netcrux

NetCrux is an interactive RTL schematic browser and signal tracer: it elaborates your Verilog/SystemVerilog/VHDL through Yosys, lays the result out as a navigable schematic, and lets you walk the hierarchy and trace drivers and loads. Open core, part of Ferrite Engineering's EDACrux suite.

NetCrux showing a small SoC elaborated through Yosys — hierarchy on the left, schematic on the right.

Status

Stable since 1.0. Implemented in this repository today:

• Yosys-backed elaboration of Verilog / SystemVerilog / VHDL, with an elaboration cache, a bounded and killable subprocess, and structured error reporting.
• ELK-based schematic layout with a tabbed, split-pane workspace, hierarchy tree, inspector, breadcrumb scope navigation, and zoom/pan.
• One-step fanin/fanout tracing with a dimming overlay.
• Substring / glob / regex design search across instances, cells and nets.
• PNG, SVG and JSON export; .netcrux sessions, .netcrux-project projects, .netcrux-workspace workspaces, and Vivado-style .f filelist import.
• A CXP cross-probe server for the rest of the EDACrux suite.
• Update checks, the in-app issue reporter, themes, rebindable shortcuts, and en/zh_CN/zh/ja/ko localization.

Try it

examples/ holds ready-to-open projects. Launch NetCrux, then File → Open Project… (Cmd/Ctrl+O) and pick one:

• examples/adder4/ — the smallest thing NetCrux draws: five ports and two $add cells. The fastest way to confirm your Yosys install works.
• examples/cdc-capture/ — the suite's shared two-clock-domain demo design: 18 cells and 7 flops, enough to exercise the hierarchy tree, design search, the inspector, and fanin/fanout tracing.

Both need yosys on your PATH — see Prerequisites. Unlike its sibling tools, NetCrux has no toolchain-free entry point: a schematic is a view of an elaborated netlist, and on desktop only a live Yosys run produces one. Without Yosys the examples open a tab and say so on the canvas rather than failing silently.

Pattern reference

netcrux follows the same open-core + Pro/Enterprise overlay pattern as WaveCrux:

• This repository is the open-core viewer/tool.
• The closed-source Pro/Enterprise overlay consumes this repo as a Git submodule and depends on it through a pubspec path: ./netcrux entry, layering its features via a proOverrides list spread into the open-core ProviderScope.

When in doubt about a convention, file layout, naming choice, or architectural seam, consult the WaveCrux reference implementation. Match its pattern unless this project has a documented reason to diverge.

Prerequisites

NetCrux does not ship Yosys. Install it and put it on your PATH — NetCrux looks for yosys (yosys.exe on Windows). Without it, elaboration fails with "Yosys could not be found or run"; you can also point Settings → Engines at a custom Yosys path, or pass --yosys-path.

VHDL additionally needs ghdl on your PATH. NetCrux lowers VHDL to Verilog with a standalone ghdl --synth --out=verilog invocation before Yosys runs, so a plain GHDL build is enough — no ghdl-yosys-plugin and no plugin-capable Yosys build.

Build & run

git submodule update --init --recursive   # crux-shared
flutter pub get
flutter run -d macos      # or -d linux, -d windows
flutter analyze
flutter test

Settings → Engines offers Auto-detect and Custom for the Yosys binary. No Yosys binary ships inside the release distribution, so there is no Bundled choice. A setting saved as Bundled by an earlier version still loads and shows as Auto-detect; it resolves through the PATH lookup unless the NETCRUX_BUNDLED_BIN_DIR environment variable points at a binary directory. See NOTICES §1.

Platform support

Platform	State	Notes
Linux	Supported	Primary target.
macOS	Supported	macOS 12.0 or later.
Windows	Supported
Web	Supported	Read-only schematic viewer — no Yosys runs in a browser, so it renders netlists elaborated elsewhere.

No mobile build: a schematic browser is a pointer-and-keyboard tool, and the elaboration step needs a local toolchain.

Contributing

Read CONTRIBUTING.md first — contributions require a signed Contributor License Agreement (CLA.md). docs/ARCHITECTURE.md is the engineering reference: tech stack, architectural rules, and the extension-point seams the Pro overlay plugs into. User documentation lives at docs.netcrux.app, and its source is in docs-site/docs/.

The quality gates, all of which must pass:

flutter analyze --fatal-infos --fatal-warnings   # zero-warning policy
flutter test

License

NetCrux open core is licensed under the Apache License 2.0. See LICENSE for the full text and NOTICES for third-party attributions. Contributions require a signed Contributor License Agreement — see CONTRIBUTING.md.

Apache-2.0 §6 grants no trademark rights, so the name and logo are covered separately — see TRADEMARK.md. Forks are welcome; they just need a different name.