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.
Note
：
The default temperature detect is disable, 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.
Reset Function
SIM800H also has a RESET pin (pin 49) used to reset the module. This function is used as an emergency reset
only when AT command “AT+CPOWD=1” and the POWER_ON pin has no effect. User can pull the RESET pin
to ground, then the module will reset.
This pin is already isolated in the module, so the external isolation is not necessary. Following figure is internal
circuit of the RESET pin.
Figure 14: Reset circuit
The typical value of RESET pin at High level is 2.8V, so for the 3V or 3.3V, customer could use MCU’s GPIO to
driver this pin directly, cascading some resistors could enhance the ESD performance but the value should not be
too big; otherwise the level of RESET could be lower than threshold value; RESET hardware parameters can
refer to the table below:
SIM800H_Hardware_Design_V1.01
26
2013-08-20
