Quote Originally Posted by devmonkey View Post
Question for Doddy,

I've scoped the common mode noise and it isn't sufficient to cause a phantom step to be read at the 328p. I think the phantom steps I was detecting that I have 'fixed' by debouncing the read are actually being caused by reflections and/or induced voltage spikes as the differential pair switches. If this is correct placing a termination resistor across the pair as you do for rs485 should help do you concur?

Cheers, Joe
I guess you know a bit about signal theory - you're trying to match the characteristic impedance of the transmission line at both ends - just randomly throwing resistors on won't be as effective as a properly matched terminator - and yes, as per 485. What's the driving system?, have a look at that and match it.