A few days ago, we covered the KiCAD designed OrangeCrab open-source hardware board powered by a Lattice Semi ECP5 FPGA, and compliant with Adafruit Feather form factor.

It’s turned out there’s another Lattice Semi ECP5 FPGA board that’s also designed with KiCAD and open source hardware. Radiona ULX3S differs are it’s larger and exposes more I/Os since it was specifically designed to meet the meets of the digital logic course at the Faculty of Electrical Engineering and Computing (FER) of the University of Zagreb in Croatia.

ULX3S specifications:

FPGA – Lattice ECP5 LFE5U-85F-6BG381C with 84K LUT

System Memory – 32MB SDRAM @ 166 MHz

Storage – 4–16MB Quad-SPI Flash for FPGA config and user data storage; MicroSD slot

Audio – 3.5 mm jack with 4 contacts (analog stereo + digital audio or composite video)

Video – Digital video (GPDI General-Purpose Diferential Interface) with 3.3V-5V I2C bidirectional level shifter

Display – Placeholder for 0.96″ SPI color OLED display (SSD1331 driver)

Wireless Connectivity WiFi + Bluetooth placeholder for ESP32 (Standalone JTAG web interface over WiFi) Antennas – 27, 88–108, 144, 433 MHz FM/ASK onboard

USB – 2x micro USB ports, one connected to FTDI FT231XS and the other to the FPGA

Expansion 56 GPIOs (28 differential pairs) PMOD-friendly with power out 3.3V/1A 2.5V/1.5A 8-channel ADC, 12 bit, 1 MSa/s via MAX11125

Misc – 11x LEDs 11 (8x user, 2x USB, 1x WiFi); 7x buttons (4x direction, 2x fire, 1x power); 25 MHz crystal onboard, external differential clock input; RTC with battery backup

Power Supply 5V input via USB port 3x Switching voltage regulators: 1.1V, 2.5V, 3.3V 5V output Low power sleep – 5uA/5V standby

Dimensions – 94 × 51 mm

The hardware design files are hosted on Github, and you’ll find the project’s log on Hackster.io. It supports Project Trellis open-source toolchain, as well as Arduino IDE (ESP32).

The buttons’ names look “suspicious” (fire, direction), and indeed you can emulate arcade machines or retro computers like Minimig(Amiga), but you could also run MIPS/RISCV softcore. The video below shows the web interface running on ESP32 that allows you to easily flash bitstreams to the FPGA, and the board running a retro game while connected to an HDMI monitor.

There’s no easy online purchase for the board, but it’s estimated to cost between $60 and $200 to manufacture, and you could it do yourself via Kitspace. Alternatively, you can order a ULX3S board sample with ECP5-12F FPGA for 75€ plus shipping by contacting the developers by email, and I was told the ECP5-85F would be coming soon. More details may be found in the product page.