Using an MCP23017 Expander as a Virtual Board (16 Pin Digital IO). Pins 15-17 are used to set the I2C hardware address. By default, these pins must be connected to ground. See page eight of the data sheet

Breadboard for "Expander - MCP23017"


Fritzing diagram: expander-MCP23017.fzz


Run this example from the command line with:

node eg/expander-MCP23017.js
const { Board, Expander, Leds } = require("johnny-five");
const board = new Board();

board.on("ready", () => {
  const virtual = new Board.Virtual(
    new Expander("MCP23017")

  const leds = new Leds(
    Array.from(Array(8), (_, i) =>
      ({ pin: i * 2, board: virtual })




Component Classes in this example:

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