MC45 Hardware Interface Description
P R E L I M I N A R Y
MC45_HD_01_V00.02a
Page 36 of 90
12.08.2002
3.3.2 Power saving
SLEEP mode reduces the functionality of the MC45 module to a minimum and, thus,
minimizes the current consumption to the lowest level. SLEEP mode is set with the
AT+CFUN command which provides the choice of the functionality levels <fun>=0, 1, 5, 6, 7
or 8, all explained below. Further instructions of how to use AT+CFUN can be found in [1].
IMPORTANT: The AT+CFUN command can be executed before or after entering PIN1.
Nevertheless, please keep in mind
that power saving works only while the module is
registered to the GSM network
. If you attempt to activate power saving while the module is
detached, the selected <fun> level will be set, though power saving does not take effect.
To check whether power saving is on, you can query the status of AT+CFUN if you have
chosen CYCLIC SLEEP mode. If available, you can take advantage of the status LED
controlled by the SYNC pin (see Chapter 3.8.2.2). The LED stops flashing once the module
starts power saving.
The wake-up procedures are quite different depending on the selected SLEEP mode. Table
10 compares the wake-up events that can occur in NON-CYCLIC SLEEP mode and in the
four CYCLIC SLEEP modes.
3.3.2.1 No power saving (AT+CFUN=1)
The functionality level <fun>=1 is where power saving is switched off. This is the default after
startup.
3.3.2.2 NON-CYCLIC SLEEP mode (AT+CFUN=0)
If level 0 has been selected (AT+CFUN=0), the serial interface is blocked. The module
shortly deactivates power saving to listen to a paging message sent from the base station
and then immediately resumes power saving. Level 0 is called NON-CYCLIC SLEEP mode,
since the serial interface is not alternatingly made accessible as in CYCLIC SLEEP mode.
The first wake-up event fully activates the module, enables the serial interface and
terminates the power saving mode. In short, it takes MC45 back to the highest level of
functionality <fun>=1.
3.3.2.3 CYCLIC SLEEP mode (AT+CFUN=5, 6, 7 and 8)
The functionality levels AT+CFUN=5, AT+CFUN=6, AT+CFUN=7 and AT+CFUN=8 are
referred to as CYCLIC SLEEP modes. The major benefit over the NON-CYCLIC SLEEP
mode is that the serial interface is not permanently blocked and that packet switched calls
may go on without terminating the selected CYCLIC SLEEP mode. This allows MC45 to
become active, for example to perform a GPRS data transfer, and to resume power saving
after the GPRS data transfer is completed.
The four CYCLIC SLEEP modes give you greater flexibility regarding the wake-procedures:
Basically, you can enter AT+CFUN=1 to permanently wake up the module. Also, MC45 can
automatically resume power saving, after you have sent or received a short message or
made a call. Please refer to Table 10 for more details.
