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Keyboards & Input Devices


An open source rotary encoder with a 1.27" TFT customizable display

$15,115 raised

of $12,700 goal

119% Funded! Order Below

Funding ended on May 17, 2022 at 04:59 PM PDT.

Recent Updates

You'll be notified about news and stock updates for this project.

RoenDi is a visually adaptable rotary encoder capable of displaying customized graphics. Having a built-in screen allows it to provide visual feedback unlike any other encoder we’ve seen. RoenDi is designed with simplicity and versatility in mind. Just connect a MicroUSB cable or ST-LINK connector, upload your code to the MCU, and you’re ready to go!

An Innovative & Versatile Platform

The potential uses for RoenDi are up to your imagination, and we can’t wait to see the unique applications you all come up with. Some examples of potential uses are:

With RoenDi, you can create unique custom interfaces that stand out from the rest and provide responsive visual feedback to the user.

Open Source Software

RoenDi uses a powerful STM32L433 MCU, which can be programmed with the Arduino IDE. This makes it easier for novice makers to get involved, while allowing experts to enjoy the benefits of ST’s inline debugging tools. The code base from ST and Arduino is robust, which means there is plenty of sample code to work with.

To help get you started customizing your RoenDi, we have provided sample code using several well documented code libraries. For Arduino lovers, we have provided examples using the Adafruit GFX library, which means you can add text, images, and other graphical objects to the screen with just a few lines of code. If you prefer STM32CubeIDE, we have provided examples using the robust TouchGFX library, which is designed specifically for interactive display interfaces like RoenDi.

Below is an demonstration of RoenDi being used as a combination lock:

Open Source & Fully Customizable Hardware

RoenDi hardware and software are open source, so you can modify and customize its components as you wish. We also worked to build RoenDi with readily available off-the-shelf parts, so you can modify and repair your RoenDi if you ever need to.

The encoder-and-displays MCU also contain a multitude of available IO pins to work with. They are broken out to pads on the side of the PCB so you can easily connect to the UART, CAN, I²C, PWM, DAC, and SAI peripherals. These interfaces can be used to communicate with a large variety of third-party ICs, including LED drivers, speakers, motors, and sensors that detect temperature, humidity, and light, to name just a few examples. One of the great things about the STM32L4 MCU is that all pins tolerate 5 V for easy interfacing.

RoenDi can also be used in conjunction with other connected devices, such as Wi-Fi and Bluetooth modules, which makes RoenDi great for wireless interfaces and IoT applications.

RoenDi pinout diagram

Features & Specifications


RoenDiGrayhill TE-M32M1-A11CSLB-10-40-0
Material Aluminum & PLA Stainless & Plastic Aluminum & Plastic
Power supply 3.3 V DC to 5 V DC 4.75 V DC to 18 V DC 3.3 V DC
Resolution 240 x 240 320 x 300 240 x 204
Display colors 4 K / 65 K / 262 K unknown 262 K
MCU + on board memoryyes yes no
Open source & open hardwareyes no no
Customizable encoder bodyyes no no
Breakout for GPIOyes no no
Capable for standalone applicationsyes yes no
Touch sensorno yes no
Brightness400 Cd/m2 200 Cd/m2 unknown
Arduino compatibleyes no yes
Boot timeless then 1 second 5 seconds to O.S. N/A (display only, no processor)
USByes yes no
CANyes yes no
SAI, PWM, I²C, DAC, RTCyes no no
Price$128 $212 $131

Support & Documentation

All hardware and software documentation for RoenDi will be published and openly maintained in our GitHub repositories.

We will also be releasing a series of tutorials that will walk you through the process of using RoenDi for various applications.

Manufacturing Plan

Production RoenDi boards will be fabricated and quality assured by PCBWay, a contract manufacturer with whom we have worked to produce various RoenDi prototypes. Each board will be tested at their factory to ensure consistent quality, and then assembled in Bulgaria as soon as all components are available after the campaign is completed.

RoenDi uses a STM32L4 as its primary microprocessor. As of February 2022, due to the worldwide chip shortage, the availability date for the STM32L4 is April 2023, which means the necessary components will be available to be ordered in the second quarter of 2023. From there, we will continue the manufacturing, assembly, and testing process, so that our products can be sent to Mouser and distributed worldwide to our backers.

Fulfillment & Logistics

After testing and packaging the production batch, we will ship all RoenDi units to Crowd Supply’s fulfillment partner, Mouser Electronics, who will distribute them to backers worldwide. You can learn more about Crowd Supply’s fulfillment service under Ordering, Paying, and Shipping in their guide.

Risks & Challenges

Due to the worldwide chip shortage, the RoenDi project could be further delayed if factory lead times increase yet again. We are researching alternative ICs in case this happens, and we will provide updates on the production process as manufacturing moves forward.

In the Press


Produced by Xtech in Rousse, Bulgaria.

Sold and shipped by Crowd Supply.

RoenDi Ready to Go

Everything you need! Parts included: Main encoder board, Display board with connection cable, Matte black aluminum body, ST-LINK adaptor board + cable

$128 $8 US Shipping / $18 Worldwide

Want to buy this item? Check the current project page for the latest information.

RoenDi Essential Kit

3D print your own knob enclosure! You will get a main encoder board and display board with connection cable

$99 $8 US Shipping / $18 Worldwide

Want to buy this item? Check the current project page for the latest information.

About the Team


Rousse, Bulgaria  ·

I am software engineer who likes to develop embedded systems. I am passionate about aviation and everything flying.

Dimitar Dyakov

See Also

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