The Pololu 3pi robot is a complete, high-performance mobile platform featuring two micro metal gearmotors, five reflectance sensors, an 8×2 character LCD, a buzzer, and three user pushbuttons, all connected to a C-programmable ATmega328 microcontroller. Capable of speeds exceeding 3 feet per second, 3pi is a great first robot for ambitious beginners and a perfect second robot for those looking to move up from non-programmable or slower beginner robots.
The 3pi robot is designed to excel in line-following and maze-solving competitions. It has a small size (9.5 cm/3.7" diameter, 83 g/2.9 oz without batteries) and takes just four AAA cells (not included), while a unique power system runs the motors at a constant 9.25 V independent of the battery charge level. The regulated voltage allows the 3pi to reach speeds up to 100 cm/second while making precise turns and spins that don’t vary with the battery voltage.
The 3pi robot makes a great platform for people with C programming experience to learn robotics, and it is a fun environment for ambitious beginners to learn C programming. At its heart is an Atmel ATmega328P microcontroller running at 20 MHz and featuring 32 KB of flash program memory, 2 KB RAM, and 1 KB of persistent EEPROM memory. The popular, free GNU C/C++ compiler works perfectly with the 3pi, Atmel Studio provides a comfortable development environment, and an extensive set of libraries provided by Pololu makes it a breeze to interface with all of the integrated hardware. The 3pi is also compatible with the popular Arduino development platform. We provide a number of sample programs to show how to use the various 3pi components, as well as how to perform more complex behaviors such as line following and maze solving.
An external AVR ISP programmer, such as our USB AVR programmer is required to program the 3pi. We offer a combination deal that includes a 3pi robot, USB AVR programmer, and USB cable.
The 3pi is powered by 4 AAA batteries, which are not included. We recommend rechargeable NiMH cells, which may be purchased from Pololu or at a local store carrying electronics. (We also carry a battery charger that works well with these NiMH cells and can be used to charge the batteries while they are still in the robot.)
We currently offer three expansion kits for the 3pi that give you room to augment your 3pi with your own custom electronics. Two are basic kits that simply give your 3pi a second level (with prototyping space and key electrical connections to the 3pi base) to which you can add your own electronics. These basic expansion kits are available with black or red solder masks and with or without cutouts. The version with cutouts lets you view the LCD below and allows you to reach the power button, reset button, and ISP programming header on the base. The version without cutouts is a full circle that replaces the LCD, giving you access to more I/O lines and more prototyping space. The pictures below show the black versions of these two basic expansion kits.