🛠 LED et bouton avec libgpiod sur le port 40 broches

Objectives

The BPI-M2 Zero features a 40-pin connector whose pinout matches that of the Raspberry Pi (Zero W cases and hats fit), but the pins belong to Allwinner banks: gpiochip0 covers banks A to E (PA6 = pin 7, already wired as PWM1 by default) and gpiochip1 covers the R_PIO PL bank (PL2 = pin 32, PL4 = pin 36; PL10 drives the red power LED). You will blink an LED and read a button using libgpiod tools, without any proprietary library.

Hardware

• BPI-M2 Zero running Armbian (mainline kernel)
• LED + 330 Ω resistor between pin 7 (PA6) and a GND pin (the logic level is 3.3 V, never apply 5 V to a pin)
• Push button between pin 32 (PL2) and pin 6 (GND)
• Breadboard and Dupont wires

Complete code

sudo apt update && sudo apt install -y gpiod

# Repérer les puces et le nom des lignes du connecteur (CON2-Pxx)
gpiodetect
gpioinfo gpiochip0 | grep -e CON2-P07 -e CON2-P11

# PA6 est PWM1 par défaut : libérer la broche si un overlay pwm la revendique
sudo armbian-config    # System > Hardware > décocher_pwm/pwm-user, puis reboot

# Clignoter 10 fois sur PA6 (broche 7), impulsions de 500 ms
for i in $(seq 10); do
  gpioset -c gpiochip0 PA6=1 --time 500ms
  sleep 0.5
done

# Écouter le bouton sur PL2 — attention : banque PL = gpiochip1 !
gpiomon --num-events 5 --rising-edge gpiochip1 PL2

Expected verification

The LED blinks ten times; gpiomon displays one event per press (rising-edge thanks to the internal pull-up or wiring to GND); gpioinfo shows the PA6 line as "requested" during the gpioset command. The red PWR LED (PL10) remains permanently lit, it is not the test LED.

Common errors

• Looking for PL2 on gpiochip0: the R_PIO bank is a second controller, gpiochip1 — gpiodetect shows this.
• Forgetting that PA6 is claimed by the PWM driver: gpioset fails until the overlay is disabled (or use a free pin).
• Sending 5 V to a logic pin: the connector provides 3.3 V logic, the pins are not 5 V tolerant everywhere.
• Running gpioset without permissions: use sudo or add the user to the gpio group.
• Confusing the numbering: here we name the lines (PA6, PL2), not the wiringPi indices which differ depending on the forks.