I am trying to make a simple MAC-layer transceiver using Arduino environment. I have some code derived from this example: https://github.com/IoTS-P/nRF52-802154-Raw-Transmitter
and have discovered that it hangs after one to a few hundred transmissions. I have gone over the datasheet for the 802.15.4 radio section and I do not see where the problem is.I am using a Zena receiver to monitor the transmissions. I noticed that the CCA appears to take some tens-of-mS fairly often while the Zena does not show any other messages arrived during that time. What am I doing wrong with the radio hardware?
<project files attached>