Learning JavaScript Robotics

A NodeBot is any piece of hardware that is controlled using JavaScript and/or Node.JS. This can encompass a wide variety of projects; there are hundreds of ways to create a NodeBot. In this book, we are going to use the Johnny-Five library, an open source project created by Rick Waldron.

We're going to use a microcontroller for our projects. What microcontroller should you use? Luckily, our use of Johnny-Five means that we can choose from a large array of different microcontrollers and still write the same code as you'll see in this book!

What exactly is Johnny-Five, and how does it make our lives easier?

Johnny-Five (http://johnny-five.io) is an open source robotics library for Node.JS. It was created by Rick Waldron and has a thriving community of contributors and supporters. This module has been known to work on Windows, Mac, and Linux computers without any issues at the time of writing this book using Node.JS version 4.x.

Johnny-Five was built on top of node-serialport and allows us to write JavaScript applications that communicate with different microcontrollers using different types of connection. For some microcontrollers, such as Arduino-compatible boards, Johnny-Five uses a serial connection. For some newer boards, Johnny-Five emulates this serial connection over an Internet service!

The capability of Johnny-Five to use multiple board types is implemented using its wrapper system. Once the core system is installed, you can install a wrapper for your particular microcontroller, and the APIs will remain the same. This is a powerful concept—you can write code for one platform and quickly move it to another without having to change it.

For the examples in this book, we'll use an Arduino Uno board. You can get these boards from sites such as Adafruit (www.adafruit.com), SparkFun (www.sparkfun.com), and so on. You can also use a board that is Arduino Uno-compatible. SainSmart, for instance, sells Uno-like boards that will work fine for our purposes. For this chapter, you'll need the board itself and a USB cable for it.

In later chapters, we'll be using other components—there will be a table in each chapter with an accessible list of materials for the projects within.

If you don't have Node.JS already installed, you can download an installer for your platform from nodejs.org. This installer will also install NPM or Node Package Manager, which will be used to manage the rest of the software that we'll be using.

Run the installer on your machine, which may require a restart. After this, open up your terminal application and run the following command:

node –-version

The output from this command should be 4.x.x, where x are integers.

In your terminal, create a folder for your project and change directories to this folder:

mkdir my-robotics-project
cd my-robotics-project

Next, we're going to install Johnny-Five:

npm install johnny-five

You should see a spinner, followed by some output. Unless you see an ERR NOT OK message at the end of your output, you're good to go with Johnny-Five.

First, you should get the Arduino IDE. Yes, we are still using JavaScript; however, we must make sure that there's a particular sketch (that's Arduino-speak for program) running on our board in order for Johnny-Five to communicate properly.

You can get the installer at the Arduino website (http://www.arduino.cc/en/Main/Software). This book assumes that you have version 1.6.4, but the versions in the 1.4 range should work as well.

Once you've downloaded the software, open it. Then, we'll make sure that your serial connection works.

Plug the USB cable into both the board and the computer. A few LEDs should light up on this board—this is normal. Then, go to the Tools menu in the Arduino IDE and hover over the ports submenu. You should see a list of ports that looks somewhat like the following screenshot:

You should see at least one entry in this list that fits the following format: /dev/cu.usbmodem*****. It may or may not have Arduino Uno next to it. If you see this, go ahead and click on it, because this is the port you will want to use for the Firmata installation. If you have this, it means your board can communicate with your computer, and you're ready to install Firmata.

To install Firmata on your board, go to File | Examples | Firmata | StandardFirmata, as shown in the following screenshot:

Once you've opened the sketch, you should get an IDE window that looks like the following screenshot:

Once this sketch is up, click on the Upload button (it looks like an arrow pointing to the right) to upload Firmata to your board. Once the uploading is done, you can close the Arduino IDE, and you will be ready to start working with JavaScript.

In your favorite IDE, create a new hello-world.js file in your project directory. Then, copy and paste, or write, the following code:

var five = require("johnny-five");
var board = new five.Board();

board.on("ready", function() {
  var led = new five.Led(13);
  led.blink(500);
});

We'll go over more of what this script does in Chapter 2, Working with Johnny-Five, but the basic overview is this: we require this script in the Johnny-Five module and use it to create a new board object. When this board is ready, we will create an LED object at pin 13 (this pin is wired to the onboard LED on an Arduino Uno board). We then program this LED to blink every half second.

In order to run the script, go to your terminal, and in your project folder, run the following:

node hello-world.js

You should see an output that looks like the following:

You should see an LED blink on your Arduino Uno. The following figure shows where the LED is on the board:

If all is well and the LED is blinking, congratulations! You're ready to start building robots and applications with Arduino and Johnny-Five!