Toolduino is an open-source software tool that you use to test your Arduino circuits. Toolduino communicates with your Arduino through a serial connection so that you can manipulate the pin outputs and read the inputs. Go to the Toolduino page to download it and for all the details on how to use it!

Difficulty Level = 8 [What's this?]

I built a wireless robotics platform from a cheap R/C car, an Arduino with XBee shield, small microswitch sensors, and a Processing program running on a remote computer to control the vehicle. The vehicle is completely controlled by the code running on the remote computer which allows very rapid prototyping of the code to tell the vehicle what to do and how to react to the sensor events received from the vehicle. I’m hoping this is a good way to teach my 9-year old son about programming.

Wireless computer-controlled robotics platform built on cheap RC vehicle, Arduino microcontroller, and XBee radios

Before I get into details, here’s an overview of the features:

• All logic controlling the vehicle is performed in a Processing program running on remote computer. The Arduino program listens for commands from the remote computer.
• Bi-directional wireless communication over XBee radios with (theoretical) 1-mile range. I’ve accomplished 1/4 mile range with these radios.
• Sensor events are transmitted from the vehicle to the controlling computer. This vehicle has 3 microswitches – two on front bumper and one at the rear.
• Original circuitry of vehicle replaced with dual H-Bridge circuit to control drive motor and turn motor. Drive motor is controlled with variable speed.
• Power: Vehicle motors powered by 4 AA batteries. Arduino with XBee shield powered by 9V battery mounted at front of vehicle.
• Simple communications protocol: 2 byte commands from controller to vehicle, one byte sensor readings from vehicle to controller.

The Hardware

There’s nothing special about the configuration of the XBee radios. They are running the AT firmware (“transparent mode”) which allows them to simply exchange serial data. The Libelium XBee shield on top of the Arduino makes it easy to read/write serial data from Arduino code.

Arduino and XBee shield on top of the vehicle

Inside the vehicle is a simple circuit board with an L293 quadruple half-H driver to drive the motors. The drive motor and turn motor are connected. I had to rip out the original circuit board (but I saved it!).

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Difficulty Level = 5 [What's this?]

Here is a device I call the Hack-a-Sketch. The screen is a normal laptop (an old one), but it has real knobs which control the stylus on the screen.

The Hack-a-Sketch

An Arduino board reads the inputs from two potentiometers (the knobs), and sends the information via USB to a Processing sketch which displays the path of the stylus on the screen. This was extremely easy to build because the Arduino is just running the StandardFirmata firmware. No custom code on the board. The Processing sketch was surprisingly easy to write. Using this really did feel like using an Etch-a-Sketch.

Here’s the Hack-a-Sketch in action. Wait for the big finish where I erase the image…

How did I erase the drawing by shaking the computer? There’s a mercury switch hidden behind the panel holding the knobs. When the code senses shaking, the image is slowly erased. More shaking = more erasure.

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