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Illegal- 1010- and 1111-exception on perfectly legal instructions

Question asked by Rob Platt on Mar 11, 2013
Latest reply on Jan 4, 2015 by Rob Platt

We are seeing random Illegal- 1010- and 1111-exception on what  i expect to be perfectly legal instructions with a 68EN360

the code is running out of FLASH (29F800 or similar)

In our exception handler I read the instruction at the faulted program counter so I can compare. It always matches.

 

I considered a wrong jump to the middle of a 3-word instruction, but I have also seen it in the middle of a series of several simple 1-word instructions (Simple register moves, register arithmetic etc.). I have also seen F-line emulation exceptions on instructions that don't begin with Fxxx.

Additionally oddly, the problem appeared after a SW update, disappeared after a later update, and then came back again with the update after.

 

We have had the occassional buserror due to bad pointers and very obvious illegal instructions due to a return from a corrupted stack, these we mostly identified the problem more or less immediately.

 

This one really has us stumped, and we are under strong pressure to fix it in our software.

 

I wonder if it is related to https://community.freescale.com/message/87784#87784

Any ideas please?

 

regards,

L di/dt

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