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FPGA - Open Source Tools

There are several open-source tools available for FPGA programming, offering support for various aspects of FPGA design such as synthesis, simulation, place-and-route, and bitstream generation. These tools provide free alternatives to proprietary software like Xilinx Vivado or Intel Quartus. Below are some notable open-source FPGA programming tools:

1. Yosys

Purpose: Synthesis Tool
Yosys is a powerful open-source logic synthesis framework that is widely used for converting HDL code (primarily Verilog) into gate-level netlists.

  • Features:
    • Supports Verilog and SystemVerilog for synthesis.
    • Works well with a variety of open-source and commercial place-and-route tools.
    • Can be extended with plugins for additional functionality.
  • Usage: Primarily used for digital logic synthesis, it supports a wide range of FPGA families, especially Lattice FPGAs.
  • Integration: Often used with nextpnr for place-and-route.

Website: https://yosyshq.net/yosys/

2. nextpnr

Purpose: Place-and-Route Tool
nextpnr is an open-source FPGA place-and-route tool that works with several FPGA architectures, including Lattice, Xilinx, and Intel.

  • Features:
    • Supports multiple FPGA architectures such as Lattice iCE40, ECP5, and Xilinx Artix-7.
    • Uses the EBLIF netlist format generated by synthesis tools like Yosys.
    • Offers support for constrained placement and timing-driven routing.
  • Integration: Works seamlessly with Yosys for a full FPGA synthesis and place-and-route flow.

Website: https://github.com/YosysHQ/nextpnr

3. Verilator

Purpose: HDL Simulator
Verilator is an open-source Verilog simulator and linting tool that converts Verilog designs into C++ or SystemC for fast cycle-accurate simulations.

  • Features:
    • Extremely fast simulation performance compared to event-driven simulators.
    • Generates human-readable C++/SystemC models from Verilog.
    • Ideal for co-simulation, integration with C++/SystemC testbenches.
  • Limitations: Does not support all SystemVerilog constructs (focuses on synthesizable subsets).

Website: https://www.veripool.org/verilator/

4. SymbiFlow

Purpose: FPGA Toolchain
SymbiFlow is a fully open-source FPGA toolchain that provides a complete end-to-end flow, from synthesis to bitstream generation for specific FPGA architectures.

  • Features:
    • Supports FPGAs such as Lattice iCE40, Xilinx 7-Series (Artix-7, Kintex-7), and ECP5.
    • Offers integration with Yosys and nextpnr for a complete design flow.
    • Includes open-source bitstream generation tools like icestorm (for iCE40) and prjxray (for Xilinx 7-Series).
  • Use Case: SymbiFlow is ideal for users seeking an entirely open-source flow for FPGA programming.

Website: https://symbiflow.github.io/

5. Project Icestorm

Purpose: FPGA Bitstream Generation (Lattice iCE40)
Project Icestorm provides a complete open-source toolchain for Lattice iCE40 FPGAs, including tools for bitstream generation.

  • Features:
    • Supports synthesis (using Yosys), place-and-route (nextpnr), and bitstream generation.
    • Full documentation and support for reverse-engineering the iCE40 bitstream format.
    • Compatible with Lattice iCE40 LP/HX/UP FPGA devices.

Website: http://www.clifford.at/icestorm/

6. Project Trellis

Purpose: Bitstream Generation (Lattice ECP5)
Project Trellis provides the infrastructure for an open-source bitstream for the Lattice ECP5 FPGA family.

  • Features:
    • Reverse-engineered bitstream format for Lattice ECP5.
    • Works with Yosys for synthesis and nextpnr for place-and-route.
    • Includes tools and utilities for testing and bitstream manipulation.
  • Use Case: Open-source development for the Lattice ECP5 FPGAs.

Website: https://github.com/YosysHQ/prjtrellis

7. GHDL

Purpose: VHDL Simulation
GHDL is an open-source VHDL simulator that can compile and simulate VHDL designs.

  • Features:
    • Supports the VHDL-2008 standard.
    • Can be used to create executables for simulations and works with third-party waveform viewers.
    • Integrates with open-source tools like Yosys (for mixed Verilog/VHDL projects) and GTKWave (for waveform analysis).

Website: https://https://github.com/ghdl/ghdl/releases/

8. OpenOCD (Open On-Chip Debugger)

Purpose: JTAG Debugging and FPGA Programming
OpenOCD is an open-source tool that provides on-chip debugging, in-system programming, and boundary-scan testing for a wide range of devices, including FPGAs.

  • Features:
    • Supports JTAG interfaces for configuring and debugging FPGAs.
    • Works with a variety of hardware adapters (e.g., USB JTAG adapters).
    • Often used for low-level debugging and FPGA programming in conjunction with other tools.

Website: http://openocd.org/

9. FuseSoC

Purpose: FPGA Build System
FuseSoC is an open-source package manager and build system for HDL (Verilog, VHDL) projects that automates toolchain setup and IP core management.

  • Features:
    • Supports various FPGA and ASIC flows, including Yosys and nextpnr.
    • Manages dependencies for IP cores and includes libraries of reusable HDL components.
    • Simplifies FPGA project setup and configuration, particularly for large projects.

Website: https://github.com/olofk/fusesoc

10. Apio

Purpose: FPGA Development Environment
Apio is an open-source development environment that provides a simple interface for FPGA development with support for various toolchains like iCE40 (Project Icestorm) and ECP5 (Project Trellis).

  • Features:
    • Provides a command-line interface to manage FPGA toolchains.
    • Includes support for multiple FPGAs (mainly Lattice).
    • Easy to use for beginners, offering a simplified setup process for FPGA development.

Website: https://github.com/FPGAwars/apio

Conclusion

Open-source FPGA tools are becoming more popular, offering developers an accessible and customizable alternative to proprietary software. The key tools for programming FPGAs include Yosys for synthesis, nextpnr for place-and-route, and specific bitstream generation tools like Project Icestorm and Project Trellis. These tools enable a complete open-source flow for FPGA design, especially for Lattice and some Xilinx FPGAs. These tools have made FPGA development more flexible, transparent, and affordable.