M5Stack LTE module(M8321) not communicating or responding to serial commands?

  • I'm trying to get it working at the moment, however no luck so far. From the schematic i've deduced that its operating as a generic modem, with a basic serial connection from the core to the LTE module on GPIO pins 16 and 17. However when attempting to send modem AT commands there is no response from the module?

    I am programming this in arduino, and I have set up a very simple sketch to send the commands from the stack to the LTE module

    #include <M5Stack.h>

    void setup() {
    Serial.begin(9600); // set up serial
    Serial2.begin(9600, SERIAL_8N1, 16, 17); // set up a second serial that will comunicate directly with the LTE shield

    //set pin 2 high for using the modem (simulates a power button press)
    pinMode(2, OUTPUT);
    digitalWrite(2, 0);
    digitalWrite(2, 1);

    void loop() {

    while (Serial.available()){  // forward data from monitor to LTE module
      uint8_t recieve = Serial.read();
    while (Serial2.available()){  // forward data from LTE module to monitor


    I then manually input the AT commands and wait for a response from the board, however there is no response.

  • M5Stack

    I have an LTE Module but this is not really my field of expertise. If you supply the full code I can test on mine to see if it's an issue specific to your module. By the way what country are you in? The module may only work if your countries mobile networks are supporting the same frequency bands as the module is compatible with, please check the docs page in the product features area https://docs.m5stack.com/#/en/module/lte

  • Did you get it to work?
    I'm currently working on it, using the example from the documentation. It's still unstable so I have some work to do..

  • M5Stack

  • @m5stack

    Yes, I found and used this example.

    Although the code Serial.printf("FUCK STC\n"); on line 305 was not very inspiring, I did get something to work.
    The device registers with my provider after setting it to auto and entering the pin, it is getting an ip number and two dns servers but the ping test fails with the message: +CME ERROR: 30 (No network service)
    No clue yet to how to fix it.
    I did find the 350 page at command reference and am using a combo of the chinese original and a google translated page, but a working sample would definitly help.
    The data-only sim works just fine in a phone btw.

    Thanks for your response btw ;)

  • Ok, it seems the unit is responding, I can set it up, make and receive calls but am unable to get any functional IP traffic.

    Current status:

    • Unit enabled
    • PDP configured (same as reported by a phone)
    • LTE connection
    • network attached
    • network activated
    • can configure either LTE,GPRS or WCDMA
    • unit reports to have a connection
    • can make a call
    • can recieve a call

    +CFUN: 1
    +COPS: (2,"T-Mobile NL","T-Mobile NL","20416",7,1),,(0-4),(0-2)
    +ZPLMNBAND: 3,20416,3
    +CGDCONT: 1,"IPV4V6","smartsites.t-mobile","",0,0,0,0,0,0
    +CEREG: 1,1
    +CGATT: 1
    +CGACT: 1,1
    +ZPLMNINFO: "20416","T-Mobile NL","T-Mobile NL",2
    +CSQ: 140,99,17

    I'm unable to make a network connection. no IPSTART, or CMPING, they all return:

    +CME ERROR: 30

    Which, as far as I can see, means : "No network service"

    What seems illogical is:
    +ZPLMNBAND: 3,20416,3

    Which would indicate the750mhz band, which is weird, as it should be 900 or 1800
    +COPS: (2,"T-Mobile NL","T-Mobile NL","20416",7,1),,(0-4),(0-2)

    I must be doing something wrong, but what..
    Any suggestions would be greatly appreciated.

  • I have the same problems.
    My experience:

    +CREG: 2
    +CGREG: 2
    +CEREG: 2
    +CREG: 1
    ^MODE: 17,10
    +CREG: 1
    +CEN1: 1,204
    +CEREG: 1
    +CIREPI: 0
    +CNEMS1: 0

    +COPS: (2,"T-Mobile NL","T-Mobile NL","20416",7,1),,(0-4),(0-2)
    +CME ERROR: 30

    I too get +CME ERROR: 30 on all ping actions.
    The sim is ok, I get data when I use it in a smartphone.

    Is anybody out there successfully transmitting data with this unit?

    any help would be greatly appreciated!