🛠 Détecter l'inclinaison et les gestes avec l'accéléromètre

Objectives

Use the onboard combined accelerometer + magnetometer sensor (ST LSM303, or NXP FXOS8700CQ depending on the manufacturing batch) to read tilt (x, y, z in milli-g) and recognize official gestures: shake, tilt up/down/left/right, face up/down, freefall.

Hardware

• 1 micro:bit V2 board
• 1 micro-USB cable for flashing, then autonomous operation on battery

Complete code

from microbit import *

while True:
    # Inclinaison continue : flèches directionnelles
    if accelerometer.get_y < -300:      # penché vers le haut
        display.show(Image.ARROW_N)
    elif accelerometer.get_y > 300:     # penché vers le bas
        display.show(Image.ARROW_S)
    elif accelerometer.get_x < -300:    # penché à gauche
        display.show(Image.ARROW_W)
    elif accelerometer.get_x > 300:     # penché à droite
        display.show(Image.ARROW_E)
    # Gestes ponctuels
    elif accelerometer.was_gesture('shake'):
        display.show(Image.YES)
        sleep(400)
    elif accelerometer.is_ready:
        display.show(Image.HAPPY)
    sleep(50)

get_x/get_y/get_z return acceleration in milli-g (at rest, the downward-facing axis indicates approximately 1000). The ±300 thresholds prevent false triggers.

Expected verification

Tilt the board: an arrow points in the direction of movement. Shake it: the "yes" checkmark appears. Laid flat: a smiley face. Everything works when unplugged.

Common errors

• Comparing against thresholds that are too small (< 100): the display flickers constantly due to sensor noise.
• Confusing was_gesture (instantaneous, clears history) with current_gesture (continuous state).
• Swapping the x/y axes depending on how you hold the board: test before writing the thresholds.
• Expecting the magnetometer here: the compass is handled at the intermediate level.