`clignotante.py`

BeagleBone Black (TI Sitara AM3358) · File : clignotante.py · Language : Python · Use case : Faire clignoter une LED depuis un script Python

The getting-underway script on an SBC: an LED on the GPIO header blinks at 1 Hz. python3-gpiod drives the GPIO chip straight through the kernel, with no proprietary library.

Hardware required

A BeagleBone Black (TI AM3358) on the official Debian image, powered by 5 V mini-USB, with its 3.3 V P8/P9 headers (never put 5 V on the pins!). 1 LED + 330 Ω resistor (the pins are 3.3 V on all these boards).

Wiring

LED anode on the chosen GPIO pin (see the board schematic and gpioinfo) through 330 Ω, cathode to GND.

How it works

The script sets the pin as output, alternates high/low with sleep(1), and cleanly releases the pin (finally) even on Ctrl-C. On Debian: sudo apt install gpiod python3-gpiod; the P8/P9 pins are devicetree-named (gpioinfo). Analog inputs AIN0-6 sit on P9 (1.8 V max, via IIO).

Going further

Replace sleep with a pattern (PWM ramp via gpiozero PWM / gpiod + threads), or wire several LEDs in a ring.

clignotante.py

#!/usr/bin/env python3
# Clignotement LED avec python3-gpiod (API 1.x, Debian/Armbian).
# Installation : sudo apt install python3-gpiod gpiod
# Puce disponible : gpiodetect ; broches : gpioinfo <puce>
import gpiod
from time import sleep

PUCE = "gpiochip1"   # a verifier avec gpiodetect (varie selon la carte)
LIGNE = 17           # numero GPIO du schema de la carte

chip = gpiod.Chip(PUCE)
line = chip.get_line(LIGNE)
line.request(consumer="clignotante", type=gpiod.LINE_REQ_DIR_OUT,
             default_val=0)

print("Clignotement (Ctrl-C pour arreter)")
try:
    while True:
        line.set_value(1)
        print("LED ON")
        sleep(1)
        line.set_value(0)
        print("LED OFF")
        sleep(1)
finally:
    line.release()

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