A language and tools for designing electronics as code: schematics, solvers, checks and PCB fabrication outputs. A board is a set of parts and the nets that join their pins, written as text. netsmith checks it, picks real parts that work in the worst case, and exports files for CAD tools and for a board house. It writes a KiCad 9 schematic, and a placed and routed PCB with a Gerber package for JLCPCB, on two layers or on four with ground and supply planes inside. The editor (netsmith editor) shows the source and the board in a browser.

Status: early (version 0.0.1). The examples in examples/ build and pass KiCad's checks.

An example

examples/led.nsm is a board with a 5 V supply, a resistor and an LED. The == line states the circuit's equation; netsmith picks a resistor and an LED from a catalog so that it holds in the worst case, for every tolerance.

board LedExample {
    .process: TwoLayer {
        .stackup.thickness &= 1.6mm
    }

    .supply: Rail {
        .voltage &= 5V +/- 5%
        .pos.net &= "VCC"
        .neg.net &= "GND"
    }
    .led: Led {
        .current &= 5mA..15mA
    }
    .r1: Resistor {}

    .power_in: Header1x2
    .supply.pos ~ .power_in.p1
    .supply.neg ~ .power_in.p2

    .led.current == (.supply.voltage - .led.forward_voltage) / .r1.resistance
    .supply.pos ~> .r1 ~> .led ~> .supply.neg
}

The imports and doc comments are left out here; the complete file is examples/led.nsm.

Install

• Build from a checkout: cargo install --path crates/netsmith. It needs only Rust; the editor's page is committed as a built bundle.
• Or take the netsmith-<version>-<target>.tar.gz archive (.zip on Windows) from the releases, check it against its .sha256 file and put the binary on your PATH. scripts/release-build.sh makes the archives. No release is published yet (#7).

build and fab read KiCad's symbol and footprint libraries for the parts netsmith does not generate itself, so install KiCad 9 (8 also works). netsmith finds the symbols and footprints folders by itself; set NETSMITH_KICAD_SYMBOLS and NETSMITH_KICAD_FOOTPRINTS to name them. If it finds none, it stops and lists every place it looked (ADR 0021). Only Windows KiCad 9 under WSL has been tried on a real install (#6). The program kicad-cli is $KICAD_CLI, else on PATH, else (under WSL only) the newest Windows KiCad in /mnt/c/Program Files/KiCad/<version>/bin; without any, the editor says "KiCad not found: set KICAD_CLI or install KiCad".

Use it

mkdir blink && cd blink
netsmith init       # netsmith.toml, src/main.nsm (a working LED board), agent files
netsmith build      # a KiCad schematic in out/
netsmith editor     # the source and the board in a browser, at 127.0.0.1:8787
netsmith fab        # a package for JLCPCB in fab/: Gerbers, drill, bom.csv, cpl.csv, fab-notes.txt
netsmith compare a.kicad_sch b.nsm   # are two designs the same circuit?

Without a project, netsmith build examples/led.nsm --out out works on one file. netsmith --help lists every command and flag, and docs/LANGUAGE.md ("Projects and netsmith.toml") describes the project folder.

Read fab-notes.txt before you order. It lists what netsmith could not verify, for example the pick-and-place rotation of a package that no board of yours has been assembled with. Check JLCPCB's order preview for those.

Where to read next

• docs/LANGUAGE.md: the language guide, with a quick start, every construct with a tested example and the real error you get when you misuse it, and the standard library.
• docs/CONCEPTS.md: how parts, modules, boards and systems combine. docs/PROJECT-LAYOUT.md: a repository with several boards.
• GLOSSARY.md: the vocabulary. docs/DESIGN-RULES.md: the rules the language follows. docs/adr/: the decisions behind the design.
• Contributors and agents: AGENTS.md. Open work is in the GitHub issues.

Limitations

• Price and stock are unknown until a supply provider is asked, and no provider asks a supplier yet (#8, #30). Catalogs hold only verified parts (#66); only resistors can be generic (#31).
• netsmith writes its own Gerbers, drill and placement files, and JLCPCB has not yet taken them (#12, #61).
• A board outline is a rectangle with equal rounded corners (#57). A panel repeats one board on a V-cut grid (#62).
• The placer and router can leave a tight board unrouted (#3, #58).
• Physical intent (the outline, cutouts, holes, keepouts and where parts must be) is in a file of its own beside a board, <stem>.physical.nsm, and the same lines in the board are an error (ADR 0048, #52). The board level is built; the module layer, a physical file for a system or a panel, evaluating a relation between two parts, and the editor writing its keepouts to that file (it writes the layout file) are not. The provisional readings are in the ADR's "Built".
• Several of the decisions in docs/adr/ are provisional and unreviewed (#10).

Licence

netsmith is MIT licensed (LICENSE).

netsmith keeps no copy of KiCad's symbols or footprints. It reads the symbols, and the footprints that it does not make itself, from the ones installed with KiCad (CC-BY-SA 4.0 with a design exception) at run time, and the tests that need no KiCad write small libraries of their own (netsmith_kicad::testlib). The footprints it makes are original code that computes IPC-7351B land patterns from published package dimensions (ADR 0043); the test that checks them reads KiCad's footprints and bundles none. The formulas and tables were learned from the kicad-footprint-generator repository (GPL-3.0-or-later; no code was copied) and the package dimensions of the QFN rows are numbers from its data files and the datasheets they cite.