pcad — schematic pictures from JSON, in the ProfiCAD file format

pcad.py generates electrical/electronics schematics as ProfiCAD .sxe drawings from a small JSON spec, and renders them to PNG/SVG with a clean-room pure-Python renderer. ProfiCAD itself is not required — the symbol library is bundled under lib/ and both the writer and the renderer are plain Python.

The symbol library is an independent clean-room drawing of the EN 60617 (= IEC 60617; Czech ČSN EN 60617) graphical symbols. A facts-only specification (symbol name, standard clause, ordered connection points and pin-number order, drawn size, inside markings — no drawing data of any kind) was written from the standard, and separate drawing teams rendered those facts into ProfiCAD-format .ppd files with no access to any third-party symbol library. Pin positions and pin-number order follow the standard, so wiring carries the standard's connection numbering; the geometry is this project's own. The library plus the .picd ICs and the junction dot are MIT-licensed, © 2026 miromraz — see lib/NOTICE for the clean-room process and lib/LICENSE.

Requirements

• Python 3 (standard library only) for build, search, pins, inspect, verify, and SVG rendering.
• Pillow only for PNG rendering.

Commands

python3 pcad.py search <words...>            find library symbols (AND match on path)
python3 pcad.py pins <symbol>                list a symbol's pins/outlets
python3 pcad.py build <spec.json> <out.sxe>  generate a drawing
python3 pcad.py render <in> <out.png|.svg>   render (.sxe/.ppd/.picd; PNG needs Pillow)
python3 pcad.py verify <out.sxe>             ERC on the drawing geometry (nets + checks)
python3 pcad.py inspect <file.sxe>           summarise an existing drawing
python3 pcad.py import-lib [SRC] [DEST]      copy ProfiCAD's stock symbols from your own install
python3 pcad.py selftest                     run internal asserts

A <symbol> is a library-relative path without extension, e.g. electronics/passive/resistors/resistor, electronics/meters/ammeter, ic/555. Use search to find the exact path.

Using ProfiCAD's stock symbols

For the stock ProfiCAD symbol shapes, follow the stock-library extraction tutorial. It covers extracting ProfiCAD's official portable ZIP (no installation or Wine needed), importing from an existing Windows/Wine installation, selecting the library, and giving an agent a working setup.

The stock library is not included in this repository. Each user obtains it from ProfiCAD and keeps it outside their checkout, normally at ~/.pcad/proficad-lib. The bundled lib/ remains this project's independent library. Stock symbol paths and pin layouts can differ: run search and pins after switching. The renderer uses the selected symbol geometry; fonts and unsupported drawing features can differ from ProfiCAD's own export.

PCAD_LIB accepts a directory containing ProfiCAD-format .ppd/.picd files; it defaults to the bundled lib/. Set it for every search, pins, and build command that should use the stock library. Built .sxe files embed the symbols they use, so rendering an existing drawing does not require that library.

JSON spec format (coords in mm)

{
  "parts": [
    {"sym": "electronics/passive/resistors/resistor", "ref": "R1", "val": "330R",
     "x": 30, "y": 30, "rot": 90, "mirror": "x", "hide_ref": true}
  ],
  "wires": [
    ["R1.1", [30, 20], "D1.2"],
    {"pts": [[20, 20], [90, 20]], "name": "L1", "dots": false}
  ],
  "texts": [{"x": 10, "y": 5, "text": "note", "size": 70, "color": "008000"}],
  "title": {"title": "...", "author": "...", "date": "...", "name": "..."}
}

• x,y = part centre in mm. rot = degrees (90, -90, 180). mirror = "x" (left-right) or "y" (top-bottom); pins and wires follow the mirror. hide_ref hides the reference label.
• A wire point is [x,y] in mm, or "REF.pin": for a .ppd part the pin is the 1-based outlet index (pins lists them); for a .picd IC it is the printed pin number. Add [x,y] corners for right-angle routing.
• Junction dots are added automatically where a wire end meets another wire. Set "dots": false on a wire to suppress them for that wire.
• Named wires ("name": "L1") are busbars: same-name wires form one net and their open ends are treated as labelled terminals.

Workflow: search → pins → write spec → build → verify (fix until PASS) → render → look at the PNG → iterate.

Agent skill (Codex and Claude Code)

Clone the repository and install the skill by symlinking it, so its tools and references remain available. These commands are for Linux/macOS or WSL:

git clone https://github.com/miromraz/pcad.git "$HOME/pcad"
cd "$HOME/pcad"
# Codex:
mkdir -p "$HOME/.agents/skills"
ln -s "$PWD/skills/proficad-schematic" "$HOME/.agents/skills/proficad-schematic"
# Claude Code (optional):
mkdir -p "$HOME/.claude/skills"
ln -s "$PWD/skills/proficad-schematic" "$HOME/.claude/skills/proficad-schematic"

If a skill already exists at the destination, inspect it before replacing it. Start a new agent session after installation. On Windows, an agent can read skills/proficad-schematic/SKILL.md directly from the checkout; keep that checkout available to it.

The skill covers search → pins → spec → build → verify → render and visual inspection. For the stock look, complete the library tutorial first, then tell the agent the absolute checkout and library paths. Do not copy only SKILL.md: it needs the tools in this repository.

Credits

• Symbol library: an independent clean-room drawing of EN 60617 / IEC 60617 (ČSN EN 60617), drawn from a facts-only specification by separate drawing teams with no access to any third-party symbol library. MIT, © 2026 miromraz. See lib/NOTICE for the clean-room process.
• Code: MIT, © 2026 miromraz. See LICENSE.

ProfiCAD is a trademark of its respective owner. This project is independent and unaffiliated; it only reads and writes the documented .sxe/.ppd/.picd file structures (see RE_NOTES.md).