LoRaWan And M5 Fire hardware modification



  • I want to use the LoRaWAN module with the Fire Core.
    I am confused about the necessary hardware modifications. It says:

    • M5Stack Fire has occupied GPIO16 / 17 to connect with the PSRAM by default, it's conflict with TXD / RXD (GPIO16, GPIO17) in this module. Therefore, when using the LoRaWAN module with the M5Stack Fire, you might have to cut the TXD and RXD from GPS module and wire fly to another set of UART pin, if you gonna use the PSRAM.

    Why does it talk about a GPS module? What connections am I meant to cut? Could someone please clarify?



  • This is a very old post but surprisingly has yet to get a reply - is no-one using a LoraWan module with the fire (or with a GPS)?

    The answer to the original question is that for some reason the designers of the Fire decided to use the only serial connections guaranteed to clash with pretty much everything - GPIO16/17 (a.k.a Serial2).

    Both the GPS and the LoraWan module are wired up to use GPIO16/17 by default (again, designers - what were you thinking???) but both have links on the board to allow alternate pins to be used.

    The GPS has PCB tracks linking the defaults which must be cut to allow the use of the alternatives - GPIO 3/1 or GPIO 13/5. (This is what the note is referring to I think.)

    In the case of the LoraWan module the links are made with Zero ohm resistors and you can move them to link to GPIO5/2.

    Unfortunately this is where you and I (and anyone stumbling across this old question) hit a brick wall because the documentation for the serial ports seems to be non-existent.

    Hopefully someone else can shed some light on this.


  • M5Stack

    that is a description mistake. that mean should be cut the TXD and RXD from LoRaWAN module and wire fly to another set of UART pin.

    in the case of the LoraWan module the links are made with Zero ohm resistors and you can move them to link to GPIO5/2.

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  • Since this concerns many modules a photo of the necessary modification would be helpful.