neopixel.py
A white head followed by a red trail moves along a 12-LED NeoPixel (WS2812B) strip, driven natively by MicroPython through machine.NeoPixel. Each LED gets its color in a single frame sent by write().
Hardware
A Raspberry Pi Pico 2 (RP2350 dual Cortex-M33 @ 150 MHz) with MicroPython installed, powered over USB. 1 strip/ring of 12 NeoPixel (WS2812B) LEDs; external 5 V supply recommended.
Wiring
Data (DIN) to GP16 (330 Ω resistor advised), VCC to external 5 V, GND tied to the board.
How it works
ruban[i] = (R, G, B) writes into the buffer; write() generates the unique pulse sequence that addresses each LED. The % modulo wraps the head around.
Running it
Install the « Pico 2 » MicroPython build (hold BOOTSEL, plug USB, drop the .uf2), then copy the script via Thonny. Auto-starts when named main.py.
Variants
Use several NeoPixel objects on different pins for two strips, or animate colors with a sinusoidal gradient.
neopixel.py
# Animation sur ruban NeoPixel/WS2812 avec le module machine.NeoPixel.
from machine import NeoPixel, Pin
import time
NB_LED = 12
ruban = NeoPixel(Pin(16), NB_LED) # data sur GP16
tete = 0
while True:
# Eteindre tout puis dessiner la scene.
for i in range(NB_LED):
ruban[i] = (0, 0, 0)
ruban[tete] = (255, 255, 255) # tete blanche
ruban[(tete - 1) % NB_LED] = (200, 0, 0) # comete rouge
ruban[(tete - 2) % NB_LED] = (80, 0, 0) # trainee
ruban.write() # une trame vers les LED
tete = (tete + 1) % NB_LED
time.sleep_ms(80)
# Attention a l'intensite : 12 LED a 255 blanc tirent plus de
# 700 mA. Alimenter le ruban par une source 5 V externe separee.