Incorrect FCnt start value?
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It has previous been mentioned that uplink FC starts with 1 instead of 0 here #890
When reading the LoRaWAN specification 1.0.4 it seems that it has been updated and clarified that the FCnt should start with 0 after a successful join procedure.
Is it correctly understood that the FCnt should increment after each uplink, so the first uplink FCnt should be 0 and not 1?
We believe that the FCntUp management is correct and compliant with LoRaWAN 1.0.4 specification or any other LoRaWAN specification version.
The specification says that after receiving the JoinAccept the FCnt variables value must be reset to 0. (First highlighted sentence)
Then it says that every new uplink must use an FCnt value incremented by 1. (Second highlighted sentence)
The specification also says that FCnt values equal to 0 must be accepted which makes this an exception. (Third highlighted sentence)
Therefore according to the specification we believe that a first uplink using an FCntUp=0 or FCntUp=1 are accepted behaviors.
In the future it would be nice if you could post this kind of questions on the project Discussions tab. It is a better place to engage discussions and then we can agree if it is an issue or not.
If you don't mind I move this issue to the Discussions tab.