These Open Source Arduino-Inspired Microcontroller Boards Offer a Few Twists on the Norm

Semi-pseudonymous maker Rasmus "rallekralle11" has created a pair of development boards designed to offer a twist on popular Arduino devices: the Epi 32U4 and the Anna2040.

"[It's] named after the Epipactis genus of orchids," Rasmus writes of the Epi 32U4. "The flower of one appears on the board. [It] has basically the same pinout as the [Arduino] Pro Micro, but with 1.27mm headers and a few extra pins at the bottom."

One end of the board is dominated by a USB Type-C connector, sunken into a cut-out section of PCB to reduce board height, which provides data and power connectivity. While the pinout is largely copied from the Arduino Pro Micro, it's not one-for-one — even ignoring the extra pins opposite the USB connector, the board switches from the more common 2.54mm pin spacing to 1.27mm in order to reduce its footprint.

Other features of the board include electrostatic discharge (ESD) protection, crenellated pins allowing for surface-mount installation as a module, support for running from 5.5V down to 2.7V at 8MHz, and a pair of indents designed to accept M2 bolts for secure installation.

Rasmus' second board, the Anna2040, is considerably larger — taking, as it does, inspiration from the classic Arduino Uno footprint. There's no Microchip ATmega328 at its heart, however, but Raspberry Pi's popular dual-core RP2040 microcontroller — the same chip which powers the Raspberry Pi Pico and Raspberry Pi Pico W.

The Anna2040 includes Arduino-compatible headers along two edges, with additional pins brought out to extra headers at the far end. The other side includes a DC jack and battery connector for power, a USB Type-C connector for power and data, and physical buttons for reset and boot select.

Design files for both boards are available on Rasmus' GitHub repositories for the Epi 32U4 and Anna2040 respectively, under the CERN Open Hardware License Permissive Verison 2.