ExAce (FPGA Expansion Card)
ExAce (Expansion Card Accelerator) is a community-designed FPGA acceleration card in a Framework expansion card form factor12. Created by cdg66, it uses a CologneChip Gatemate A1 FPGA with an open-source toolchain and USB 3.0 SuperSpeed SERDES, targeting ML inference, signal processing, and hardware acceleration workloads12[^3].
ExAce is in pre-production as of June 2025. Boards have been sent for fabrication but have not yet been tested or verified1.
Design
The card is built around a CologneChip Gatemate A1 (or A2/A4) FPGA, offering 20,480 to 81,920 8-input LUT-trees depending on the variant2. An STM32L422RBI6 coprocessor handles programming and communication. The FPGA's SERDES lines are routed to the USB Type-C connector for SuperSpeed USB 3.0 connectivity12.
A USB 2.0 interface is shared between the FPGA and MCU via a USB mux2. The card also includes onboard sensors for data acquisition:
- PDM microphone
- 6DoF IMU
- Magnetometer
- Thermometer
Additional features include 8 user-programmable LEDs, 1 LVDS I/O for multi-board clustering, I²C between FPGA and MCU, and a shared ground plane2.
The PCB is designed in KiCad with a 0.8 mm thickness and a recommended JLCPCB stackup (JLC08081H-1080A)2.
Specifications
| Specification | Details |
|---|---|
| FPGA | CologneChip Gatemate A1/A2/A4 (20k–82k LUTs)2 |
| Coprocessor | STM32L422RBI62 |
| USB | USB 3.0 SuperSpeed SERDES + USB 2.0 (muxed)12 |
| Sensors | PDM mic, 6DoF IMU, magnetometer, thermometer2 |
| LEDs | 8 user-programmable2 |
| Cluster I/O | 1 LVDS for multi-board interconnect2 |
| Toolchain | Open-source (CologneChip)12 |
| Design tool | KiCad2 |
| License | CC BY 4.02 |
| Source | cdg66/ExAce (GitHub)2 |
| Est. cost | ~$130 USD (parts + PCB + assembly)1 |
Related Projects
| Project | Description |
|---|---|
| Frameoscope | Oscilloscope expansion card with iCE40 FPGA |
| RP2350 20-pin GPIO Expansion Card | RP2350A GPIO breakout card |