New SMS module for SIM800/900/etc

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  • ah sorry.

    I see, it is the AT+CPOWD=1 or =0 command, it turns off the connection, but red light stays on on the phone, and after ten seconds or so the phone restarts and the connection comes back up.

  • I guess they must have wired the module up in such a way that the SIM800 can't turn itself off properly - realistically the RED LED is probably just wired across the power lines as well.

    So yes, it looks like your only option is to turn the module on and off with an FET/similar - unless you bought a different module that had the power pin exposed - which might be an easy option?

    Which microcontroller are you using? Puck.js isn't 5v tolerant, which can cause issues if you turn the module on and off by switching the actual voltage line (rather than GND). If you disconnect GND then the voltage on the data wires will rise to the voltage on the power lines (I guess that of a LiPo battery?) which will be too much for the microcontroller.

    In that case you'd have to use something like a PFET to switch the positive voltage wire.

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New SMS module for SIM800/900/etc

Posted by Avatar for Gordon @Gordon

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