MPC850 - Intermittent Machine Check Exception

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Has anyone had any experience with intermittent machine check
exceptions on the MPC850 ?
According to the MPC850's registers it fails on one particular
instruction fetch (to SDRAM using UPMA) which is called by a branch
instruction
However our test equipment shows that it never gets to this
instruction fetch as there is a phantom attempted transfer on the bus
with a non existent address and a TS* issued but no chip selects
this phantom transfer times out after the bus monitor time due to no
TA* - causing a machine check

Note that this code usually runs fine and only fails occasionally

I've checked through the Chip Errata but can't find anything that
relates to this problem

Anyone got any ideas or know what could be causing the phantom
transfers

Thanks in anticipation
Dave P.

Re: MPC850 - Intermittent Machine Check Exception
I'm still pretty new to this but what about the watchdog timer and bus
monitor?
Those my not cause the machine check exceptions but I thought I would just
through this out
since I had problems with these.

Wayne

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