🛠 Premier script Python sur Raspbian legacy

Objectives

Write, make executable, and run a first complete Python script on the Model B Rev 2: text display, loop, and LED control using RPi.GPIO, the standard library from the Raspbian era.

Hardware

• Raspberry Pi Model B Rev 2 (512 MB), HDMI screen or SSH session, keyboard
• LED + 330 Ω resistor on GPIO17 (P1-11) to GND
• sudo apt install python-rpi.gpio (Raspbian legacy 32-bit, python2; ARMv6 is no longer supported by recent images)

Complete code

#!/usr/bin/env python
# hello_led.py - premier script: bonjour + LED qui clignote sur GPIO17
import RPi.GPIO as GPIO
import time

LED = 17
GPIO.setmode(GPIO.BCM)
GPIO.setup(LED, GPIO.OUT)
print("Bonjour depuis le Raspberry Pi Model B Rev 2 (BCM2835, 512 MB)")
try:
    for i in range(10):
        GPIO.output(LED, GPIO.HIGH)
        print("iteration %d" % (i + 1))
        time.sleep(0.5)
        GPIO.output(LED, GPIO.LOW)
        time.sleep(0.5)
finally:
    GPIO.cleanup
print("Termine.")

Expected verification

nano hello_led.py
chmod +x hello_led.py
sudo ./hello_led.py

The terminal displays the message followed by the ten iterations; the LED blinks for one second per cycle; the script stops on its own and turns off the LED.

Common errors

• Forgetting chmod +x or the shebang #!/usr/bin/env python: "command not found" when launching directly.
• Mixed indentation (spaces/tabs): Python 2 is permissive, Python 3 is not.
• Running without sudo on an image where the gpio group is not configured.
• Missing GPIO.cleanup: the pin remains claimed and the second run fails.