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Learning Javascript Robotics

By : Kassandra Perch

4.3 (6)

Learning Javascript Robotics

4.3 (6)

By: Kassandra Perch

Overview of this book

There has been a rapid rise in the use of JavaScript in recent times in a variety of applications, and JavaScript robotics has seen a rise in popularity too. Johnny-Five is a framework that gives NodeBots a consistent API and platform across several hardware systems. This book walks you through basic robotics projects including the physical hardware builds and the JavaScript code for them. You'll delve into the concepts of Johnny-Five and JS robotics. You'll learn about various components such as Digital GPIO pins, PWM output pins, Sensors, servos, and motors to be used with Johnny-Five along with some advanced components such as I2C, and SPI. You will learn to connect your Johnny-Five robots to internet services and other NodeBots to form networks. By the end of this book, you will have explored the benefits of the Johnny-Five framework and the many devices it unlocks.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Getting Started with JS Robotics

1. Getting Started with JS Robotics

Understanding JS Robotics, NodeBots, and Johnny-Five

Setting up your development environment

Hello, World! – Blinking an onboard LED

Summary

2. Working with Johnny-Five

2. Working with Johnny-Five

What you'll need for this chapter

How a Johnny-Five program works

Understanding events in Johnny-Five

Wiring up an external LED

Using the Read-Eval-Print-Loop (REPL)

Summary

3. Using Digital and PWM Output Pins

3. Using Digital and PWM Output Pins

What you'll need for this chapter

How GPIO pins work

Multiple pins with several LEDs

Using PWM pins with the Piezo element

Summary

4. Using Specialized Output Devices

4. Using Specialized Output Devices

What you'll need for this chapter

Outputs that require multiple pins

Checking compatibility with Johnny-Five

Obtaining documentation, wiring diagrams, and so on

Project – character LCD display

Summary

5. Using Input Devices and Sensors

5. Using Input Devices and Sensors

What you'll need for this chapter

How analog input pins work

Johnny-Five sensor events

Using basic inputs – buttons and potentiometers

Using sensors – Light and Temperature

Summary

6. Moving Your Bot

6. Moving Your Bot

What you'll need for this chapter

The different kinds of servos and motors

Special concerns when using motors and servos

Wiring up servos and motors

Creating a project with a motor and using the REPL

Creating a project with a servo and a sensor

Summary

7. Advanced Movement with the Animation Library

7. Advanced Movement with the Animation Library

What you'll need for this chapter

What is the Animation API?

Looking at the Animation API

Writing Servo Animations

Animation events

Summary

8. Advanced Components – SPI, I2C, and Other Devices

8. Advanced Components – SPI, I2C, and Other Devices

What you'll need for this chapter

Why do we need the I2C and SPI protocols?

Exploring SPI (Serial Peripheral Interface) devices

Exploring I2C devices

External Devices

Summary

9. Connecting NodeBots to the World, and Where to Go Next

9. Connecting NodeBots to the World, and Where to Go Next

What you'll need for this chapter

Connecting NodeBots to the Web

Johnny-Five and the wide world of microcontrollers

Other JS libraries and platforms

Where to go from here

Index

Index

Using the Read-Eval-Print-Loop (REPL)

The Read, Eval, Print Loop, or REPL, is a concept relative to many scripting languages, but it is new to libraries, and definitely new to robotics. Think about how you alter the state in a typical Arduino program: you modify the source code, re-load it onto the board, and wait for it to run.

However, due to the way Johnny-Five works, we can modify the state of our robot code while the code is running. This is because we use Firmata—the board is just a thin client that reacts to instructions from our node program, so if we let our Node programs send different instructions, we can change how our robot works in real time.

The way to do this in a Johnny-Five program is by injecting components into the REPL, which allows us to use them.

Making components available to the REPL

We're going to modify our script from the previous section in order to manipulate our LED. To do this, we're going to use the this.repl.inject() function. The this keyword...

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