A rotary encoder is a device that senses the rotation and direction of an attached knob. It works by having 2 internal contacts that make and break a circuit as the knob is turned. As you turn the knob you can feel it “click” indicating that one position has been rotated. If the internal contacts were originally HIGH (or making the circuit) after a single click, they would now both be LOW (breaking the circuit). With a simple bit of logic, you can work out the direction of the rotation!

This Keyes Rotary Encoder breakout board is neatly pre-soldered and comes with attached and labelled header pins for easy interfacing. The board also features built in 10k resistors, which means it can be wired directly to the Raspberry Pi GPIO pins without fear of causing damage. We recommend you use the 3V3 pins for best results!

KY-040 rotary encoder is a device that generates an electrical signal based upon how much the
rotary input device (knob) is rotated and the direction it is rotating in. It is a position sensor with a knob and can be used to control stepper or servo motors with precision.