Raspberry Pi CM4 Carrier PCB Design — KiCad, PCBWay-ready

## Overview I need an experienced PCB designer to take a complete written specification and deliver a **fabrication-ready custom carrier board for the Raspberry Pi Compute Module 4 (CM4)**, designed in **KiCad**, with output I can **send directly to PCBWay** for fabrication + turnkey assembly with no further engineering. This is a personal/small-batch product (a baby monitor compute box). **No formal certification (FCC/UL) is required.** A full spec, reference designs, and a KiCad starter project are provided. ## What the board does It's a CM4 carrier that: - Takes a single **56 V DC** input (external brick) and on-board: injects **PoE** to a camera and bucks down to **5 V** for the CM4. - Provides **two RJ45 ports** — one with **802.3af PoE injection** (Silvertel Ag6130 PSE module) for the camera, one plain gigabit for the home network (Microchip LAN7800, USB→GbE). - Supports CM4 Wi-Fi (external antenna) and rpiboot eMMC flashing over USB-C. It is a fork of the **official Raspberry Pi CM4 IO Board** KiCad design — you reuse its proven CM4 connector, power, and USB/rpiboot blocks, strip the unused parts (PCIe, HDMI, CSI, DSI, 12 V), and add the PoE injector, 56 V→5 V DC-DC module, and LAN7800 second NIC. ## Key technical requirements - **4-layer, controlled impedance**, designed to **PCBWay's standard 4-layer 1.6 mm stackup**. - **100 Ω differential** Ethernet pairs and **90 Ω differential** USB pair, routed correctly (top layer over solid ground, length-matched, unbroken reference plane). - Module-down PoE (Silvertel Ag6130) and a wide-input 56 V→5V DC-DC module — no discrete switcher/PSE design needed. - Must pass DRC against PCBWay's standard capabilities. - **KiCad** (so I can maintain the source). KiCad 8 or 10. ## Deliverables (must be directly PCBWay-orderable) 1. **Editable KiCad source** — full project (schematic + PCB + libraries), DRC-clean, ERC-clean. 2. **Gerbers** (RS-274X) + **Excellon NC drill** files. 3. **BOM** with manufacturer part numbers **and Mouser/Digikey distributor part numbers** for every line (PCBWay turnkey sources from these distributors). 4. **Pick-and-place / centroid (CPL)** file, top + bottom. 5. **Assembly drawing** + **impedance-controlled stackup spec sheet** (the doc I attach to a PCBWay impedance-control order). 6. Schematic PDF + a short design-decisions/README note. Acceptance = I can upload your package to PCBWay and place a fab + assembly order with zero additional engineering or back-and-forth on missing files. ## What I provide - A complete written design spec (every block, part numbers, voltages, stackup, net classes). - Reference designs: the CM4 IO Board KiCad files, Seeed dual-GbE schematic, Silvertel Ag6130 and LAN7800 datasheets. - The forked KiCad starter project with stackup + net classes already configured. ## Required experience - Multiple shipped **SoM/compute-module carrier boards** (CM4, or similar SoM with high-density board-to-board connectors). - **Controlled-impedance** routing (Ethernet/USB differential pairs) on 4-layer boards. - **Power over Ethernet** and DC-DC power design experience. - Proficient in **KiCad** and in preparing **PCBWay/JLCPCB fab + assembly** packages. - Please share examples (CM4/PoE/Ethernet boards especially). ## Engagement - **Fixed-price, milestone-based:** 1. Schematic + BOM for review. 2. PCB layout + impedance routing, DRC/ERC clean. 3. Final PCBWay-ready fabrication + assembly package. ## Screening questions 1. Have you designed a Raspberry Pi CM4 (or similar SoM) carrier? Link an example if so. 2. Describe your approach to hitting 100 Ω / 90 Ω differential impedance on a PCBWay 4-layer board. 3. Have you done PoE (PSE-side) and a 48–56 V input power stage before? 4. Confirm you'll deliver editable KiCad source + a complete PCBWay fab/assembly package (Gerbers, drills, BOM with distributor PNs, CPL, stackup spec). 5. Rough fixed-price quote and timeline for the scope above with those milestones.