🛠 Bouton poussoir et messages dans la console

Objectives

Wire a push button, understand the internal pull-up, and display a message in the console on each press. You will write two versions: polling and event-driven, the latter being the method recommended by the official gpiozero documentation.

Materials

• Raspberry Pi 4B, breadboard, Dupont cables
• 1 push button, 1 LED, 2 330-ohm resistors
• python3-gpiozero (pre-installed on the desktop, otherwise sudo apt install python3-gpiozero)

Complete Code

#!/usr/bin/env python3
# bouton.py - GPIO17 (broche 11) -> 330R -> LED -> GND ; GPIO27 (broche 13) <- bouton <- GND
from gpiozero import LED, Button
from signal import pause

led = LED(17)                       # sortie active a l'etat haut
btn = Button(27, pull_up=True)      # pull-up interne, appui actif a l'etat bas

while True:
    if btn.is_pressed:
        print("Bouton appuye !")
        led.on
    else:
        led.off

# Version evenementielle recommandee :
# btn.when_pressed = led.on
# btn.when_released = led.off
# pause

Expected Verification

Run python3 bouton.py then press the button: the message "Bouton appuye !" is displayed and the LED lights up; it turns off when released. Ctrl+C terminates the script cleanly.

Common Errors

• Forgetting the pull-up (internal or 10 kOhm external): the input floats and displays phantom presses.
• Wiring the button to 3.3 V instead of GND: with the pull-up active, the button must connect to GND when pressed.
• Missing pull_up=True in the code while the wiring assumes an external pull-up.
• Tight polling loop that consumes an entire CPU core: prefer when_pressed and pause.
• Confusion between physical/BCM pin numbering: pin 13 = GPIO27, pin 11 = GPIO17.