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Rx1 window causes join issue

Semtech Transceivers SX126x family
#1

Hello,

I work with a sx1262 and based my code on the SWL2001 project.
I have an issue with the Rx1 window.

In stmc_real.c/smtc_real_get_rx_window_parameters(…), when I keep as is, below code, JOIN doesn’t work.

*rx_window_symb =
MIN(MAX(((*rx_timeout_symb_in_ms * 1000) / tsymbol_us), MIN_RX_WINDOW_SYMB), MAX_RX_WINDOW_SYMB);
*rx_timeout_preamble_locked_in_ms = 3000;

The work around consists in defining those variable as below :

*rx_window_symb = 0;
*rx_timeout_preamble_locked_in_ms = 10000;

Once JOIN is done former parameters work well.

Do you have any clue where it comes from?

Sincerely yours,

Jean

#2

It looks to me like the work-around you’re using uses a much longer window to receive a JoinAccept, which could be needed if there is some latency in gateway transmission. Out of curiosity, what LoRa gateway and network server are you using?
Have you tried waiting ~10 minutes for it to join?
During the join procedure, the end device cycles through each 8-channel LoRa sub-band to find one that the gateway is set to. This may take a minute or two, then it starts again with slightly adjusted RX window timing.

#3

Hello kmuster,

Thank you for your answer.
LoRa gateway is Dragino, connected to AWS IOT LoRa servers.
When I set back SWL2001 original code.
On device boot, I have my first JoinFail around 5s after smtc_modem_init.
Then, handled by smtc_modem_run_engine, I have an other JoinFail around 185s.

It is not working

#4

Any advice?