About

Project Summary We’re developing a compact wearable sensor device that measures both motion and impact data for sports performance applications. We currently have a working prototype built from development boards (Adafruit nRF52840 + sensors), and now need a custom PCB design that integrates everything into one lightweight, production-ready setup for manufacturing and field testing. What You’ll Do Design one main PCB that contains the BLE MCU, power system, and storage. Design two small satellite boards, each containing a high-G accelerometer, which will connect to the main board via short cables (SPI shared, individual CS + INT). Integrate a Li-ion battery charging circuit with USB-C input (similar to the Adafruit Micro-Lipo Type-C charger). Prepare all files required for JLCPCB turnkey assembly (Gerbers, BOM with LCSC part numbers, Pick & Place). Ensure all boards are compact, impact-resistant, and easy to mount in a wearable housing. Components to Include Core MCU nRF52840 module (Raytac MDBT50Q or equivalent pre-certified BLE module) Sensors ST ISM330DHCXTR – 6-axis IMU (replaces older MPU-6050) via I²C or SPI 2× ADXL375 – High-G accelerometers (SPI, separate CS + INT each) Storage W25Q128JV – 16 MB SPI NOR Flash (Optional pads for microSD) Power Li-ion charger circuit (MCP73831 or BQ24074) 3.7 V Li-ion battery input (JST-PH connector) 3.3 V LDO regulator (AP2112K-3.3 V) USB-C port for charging/data Optional MAX17048 fuel-gauge IC (I²C) Other SWD header for programming/debug Status LED(s), reset button Mounting holes and BLE antenna keep-out area per module datasheet Deliverables Schematic (.sch) PCB layouts for 1 main board + 2 satellite boards Gerber, BOM (with JLCPCB/LCSC part numbers), and Pick & Place (CPL) files 3D board render (optional) Design Specs Main board: ~50 × 50 mm, 4-layer ENIG finish Satellite boards: ~20 × 20 mm each All parts from the JLCPCB/LCSC library where possible Use connectors rated for flex/vibration (JST-GH or FFC) Cable length ≤ 15 cm Budget & Timeline Budget: $300 USD Timeline: 2 – 3 weeks We’ll order 5 fully assembled prototypes from JLCPCB once design files are ready. What We’ll Provide Parts list (BOM) Wiring/block diagram Ideal Candidate Experience with nRF52 BLE modules and JLCPCB assembly Background in wearables / IoT boards Knowledge of SPI, I²C, Li-ion charging, and sensor layout best practices Bonus Can verify ISM330DHCXTR + ADXL375 availability in JLCPCB inventory Can support one follow-up revision (v0.2) after prototype testing How to Apply Please include: Example of a previous wearable or sensor board you designed Your preferred PCB tool (KiCad or Altium) Estimated delivery time for schematic + layout Confirmation that you can produce JLCPCB-ready manufacturing files ✅ Goal: A production-ready PCB design (main + two sensor satellites) we can send directly to JLCPCB for assembly and testing.