Ping Hobbyelektronik's Epi C3 Is a Fingertip Development Board Built Around the Espressif ESP32-C3

Mononymous maker Rasmus, also known as "rallekralle11" of Ping Hobbyelektronik, has launched a successor to the fingertip-sized Epi 32U4, built around the Espressif ESP32-C3 — and the Epi C3, as the new device is called, is only a smidgen larger for all the extra features it packs.

"[Epi C3 is] an absolutely tiny development board based on the [Espressif] ESP32-C3," Rasmus explains of the new development board. " It has a sturdy USB [Type]-C port sunk into the board to minimize the thickness. Beside the port are 2mm [around 0.078"] slots for the device to be screwed down. The port also protrudes past the PCB edge for flush panel mounting."

The original Epi 32U4 was based, as the name suggests, around the Microchip ATmega32U4, a surface-mount eight-bit AVR microprocessor. The new Epi C3 swaps this out for an Espressif ESP32-C3, meaning a move to a considerably more capable 32-bit RISC-V processor core running at up to 160MHz, 400kB of static RAM (SRAM), and 4MB of flash storage, plus a Bluetooth 5.0 Low Energy (BLE) radio connected to an ultra-compact Johanson Technology chip antenna, which Rasmus says offers "surprising range for its size."

Elsewhere on the board are 11 general-purpose input/output (GPIO) pins, brought out to castellated headers on the sides — though the board's not compatible with standard solderless breadboards, as it uses smaller 1.27mm pin spacing to keep the footprint to a minimum. The USB data lines include TVS diodes, there's a 500mA fuse on the power line, and ferrite beads to reduce noise — while the on-board linear voltage regulator can push 600mA at 3.3V.

Rasmus has released board design and production files for the Epi C3 on GitHub under an unspecified open source license; assembled units are available to order on Tindie at $20 each. For those who'd prefer to use an external antenna, Rasmus has also designed a variant with a U.FL connector — though this was not available to purchase at the time of writing.