Smartphone Bluetooth controlled toy

I was doing a research about something different and came up with the idea to add the ability to control the toy using Scratch from your PC over Bluetooth. So the toy will not just teach the kid to build things, but also learn some basics of programming using Scratch progarmming language.

I also started to develop Android and iOS apps to control the toy. I went through several joystick-like libraries, but there is nothing I liked. I may need to develop my own or heavily customize some existing one. If you know something, feel free to buzz me about it.

Not sure why I started with WP8 app. I guess this is because I like C# or have WP8 or both. Anyway, my first version looked nice. Once I installed it on my phone and let my son to play with it, he immediately discovered several UI flaws (you can see some on the included Video), so I had to make changes to make UI run smoothly.

I'm still in the process of cleaning and fixing the code. I'll be posting the source code on GitHub once done. In case if you don't have Windows Phone Developers account, you can get the app from the Windows Store: http://www.windowsphone.com/en-us/store/app/bt-control/fe4d8895-3623-4633-8d42-edbb17857368

The sketch is pretty simple and straight forward. All commands are received in ASCII to simplify development and debugging. It uses SerialCommand library to parse incoming commands and decide what to do.

I have the sketch available on GitHub: https://github.com/nochkin/RobotChassis-Bluetooth/tree/master/Arduino

Arexx Mr Basic TR-3: I picked this 4WD platform as the cheapest and still durable platform for my project. The price is about $30 or so. It survived some moderate hits and crashes during my tests.

Li-Pol battery: I decided to go with it just to make runs longer and charging easier. However, the Arexx and many other cheap platforms come with 4xAA or similar battery holder for more usual battery cells like AA. Having them as rechargeable Ni-MH is highly recommended.

KIW-3312S DC-DC step down power converter: If you don't have anything like this, you can easily go with linear voltage converter without losing too much since all low-voltage components drain low power anyway. Something like LM1117-33 will do.

Motor driver: L298N seems to be a popular choice. I also designed Android sketch to support LMD18200. In case of LMD18200, you'll need two of those to control two motors while L298N has all channels in one chip. I purchased an assembled board with L298N to simplify that part of the build.

Bluetooth HC-05 module: the module is cheap enough (about $5-$10) and versatile enough. It's popular too, so there should not be a problem to find it online.

Arduino Pro Mini: any Arduino-based board will do. I like Pro Mini due to their size.

LEDs for head lights: just see what looks cool on your platform and use them.