johnnyfive-i2c.md

Basic Johnny Five example

This example uses johnny five to control a neopixel strip using an I2C backpack.

To install the I2C backpack, see the Installation Guide.

Wiring

Wire the neopixel strip up as shown below. This can be done on any I2C compatible board that Johnny Five supports. This example uses a Raspberry Pi.

The example below uses and arduino Uno.

I2C LED pins

Note that you can't specify the pins to use when using I2C. As such you must start with pin 0 and work upwards from there to 8 max.

Example code

var five = require("johnny-five");
var pixel = require("node-pixel");

var opts = {};
opts.port = process.argv[2] || "";

var board = new five.Board(opts);
var strip = null;

var fps = 20; // how many frames per second do you want to try?

board.on("ready", function() {

    console.log("Board ready, lets add light");

    strip = new pixel.Strip({
        color_order: pixel.COLOR_ORDER.GRB,
        board: this,
        controller: "I2CBACKPACK",
        strips: [8],
    });

    strip.on("ready", function() {

        console.log("Strip ready, let's go");

        var colors = ["red", "green", "blue", "yellow", "cyan", "magenta", "white"];
        var current_colors = [0,1,2,3,4];
        var current_pos = [0,1,2,3,4];
        var blinker = setInterval(function() {

            strip.color("#000"); // blanks it out

            for (var i=0; i< current_pos.length; i++) {
                if (++current_pos[i] >= strip.length) {
                    current_pos[i] = 0;
                    if (++current_colors[i] >= colors.length) current_colors[i] = 0;
                }
                strip.pixel(current_pos[i]).color(colors[current_colors[i]]);
            }

            strip.show();
        }, 1000/fps);
    });
});

Running

To run the example:

node examples/johnnyfive-i2c.js

You can optionally pass a port in as a parameter.