RoenDi is a rotary encoder with an integrated round color display. Based on an STM32L4 MCU, it can be programmed with the STM32CubeIDE or the Arduino IDE, and be used as an information display, an IoT controller, a locking mechanism, as well as in audio applications.
- MCU – STMicro STM32L433 Arm Cortex-M4 microcontroller @ 80 MHz with 256 KB flash memory
- Storage – 128 Mbit SPI NOR flash
- Display – Round 1.28-inch TFT LCD display with 240 x 240 resolution, up to 262K colors
- Rotary Encoder – 15 pulses / 30 detents
- USB – Micro USB connector
- I/Os – Breakout pads for peripherals: I2C, GPIO, PWM, CAN; 5V tolerant
- Debugging – Adaptor board and cable for ST-LINK
- Misc – BOOT boot, RTC (built-in into STM32 MCU)
- Power Supply – 3V to 5V DC input, 3 V, 400 mA LDO
- Dimensions – 40 x 40 mm (PCB)
- Enclosure – Milled Aluminum or 3D-printed body (CAD files will be available for custom prints)
The board is partially open-source hardware with the PDF schematics, documentation, component datasheets, and sample code for the Arduino IDE and STM32CubeIDE 1.6.1 available on Github. There’s are also two Instructables with instructions for hardware assembly and to get started with programming.
The video below shows the Roendi rotary encoder in action with a password lock demo with four adjustable digits on the display.
While I don’t think I had ever seen this type of hardware before, Xtech compared Roendi to two other similar products with the $220 GRAYHILL TE-M32M1-A11U rotary encoder with a touchscreen display but no I/Os, and the ~$130 SLB-10-40-0 rotary encoder with integrated display, but lacking a microcontroller.
RoenDi rotary encoder with display can be found on Crowd Supply for $99 with free worldwide shipping, but that’s without an enclosure. You’d need to pledge $128 for a complete kit adding a matte black aluminum enclosure, and an ST-LINK adaptor board with cable for programming. Backers will need to be patient, as deliveries are expected to start by June 30, 2023. The main culprit for the long lead time is the STM32L4 microcontroller that should be in stock in April 2023 for orders placed now.
Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.