Tradewind

Tradewind TW-1 · solar LoRaWAN field sensor

Tradewind is a sealed, solar-powered sensor for farms and remote sites. It measures air temperature and humidity, soil moisture and rainfall, and reports over LoRaWAN every 5 minutes (every minute in rapid mode). It is a complete reference design by Binary Beach: requirements, simulation, schematic, a 4-layer board, enclosure, firmware, bring-up, characterization and a 30-day field pilot.

The full story is in the documents. This README is a map of the repository.

Results at a glance (rev B)

13 of 15 requirements pass outright, R6 (charge window) passes marginally, and R10 (IP66 jet) is open pending an accredited lab. See test/compliance.csv.

Bench and field figures in this release are representative values for the reference design. The analysis scripts in test/ run unchanged on new logs.

How the design flows

flowchart LR
  spec[docs/design-spec.md] --> d[tools/design.py<br>parts · values · nets]
  d --> sch[gen_schematic.py<br>4-sheet KiCad schematic] --> erc[ERC + netlist check]
  d --> pcb[gen_pcb.py place<br>placement · planes · RF · fan-out] --> fr[Freerouting] --> ses[gen_pcb.py ses<br>import · pours · cleanup] --> drc[DRC + schematic parity]
  drc --> fab[export_fab.sh<br>Gerbers · BOM · CPL · STEP · GLB]
  spec --> sim[sim/<br>ngspice + Python]
  fab --> mech[mechanical/<br>CadQuery enclosure]
  fab --> rnd[render/<br>Blender Cycles]
  sim & mech & rnd & test[test/ analysis] --> docs[gen_report.py · gen_datasheet.py]

The schematic and the board are generated from one design file, tools/design.py, so they can't drift apart. tools/check_netlist.py checks KiCad's exported netlist against that file pin by pin (233 pins, 47 nets), and DRC runs with schematic parity. The KiCad project is an ordinary KiCad 9 project, so you can open it and edit it by hand.

Repository walkthrough

docs/         design spec, report + datasheet (HTML sources and PDFs), figures, schematic PDF/SVG
hardware/     KiCad 9 project (tradewind/) and fabrication outputs (fab/)
mechanical/   CadQuery enclosure system: sources, STEP/STL/GLB, drawings, mechanical BOM
firmware/     RAK3172 / RUI3 firmware, payload codec, network-server decoder, host tests
sim/          10 simulations (ngspice decks + Python models) and their results
test/         test logs (CSV), analysis scripts, compliance table, bring-up log
render/       Blender render script and the renders
tools/        generators: schematic, PCB, 3D models, BOM, fab export, layout audit, docs, plot style

hardware/: schematic and board

• tradewind/tradewind.kicad_pro: open this in KiCad 9. Root sheet plus power, mcu_rf and sensors_io sheets; tradewind.kicad_pcb is the routed board.
• tradewind/tradewind.kicad_sym: project symbol (DRV5032 hall switch). tradewind/3d/ holds the 3D models we made because the library has none (RAK3172, JST PH side-entry, VQFN-16, SHT4x, 18650 cell).
• fab/: tradewind_revB_gerbers.zip (11 Gerber X2 layers plus drill), assembly/tradewind_revB_cpl.csv, BOM_tradewind_revB.csv (costed at 10/100/1k), BOM_JLCPCB.csv, the board as STEP and GLB, per-layer SVGs, erc_report.txt and drc_report.txt.
• Board: 96 × 70 mm, 4 layers (JLC 7628 stackup), matte black ENIG, 85 footprints, 50 Ω CPWG RF line, SHT40 on a slotted thermal island.
• tools/layout_audit.py measures the routed board (copper per net, current-path resistance, hot-loop areas, separations, RF geometry) into fab/layout_audit.json; tools/layout_figs.py draws the layout figures from it: each part outline comes from that part's pads, and numbered markers sit on computed features. The report's section 4 (electrical, BOM, layout, EMI/EMC) is built on those numbers.

sim/: design analysis

Run sim/run_all.sh (about 20 s). It regenerates every docs/figures/sim_* figure and sim/results.json.

mechanical/: enclosure

src/assembly.py builds the whole system (box, lid, gasket, sun roof with panel, radiation shield, bracket, glands, antenna) from parametric CadQuery parts. It checks fit against the board STEP and exports out/tradewind_assembly.step, print-ready STLs and web GLBs. Materials, sealing math, print settings and the assembly order are in mechanical/README.md.

firmware/: RAK3172 (STM32WLE5) on RUI3

Class A OTAA, US915 sub-band 2. Default interval 5 min, with a rapid 1-minute mode. Rain counting and magnet wake work while asleep. make test runs the C++ payload tests and the JavaScript decoder tests against shared golden vectors. The payload format is in firmware/PAYLOAD.md. The decoder for The Things Stack and ChirpStack is firmware/decoder/ttn_decoder.js.

test/: characterization

test/run_all.sh turns the CSV logs in test/data/ into every docs/figures/test_* figure, results.json and compliance.csv. The test plan with pass criteria is test/README.md. The step-by-step bring-up (and the two rev A bugs) is in test/BRINGUP.md.

render/ and docs/

• render/scripts/render.py: Blender Cycles shots from the CAD and board exports (studio, outdoor, exploded, lid off, board, turntable).
• tools/gen_report.py and tools/gen_datasheet.py build docs/report/ and docs/datasheet/. Every number comes from the result files, through tools/docdata.py.
• tools/paginate.py lays the report out in headless Chrome: each chapter flows across Letter pages, a heading never ends a page, and a full-width chart is never squeezed into half a column.
• tools/build_docs.py --pdf collects the images and prints both PDFs. tools/check_pages.py fails a page if its content overflows the Letter sheet.

Rebuilding everything

python3 tools/gen_schematic.py                                   # schematic from tools/design.py
snap run --shell kicad.kicad-cli -c "python3 tools/gen_pcb.py place && python3 tools/gen_pcb.py dsn"
(cd hardware/tradewind && xvfb-run -a java -jar freerouting-1.9.0.jar -de tradewind.dsn -do tradewind.ses -mp 40)
snap run --shell kicad.kicad-cli -c "python3 tools/gen_pcb.py ses"   # import routes, pour ground, clean up
tools/export_fab.sh                                              # ERC, DRC, Gerbers, BOM, CPL, STEP, GLB, renders, layout audit
sim/run_all.sh && test/run_all.sh                                # simulations and test analysis
python mechanical/src/assembly.py                                # enclosure (conda env)
blender -b --python render/scripts/render.py                     # renders
python3 tools/build_docs.py && (cd tools && python3 gen_report.py && python3 gen_datasheet.py) && python3 tools/build_docs.py --pdf

License

Hardware (hardware/, mechanical/): CERN-OHL-P-2.0. Firmware, simulations and tools: MIT. Documentation, figures and renders: CC BY 4.0. Component datasheets belong to their manufacturers and are not included.

Designed by Maxwell Pauly · Binary Beach LLC · Honolulu, Hawaiʻi · maxwell.pauly@binarybeach.tech