Raspberry Pi Pico Interfacing with Rotary Encoder

This project integrates a rotary encoder with a Raspberry Pi Pico to detect angular rotation and momentary switch presses using MicroPython. A rotary encoder contains internal mechanical contacts—specifically, two quadrature outputs (often labeled A and B) and a common ground, alongside an integrated push button. As you turn the shaft, the A and B terminals generate a sequence of square wave pulses. By monitoring the phase relationship between these two signals, the Pico's GPIO pins can determine both the exact direction of rotation (clockwise versus counter-clockwise) and the relative speed of the turn. The specialized rotary_irq_rp2 library handles the low-level interrupt service routines required to capture these rapid state transitions reliably without missing steps. Simultaneously, the encoder's push-button mechanism functions as a standard tactile switch: pressing the shaft closes a circuit to ground, pulling a designated Pico GPIO pin LOW, which can be registered as a discrete click or selection input. Connected via a breadboard and jumper wires, the Pico reads these quadrature states and button closures in real time, processing the input data to control variables such as numerical values, menu navigation states, or system parameters.