Ping Hobbyelektronik's Epi 32U4 Is a Tiny Arduino-Compatible Board with USB Type-C Connectivity

Semi-pseudonymous maker Rasmus "rallekralle11," of Ping Hobbyelektronik, is heading to the crowdfunding circuit with an ultra-compact take on the Arduino compatible, a fingertip-sized Microchip ATmega32U4-based development board dubbed the Epi 32U4.

"Epi 32U4 is an Arduino-compatible, ATmega32U4-based microcontroller board with a pinout based on the [Arduino] Pro Micro," Rasmus explains of the board design. "All pins are broken out to castellated holes with 1.27mm spacing. We designed Epi 32U4 to accommodate noisy environments — even without voltage regulators — thanks to a ferrite power filter, a fuse, ESD protection, and surge protection. With an ATmega32U4 at its core, it can act as a USB device, which makes it perfect for keyboards and other space-constrained projects that require a compact controller."

Small enough to sit on the tip of a finger, the Epi 32U4 runs its ATmega32U4 at 16MHz via an external crystal and offers 2kB of static RAM (SRAM) and 32kB of program memory plus 1kB of electrical erasable PROM (EEPROM). Of the 23 available general-purpose input/output (GPIO) pins brought out, seven support pulse width modulation (PWM) while there are 12 analog to digital conversion (ADC) inputs with a maximum resolution of 10 bits.

The biggest feature of the Epi 32U4, though, is its smallest: size. Designed with components on only one side, the board can be used with pin headers or soldered as a surface-mount module — though the 1.27mm pin spacing means that it's not directly compatible with common 2.54mm (0.1") solderless breadboards.

The electrical protections on the board, which include a 500mA polyfuse and full electrostatic discharge (ESD) and surge protection on the USB data lines and power input, hearken back to an earlier design of Rasmus': the Dact, an open-hardware alternative to the Arduino Nano R3 that offered a more traditional 2.54mm pin spacing.

The Epi 32U4 is due to launch on Crowd Supply in the near future, with interested parties invited to sign up on the campaign page to be notified when it goes live. The design files, meanwhile, are available on GitHub under the CERN Open Hardware License Version 2 - Permissive.