Sony Ericsson GM29 - Manual (Page 10)

10 Operation
Operation
Before the GM29 can be operated the following
conditions must apply:
• SIM card inserted (with the modem
unpowered);
• antenna connected;
• RS232 port connected to the application
computer;
• power applied.
Operation is not dependent on a handset being
fitted. The type of application will dictate
whether a handset is necessary.
Switching 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.
Switching Off the Modem
There are two ways to switch off the modem as
described below:
• either use the appropriate AT 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.
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 > 3.5 s.
Operating States/LED
The GM29 has a green LED, as shown below,
used to indicate various operating states. These
states are described in the following table.
Operating state LED
After switching on the modem On after 4 s
Switch off or power removed Off
Standby or talk Flashing
Modem on with one of the fol-
lowing conditions:
No network, network search,
no SIM card, no PIN entered On
LED