Inspired by the Arduino UNO Refresh, "Polia31" Builds a Breadboard-Friendly Renesas RA4M1 Dev Board
Designed around the same chip as Arduino's UNO R4 Minima and WiFi boards, this gumstick-style design has a minimal footprint.
Pseudonymous maker "Polia31" has designed a compact, breadboard-friendly development board powered by the Renesas RA4M1 — the same chip at the heart of Arduino's recently-refreshed UNO R4 WiFi and Minima boards.
"The R4 Minima inspired me to explore the full potential of the [Renesas RA4M1] chip, especially since many of its features often go underutilized — like the unused RTC battery pins," Polia31 explains of the thinking behind the custom board. "So, I decided to create my own microcontroller [board], making sure to make the most of every pin."
The resulting design is breadboard-friendly, bringing out as many general-purpose input/output (GPIO) pins as possible to 0.1" headers at either side of the gumstick footprint. These include no fewer than 12 pulse width modulation (PWM) capable pins, eight with hardware interrupts, and 11 connected to a 14-bit analog to digital converter (ADC). There's also a STEMMA QT connector for solderless expansion and a Serial Wire Debug (SWD) debugger.
"I added USB [Type]-C, fuse-protection, [a] user button, and made it breadboard-compatible," Polia31 explains of the board's core features. "Plus, it supports HID [Human Interface Device], DAC [Digital to Analog Converter], and CAN bus, covering more ground for different applications without leaving anything behind."
More details are available in Polia31's Reddit post; at the time of writing, design files had yet to be shared.