SIM800H datasheet(25/73 Pages) SIMCOM

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mode can also be indicated by STATUS or VDD_EXT, 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].

4.2.2.5. Restart SIM800H&SIM800L by PWRKEY Pin:

When the module works normally, if the customer wants to restart the module, follow the procedure below:

Power down the module.

Wait for at least 800ms after STATUS pin changed to low level.

Power on the module.

Figure 14:Timing of restart SIM800H&SIM800L

4.2.3.

Reset Function

SIM800H&SIM800L 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 PWRKEY pin has no effect. Customer 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 15: 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

SIM800H&SIM800L_Hardware Design_V2.02

2015-07-27

SIM800H Arkusz danych(PDF) 25 Page - SIMCom