RF/IoT PCB Design Engineer — Raspberry Pi / ESP32-P4-POE-ETH Dual-Compatible HAT

We need an experienced PCB design engineer to design a Raspberry Pi HAT (form factor + 40-pin GPIO header compliant with the official Raspberry Pi HAT specification) that is also electrically/mechanically compatible with the 40-pin header on the Waveshare ESP32-P4-WIFI6-POE-ETH board (link below), so the same board can be stacked on either a Raspberry Pi or that ESP32-P4 board. It hosts two ESP32-C5 modules and provides connectivity for a 4G/LTE cellular module and a footprint-only ADS-B receiver stage. The board will be manufactured in a small production run (10 units) as part of this engagement. Please submit an open bid — we are not pre-setting a budget and want to review proposals. This is a schematic capture + PCB layout + manufacturing sourcing job in KiCad. The final deliverable is a complete, DRC-clean, production-ready KiCad project plus 10 manufactured PCBs (see "Manufacturing & Procurement" below). Board concept Form factor: Raspberry Pi HAT (per the official Raspberry Pi HAT mechanical/electrical spec — link below), physically stacking on and electrically interfacing with a Raspberry Pi 40-pin GPIO header. Dual header compatibility requirement: the same 40-pin header must also mate correctly with the Waveshare ESP32-P4-WIFI6-POE-ETH board (product/pinout link below), which exposes its own 2×20 40-pin header. The contractor must reconcile the Raspberry Pi GPIO pinout with the ESP32-P4-WIFI6-POE-ETH pinout diagram pin-by-pin and flag any conflicting pin functions (e.g., a pin that is GPIO on one host and a fixed power/special-function pin on the other). Both hosts run 3.3V logic, but function mapping is not guaranteed to match — where a hard conflict exists, propose a solution (e.g., selectively populated pins, solder-jumper selectable routing, or documented host-specific limitations) as part of your proposal rather than assuming full pin-for-pin compatibility out of the box. Two ESP32-C5-WROOM-1U modules on board. This is the "U" (connector) variant of Espressif's official WROOM-1 module — it must use its built-in IPEX (U.FL) antenna connector directly, not a PCB antenna or a third-party dev-board carrier. Datasheet link below. One connector to interface with the SIM7600E-H1C breakout module (AND-Global BK-SIM7600E-H1C, product link below). Scope here is limited to breaking out and connecting to this module — no SIM7600 RF/antenna circuitry needs to be designed, since the module is a self-contained breakout board with its own antennas. Contractor should confirm the exact connector type/pinout from the module's documentation (request datasheet from AND-Global if not published) and add the mating connector + required signal/power lines (UART, power, and any control/status lines the module exposes) to the HAT. Footprint provisioning (unpopulated, for a future assembly phase) for the EXD-SC1 ADS-B receiver module (stamp-hole SMT, datasheet link below) so it can be soldered directly onto the HAT — not via an evaluation/breakout board. This includes: The 26-pad stamp-hole land pattern per the datasheet's recommended PCB package (Section 4.2/4.3 of the datasheet). Routing/provisioning for VCC (3.3V, low-ripple LDO with 22µF + 100nF decoupling per datasheet guidance), GND, TX0/RX0 (UART to host), and RF_IN (50Ω matched trace to the antenna connector, kept as short as possible per datasheet layout guidance). An IPEX (U.FL) connector for the 1090MHz ADS-B antenna feed, placed close to the module's RF_IN pin. A status LED wired to the module's Frame_detect pin (per datasheet: "external LED" indicating ADS-B frame reception). Ground fill/isolation around the module per the datasheet's RF layout precautions (keep other high-frequency/high-amplitude digital signals away from the module). Status/indicator LEDs for the two ESP32-C5 modules. Power architecture must support the Pi 5V rail plus any regulation needed for the two C5 modules, the SIM7600E-H1C