Quick start

This guide walks you through installing FABulous, generating a fabric, and producing a bitstream in under five minutes. For detailed installation options see the Installation section.

1. Install FABulous

Install uv (if you don’t have it already), then install FABulous as a tool:

# Install uv (Linux/macOS)
curl -LsSf https://astral.sh/uv/install.sh | sh

# Install FABulous
uv tool install fabulous-fpga

If you already have pipx installed, pipx install fabulous-fpga works as well.

Verify the installation:

FABulous --version

Tip

See the Installation section for alternative methods (venv, Docker, Nix) and platform-specific instructions.

2. Install CAD tools

FABulous requires Yosys and nextpnr-generic for synthesis and place-and-route. The easiest way to install them is through the bundled installer:

FABulous install-oss-cad-suite

This installs the OSS CAD Suite, which includes Yosys, nextpnr, simulators, and all other required tools. VHDL users will also get ghdl and the ghdl-yosys-plugin through this installer. For manual installation or more details, see CAD tool installation.

3. Create a project

FABulous create-project demo

This creates a demo/ directory with a default fabric definition and example user designs.

4. Generate fabric and bitstream

You can run the full flow either interactively or as a one-liner.

Option A – Interactive shell:

cd demo
FABulous start

Inside the FABulous shell:

fabulous> run_FABulous_fabric
fabulous> run_FABulous_bitstream user_design/sequential_16bit_en.v

Option B – Command line (batch mode):

FABulous -p demo run "run_FABulous_fabric; run_FABulous_bitstream user_design/sequential_16bit_en.v"

5. Check the outputs

After a successful run:

  • Tile RTL files are in demo/Tile/

  • Fabric RTL file is in demo/Fabric/

  • Bitstream is at demo/user_design/sequential_16bit_en.bin

  • Synthesis and PnR logs are in demo/user_design/

What’s next?