byte enc1oldPins = 0; // will hold state of pins last time encoder was read byte enc2oldPins = 0; byte enc1newPins = 0; // will hold new encoder pin reading, to be compared with last time's pin states ...

For example, HP inkjet printers have a quadrature encoder that consists of 150 lines per inch ruled on a mylar strip. So that is a line about 1/300 inch wide followed by a space about 1/300 inch.

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.

“Roendi (Rotary Encoder with Display) features a STM32L433 MCU, 1.28″ TFT round display and a Alps Alpine 15Pulses/30Detent encoder. It can be programed either using ST-LINK/V2 or Arduino IDE ...