Romi 32U4 Control Board

The Romi 32U4 Control Board turns the Romi chassis into a programmable robot based on the Arduino-compatible ATmega32U4 MCU. Its features include integrated dual motor drivers, a versatile power circuit, and inertial sensors, as well as connections for quadrature encoders and an optional LCD.

AUD$ 95.95

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Romi 32U4 Control Board, top view with dimensions.


The Romi 32U4 Control Board is designed to be assembled with a Romi chassis to create a capable integrated robot platform that can easily be programmed and customised.

Like our A-Star 32U4 programmable controllers, the Romi 32U4 Control Board is built around a USB-enabled Atmel ATmega32U4 AVR microcontroller, and it ships preloaded with an Arduino-compatible bootloader. The control board features two H-bridge motor drivers and is designed to connect to a Romi Encoder Pair Kit (available separately) to allow closed-loop motor control. It also includes a powerful 5 V switching step-down regulator that can supply up to 2 A continuously, along with a versatile power switching and distribution circuit. A 3-axis accelerometer and gyro enable a Romi 32U4 robot to make inertial measurements, estimate its orientation, and detect external forces. Three on-board pushbuttons offer a convenient interface for user input, while indicator LEDs, a buzzer, and a connector for an optional LCD allow the robot to provide feedback.

Romi 32U4 Control Board on a Romi chassis, top view.

Romi 32U4 Control Board with LCD on a Romi chassis.

The Romi 32U4 Control Board can be used either as a standalone control solution or as a base for a more powerful Raspberry Pi controller. Its on-board connector and mounting holes allow a compatible Raspberry Pi (Model B+, Model A+, Pi 2 Model B, or Pi 3 Model B) to plug directly into the control board. Integrated level shifters make it easy to set up I²C communication and interface other signals between the two controllers, and the control board automatically supplies 5 V power to an attached Raspberry Pi. In this setup, the Raspberry Pi can handle the high-level robot control while relying on the Romi 32U4 Control Board for low-level tasks, like running motors, reading encoders, and interfacing with other analogue or timing-sensitive devices.

Romi 32U4 Control Board with Raspberry Pi on a Romi chassis.

The I/O lines of both the ATmega32U4 and the Raspberry Pi are broken out to 0.1″-spaced through-holes along the front and rear of the control board, and the board’s power rails are similarly accessible, enabling sensors and other peripherals to easily be connected.

A software add-on is available that makes it easy to program a Romi 32U4 robot from the Arduino environment, and we have Arduino libraries and example sketches to help get you started. A USB A to Micro-B cable (not included) is required for programming.

Included components

Romi 32U4 Control Board, shown with included hardware.

The Romi 32U4 Control Board ships with all of its surface-mount components populated, and it includes a number of through-hole parts and mounting hardware, as shown in the picture above. Note that assembly (including soldering) is required; please see the user’s guide for assembly instructions.

The Romi chassis itself and other parts required to build a complete Romi 32U4 robot are not included; these are listed below, along with some optional additions.

What you will need

To build a robot with the Romi 32U4 Control Board, you will need a few additional parts:

  • a Romi Chassis Kit (this includes motors, wheels, one ball castor, and battery contacts)
  • a Romi Encoder Pair Kit
  • six AA batteries; The Romi chassis and control board work 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
  • tools to help with kit assembly; see the user’s guide for a list of specific tools

Optional accessories

You might also consider getting these for your Romi 32U4 robot:

Other Romi boards, robots, and robot controllers

In addition to the Romi 32U4 Control Board, we have some more basic boards designed to mount onto a Romi chassis:

  • The Motor Driver and Power Distribution Board for Romi Chassis includes the same motor drivers and power circuit (including 5 V regulator) as the Romi 32U4 Control Board, but offers you flexibility in choosing and connecting your own microcontroller.
  • The Power Distribution Board for Romi Chassis only includes reverse voltage protection and a pushbutton power switch circuit; it is intended to be a convenient way to access the chassis’s battery power and pass it on to the rest of your electronics.

The Romi 32U4 Control Board uses the same microcontroller and includes many of the same features as some of our other programmable robots and controller boards. Consider these alternatives if you want similar electronics on a different chassis:

  • The Zumo 32U4 is a smaller tracked robot sized to qualify for Mini Sumo competitions and equipped with appropriate sensors. It is available fully assembled or as a kit.
  • The A-Star 32U4 Robot Controller SV with Raspberry Pi Bridge shares most of the same functionality as the Romi 32U4 Control Board, including the ability to interface with a Raspberry Pi, but it is a smaller board with a more general-purpose form factor instead of being designed to work with a specific chassis. It is also available in a lower-voltage LV version.



Size: 4.4″ × 3.3″ × 0.38″1
Weight: 35 g1

General specifications

Current rating: 5 A2
Processor: ATmega32U4 @ 16 MHz
RAM size: 2560 bytes
Program memory size: 32 Kbytes3
Motor driver: DRV8838
Motor channels: 2
Minimum operating voltage: 2.5 V
Maximum operating voltage: 10.8 V
Continuous output current per channel: 1.8 A
Logic voltage: 5 V
Reverse voltage protection?: Y
External programmer required?: N

Identifying markings

PCB dev codes: rom04a
Other PCB markings: 0J10217


Without included hardware.
This is the rating for the battery power switching circuit and limits the current available at VSW.
Note that 4 KB of the MCU's 32 KB of flash memory is used by the pre-installed USB bootloader. All 32 KB is available when programming via the ISP header rather than the bootloader.


Documentation and other information

Romi 32U4 Control Board User’s Guide

User’s manual for the Romi 32U4 Control Board.

File downloads

Schematic diagram of the Romi 32U4 Control Board (646k pdf)
Dimension diagram of the Romi 32U4 Control Board (1MB pdf)
Drill guide for the Romi 32U4 Control Board (346k dxf)
This DXF drawing shows the locations of all of the board’s holes.

Recommended links

Romi 32U4 Arduino library
The Romi32U4 library for the Arduino IDE helps interface with the on-board hardware on the Romi 32U4 Control Board.
Romi 32U4 library documentation
This library for the Arduino IDE helps interface with the on-board hardware on the Romi 32U4 Control Board.

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