After building Terminator 2 last week, this week I built Rambo. Rambo runs off an ATTiny85 as well, and can be remote controlled via the HC-05 Bluetooth module. So technically this isn’t really a robot, as it doesn’t have any autonomous functionality, but whatever.

For this model I used these components:

• 1 x Perfboard
• 1 x ATTiny85
• 1 x HC-05 Bluetooth Module
• 1 x 8 pin socket
• 2 x NPN transistors (PN2222A)
• 2 x Pager motors
• 1 x 2 pin header
• many LR2032 rechargable batteries
• Heat shrink tubing, various sizes
• Hookup wire

I was too lazy to write an interface for my phone to control the robot, so I simply mapped keyboard key codes to certain movements. Key strokes on the top part of the keyboard move the robot straight, the left part of the keyboard turns the robot left and so forth. You can view the mappings in the sketch. To send button presses via bluetooth I’m using the free Andrioid app BlueTerm. The advantage of simply using key codes is that any device with a serial terminal can be used to control the robot. The ATTiny doesn’t natively support UART so I ended up using the Arduino Software Serial library which allows to map RX and TX on any pin. It uses 30% of the ATTiny’s program memory which might be a problem for more complicated programs but is fine for this simple sketch.

The wiring of this project is very similar to the wiring of the previous robot. There are no sensors, but RX/TX of the Bluetooth module is hooked up to pins 3 & 4 instead. All the components fit comfortably on a 10 x 10 piece of perfboard.

Bottom wiring:

Family photo:

My next project might be to build a version that combines the 2 robots. It would be cool to have a robot that operates autonomously and sends the sensor data via Bluetooth to my PC or phone. I ordered some gyroscope and 3 axis magnetic field modules which I will probably add to the next iteration. The modules are pretty small and if I attach them upright it should be possible to maintain a similar footprint.