🛠 Premier script Python : faire clignoter la LED

Objectives

Issue commands to programs: write, run, and cleanly stop a first Python 3 script that blinks the LED from tutorial 1, using the RPi.GPIO library still provided on legacy images (ARMv6).

Hardware

• Raspberry Pi Model B+ running 32-bit Raspberry Pi OS legacy
• LED + 330 Ω resistor wired to GPIO17 (pin 11) and GND (pin 14), as in tutorial 1
• Keyboard/HDMI screen or SSH session over the B+'s Ethernet

Complete code

# Installation de la bibliothèque GPIO pour Python 3
sudo apt update && sudo apt install -y python3-rpi.gpio
nano blink.py   # coller le script ci-dessous, puis Ctrl+O, Ctrl+X
sudo python3 blink.py

#!/usr/bin/env python3
"""Clignotant LED sur GPIO17 (broche 11) — Raspberry Pi Model B+."""
import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)          # on raisonne en numérotation BCM
GPIO.setup(17, GPIO.OUT)
try:
    for _ in range(10):         # 10 clignotements
        GPIO.output(17, GPIO.HIGH)
        time.sleep(0.3)
        GPIO.output(17, GPIO.LOW)
        time.sleep(0.3)
finally:
    GPIO.cleanup              # rend la broche propre à la sortie

Expected verification

The LED blinks 10 times (0.3 s on / 0.3 s off) then the script terminates without any message. Ctrl+C interrupts the program and still triggers GPIO.cleanup thanks to the finally block.

Common errors

• Forgetting sudo: RPi.GPIO raises an exception "No access to /dev/gpiomem".
• Missing setmode or confusing BCM/BOARD: "Please set pin numbering mode" or silent LED.
• Using python (Python 2) instead of python3 on a recent image: module not found.
• Script launched twice: the pin is already in use, close the other terminal.