Sorry if this has been asked before, but I searched for a while and didn't find anything that exactly answered my question.
I would like to sense the "dummy lights"(oil, neutral, etc.) in my motorcycle with my mBed. The bike runs of a 12v battery and the mBed senses at 3.3v. Now I know I can use a step-down to sense the output, but because it's a noisy system don't I want to use a optoisolator?