Hi,
There can be many reasons to cause this - COP reset, Illegal instruction, Illegal memory access, etc.
For the trigger mode usage there are 4 modes: - Automatic, - Expert, - Profiling & Coverage, - Disable.
The default mode and the option we suggest to use is the Automatic mode. By this way the tool will manage automatically the trigger function.
More detailed information about the triggers you can find in S12(X) Debugger Manual, chapter 17 On-Chip DBG Module for S12, S12S, S12G, S12P, S12X Platforms"
S12(X) Debugger Manual
Regards,
iggi