SIM548C Hardware Design
Table 10: operating modes
How to activate mode
Features
C
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arge M
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Connect charger to module’s VCHG pin
and connect battery to VBAT pin of
module while the GSM part of the module
is in Normal operating mode, including:
IDLE, TALK mode; SLEEP mode etc;
z
GSM remains operational and
registered GSM network while
charging is in progress;
z
The serial interfaces are available in
IDLE, TALK mode, the AT
command set can be used fully in this
case;
In SLEEP mode, the serial interfaces are
not available, once the serial port is
connected and there is data in transfer.
Then the GSM part of the module will
exit the SLEEP mode.
GHOST Mode
Connect charger to module’s VCHG pin
while the GSM part of the module is in
POWER DOWN mode.
IMPORTANT: In GHOST mode not all
the software tasks are running.
z
Battery can be charged when GSM
engine is not registered to GSM
network;
z
Only a few AT commands is
available as listed below.
Note:
VBAT can not provide much more than 5mA current while the module is during the DDLO
charge state. In other words it is strongly recommended that VBAT should not be the main
power supply in the application subsystem while the module is during the DDLO charge state.
Table 11: AT Command usually used in GHOST mode
SIM548C_HD_V1.01
09.05.2008
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