5. Picture and Movie of Robot Controlled by an Atari Joystick

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As you’ve seen, it is reasonable to build a circuit from off-the-shelf electronic components that interfaces a classic videogame controller to a motor driver. With Lego bricks, it is easy for you to rearrange and build a robot to look and function however you want.

A homemade robot made from Lego and standard electronics controlled by an Atari joystick.

A homemade robot made from Lego parts and standard electronics controlled by an Atari joystick.

I decided to put the printed circuit board (PCB) in the back of the robot to avoid battle damage. This was also convenient for the joystick cable to connect to the rear of the robot. With the PCB at the back, the batteries can be placed directly over the motors and wheels to significantly improve traction.

Four alkaline 'AA' batteries provide a voltage between 6.4 V (4 x 1.6 V) when fresh and 4.4 V (4 x 1.1 V) when exhausted. Rechargeable batteries are perfectly acceptable.

Unless you are pressed for space and weight, I don’t recommend using smaller 'AAA' batteries or using fewer batteries (3). The robot needs all the power it can get.

The front of the robot has a platform for attaching various Lego parts and motors. The Lego parts pop off fairly easily during battle, which is a lot of fun to watch.

To demonstrate compatibility, I installed a Lego motor for the weapon (activated when the fire button is pressed). However, I happily use the Solarbotics GM7 gearmotors for the main drive motors.

Creating Lego couplers for the motors allows for experimentation with a variety of Lego wheels. Flat tires have better traction on wood floors. Knobby tires work better on carpets and on the Lego-block-strewn battlefield. I tried installing really large tires, but the diameter was so much that the motors stalled too easily.

One last thought: Because the FAN8200 hbridges are disabled when the user isn’t pushing the joystick, the total circuit uses almost no power when idle. As such, a power switch really isn’t necessary. Instead, you could replace the power switch with a snap action switch (wired as normally-closed) on a target toward the front of each robot. Players could try to hit each other’s toggle switch to disable the opponent’s robot.

Atari Joystick Motion Movie

Click to see a movie of an Atari-joystick remote-controlled robot being exercised.

Click to see a movie of an Atari-joystick remote-controlled robot being exercised.

This first movie shows the robot going forward onto a carpet, reversing onto the floor, spinning around, and then operating the weapon motor.

Atari Joystick Robot Battle

Click to see a movie of two Atari-joystick remote-controlled robots crashing into each other.

Click to see a movie of two Atari-joystick remote-controlled robots crashing into each other.

This second movie shows two robots outfitted with various Lego parts crashing into each other.

These robots are a lot of fun to build and play with. Even if you decide to create something completely different, I encourage you to find out how easy it is to connect to a classic Atari joystick.