit switches off correctly.
3.3 Resetting 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 > 3.5s.