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RPaja.1
RPaja.1
Associate II
Apr 12, 2023 8:31 AM UTC
Question

How to Restore frame count after reset Lorawan context?

I have developed a device that joins lorawan in OTAA mode. I am testing the device and i am having some problems with conectivity.

Device joined succesfully to Lorawan Network Server, i saved the NVM Lorawan context and i reset the device, after reset NVM Lorawan context is restored, but when i send a uplink message it is ignored by Network Server because the Device frame count is less than Network server frame count.

My question is is there a way to save frame count in ROM memory and restore it in the LmHandler?

Thanks in advance

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1 reply

RPaja.1
RPaja.1Author
Associate II
Apr 17, 2023 9:24 AM UTC

I have found response to my own answer, Frame counter was included in NVM Lorawan context. The problem was that it was not saved properly, I included a function to save it every time that the device send an uplink.

LoRaMacNvmData_t Struct contains several structs with lora data, in LoRaMacCryptoNvmData_t struct have: 

LrWanVersion, DevNonce, JoinNonce, FCntList, LastDownFCnt, Crc32. 

FCntList contains  

  • FCntUp: Uplink frame counter which is incremented with each uplink  
  • NFCntDown: Network downlink frame counter which is incremented with each downlink on FPort 0 
  • AFCntDown: Application downlink frame counter which is incremented with each downlink 
  • FCntDown: In case if the device is connected to a LoRaWAN 1.0 Server this counter is used for every kind of downlink frame. (old usage) 
  • McFCntDown: Multicast downlink counters 
  • RJcount1: RJcount1 is a counter incremented with every Rejoin request 

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