connector, and the ADS-B footprint section. Scope of Work Review supplied component list, datasheets, and pinout documentation (provided at kickoff, including exact SIM7600E-H1C connector/pinout confirmation). Reconcile the Raspberry Pi 40-pin GPIO pinout against the Waveshare ESP32-P4-WIFI6-POE-ETH 40-pin header pinout and produce a short pin-mapping table identifying matches, conflicts, and the proposed resolution for each conflict, for our sign-off before layout begins. Produce schematic capture in KiCad (latest stable version) covering: dual ESP32-C5-WROOM-1U modules, SIM7600E-H1C interface connector, the dual-compatible 40-pin header, EXD-SC1 ADS-B footprint + LED + IPEX antenna connector, power regulation, and any required level shifting/protection. PCB layout in KiCad respecting the official Raspberry Pi HAT mechanical outline (mounting holes, board dimensions, connector keep-outs), mechanical compatibility with the ESP32-P4-WIFI6-POE-ETH board outline, and RF layout best practice: 50Ω-matched RF traces where relevant, antenna keep-out and ground clearance around both C5 modules and the ADS-B/IPEX feed, and adequate isolation between the two 2.4/5GHz radios and the 1090MHz ADS-B front end to minimize desense. Run DRC/ERC and provide a clean, documented KiCad project (schematic, PCB, BOM, and Gerbers/fabrication outputs). Handle the manufacturing request: source a PCB fabricator (and assembly house if applicable), place the order, and deliver 10 manufactured PCBs to us. Include estimated fab/assembly lead time as part of your proposal. Provide a brief design notes document covering key layout decisions, especially the Pi/ESP32-P4 pin-mapping resolution and RF isolation between the three radio sections. Deliverables Complete KiCad project (.kicad_pro, .kicad_sch, .kicad_pcb) with schematic and layout Bill of Materials (BOM) with sourced part numbers (Mouser/Digi-Key/LCSC preferred) Gerbers / fabrication output files 10x manufactured PCBs (bare board minimum; quote assembled option separately if feasible) Short design notes document (PDF or Markdown) explaining key layout/RF isolation decisions Reference Documentation Raspberry Pi HAT specification: https://github.com/raspberrypi/hats Raspberry Pi 40-pin GPIO pinout: https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#gpio Waveshare ESP32-P4-WIFI6-POE-ETH (40-pin header to be made compatible with): https://docs.waveshare.com/ESP32-P4-WIFI6-POE-ETH ESP32-C5-WROOM-1 / ESP32-C5-WROOM-1U datasheet (we require the -1U variant, IPEX connector): https://documentation.espressif.com/esp32-c5-wroom-1_wroom-1u_datasheet_en.html SIM7600E-H1C breakout module (AND-Global BK-SIM7600E-H1C): https://www.and-global.com/list_23/667.html EXD-SC1 ADS-B receiver module datasheet (stamp-hole footprint, pinout, recommended land pattern): https://www.exd-tek.com/wp-content/uploads/2024/12/EXD-SC1-ads-b-receiver-module-v1.3.pdf (Full component list and any additional pinout clarifications will be shared directly with the selected contractor before work begins.) Requirements Demonstrable prior experience designing multi-radio RF boards in KiCad (portfolio or example projects required) Experience with Raspberry Pi HAT-compliant board design Experience sourcing PCB fabrication/assembly runs (JLCPCB, PCBWay, Seeed Fusion, or similar) and managing that order end-to-end Comfortable working from datasheets/pinout PDFs and clarifying ambiguous requirements proactively Clear, responsive communication in English Nice to have Experience with cellular modem (SIM7xxx / Quectel) hardware integration Experience with ADS-B / SDR RF front-end layout ESP32 RF/antenna layout experience How to Apply Please include: 2–3 examples of prior multi-radio or RF-adjacent PCB designs (KiCad preferred) Your proposed approach to sourcing and managing the 10-unit manufacturing run Estimated timeline broken into: schematic capture → layout → DRC/review → fab order → delivery Your quote/bid for the full scope described above