PCB Design Execution Plan

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Project Specification
Design Summary
Status: Review
Manufacturing target: Prototype
Software / firmware: Firmware pending, hardware-first prototype
Scope
Purpose
Compact wearable GPS and IMU sports tracking pod for insertion into a soccer player's compression vest pocket. This revision targets a manufacturable first prototype optimized for low power, compact size, and JLCPCB/LCSC assembly.
In scope
  • ESP32-C6 based processing and wireless connectivity
  • u-blox MAX-M10S GNSS receiver with external u.FL antenna connection
  • Bosch BMI323 IMU on I2C
  • Single-cell LiPo charging from USB-C
  • 3.3 V regulation and switched peripheral power rail
  • SPI microSD logging
  • Optional I2C fuel gauge
  • LEDs, debug header, test points, and ESD protection
Out of scope
  • Cellular connectivity
  • On-board chip antenna for GNSS
  • Integrated display or buttons
  • Final enclosure mechanical design
System context
This board is the main electronics core of a small wearable sports tracker. It samples inertial motion, logs GNSS position data, stores activity records locally, and exposes a service/debug interface during development.
Key interfaces
  • USB-C 5 V power input for charging and bench power
  • JST-PH 2-pin LiPo battery input
  • UART between MCU and GNSS
  • Shared I2C bus for IMU and fuel gauge
  • SPI microSD logging interface
  • Compact debug/programming header
  • External GNSS antenna via u.FL
Block diagram
Diagram



  
    
  
  
    
  


















UART

I2C

I2C

SPI













USB-C node_5V Input
ESD and VBUS TVS
LiPo Charger
1S LiPo Battery
3.3V LDO
ESP32-C6-MINI-1
Peripheral Load Switch
MAX-M10S GNSS
microSD
BMI323 IMU
Fuel Gauge
u.FL Antenna
Status LEDs
Requirements
Functional
  • The board shall acquire GNSS and IMU data for sports tracking.
  • The board shall log activity data to a removable microSD card.
  • The board shall charge a single-cell LiPo battery from USB-C.
  • The board shall support low-power operation with switchable peripherals.
  • The board shall expose debug and bring-up access for firmware development.
Electrical
  • Input power: USB-C 5 V sink for charging and bench operation
  • Battery: 1S LiPo, nominal 3.7 V, target 500 mAh
  • Main rail: regulated 3.3 V
  • Average runtime target: 8 h to 15+ h at about 30 mA average load
  • Critical interfaces: UART GNSS, I2C sensor bus, SPI microSD, debug header
  • RF priority: maintain clean GNSS antenna feed and low-noise GNSS supply routing
Mechanical / environmental
  • PCB target size: 35 mm x 25 mm or slightly smaller
  • Form factor must fit a wearable vest pocket and remain lightweight
  • Total product weight target with battery: under 35 g
  • Suitable for outdoor athletic use; prioritize robust connectors and solder joints
Key constraints
  • Use a 4-layer stackup: Top signals/components, Layer 2 full GND, Layer 3 3.3 V plane, Bottom signals and antenna routing
  • Prefer JLCPCB/LCSC-friendly parts and footprints
  • Keep quiescent current low enough to preserve battery runtime in idle and sleep modes
  • Place RF connector and GNSS section to minimize interference from MCU, storage, and digital edges
  • Favor simple, compact, assembly-friendly packages over large hand-assembly footprints
Dependencies and risks
Dependencies
  • Firmware support for power-gated peripherals, GNSS parsing, IMU polling, and microSD logging
  • Mechanical confirmation of battery and vest pocket fit
  • Availability of selected LCSC/JLC assembly parts
Key risks
  • RF performance may degrade if GNSS antenna routing and keepouts are compromised
  • Wearable current spikes from microSD and wireless activity may reduce runtime below target if power sequencing is not optimized
  • Tight board area may force dense placement and reduce routing margin
Validation
Success criteria
  • Complete schematic with all major subsystems wired
  • BOM populated with production-oriented parts
  • 4-layer layout configured at 35 mm x 25 mm
  • DRC-clean or with only justified non-blocking warnings
  • Manufacturing exports available for PCB fabrication and assembly
Planned checks
  • Bench bring-up on USB and battery power
  • Charge path verification and regulator rail measurement
  • UART/I2C/SPI communication checks
  • GNSS antenna and receive-path sanity verification
  • Review checkpoint after schematic completion and again after layout/DRC
Release-facing notes
Expected deliverables
  • Schematic
  • PCB layout
  • BOM
  • Gerbers and assembly files
  • Bring-up notes in design documentation
Special release notes
  • Include test points for GND, VBAT, 3V3, and GNSS timing/debug observation
  • Fuel gauge may remain optional or DNP in first prototype if routing pressure becomes excessive
  • External GNSS antenna connector is required for RF flexibility during evaluation
Change notes / open questions
Changes in this revision
  • Initial architecture documented
  • Core component set selected and added to schematic
  • Initial wiring of main power and digital interfaces started
Open questions
  • Final confirmation of switched-rail membership for each peripheral
  • Whether the first proto keeps the optional fuel gauge populated
  • Final layout placement around GNSS antenna keepout and ESP32 RF keepout

  • Design Summary

  • Scope

  • System context

  • Requirements

  • Functional

  • Electrical

  • Mechanical / environmental

  • Key constraints

  • Dependencies and risks

  • Validation

  • Release-facing notes

  • Change notes / open questions