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SIM900 GSM/GPRS TTL UART Modem - User Manual
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Page 6
OPERATING MODES
The table below briefly summarizes the various operating modes referred to in the following chapters.
Mode
Function
Normal
operation
GSM/GPRS
SLEEP
Modem will automatically go into SLEEP mode if DTR is set to high level
and there is no on air and no hardware interrupt (such as data on serial
port). In this case, the current consumption of GSM Modem will reduce to
the minimal Level.
In SLEEP mode, the Modem can still receive paging message and SMS from
the system normally.
GSM IDLE
Software is active. Modem has registered to the GSM network, and the
modem is ready to send and receive.
GSM TALK
Connection between two subscribers is in progress. In this case, the
power consumption depends on network settings such as DTX off/on,
FR/EFR/HR, hopping sequences, antenna.
GPRS
STANDBY
Modem is ready for GPRS data transfer, but no data is currently sent or
received. In this case, power consumption depends on network settings
and GPRS configuration.
GPRS DATA
There is GPRS data transfer (PPP or TCP or UDP) in progress. In this
case,power consumption is related with network settings (e.g. power
controllevel), uplink / downlink data rates and GPRS configuration (e.g.
used multi-slot settings).
POWER
DOWN
Normal shutdown by sending the “AT+CPOWD=1” command or using the PWRKEY. The
power management ASIC disconnects the power supply from the baseband part of the
GSM Modem. Software is not active. The serial port is not accessible. Operating voltage
remains applied to the internal circuitry
Minimum
functionality
mode
(withoutremove
power
supply)
Use the “AT+CFUN” command can set the modem to a minimum functionality mode
without remove the power supply. In this case, the RF part of the modem will not work
or the SIM card will not be accessible, or both RF part and SIM card will be closed, and
the serial port is still accessible. The power consumption in this case is very low.
