uv254

Open hardware for the uv254 UV water-quality sensor. The device is three boards, each its own KiCad project:

Board	Folder	What's on it	Current design
UV-Control	hardware/uv-control	nRF52840 controller, ADS1115 ADC, color TFT, buttons, power	v0.4 (in progress: schematic draft)
UV-Emitter	hardware/uv-emitter	Inolux IN-C35PPCTGU0 UV-C LED and its driver	v0.4 (released 2026-11-08)
UV-Detector	hardware/uv-detector	SD008-2171-112 photodiode with an op-amp front end	v0.4 (released 2026-11-08)

UV-Control	UV-Emitter	UV-Detector

Each board's README has its schematic, PCB layout and 3D views.

UV-Emitter was called UV-LED-source in earlier revisions. Background notes are at https://edgecollective.io/notes/uvf/.

Repository layout

hardware/
  uv-control/                 one KiCad project per board
    uv-control.kicad_pro      open this in KiCad
    uv-control.kicad_sch
    uv-control.kicad_pcb
    sym-lib-table             -> lib/uv254.kicad_sym
    fp-lib-table              -> lib/uv254.pretty
    docs/                     schematic PDF and the images in the board's README
    fab/<version>/            fabrication files that were actually sent out
  uv-emitter/
  uv-detector/
lib/                          shared project library (custom parts only)
  uv254.kicad_sym
  uv254.pretty/
firmware/uv-control/          CircuitPython scripts for the control board
scripts/build-fab.sh          builds gerbers, drill, BOM, PDF, positions
scripts/render-images.sh      renders schematic, layout and 3D images for the READMEs
.github/workflows/kicad.yml   ERC/DRC on every push; fab package on release tags

Opening the boards

Download the latest design files (zip) if you just want to look at or build the boards, or clone the repository to work on them. Either way, open hardware/<board>/<board>.kicad_pro in KiCad 10.0.x, the version everyone on the project uses (see CONTRIBUTING.md).

Keep the folder structure as it is. Custom parts come from lib/ through each project's own library tables, so you don't need any global library setup beyond KiCad's standard libraries, but a board folder copied out on its own will be missing its custom parts.

Updating the board images

Each board's README shows its schematic, PCB layout and 3D views. These are files in hardware/<board>/docs/, made by scripts/render-images.sh, so they don't change by themselves when the design does. After changing a board, save it in KiCad, then refresh the images from the top of the repository:

scripts/render-images.sh uv-detector                         # one board
scripts/render-images.sh uv-control uv-detector uv-emitter   # all three

Then commit what changed (git status shows it) along with the design change.

What the script does:

• Writes to hardware/<board>/docs/: the schematic as PDF and PNG, the PCB layout front and back (the back mirrored, as seen from below), and 3D renders front and back.
• Updates the image section of the board's README, between the render-images markers. Anything you write between those markers gets overwritten, so put your own notes outside them.
• Only replaces files whose picture changed. A board whose 3D look changed takes about 2 minutes (two raytraced renders). An unchanged board takes about 15 seconds and leaves git clean.
• Uses KiCad's default colour theme, so everyone's images come out the same whatever their own KiCad preferences.

For a quick look while you work, --fast makes flat-shaded 3D renders in a few seconds. Commit the full renders, though: run it again without --fast before committing.

It needs KiCad 10 (kicad-cli on your PATH), plus Inkscape, ImageMagick and poppler. On Debian or Ubuntu:

sudo apt install inkscape imagemagick poppler-utils

It has only been tested on Linux.

Versions and releases

Each board is versioned on its own. A revision is a git tag named <board>/<version>:

git tag -l 'uv-detector/*'          # list detector revisions
git checkout uv-detector/v0.3       # the exact design ordered from JLCPCB in Aug 2024
git checkout main                   # back to the current work

To download one revision as a zip, use its tag, for example https://github.com/edgecollective/uv254/archive/refs/tags/uv-detector/v0.3.zip.

hardware/<board>/fab/<version>/ holds the files that were actually sent to the fab house for that revision. Each board's README has the revision history. Pushing a new tag makes CI build that board's fab package and attach it to a GitHub Release (see CONTRIBUTING.md).

The history before this repository is in gitlab.com/edgecollective/uv-water. Every tagged revision here was imported from it. The imported fab files were checked by regenerating them from the tagged design.

License

• Hardware (everything except firmware/): CERN Open Hardware Licence Version 2 – Strongly Reciprocal (CERN-OHL-S-2.0).
• Firmware (firmware/): MIT License. The bundled Adafruit libraries are also MIT, under Adafruit's copyright.

Contributors: Don Blair, Craig Versek.