Arduino Bounce Debounce Library

Overview

Mechanical switches bounce. When you press a button, the contacts open and close rapidly several times before settling — producing dozens of spurious edge transitions in the first few milliseconds. If your firmware counts rising edges to track button presses, bounce turns one press into many.

The Bounce library solves this by requiring the signal to be stable for a minimum hold time before recognizing a state change. The result: one press, one event.

Usage

#include <Bounce.h>

Bounce button = Bounce(2, 5);  // pin 2, 5ms debounce interval

void loop() {
  button.update();
  if (button.fallingEdge()) {
    // button was pressed — fires exactly once
  }
}

Why This Matters

Debouncing in hardware (RC filter + Schmitt trigger) works but adds cost and PCB space. Software debouncing in a library is free and tunable — adjust the hold time to match the specific switch you’re using. Tactile switches typically need 5–20 ms; toggle switches may need more.