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adafruit_debouncer

Works with

Any CircuitPython board.

What it does

When a physical button is pressed, the metal contacts briefly bounce — making and breaking contact many times in a few milliseconds before settling. To a microcontroller running thousands of iterations per second, that looks like the button being pressed dozens of times.

The Debouncer library filters out that noise. It watches an input and only reports a state change after the signal has been stable for a short time (5ms by default).

The two properties you'll use most:

  • fell — True for exactly one loop iteration when the pin goes from True to False (button pressed, with pull-up)
  • rose — True for exactly one loop iteration when the pin goes from False to True (button released)

Installing the library

Copy this to the lib/ folder on your CIRCUITPY drive:

adafruit_debouncer.mpy

Available in the Adafruit CircuitPython Bundle.

Quick start

import board
import digitalio
import time
from adafruit_debouncer import Debouncer
from digitalio import Pull

# Set up the raw pin
raw = digitalio.DigitalInOut(board.D2)
raw.direction = digitalio.Direction.INPUT
raw.pull = Pull.UP

# Wrap it in a Debouncer
button = Debouncer(raw)

while True:
    button.update()  # must call this every loop

    if button.fell:
        print("Button pressed")

    if button.rose:
        print("Button released")

button.update() must be called every loop iteration. That's where the debouncing happens.

Key things you can do

What you want How to do it
Detect a press (pull-up wiring) if button.fell:
Detect a release if button.rose:
Read the current stable state button.value
Check how long it's been held button.current_duration — time in seconds since last change
Check duration of last state button.last_duration
Change the debounce interval Debouncer(raw, interval=0.010) — default is 0.005s
Debounce a lambda instead of a pin Debouncer(lambda: some_condition)

Reading the official docs

Full API reference including duration tracking: https://docs.circuitpython.org/projects/debouncer/en/latest/

Projects using this library