Power Saving Mode; Minimum Functionality Mode; Sleep Mode 1 (At+Csclk=1) - SimCom SIM900D Hardware Design

4.3

Power Saving Mode

SIM900D have two sleep modes: sleep mode 1 is enabled by hardware pin DTR; sleep mode 2 is only enabled by
serial port regardless of the DTR. In sleep mode, the current of module is very low. The AT command
"AT+CFUN=<fun>" can be used to set SIM900D into minimum functionality. When SIM900D is in sleep mode
and minimum functionality, the current of module is lowest.
4.3.1

Minimum Functionality Mode

There are three functionality modes, which could be set by the AT command "AT+CFUN=<fun>". The command
provides the choice of the functionality levels <fun>=0,1,4.
0: minimum functionality.
1: full functionality (default).
4: flight mode (disable RF function).
Minimum functionality mode minimizes the current consumption to the lowest level. If SIM900D is set to
minimum functionality by "AT+CFUN=0", the RF function and SIM card function will be disabled. In this case,
the serial port is still accessible, but all AT commands correlative with RF function and SIM card function will not
be accessible.
For detailed information about the AT Command "AT+CFUN=<fun>", please refer to document [1].
Table 5:The Current consumption of Minimum Functionality Mode
<fun>
0
1
4
4.3.2

Sleep Mode 1 (AT+CSCLK=1)

User can control SIM900D module to enter or exit the sleep mode 1 (AT+CSCLK=1) by DTR signal. When DTR
is in high level and without interrupt (on air and hardware such as GPIO interrupt or data in serial port), SIM900D
will enter sleep mode 1 automatically. In this mode, SIM900D can still receive paging or SMS from network but
the serial port is not accessible.
SIM900D_Hardware Design_V2.02
Power down Delay > 800mS
PWRKEY
STATUS
Figure 15: Timing of restart SIM900D
Restart
Current consumption(uA) (sleep mode)
897
1306
967
23
Smart Machine Smart Decision
2012-05-07