`clignotante.py`

ODROID-N2 / ODROID-N2+ (Hardkernel) · 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

An ODROID-N2 (Amlogic S922X, 4 Cortex-A73 + 2 Cortex-A53, 2-4 GB) running Ubuntu Hardkernel or Armbian, with gigabit Ethernet and an eMMC socket. 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.

Running it

On Ubuntu Hardkernel or Armbian: apt install gpiod python3-gpiod; on Amlogic the header sits behind the gpiochip1 chip (confirm with gpiodetect/gpioinfo).

Variants

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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