VBot - Arduino based Quadbot

For a Software engineer who is busy writing code all through the day, working on real world objects is really a cool thing to do. Its fun to control the world around you with the code you write. I have been playing with Arduino for quite sometime and have built few hardware hacks based on that. Check out my hardware hacks here. The latest one in that series is VBot. VBot is a four legged robot which can walk, stretch and even dance. Video. There are different ways in which the bot can be controlled. The bot can receive IR signals and can be controlled using an IR remote. I have also built an Android app for controlling the bot. I have ported the firmware to JavaScript and there is a REPL interface to control to the bot from Node.js app. Fork the project on github. This project has increased my interests on hardware hacks significantly. Hoping to do more in the coming months. 

-- Varun

Arduino tweet notifier built with Johnny-Five!

If you have been following this blog, or following me(@varunkumar) on Twitter, by now you would have found out that I am a big fan of JavaScript. JavaScript is everywhere. You can use it to write web servers. You can run it on your mobile devices. You can even use it as a build tool. And, of course, you can use it in its original home, the browser. But, what about running it on embedded devices? Can we control robots with JavaScript? Yes, developers have been successful in controlling robots with JavaScript. Read this interesting article on JavaScript robotics: "The Rise of JS Robotics". In the rest of this post, I will talk about Johnny-Five, a cool JavaScript framework for interfacing with Arduino boards. I will also show how easy it is to build a Tweet notifier (LCD display connected to an Arduino board displaying the count of mentions from Twitter).

What is Johnny-Five?
Johnny-Five is a JavaScript Arduino programming framework written by the awesome JavaScript developer Rick Waldron (@rwaldron). The framework which can be installed as a node module uses Firmata protocol to communicate with Arduino boards. Firmata is a generic protocol for communicating with microcontrollers from software on a host machine. Johnny-Five is a JavaScript implementation of the Firmata protocol which provides easy-to-use modules for interfacing with Arduino boards. Check it out here. Video

Getting started

• Preparing your Arduino board. The first thing you need to do is to flash your Arduino board with Firmata. You can do it from Arduino IDE (File > Examples > Firmata > StandardFirmata). I tried it out on a Mega ADK board. Now, one end of your communication is ready. Software on the host machine will communicate this board using Firmata protocol. 
• Installing Johnny-Five. As mentioned above, Johnny-Five is a node module and can be installed using npm (npm install johnny-five). johnny-five depends on node modules firmata and serialport. Note: You might have to build serialport for your environment using "node-gyp configure build".  
• Writing Hello, world! In the context of Arduino, writing a hello world is nothing but glowing an LED. You have to write a Node.js JavaScript file and include johnny-five module. 

Arduino Tweet notifier
This is just a fun hack I have built with Johnny-Five (This is just for demo. You can do much more with JF). I have connected a 16x2 LCD display to an Arduino Mega ADK board (pins 8-13) and was writing data on it using Johnny-Five. Then, I have employed nTwitter module to get the stream of mentions from twitter. Whenever someone mentions @varunkumar on twitter, LCD will display a notification for the same. Check out the code here.

References:
Johnny-Five. Link.
Arduino & LCD getting started. Link.

-- Varun

Arduino based game controller

Being the big fan of technology that I am, I always wanted to try out the latest things happening on the technology world. Some of the buzz words being talked about in the technology world are HTML5 and mobile development. After having fun writing games during my college days, I was interested in building a HTML5 based game. Then, I came across this HTML5 based implementation of classic Helicopter game. In the mean time, I was also playing around with Android ADK and Arduino boards. Finally, made up my mind to hack something cool connecting all these technologies – HTML5, mobile and USB accessories. And, here is the result of the experiment - “Arduino based game controller”. In a nutshell, it’s a game controller which can be connected to an Android phone using which we can play HTML5 games on the browser. The heart of the hack was built over a weekend and source code of the same can be found here. Check out the video demo of the hack at the end of this post.

What is it?

Arduino based game controller is a Joystick / game controller which can be connected to an Android phone via USB.  Using the controller, we can  play games on the browser. An android driver app has been built which reads the data from the game controller (using Android ADK) and routes it to the browser over web sockets. The game has been hosted here (The multi-player mode might not work properly as the hosting site does not support web sockets). More detailed information can be found here.

The hack consists of three core modules:

1. Game module. HTML5 based Helicopter game originally written by Dale Harvey. The game uses HTML5 canvas for rendering the game elements. I have forked his code and have built the networking layer of the game. I have integrated the game with Node.js and Socket.io to support multi-user mode. In order to facilitate seamless communication between the controller and the game module, web socket technologies have been used.

2. Joystick / Controller module. For this hack, I have used Arduino Mega ADK board and a joystick shield mounted on top of it. Arduino board has been flashed with the firmware which reads analog data from the controller and sends it to the connected Android device using Android accessory protocol.

3. Android module. An android app for linking the game module and the controller. The app can be installed on any device running Android 2.3.4 (Your device needs to have the USB compatibility library). It reads the data from the controller and forwards it to the browser over web sockets.

How to contribute?

The source code is available here under MIT licence. I have added enough inline documentations all around the code. Please send any bugs, feedback, complaints, patches about the hack to me at varunkumar.n@gmail.com.

-- Varun

New toy in the house: Arduino ADK

Yay! I have got a new toy in the house to play with – Just bought Arduino ADK board. Ever since Google announced Android ADK at Google I/O 2011, I have been trying to get hold of one. I couldn’t get it till now because of my geographical location and the demand for the board. Finally, I have ordered it from SimpleLabs, Chennai and received the package yesterday. I will be playing around with it in the next couple of weeks and share my experience in this blog.

What is Android ADK?

Android 3.1 introduces powerful new APIs which allows external USB hardware to interact with an Android device. The APIs are based on a USB stack and services that are built into the platform, including support for both USB host and device interactions. Using the APIs, we can create applications that are able to discover, communicate with, and manage a variety of device types connected over USB. More info here.

Arduino ADK

The Arduino ADK is a microcontroller board based on the ATmega2560 (datasheet). It has a USB host interface to connect with Android based phones, based on the MAX3421e IC. It has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. Source: Arduino.cc

-- Varun