COM.GSM from M5Stack is Die?

  • Hi everyone!
    I bought module COM.GSM few month ago.
    Trying work with this module and examples from M5Stack library by myself. But nothing, its not WORK!
    Then I call service M5stack and describe my problems.
    First they give me another sketch example -
    But using this examples give me only errors and code of error 1.
    We checked pins of RX/TX bar. It was ok.
    Last recommendation from service put another supply voltage with 1 A currency.
    BUT still die module - NOTHING. Same errors everytimes.
    So my question is - is it module really not work and die? Or may be me and M5Stack service didn't know something for alive this?
    Please help me in this problem.

  • Hello @udafff49

    1. which M5Stack device are you using? M5Stack (Basic, Gray, Fire) or M5Core2?
    2. can you share the log file with the errors?
    3. have you double-checked the SIM card you are using works with your provider in your region? (You can check with a mobile phone.)
    4. have you double-checked the SIM card doesn't have a PIN set? (Again, you can check that with a mobile phone.)


  • Hi @felmue

    Thanks for replay.

    1. I'm using M5stack Core Fire;
    2. Of course, I attach it in next message;
    3. Yes I'm checked it more times. Also I try change sim for different samples;
    4. Yes it's checked. SIM is unlock.

  • 0_1627155205955_Rdm-QBPptMk.jpg

  • Hello @udafff49

    ok, which GPIOs are you using for TX and RX? M5Stack Fire uses GPIO 16 and 17 internally, so you'll need to switch to a different pair of GPIOs.

    From the view of the COM.GSM module TX can be 16, 5 or 15 and RX can be 17, 0 or 13.

    Whatever pair you choose you'll also need to adapt those two lines in the sketch:

    #define TX_PIN 16
    #define RX_PIN 17


  • Hi @felmue
    Yes, this is step I made. I know about several GPIO for RX/TX. In my case I used 16/17 GPIO.
    Screen I attach in next message.

  • 0_1627201444475_Снимок экрана 2021-07-25 в 11.18.45.png

  • Hello @udafff49

    sorry if I was unclear. You can not use GPIO 16 and GPIO 17 with M5Stack Fire. Those two GPIOs are internally used for the PSRAM. Please see here.

    You need to use a different pair, for instance GPIO 5 and GPIO 13, adapt the sketch and change the dip switches on the COM.GSM module accordingly.


  • Oh, I see. Thanks, I try it. Never know before about 16/17 GPIO is busy.

  • Hi @felmue
    Your advice was useful. I changed GPIO and my example sketch was work. Thanks!

  • Hello @udafff49

    You are very welcome. I am glad you got it working.