rpi-ws281x

This is a npm module for connecting a Raspbery Pi to Neopixel strips. It uses the library from jgarff https://github.com/jgarff/rpi_ws281x.

Installation

$ npm install rpi-ws281x --save

Usage

var ws281x = require('rpi-ws281x');

// One time initialization
ws281x.configure({leds:16});

// Create my pixels
var pixels = new Uint32Array(16);

// Render pixels to the Neopixel strip
ws281x.render(pixels);

Methods

This module is simple and only has three methods configure(), render() and reset().

• configure(options) - Configures the ws281x strip. Must be called once and before anything else. See examples below.
• render(pixels) - Renders the pixels specified to the strip. The pixels parameter must be an Uint32Array representing the color values of all pixels and the same size as the number of leds specified when configuring.
• reset() - Resets configuration.
• sleep(ms) - Sleeps for the specified number of milliseconds.

Examples

Filling the Neopixel strip with a color

var ws281x = require('rpi-ws281x');

class Example {

    constructor() {
        this.config = {};

        // Number of leds in my strip
        this.config.leds = 169;

        // Use DMA 10 (default 10)
        this.config.dma = 10;

        // Set full brightness, a value from 0 to 255 (default 255)
        this.config.brightness = 255;

        // Set the GPIO number to communicate with the Neopixel strip (default 18)
        this.config.gpio = 18;

        // The RGB sequence may vary on some strips. Valid values
        // are "rgb", "rbg", "grb", "gbr", "bgr", "brg".
        // Default is "rgb".
        // RGBW strips are not currently supported.
        this.config.stripType = 'grb';

        // Configure ws281x
        ws281x.configure(this.config);
    }

    run() {
        // Create a pixel array matching the number of leds.
        // This must be an instance of Uint32Array.
        var pixels = new Uint32Array(this.config.leds);

        // Create a fill color with red/green/blue.
        var red = 255, green = 0, blue = 0;
        var color = (red << 16) | (green << 8)| blue;

        for (var i = 0; i < this.config.leds; i++)
            pixels[i] = color;

        // Render to strip
        ws281x.render(pixels);
    }

};

var example = new Example();
example.run();

Walking a pixel through the strip

var ws281x = require('rpi-ws281x');

class Example {

    constructor() {
        // Current pixel position
        this.offset = 0;

        // Set my Neopixel configuration
        this.config = {leds:169};

        // Configure ws281x
        ws281x.configure(this.config);
    }

    loop() {
        var pixels = new Uint32Array(this.config.leds);

        // Set a specific pixel
        pixels[this.offset] = 0xFF0000;

        // Move on to next
        this.offset = (this.offset + 1) % this.config.leds;

        // Render to strip
        ws281x.render(pixels);
    }

    run() {
        // Loop every 100 ms
        setInterval(this.loop.bind(this), 100);
    }
};

var example = new Example();
example.run();

Walking a pixel with pixel mapping

var ws281x = require('rpi-ws281x');

class Example {

    constructor() {
        // Current pixel position
        this.offset = 0;

        // Set my Neopixel configuration
        this.config = {};

        // By setting width and height instead of number of leds
        // you may use named pixel mappings.
        // Currently "matrix" and "alternating-matrix" are
        // supported. You may also set the "map" property
        // to a custom Uint32Array to define your own map.
        this.config.width = 13;
        this.config.height = 13;
        this.config.map = 'alternating-matrix';

        // Configure ws281x
        ws281x.configure(this.config);
    }

    loop() {
        var leds = this.config.width * this.config.height;
        var pixels = new Uint32Array(leds);

        // Set a specific pixel
        pixels[this.offset] = 0xFF0000;

        // Move on to next
        this.offset = (this.offset + 1) % leds;

        // Render to strip
        ws281x.render(pixels);
    }

    run() {
        // Loop every 100 ms
        setInterval(this.loop.bind(this), 100);
    }
};

var example = new Example();
example.run();