PCB layout + bring-up for nRF52840 solar IoT sensor unit (trial task, then production NPI)

Bin Bypass (binbypass.com) makes container-collection street furniture — about 4,800 units in the field across Australia. We're adding a solar-powered smart sensing layer and need a hands-on hardware engineer to take a working benchtop prototype to a manufacturable, testable product. THE SYSTEM - RAK4631 core (nRF52840 + SX1262 LoRa) - 6x VL6180X time-of-flight sensor nodes on a shared I2C bus (XSHUT re-addressing, 2.8V sensor rail) - SIM7080G Cat-M1/NB-IoT modem + MFF2 eSIM + GNSS - Solar + LiFePO4 power with adaptive duty cycling - Firmware compiles and runs on devkits today. Full private engineering repo provided: pin maps, BOM, protocol docs, robustness/assembly/bring-up guides. The repo is a working starting point, not gospel. If you see a better part, topology or approach — a smarter power path, a cleaner sensor interconnect, a cheaper module that does the same job — argue for it. We would rather change the design than ship a worse product, and we can move fast on decisions (founder-led, no committees). MECHANICAL CONSTRAINT The electronics live in a compact pod inside a 100x100mm metal tube (solar panel on top, sensor nodes strip out along a 500mm cradle). The carrier board must be sized for that pod, and the metal enclosure means antenna placement (LoRa, cellular, GNSS) has to be designed in, not bolted on. Tell us how you'd approach it. PHASE 1 (this job) — BOARDS TO WORKING PROTOTYPE - Trial task first (own fixed-price milestone): layout of the 6-sensor node board from our pin map — EasyEDA or KiCad, JLCPCB-ready gerbers/BOM/CPL plus a written bring-up checklist - Then: carrier board layout to the 100x100 pod constraint, JLCPCB DFM-clean turnkey order (5 carriers + a node panel, assembled), first-article bring-up, findings folded into v2 files - Exit test: a WORKING PROTOTYPE — assembled carrier + node boards in the enclosure form factor, running our firmware end-to-end on the bench: sensors detecting, LoRa uplinking, solar charge path proven. Not just boards that pass DRC — a unit we can hold. LATER PHASES (separate contracts, same person if Phase 1 goes well) - v2 board spin + production flash/test jig (pogo fixture, automated flash/test/cal station) - Pilot build of 20 units + photo-per-step assembly work instructions - Handoff pack so a 500-unit run can execute from documents alone (kitting spec, incoming QC, RCM compliance coordination) YOU HAVE - Taken 2+ electronic products from prototype to 500+ units shipped - Nordic nRF52 experience strongly preferred; battery + solar + cellular/RF product experience a big plus - JLCPCB/LCSC (or equivalent CM) turnkey experience — gerbers, BOM, CPL, DFM - War stories about what went wrong at first production and what you changed — we will ask Deliverables are source files (EasyEDA/KiCad), fab outputs and documentation committed to our GitHub repo as you go; IP assigned to Bin Bypass Pty Ltd. Remote is fine — we're in Brisbane, Australia. The budget shown covers Phase 1; we'll structure milestones starting with the trial task, and later phases are quoted separately. Start your proposal with the word "cradle" so we know you actually read this, and tell us about one board you designed AND brought up yourself.