Epi 32U4 is a tiny Arduino-compatible development board based on a Microchip ATmega32U4 8-bit AVR microcontroller with just a USB-Type-C port and 23 I/O pins accessible through castellated holes that can be soldered to headers or another PCB.
The board also includes some protection such as a fuse, ESD protection, a ferrite bead, and a low-pass filter for the analog reference voltage. Ping Hobbyelektronik, the developer, says it’s especially useful for compact USB keyboards, but it also has more I/O ports than a standard Pro Micro board, so it’s appropriate for a range of other projects as well.
Epi 32U4 board specifications:
- MCU – Microchip ATmega32U4 8-bit AVR microcontroller @ 8MHz or 16 MHz with 32 KB flash, 2.5 KB SRAM, 1 KB EEPROM
- 1x USB Type-C port for power and programming
- USB D+ and D- lines are broken out
- ESD and surge protection on USB data lines and power input
- I/Os – 29x castellated holes (1.27mm pitch) with 23x GPIOs, I2C, UART, SPI, analog inputs, Reset, 5V, GND
- 16 MHz crystal
- 500-mA poly fuse
- Ferrite bead for power filtration
- Low-pass filter for analog voltage reference
- LED on pin 13
- Operating Voltage – Runs 4.5 – 5.5 V for the 16 MHz version, down to 2.7 V at 8 MHz
- Dimensions – 22.75 x 12.75 mm
You’ll find the KiCAD hardware design files for the board on GitHub. We’ve written about many tiny ATmega32U4 boards over the years, many of which did not stand the test of time, and the Epi 32U4 board is compared to some of the boards in the table below.
The Epi 32U4 board is currently listed on Crowd Supply with two versions: one running at 8 MHz, and the other at 16 MHz. Both variants sell for $25 each, but you’d still have to add $8 shipping to the US, or $18 to the rest of the world. The cost is rather higher, but that’s because it’s being manufactured in Sweden before being shipped to Mouser Electronics in the US, who will handle distribution to backers worldwide. Deliveries are scheduled to start around mid October 2023.
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.