/ Zagreb Makerspace
FPGA Boards


A powerful, open hardware ECP5 FPGA dev board

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ULX3S is a fully open source, compact, robust, and affordable FPGA dev board equipped with a balanced selection of additional components and expansions. Although it was designed primarily as a teaching tool for mastering the principles of digital circuit design, ULX3S incorporates a wide array of features and interfaces that allow it to serve as a broadly useful module for installation in complex devices.

Built around a powerful Lattice Semiconductor ECP5-series FPGA chip and supported by the latest open-source toolchains, ULX3S is one of the most powerful and desirable platforms available for FPGA enthusiasts. It comes equipped with onboard Wi-Fi, display, buttons, LEDs, and storage. Flash it with an over-the-air (OTA) update using the Wi-Fi connection or take advantage of the onboard OLED display and buttons to browse the contents of an SD card and select a bitstream.

Energy Efficient, Versatile, and Easy to Program

Due to its battery-backed RTC, ULX3S can power down completely and wake up only in response to certain events. This feature makes it perfect for use in low-power applications such as battery-powered remote sensor nodes.

And if you’re not the low-power type, on-board peripherals like SDRAM, USB, digital video out, FM/ASK antenna, ADC, and DAC make it an audio/video powerhouse for signal processing and synthesis, motor control, and SDR use cases. It can emulate arcade machines and retro computers like the Minimig (Amiga) or modern systems like the F32C (MIPS/RISCV). It has 56 GPIO pins, all routed as differential pairs, and a PMOD compatible pinout, which opens it up to a wide range of expansion options.

Finally, if you are just starting out with FPGAs, you can use the Arduino IDE to program ULX3S in seconds.

On-Board ESP32

Software engineers, embedded developers, and programmers learning Verilog will enjoy having a built-in ESP32 that can work cooperatively with or independently of the FPGA. Program the ESP32 natively using C/C++ with the Arduino IDE, the Visual Micro extension for Visual Studio, or the Espressif IDF commandline toolchain. You can also configure the ESP32 for use with MicroPython, Espruino, the JavaScript SDK, NodeMCU, LUA, mruby, .Net C# nanoFramework, and more!

Stable Design

ULX3S has been actively developed since 2016 and is the result of a collaboration between / Zagreb Makerspace and FER – the Faculty of Electrical Engineering and Computing – at the University of Zagreb in Croatia.

Our PCB design was authored by Electronic Mechanic Aerodynamic Research & Development (EMARD).

