Join fails

[mdede439]

I have a couple of the 1.0 version of the T-Beam modules. I have been playing around with the code here as a generic sketch and adding additional credential.h folders to hold different credentials for different end devices I create on TTN. This works, kind of. I am running in to an issue if I use the credentials to program a device with one set of credentials and then try and reprogram it with another set defined for a different end device. It appears it retains the old credentials regardless of what I try and overwrite it with in the new sketch. I was able to fool it and force it to do LMIC_startJoining(); and that seems to write in the new keys and it I see it working on the TTN console. However, I have two of these boards and I can only get it to work with one of them. Doing this procedure with the second board does write the new keys out to it, because I can see the device address change and I can see the accept join-request and forward join-accept messages but then nothing. No further packets end up in the end device application. I see the packets in the gateway from that device address every 20 seconds, as per the sketch, but they don't go where I want them.

Two questions: Is this code written to program a device just once or is there a facility I have not seen to rewrite the keys in the NVRAM or EEPROM to change the keys?

And what do you think is happening if the end device sends a join and it is accepted but not actually joins? Any thoughts on where I can look to diagnose this issue?

Thanks for listening and thanks for the code!!

[J-Paul0815]

I don't know if it helps or if there is a correlation, but this is how I was able to solve my problems, which were already described here:

#28

On Screen: Join TTN, Message queued, TRANSMITTED But nothing in TTN, no Join, no Data.
After editing configuration.h

//Uncomment to enable discarding network settings by long pressing second button
#define PREFS_DISCARD

and new flash the T-Beam, I was able to solve my problems by long pressing the middle button after switching it on.
After that everything worked as it should.

[mdede439]

Thanks for the reply. That ended up being exactly what I tried and it worked for as well. I looked more thoroughly through the code and found that option for the the user button to erase the preferences. After implementing it and giving it a try it worked first time!! I am still curious what it was keeping saved that even after forcing a rejoin with new credentials that it would not join. But like I always say, you can learn more when things don't work than when everything does.