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NeoPixel Rainbow Chaser

NeoPixel Rainbow Chaser

Simulate individually addressable RGB strips. This project demonstrates how to orchestrate a 12-LED WS2812B strip to create a moving color chaser effect using the high-level Intarva SDK.

Project Goal: Drive a 12-LED NeoPixel strip on GP15. The logic generates a random RGB value and “chases” it down the strip, clearing previous pixels as it advances.

1. Wiring Blueprint

From Component NeoPixel Pin Pico Pin Notes
WS2812B StripDINGP15Single-wire Data In
WS2812B Strip5V / VCCVBUSPower Rail (5V)
WS2812B StripGNDGNDCommon Ground

2. JavaScript Implementation

This project leverages the native NEOPIXEL_WRITE event for high-performance color updates.

JavaScript (SDK) 
import intarva, { Pin, sleep } from 'intarva';

async function main() {
    const NUM_LEDS = 12;
    const dinPin = 'GP15';

    // High-Level SDK Helper for NeoPixel Arrays
    function show(colors) {
        intarva.native.emit('NEOPIXEL_WRITE', {
            pin: dinPin,
            colors: colors
        });
    }

    let currentLed = 0;

    // Generate random [R, G, B] color
    function getRandomColor() {
        return [
            Math.floor(Math.random() * 256),
            Math.floor(Math.random() * 256),
            Math.floor(Math.random() * 256)
        ];
    }

    while (true) {
        const stripColors = [];
        const activeColor = getRandomColor();

        for (let i = 0; i < NUM_LEDS; i++) {
            stripColors.push(i === currentLed ? activeColor : [0, 0, 0]);
        }
        
        show(stripColors);
        
        currentLed = (currentLed + 1) % NUM_LEDS; // Chaser cycle
        await sleep(150); // Speed control
    }
}

main().catch(err => console.error(err));