Features & Specifications


Comparison Table

ULX3SLattice ECP5 Evaluation BoardLattice ECP5 VersaTinyFPGA EXFleaFPGA 'Ohm'KONDOR AXTrellisBoard
Model ECP5 12F, 45F, or 85F ECP5 85F ECP5 45F ECP5 12F, 45F, or 85F ECP5 25F ECP5 85F ECP5-5G 85F
LicenseOSHW Proprietary Proprietary OSHW OSHW Proprietary OSHW (MIT)
Price Range$99 - $155 $100 $250 Unreleased$45 $1500 - $2000? $500 - $1000
Schematics Published?Yes Yes Yes Yes Yes Yes Yes
Design Files Published?Yes No No Yes No No Yes
Physical Dimensions94 × 51 mm 180 × 100 mm 165 × 110 mm 61 × 18 mm 65 × 30 mm 180 × 130 mm 200 x 112 mm
LUT Capacity12 K – 84 K 84 K 44 K 12 K – 84 K 24 K 84 K 84 K
Embeded Memory (Kbits)3744 (on 85F) 3744 1944 3744 (on 85F) 1008 3744 3744
USB-Serial JTAGFT231X FT2232H FT2232 None FT230X FT2232 FT2232H
Direct USB to FPGAYes No No Yes Yes No via EHCI
User IOs56 178 Up to 29 42 29 365 104
Differential Pairs28 9 UnknownNo 12 Unknown36
Single-Ended5 178 Unknown42 29 Unknown22
SERDES0 9 1 0, 2 (only EX85-5G variant) 0 4 4 (PCIe x2 and m.2 x2)
PMOD Connector Placeholders4 1 No No No No 2
User Buttons7 3 2 1 No 2 4
DIP Switches4 8 8 No No 10 8
User LED8 8 8 1 1 8 12
Indicator LED3 9 10 1 No 6 13
Onboard Clock25 MHz 12 MHz, 50 MHz, 200 MHz 100 MHz 48 MHz, 200MHz 25 MHz 100 MHz 12 MHz, 100 MHz, programmable
Flash32–128 Mbit QSPI 128 Mbit QSPI 128 Mbit QSPI 64 Mbit QSPI 8 Mbit SPI 64 Mbit QSPI 128 Mbit
Onboard RAM32 MB SDRAM No 1024 MB DDR3 up to 16 MB HyperRAM 32 MB SDRAM 512 MB DDR3 1 GB
Video OutDigital (GPDI), Analog Composite PAL/NTSC (3.5 mm jack) No No No Digital (GPDI) Digital (HDMI) DVI via TFP410
Audio OutDigital S/PDIF (3.5 mm jack), Digital (GPDI), Analog stereo (3.5 mm jack) No No No Digital (GPDI) Digital (HDMI) No
ADCMAX11125 No No No Sigma-Delta No No
StorageMicro-SD No No Micro-SD Micro-SD Micro-SD, 8 GB eMMC Micro-SD
EthernetVia ESP32, USB No Yes No No Yes Gigabit (RGMII)
DisplayPlaceholder for 0.96" SPI color OLED SSD1331 No 14-segment LED No No No No
Antenna27, 88–108, 144, 433 MHz FM/ASK onboard No No No No No No
RTC (Real-time Clock)MCP7940N, Low Power Sleep, Wakeup No No No No No No
Power InputUSB 5 V 12 V 12 V USB 5 V USB 5 V 12 V USB-C 5 V, barrel jack 12 V
GPIO Bank Voltage Levels3.3 V, 2.5 V (jumper selectable) 3.3 V 3.3 V 3.3 V 3.3 V 3.3 V 3.3 V, 2.5 V, 1.8 V
Power Reserve to Drive External Circuits3.3 V at 1 A, 2.5 V at 1.5 A UnknownUnknownUnknownUnknownUnknown3.3 V, 2.5 V, 1.8 V at 2 A
Open Source ToolchainYes Yes Yes Yes Yes Yes Yes
Arduino Support (FPGArduino)Yes Not yet Not yet Not yet Yes Yes No
Confirmed Working Retro Games ConsolesYes No No No Yes No No

Support & Documentation

You will find setup and configuration guides, tutorials, and sample code in our FPGA Odysseus repository on GitHub. Additional resources are available in our Community Projects repository, or you can also reach out to other ULX3S developers through our Gitter community.

In the Press

Hackster News

"This is a really awesome dev board option that a newer FPGA developer can definitely grow into, and more experienced developers can really do some amazing things with."


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Produced by / Zagreb Makerspace in Zagreb, Croatia.

Sold and shipped by Crowd Supply.

ULX3S with ECP5 12F

ULX3S development board with a Lattice ECP5 (LFE5U-12F-6BG381C) FPGA. 12k LUTs and a whole lot more.

$145 $8 US Shipping / $18 Worldwide

ULX3S with ECP5 85F

ULX3S development board with a Lattice ECP5 (LFE5U-85F-6BG381C) FPGA. 84k LUTs and a whole lot more.

$235 $8 US Shipping / $18 Worldwide

Expansion Boards

A set of three expansion boards for ULX3S: one dual-USB board with support for IR send and receive, one Digital Video board for GPDI input or as a second GPDI output, and one OV7670 camera connector.

$39 $8 US Shipping / $18 Worldwide

About the Team / Zagreb Makerspace

Zagreb, Croatia  · / Zagreb Makerspace works to enhance the visibility of makers' open source culture and sustainable production, as well as to help connect all possible fields of Science, Technology, Engineering, Art, and Mathematics (STEAM).

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