The samr21 starts up faster than EDBG, so on cold boot reading the ID will fail. Fix this by re-trying to get the EUI-64 from EUI. On warm boot / reset this works on the first try, but on cold boot it can spin a couple thousand times.
The samr21 starts up faster than EDBG, so on cold boot reading the ID will fail. Fix this by re-trying to get the EUI-64 from EUI. On warm boot / reset this works on the first try, but on cold boot it can spin a couple thousand times.