3pi+ 32U4 Robot - Turtle Edition (75:1 LP Motors), Assembled

Overview

The 3pi+ 32U4 is a versatile, high-performance, user-programmable robot that measures just 9.7 cm (3.8″) in diameter. At its heart is an ATmega32U4 AVR microcontroller from Microchip (formerly Atmel), and like our A-Star 32U4 programmable controllers, the 3pi+ 32U4 features a USB interface and ships preloaded with an Arduino-compatible bootloader, so all you need to program it is a USB A to Micro-B cable (not included). A software add-on is available that makes it easy to program the robot from the Arduino environment, and we have Arduino libraries and example sketches to help get you started. For advanced users who want to customize or enhance their robots with additional peripherals, the robot’s power rails, power system controls, and microcontroller’s I/O lines can be accessed via several 0.1″-pitch expansion ports.

3pi+ 32U4 Robot, front view.

3pi+ 32U4 Robot, side view.

3pi+ 32U4 Robot, rear view.

The 3pi+ (or 3𝜋+) features two H-bridge motor drivers and a variety of integrated sensors, including a pair of quadrature encoders for closed-loop motor control, a complete inertial measurement unit (3-axis accelerometer, gyro, and magnetometer), five downward-facing reflectance sensors for line-following or edge-detection, and left and right bump sensors along the front face of the robot. Three on-board pushbuttons offer a convenient interface for user input, and an LCD, buzzer, and indicator LEDs allow the robot to provide feedback.

The robot also features a unique power system that runs the motors at a constant 8 V independent of the battery charge level, so the speed of the motors does not vary with the battery voltage.

The 3pi+ 32U4 robot is available as a kit or fully assembled with three different motor options:

3pi+ 32U4 Version	Products	Micro Metal Gearmotor	Top Speed	Comments
Standard Edition	assembled or kit	30:1 MP 6V	1.5 m/s	good combination of speed and controllability
Turtle Edition	assembled or kit	75:1 LP 6V	0.4 m/s	longest battery life, easiest to control, good for swarm robots or introductory robotics courses
Hyper Edition	assembled or kit	15:1 HPCB 6V	~4 m/s	very fast and difficult to control, easy to damage; only recommended for advanced users

For those who would prefer to use different motors than these versions above, the 3pi+ chassis and 3pi+ 32U4 control board are available separately and can be combined with a pair of motors to make a custom kit.

What else you will need

• four AAA batteries: the 3pi+ robot works with both alkaline and NiMH batteries, though we recommend rechargeable NiMH cells
• a USB A to Micro-B cable to connect the robot to your computer for programming and debugging

Assembling the kit version

Details for item #3738

This an original 3pi+ 32U4 Robot with an LCD. We recommend the newer 3pi+ 32U4 OLED instead, which includes a graphical OLED display; the updated version of this item is the 3pi+ 32U4 OLED Robot – Turtle Edition (75:1 LP Motors), Assembled.

This product is the assembled Turtle Edition of the 3pi+ 32U4 Robot.

3pi+ 32U4 versions

This original version of the 3pi+ 32U4 includes an 8×2 character LCD, while the newer 3pi+ 32U4 OLED incorporates a graphical OLED display instead. The name “3pi+ 32U4” can generally be used to refer to both the original (LCD) and OLED versions, and the documentation in our updated user’s guide covers both versions.

Our Arduino library for the 3pi+ 32U4 generally allows code written for the LCD version to work on the OLED version with minimal changes (and the reverse is also true as long as your code does not make use of the OLED’s graphical capabilities).

3pi+ 32U4 Robot, top view.

3pi+ 32U4 OLED Robot, top view.

Comparison with the original 3pi

Original Pololu 3pi robot.

The 3pi+ 32U4 offers many major improvements over the original 3pi, including:

• ATmega32U4 microcontroller with Arduino-compatible bootloader can be programmed directly through a USB connection
• Quadrature encoders on both motors for closed-loop position and speed control
• Full 9-axis IMU (three-axis gyro, accelerometer, and compass)
• Bottom-loading battery holders keep batteries accessible even if additional levels are added
• Full wrap-around bumper to protect electronics from collisions
• Two bump sensors on the front

The 3pi+ 32U4 uses a different microcontroller with different pin mappings compared to the older 3pi, and some of the software library interfaces are different, so programs written for the original 3pi will not work on the 3pi+ 32U4 without modification.