Raspberry Pi - Button

#raspberrypi #electronics #tutorial #beginners

A push button looks trivial but trips up a lot of beginners because of two things: floating inputs and mechanical chatter. This walks through wiring a button to a Raspberry Pi and reading its state in Python, using the internal pull-up resistor so you don't need any extra parts beyond the button itself.

The full tutorial, with every detail and the line-by-line code explanation, is on our site: Raspberry Pi - Button

What you need

Raspberry Pi 5
Breadboard-mount Button with Cap
Breadboard-mount Button Kit
Panel-mount Push Button
Push Button Module
Breadboard
Jumper Wires
Screw Terminal Block Shield for Raspberry Pi
Raspberry Pi Prototyping Base Plate & Breadboard Kit
DIYables Sensor Kit (18 sensors/displays)
DIYables USB Type-A to Type-B Cable

Wiring

A button has four pins, but internally they're linked in pairs, so only two are actually independent. Connect one of those two pins to GND and the other to a Raspberry Pi GPIO pin, for example pin 16. For a panel-mount button the idea is the same; if you want tidier connections, a Screw Terminal Block Shield for the Raspberry Pi makes it easier to secure the wires instead of relying on breadboard jumpers.

How it works

Inside the button there are two pins, call them A and B. When the button is not pressed, A and B are disconnected. Pressing the button connects them. Since one pin is wired to GND and the other to a GPIO pin, this turns a mechanical press into an electrical change you can read in code.

Using the Raspberry Pi's internal pull-up resistor on that GPIO pin means the pin reads HIGH when the button is untouched, and LOW the moment it's pressed, with no external resistor needed.

Code

In Python, GPIO.setup() configures the pin as an input with pull_up_down=GPIO.PUD_UP, enabling the internal pull-up. From there, GPIO.input() returns the current state, and because of the pull-up wiring, a LOW reading means the button is pressed. One script just polls and prints the state continuously; a second script is built around detecting the moment of a press rather than just the current level.

raspberry-pi-button.py

"""
This Raspberry Pi code was developed by newbiely.com
This Raspberry Pi code is made available for public use without any restriction
For comprehensive instructions and wiring diagrams, please visit:
https://newbiely.com/tutorials/raspberry-pi/raspberry-pi-button
"""


import RPi.GPIO as GPIO
import time

# Define the GPIO pin connected to the button
BUTTON_PIN = 16

# Set the GPIO mode to BCM
GPIO.setmode(GPIO.BCM)

# Initialize the pushbutton pin as an input with a pull-up resistor
# The pull-up input pin will be HIGH when the switch is open and LOW when the switch is closed.
GPIO.setup(BUTTON_PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP)

try:
    while True:
        # Read the state of the switch/button
        button_state = GPIO.input(BUTTON_PIN)

        # Print out the button's state
        print(button_state)

        # Small delay to avoid unnecessary printing
        time.sleep(0.1)

except KeyboardInterrupt:
    print("\nExiting...")
    # Clean up GPIO settings
    GPIO.cleanup()

Things that go wrong

If you skip the pull-up or pull-down resistor, the input pin floats, meaning it picks up random noise and the value it reports has nothing to do with whether the button is actually pressed. Using the internal pull-up as described avoids this entirely.

The other common issue is chattering: mechanically, a single press can cause the pin to flicker between LOW and HIGH several times in rapid succession, so your code sees multiple presses instead of one. This is a known physical quirk of switches, not a bug in your code.

Full tutorial

The complete tutorial - wiring diagram, code explanation and troubleshooting - is here: https://newbiely.com/tutorials/raspberry-pi/raspberry-pi-button

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