rpi-ws281x/README.md

rpi-ws281x

# 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

````bash
$ npm install rpi-ws281x --save
````


## Usage

````javascript

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

````javascript

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

````javascript

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

````javascript

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();

````