🛠 Lire un bouton poussoir et afficher l'état dans la console

Objectives

Wire a push button to the 40-pin connector of the Orange Pi 3B, read its state from the command line using gpioget, and display each state change in the console.

Hardware

• Orange Pi 3B running Armbian, 5 V / 3 A power supply
• 1 push button, 1 10 kΩ resistor (pull-up to 3.3 V), Dupont cables
• gpiod package installed (sudo apt install gpiod)

Complete code

# 1. Lecture ponctuelle de la broche (gpioget la configure en entrée)
sudo gpioget -c gpio1 35          # 0 ou 1 selon l'état du bouton

# 2. Journal des appuis dans la console
#!/bin/bash
# fichier : bouton.sh  ->  bash bouton.sh
CHIP=1
PIN=35   # gpio1_b3 en exemple : vérifier une broche libre sur le plan officiel
dernier=""
while true; do
  etat=$(sudo gpioget -c gpio$CHIP $PIN)
  if [ "$etat" != "$dernier" ]; then
    echo "$(date +%T) - bouton = $etat"
    dernier=$etat
  fi
  sleep 0.05
done

Expected verification

At rest, gpioget returns 1 (pull-up to 3.3 V); when the button is pressed, it returns 0. The script displays a timestamped line for each state change, both on press and release.

Common errors

• Forgetting the pull-up resistor and leaving the pin floating: the state will then display random values. The internal libgpiod pull (bias) also works, but the hardware pull-up is more educational.
• Choosing a pin that is already in use (UART, or the I2C pins 3/5 of the connector).
• Confusing logic 0 with the button being pressed: with a pull-up + button to ground, the logic is active-low (inverted).
• Running the script without sudo: GPIO lines are reserved for the gpio group if udev is not configured.
• Mechanical bounce: a single press may produce multiple lines; filter them with sleep 0.05 or a software debounce.