Section 01 · J-003Field Journal
Field Entry J-003

Propagation Unit No. 01

The goals, and the full build list, for the first semi-automated propagation bench.

The propagation unit’s live board in observation mode — bench status, reservoir, active shelves and per-bay readingsFig · The unit’s live board, observation mode · telemetry is a styled placeholder until the controller API is online

The first Propagation Unit is a three-shelf bench that raises native restoration stock from seed and cutting with as little daily babysitting as the work allows. It's deliberately small — one rack, off-the-shelf parts, and a controller anyone could rebuild in a weekend. The point was never to build something clever. It was to see how much of a nursery routine you can hand off to a cheap sensor and a valve, so the crew can spend its hours out in the sections instead of standing at a hose.

What it must do

Hold each shelf inside a target moisture band. Run the lights on a per-shelf photoperiod. Move air with a fan. Water a shelf only when it drops below its floor, and never more often than its cooldown allows. And log every reading and every cycle, so a season can be reviewed instead of just remembered.

  • Rack — three growing shelves, 01 through 03, on a steel wire frame
  • Controller — a single-board Piconium reading moisture, temperature and reservoir level
  • Water — 120 L reservoir, diaphragm pump, one solenoid valve per shelf
  • Light — full-spectrum bars on a per-shelf schedule
  • Air — USB circulation fans on the rack
  • Interface — a 5″ Waveshare touchscreen at the rack and a web dashboard
On the benchThe unit is instrumented, not autonomous. A person still decides what grows where and signs off on any change. The software just keeps the shelves honest between visits.

Bill of materials

The full parts list, with the engineering notes, lives in the repo at docs/HARDWARE.md. The short version:

  • Compute — a Piconium single-board computer (x86, 4 GB RAM) running Debian
  • Display — Waveshare 5″ 800×480 touchscreen (HDMI + USB touch)
  • Relays — Numato 8-channel USB relay module
  • Serial — an FTDI RS485 adapter (FT232RQ + SP485EN)
  • Grow lights — Barina full-spectrum bars, 120 VAC
  • Fans — 12 V USB circulation fans
  • Pump — a SEAFLO 12 VDC diaphragm pump
  • Valves — four U.S. Solid 12 VDC solenoid valves, normally closed (they fail shut on power loss)
  • Soil probes — RS485 multi-parameter soil probes (moisture, temperature)
  • Reservoir sensor — a submersible hydrostatic level transmitter (RS485)
  • Reservoir — a 120 L tank
  • Rack — a three-shelf steel wire frame

The interface is public. You can open the same rack screen and dashboard the crew uses over on Instruments & Infrastructure — in observation mode, so you can click through every screen without touching the live bench.

The code is open source too — the full build, controller and dashboard live at github.com/Short-s-Resort-Field-Station/propagation-controller.

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