LoRaWAN how to use session

[StevenCellist]

I'm trying to use an ESP32-S3 with SX1262, together with LoRaWAN from RadioLib.
On first boot, it all worked fine (properly joined, nicely sending uplinks and receiving downlinks - although I still need to look how to format downlinks such that I receive what I send from TTN).
Minor note is that it defaults to SF12 (join and uplinks) which is not great practice, but I'll at least wait for ADR implementation.

Question is: how do I resume the session after a reset / reboot / deepsleep?
Just calling node.begin() after a power-on reset / flash reset results in Resuming previous session ... success!, but any subsequent uplinks and downlinks fail with codes -12 and -1105 respectively. What should I do?

[jgromes]

-1105 is RADIOLIB_ERR_NO_RX_WINDOW, which is probably caused by the fact that the previous uplink failed (the library keeps track of when to open the Rx window). -12 is RADIOLIB_ERR_INVALID_FREQUENCY, so most likely there is something wrong with the channel selection process when resuming existing session.

You could try running the library in debug mode to see if there is further information. As a workaround, you can force the the device to always join on startup by setting force=true in beginOTAA.

[StevenCellist]

Thanks! I'll do some testing soon with debug mode enabled and see what happens. Force-rejoining will also require resetting the device on TTN so that's not really helpful on v1.1 😅

[jgromes]

I don't think that's the case, the DevNonce will not get reset by force joining, only by node.wipe(), so it should be possible to just join again.