Hello Alexander, I have sometimes the situation that TXNSTAT = 1 / TXNRETRY1=1 / TXNRETRY0 = 1 /CCAFIL =1 -> Transmission failed (in the TXSTAT register). This register is readonly and I have no idea how to reset those bits. Actually I make a real worse workaround -> I reset the chip. Have you any idea how these bits could be reset - so that the chip can go on working...
These bits are always set because you talk with an transceiver which doesn't send an ack back! If you have a transceiver which sends an ack back it should be zero.
If the first retry was failed TXNRETRY1 is 1. If the second retry was failed TXNRETRY1 is 2. ....
up to max frame retries 3.
I cc now riot-devel this is an usual 802.15.4 handling. "Normally" at tx complete irq -> you need to read out the TXNSTAT stat and report the upper-layer if ACK was there or not. At least you 100% need such information for some part of MLME-ops.