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.