[dcb]

Anything running an atmega168 @ 16mhz is code compatable. I am currently favoring the iduino for $18 with onboard USB, but the diagrams are for the good old arduino/freeduino platform.

re inputs, can you explain why you believe the Zeners (which is a common form of circuit protection) cannot protect in this instance? Have you looked at the signal reaching the chip in a vehicle with an oscope? Have you compared the chip specs and the zener specs and applied the anticipated vehicular signals? What is that statement based on again?

The problem I have with optos is that they do add to the cost/complexity, and a zener is incredibly easy to assemble for the Do-It-Yourselfer. I'd like these to work the first time people put them together. I started with a transistor isolator myself, but managed to mess it up somehow, so I would imagine that every complication we add to the circuit will mean more folks who assemble their own will also encounter complications and frustration. This is a DIY that is trying to be as simple as possible for the largest diy audience as possible (no code changes just cut and paste the code, minimal circuitry and expense). So I request actual proof behind the statements requesting a change.