LabExam

serverside — the TraceWorks backend

A simple one-layer PCB "drawer": read a KiCad board, extract the copper traces, and turn them into travel-optimized G-code you can plot on a pen-plotter / small CNC driven by a microcontroller (GRBL — an Arduino running grbl_servo_z).

Aimed at hobby / student mini projects, not professional copper milling.

Pipeline

labExam.kicad_pcb
  → pcb_read.py          parse (custom s-expression parser; supports KiCad 10)
  → pcb_draw.py          board preview by copper layer  (labExam_wiring.png)
  → pcb_gcode.py         travel-optimized G-code         (labExam.gcode)
  → pcb_gcode_preview.py verify toolpath, no hardware     (labExam_toolpath.png)
  → pcb_send.py          stream to GRBL over USB serial (--check to validate)
  → Arduino running GRBL 1.1, over USB

pcb_send.py is the CLI streamer and is not what the web app uses. The API owns the serial port itself:

grbl/        the GRBL 1.1 stack: protocol codec, port enumeration, the
             flow-controlled streamer thread, machine state, travel limits,
             and a simulator good enough to develop against
machine.py   the one process-wide Session that owns the port
job.py       streams one board's G-code, with progress, pause, stop

Run

python main.py                # run the whole pipeline, step by step
python main.py --skip-preview # ... without the matplotlib image steps

Each stage also runs on its own — see DOCS.md for full documentation, status, and roadmap, and HARDWARE.md for the plotter build (parts list, flashing steps, starter config).

Web API + database (server side of the UI)

server.py is a FastAPI app that wraps this pipeline for the web UI in ../userpage, and drives the machine. It parses uploaded boards, generates G-code, and stores accounts and routed boards in MongoDB (mongodb://localhost:27017, database traceworks).

pip install -r requirements.txt
uvicorn server:app --reload --port 8000                  # needs a local MongoDB

TRACEWORKS_SIM=1 uvicorn server:app --reload --port 8000  # ...and no hardware

Board and account endpoints: POST /route (upload a .kicad_pcb → parsed + routed board), POST /trace (an image → a pen path), /auth/signup · /auth/login, /boards/{email}, /board/{id}.

Machine endpoints — the backend runs on the same PC as the browser, so it, not the tab, owns the COM port:

See server.py for the full list and db.py for the Mongo connection. The reusable entry point is pcb_read.extract_wiring(text).

Requirements

Python 3 and matplotlib for the CLI pipeline. The web API also needs fastapi, uvicorn, python-multipart, and pymongo (all in requirements.txt), plus a running MongoDB. (kiutils is intentionally not used — it does not support the KiCad 10 file format.)

See ../RUNNING.md for running this together with the frontend in ../userpage.