Smart Machine Smart Decision
4.2.2.4
Over-temperature or Under-temperature Power down
The module will constantly monitor the temperature of the module,
If the temperature > +80
℃
, the following URC will be reported:
+CMTE: 1
If the temperature < -30
℃
, the following URC will be reported:
+CMTE:-1
If the temperature > +85
℃
, the following URC will be reported, and the module will be automatically powered
down.
+CMTE: 2
If the temperature <
-40
℃
, the following URC will be reported, and the module will be automatically powered
down.
+CMTE:-2
At this moment, AT commands can not be executed any more, and only the RTC is still active. Power down mode
can also be indicated by STATUS pin, which is at low level at this time.
The AT command “AT+CMTE” could be used to read the temperature when the module is running.
For details please refer to
document [1].
4.2.3
Restart SIM900-DS by PWRKEY Pin
When the module works normally, if the user wants to restart the module, follow the procedure below:
1)
Power down the module.
2)
Wait for at least 800mS after STATUS pin changed to low level.
3)
Power on the module.
Delay > 800mS
Power down
Restart
PWRKEY
STATUS
Figure 13: Timing of restart SIM900-DS
4.3
Power Saving Mode
SIM900-DS 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 SIM900-DS into minimum functionality. When SIM900-DS 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.
SIM900-DS_Hardware Design_V1.00
21
2013-01-20
