COMX 868 LoRAWAN Module - How to change Spreading Factor and Transmitter Power?



  • Hello all,
    I am exploring the use of the COMX 868 LoRAWAN Module SKU M031 C (The Black Module)
    Inside is an ASR6501 and a SX1262 SEMTECH, which has been assembled on a board by HelTec CubeCell
    The interface is via a Serial Port. Apparently the board has an APP inside programmed by HelTec that allows one to control it using an AT-Command set. (So old Rockwell times revive for anyone familiar with 300 Baud modems and up.)
    The example available only allows for Normal-LoRa, so I wanted to explore the LoRaWAN capabilities of this module. I tried out all the commands found in the documentation (Using https://resource.heltec.cn/download/CubeCell/AT_Command_list/CubeCell_Series_AT_Command_User_Manual_V0.5.pdf)

    The problem: There is however one command, LoraSet that has my interest but gives an error
    Sending buf: 'AT+LoraSet=?'
    +ERROR: the command is not supported

    When issueing a RESET some information concerning the current transmission mode is given:

    Sending buf: 'AT+RESET=1'
    +OK
    Copyright @ 2019 Heltec Automation.All rights reserved.

    AT Rev 0.5

    +LORAWAN=0

    +FREQ=868000000
    +SF=7
    +TxPower=10

    So the Spreading Factor is at 7 and the TransmissionPower is set at 10 dBm as defaults.

    The command LoraSet should be supported in the V0.4 already and maybe earlier as well of the HelTec Module according to its documentation.

    I found an article-posting withe a nice example to communicate with TTN using the same module as I have and a M5Stack.
    https://www.hackster.io/kehosoftware/m5stack-com-lorawan-using-arduino-ide-38ab24

    He has published his script and uses the LoraSet-command in his recommendable example for M5Stack with the same LoRAWAN- module :

    // activate communication
    Serial.println("LoraSet=?");
    ATCommand("LoraSet", "?");
    delay(500);

    I suppose therefor that the writer of the article does not have the same problem as me in January 2021
    Apart from querying the module, one can also set the TransmitPower now default at 10, but could be even 20 or 22 dBm and the SF SpreadingFactor, which is now default at 7 which could be 12 for longer range

    So obviously I want to transmit at the longest range.

    Question: Does anyone has the same experience in the past and have found a solution to change the Spreading Factor and Transmission Power?

    Apart from that I would like to know how to put a newer version in that LoRAWAN-Module (V0.6 of Januari 2021) But I am clueless how to flash that. But it is probably possible via the TX and RX and some tricks.
    I am wondering if inside the module there is a custom made M5Stack Firmware flashed inside or not. There is obviously something different than the AT-Command document of HelTec specifies to be possible.
    All the other commands seem to work (as far as I have tested them), but AT+LoraSet is simply required to use the module using all its capabilities !