Das4-controller

das4-controller

An open-source replacement controller board for the Das Keyboard 4 Professional: same outline, same holes, same connectors, but with an RP2350B you can flash with your own firmware (pico-sdk today, KMK/CircuitPython, QMK once it supports the RP2350B). It keeps the two USB-A ports (as a USB 2.0 hub), the volume knob, the NUM/CAPS/SCROLL LEDs (now RGB, any colour) and the five buttons. Every button gets its own GPIO, so you can make them do whatever you like.

Status: ready to order after a final 1:1 fit print. Routed, DRC clean (0 unconnected, 0 real violations), with independent circuit and layout reviews, a check against Raspberry Pi's RP2350 design guide, and a firmware build for this pinout. See docs/plan.md.

Top	Bottom

Docs

• Plan and status: what's done, next steps, bring-up and firmware plan
• Design notes: architecture, circuit blocks, GPIO map, ordering, open questions
• Bill of materials: every part with its LCSC number and live JLCPCB stock
• Measurements: every dimension, where it came from and how sure we are
• Fit-check PDF: print at 100% and lay the original board on it
• Reviews: circuit, layout 1, layout 2, RPi design guide, firmware
• AGENTS.md: how the pipeline works and what to watch out for (for AI agents and humans)

Layout

hardware/
  circuit/das4.py                          the circuit (SKiDL)
  das4-controller.net                      netlist generated from it
  das4-controller.kicad_pro / .kicad_pcb   KiCad 10 project (board generated from the netlist)
  lib/jlc.*                                JLCPCB part symbols, footprints and 3D models (easyeda2kicad)
  lib/das4.pretty                          our own footprints (J4 flex solder pads)
  scripts/gen_board.py                     outline, measured positions, placement, silkscreen
  scripts/critical.py                      hand-drawn critical nets + keep-outs (RP2350 regulator, USB pair, crystal...)
  scripts/route.py, route_best.py          autorouting (Freerouting) + cleanup + GND stitching, best of 6 runs
  scripts/pretest.py, check_layout.py      pre-route DRC of the hand layout; post-route checks
  scripts/jlc_fab.py                       JLCPCB gerber zip, BOM and CPL
  scripts/jlc.py                           search JLCPCB's parts library (no login)
  scripts/bom.py                           docs/bom.md with live stock
docs/                                      notes, plan, reviews, renders, fit-check print
firmware/bringup/                          pico-sdk + TinyUSB bring-up firmware for this pinout

Building

The tools come from the KiBot/KiCad container ghcr.io/inti-cmnb/kicad10_auto_full, which is also what CI runs.

# one-time: create the container
distrobox create --name pcb --image ghcr.io/inti-cmnb/kicad10_auto_full:1.9.1-1_k10.0.5_d13.2_b4.2.4LTS

distrobox enter pcb -- make pretest       # quick DRC of just the hand layout (run before routing)
distrobox enter pcb -- make board route   # circuit -> netlist -> placed board -> autorouted (~25 min)
distrobox enter pcb -- make check         # post-route checks DRC can't do
distrobox enter pcb -- make docs drc fab  # renders, fit-check PDF, DRC, JLCPCB files (don't rebuild the board)
distrobox enter pcb -- make bom      # refresh docs/bom.md with live JLCPCB stock

Or use Docker directly: docker run --rm -v $PWD:/w -w /w ghcr.io/inti-cmnb/kicad10_auto_full:1.9.1-1_k10.0.5_d13.2_b4.2.4LTS make.

Open hardware/das4-controller.kicad_pro in KiCad 10 to look around.

Note: the board file is generated: make board rebuilds it (unrouted) from the circuit and gen_board.py, and make route routes it. Edit those, not the .kicad_pcb, or your changes get overwritten.

Ordering (JLCPCB)

distrobox enter pcb -- make fab     # -> build/jlcpcb/: gerber zip, bom.csv, cpl.csv

1. On jlcpcb.com upload the gerber zip. Pick 4 layers, 1.6 mm, and the JLC04161H-7628 stackup with impedance control.
2. Enable PCB Assembly (top side), upload bom.csv and cpl.csv, and check the placement preview: rotations, and L1's white dot on the +1V1 pad next to C165 (details in docs/design.md).
3. Order the "You solder" parts in docs/bom.md from LCSC (they can ship together).

make fab names the zip ...-UNROUTED-quote-only if the board has no traces yet.

License

MIT, see LICENSE. Not affiliated with Das Keyboard / Metadot.