It is from a long time back so things are fuzzy now but here is my recollection. I wanted to determine the source of the corrupted temperature readings but every pin on the MCU were utilized so no easy way to read it out. I noticed one pin was used just for an activity LED so I modified that routine to pump out a serial bit pattern read from a variable. Then I instrumented various parts of the code related to the temperature measurement algorithm to see the earliest point where it was corrupted. I traced it to the interrupt routine that reads the temperature sensor. In investigating that code I modified it slightly which caused the problem to disappear. Experimenting showed that a particular instruction would be the source of the problem. At that point I consulted with the ASIC designer and the confirmed the bug and identified the scope of the issue. Also should add that various debugging hardware like ICE didn&#x27;t work maybe due to timing differences.