RE: MPC860 CP / CPM Misbehaving

descriptors (BDs) from the CPM with the OV bit set (bit 14 of the RxBD
status/control field, "Overrun. Set when a receiver overrun 
occurs during
reception").

Check the following:

- SDRAM setup. If ORx(BIH)=1 makes the problem go away, your burst setup or the /TA pullup is broken. NB: Neither the SCC nor the SMC do bursts.
- Check pullups as per UM recommendation. I tend to recommend 1k.
- Did you by accident happen to enable any IDMA lines?
- Did you happen to misconfigure RCCR(DRxM)?
- Did you happen to misconfigure the SDCR?

One other thing. If you have an old BDM debugger *and* if the problem occurs *only* with the BDM debugger hooked up, you may want to check for an update or replacement. Old debuggers sometimes used a method to do BDM which could stall the DMAs in the machine and cause this kind of overrun/underrun effect.

Heinz