LoRa-Raw: Cannot transmit more than 64B



  • Hi all ,
    I'm going for some test with two lopy and LoRa send/receive exemples.
    All is working well except that i can't send more than 64 bytes.

    my code is very basic:

    on each Lopy:
    lora.init(mode=LoRa.LORA, frequency=868000000, power_mode=LoRa.ALWAYS_ON , tx_power=14, bandwidth=LoRa.BW_250KHZ, sf=7, preamble=8, coding_rate=LoRa.CODING_4_5, tx_iq=False, rx_iq=False)

    I have already changing BW(500-250-125) and sf(7-8-9) without any luck.

    when i try:
    string='123.....4' (64 char)
    s.send(string)
    -> Ok ( other side receive and print the string on the terminal)

    But when i try:
    string='123.....5' (65 char)
    s.send(string)
    -> nothing on the other side ( just 'b' )

    Don't saw anything about socket buffer or else .
    If someone got an idea ...

    Thanks in advance.
    St├ęphane A.



  • @Clemens
    Thank you Clemens to pointing this out for me ,
    Actually the Maximum Payload is 64B for the Lopy .
    i was thinking that packets were cut internally but not.
    Nice to see that no one had this problem before.

    I have already bypassed the problem by cutting the packets.

    Thanks again .



  • Btw what is the maximum payload for the LoRa module? I've seen different numbers from 64 to 256. Is the physically maximum hardware payload also the maximum I can send or is there any abstraction in the software so a bigger dataset is automatically divided and send by multiple packages. I'm coming from the RFM69 world so I'm not too confident with your hardware setup. But based on rumors your LoRa hardware could be the same as in the RFM95 modules. ;-)



  • Hi bucknall,
    The receive code was simplified to see what is coming .
    here it is:

    s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
    s.setblocking(False)

    while True:
    data=s.recv(256)
    print(data)
    time.sleep(2)


  • administrators

    Hi @stef could you post you receiving code, please?

    I believe it has to do with the buffer that you are storing your incoming data.

    Thanks!

    Alex


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