• Hi!

    I have a CoreS3 with a COM.NB-IoT. Somehow I can;t get the SIM7020 get to work. Does someone have a example code? I have changed the dipswitches to:

    #define SerialAT Serial1
    #define MODEM_TX 13
    #define MODEM_RX 7

    From the IoT_BASE_SIM7020 I have extracted the TinyGSM code for the SIM7020. But as mentioned, I can not get it to work. Does someone have a full working example? I do have the COMMU module on Serial2 on:

    #define Serial485 Serial2
    #define RS485_TX 17
    #define RS485_RX 18
    TinyGsm modem(SerialAT,0);
    void setupModem() {
      pinMode(2, OUTPUT);
      digitalWrite(2, 0);
      SerialAT.begin(115200, SERIAL_8N1, MODEM_RX, MODEM_TX);
      modem.init(); // Not working
      String modemInfo = modem.getModemName();
      CoreS3.Display.printf("Modem Name: %s\n", modemInfo);
      Serial.print("Modem Name: ");

  • Hello @markpro

    GPIO13 in M5CoreS3 is already used by the speaker amp. So it probably can't be used for serial. See schematic here.

    BTW: you don't need to set GPIO2 as output and set it to LOW as GPIO2 is not connected / used by the COM.NB-IoT module. See schematic here.


  • @felmue Thanks, after reviewing the docs I also made a mistake in the Pins. Adjusted to below and now I get a reponse of 1 on modem.test(). So looks like I have it connected :)

    #define MODEM_TX 7
    #define MODEM_RX 1

  • Hello @markpro

    glad to hear you got it working.

    BTW: GPIO1 is already used on port A (I2C). But that is fine as long as you do not need external I2C as well.