This is a repackaged version of Ben Buxton's excellent rotary library organized for the Arduino 1.x IDE, keyword highlighting, polling example, Arduino library capitalization conventions.

For example, a pair of 100nF capacitors from ground to pin A and B works well enough for me. This project also works with higher-resolution rotary encoders such as the LPD3806. Note that (at least for ...

Hooked to an Arduino, the motor made a workable encoder, later improved by sending each phase through a comparator and using digital inputs rather than using the Nano’s ADCs.

I needed a rotary encoder — I pulled a cheap one out of one of those “49 boards for Arduino” kits you see around. Not the finest encoder in the land, I’m sure, but it should do the job.