Real rotary position encoders use Gray code to prevent slight misalignments and border cases from being a problem. For some people, the term Gray code (named after [Frank Gray], the inventor) isn ...

For each encoder position, there is a different binary output -- shaft position is absolutely determined. Tracks on absolute encoders often are arranged to produce a binary output called Gray code.

There’s a problem with rotary encoders, though: it’s going to use Gray code or something weird, and getting a rotary encoder to work with your code isn’t as easy as a simple button.