Notes:
- this module uses recycled SIM800C chips
- SIM800C turns on when the PWX pin is LOW for approx. 1 second, if you want it to turn on as soon as it receives power, you need to short-circuit the PWX pin with the GND pin (e.g. using a jumper)
- the logic voltage is selected via the V_TTL pin, it must be connected to the appropriate voltage (e.g. 3.3 V or 5 V)
Pinout