USB-C WiFi BLE Sensor Design

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Completed so far:
  • Renamed the project to USB-C WiFi BLE Sensor Node.
  • Updated the project description.
  • Created the initial Project Specification file.
  • Confirmed the schematic started empty.
  • Sourced and added the main components:
    • ESP32-S3-MINI-1-N8 Wi‑Fi/BLE module
    • SHT40 temperature/humidity sensor
    • USB-C receptacle
    • USB input protection/current-limit IC
    • USB-C port protection IC
    • 3.3 V buck regulator
    • USB D+/D− ESD protection
    • BOOT and RESET buttons
    • Status LED
    • 5 V, 3.3 V, and GND test points
Still remaining:
  • Add support passives: decoupling capacitors, I2C pull-ups, USB-C CC pull-downs, regulator feedback/boot/input/output components, LED resistor, boot/reset RC parts.
  • Query datasheets for every active IC before wiring.
  • Wire the USB-C input, protected 5 V path, 3.3 V regulator, ESP32, SHT40, USB data, buttons, LED, and test points.
  • Run schematic checks and fix ERC issues.
  • Create firmware, board bring-up, and regulatory documentation.
  • After schematic validation, ask for approval before moving to PCB layout.
Wire USB-C power
Check datasheets
Add support passives
Run ERC/DRC
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Project Specification
Project Overview
Status: Draft. USB-C powered consumer temperature/humidity sensor node with Wi-Fi 2.4 GHz 802.11 b/g/n and BLE 5.x connectivity.
Intended Use
Indoor consumer environmental monitoring node powered from USB-C 5 V adapters/ports. Intended for prototype-to-production schematic baseline.
What the Device Should Do
  • Measure ambient temperature and relative humidity using a digital sensor.
  • Connect over Wi-Fi and BLE for setup/telemetry.
  • Accept USB-C default 5 V input from sources advertising roughly 0.5 A to 3 A.
  • Protect downstream electronics from reverse current/backfeed, over-voltage, under-voltage, and over-current faults.
Main Features
  • ESP32-class ultra-low-power Wi-Fi/BLE module with integrated antenna.
  • I2C digital T/RH sensor.
  • USB-C sink-only 5 V input with CC pull-downs.
  • 3.3 V regulated rail.
  • Boot/reset controls, status LED, programming over native USB where supported.
System Architecture
Diagram



  
    
  
  
    
  
















USB-C node_5V Input
Input Protection OVP UVLO OCP Reverse Blocking
3.3V Regulator
Wi-Fi BLE MCU Module
Digital Temp RH Sensor
USB D Plus D Minus ESD
I2C Bus
Hardware Subsystems
  • Power: USB-C 5 V sink, protected 5 V rail, low-noise 3.3 V regulator sized for Wi-Fi peaks.
  • Compute/Radio: ESP32-family module for Wi-Fi b/g/n and BLE 5.x; module antenna requires PCB keepout.
  • Sensor: digital I2C temperature/relative humidity sensor.
  • Protection: VBUS ESD/surge, OVP/UVLO/OCP/reverse blocking power-path protection, USB data ESD.
  • Debug/UI: native USB programming, BOOT and RESET buttons, status LED, test points.
Interfaces and Connections
  • USB-C receptacle: VBUS, GND, CC1/CC2 Rd, D+/D-.
  • I2C: SDA/SCL with one pull-up pair to 3.3 V.
  • User controls: BOOT, RESET.
  • Test points: 5 V protected, 3.3 V, GND, I2C lines.
Power and Runtime Expectations
USB-C powered only; low-power firmware should use modem sleep/light sleep between measurements. No battery runtime target.
Power Tree and Power Budget
Preliminary worst-case sizing target: 3.3 V rail approximately 350 mA peak for Wi-Fi/BLE bursts plus sensor/LED margin. USB input protection and regulator should be rated above this with margin; USB-C source-current advertisement must be respected in firmware/hardware if loads are expanded beyond this node.
Manufacturing and Assembly Expectations
Consumer-use prototype with SMD assembly, 2-layer or 4-layer PCB acceptable. RF antenna keepout required.
Firmware-Relevant Hardware Requirements
  • Initialize I2C T/RH sensor.
  • Support Wi-Fi and BLE provisioning/telemetry.
  • Native USB serial/JTAG programming if ESP32-C3/S3-class module is selected.
  • Control status LED and handle boot/reset straps correctly.
Physical Design Expectations
Place MCU module at board edge with antenna facing outward and copper keepout under antenna. USB-C at board edge. Sensor exposed to ambient airflow and thermally isolated from regulator/MCU heat.
Important Design Decisions
  • Use an ESP32 module rather than bare RF chip to reduce RF risk.
  • Use I2C digital humidity/temperature sensor.
  • Use USB-C sink-only default 5 V input; no USB-PD negotiation planned.
Assumptions
  • Consumer indoor ambient sensor; not safety-critical or medical.
  • USB-C is power plus native USB programming/debug, not USB host.
  • No display, battery, or external sensor cable unless later requested.
Change Notes
  • Initial specification created from user request.

    Project Overview

    Intended Use

    What the Device Should Do

    Main Features

    System Architecture

    Hardware Subsystems

    Interfaces and Connections

    Power and Runtime Expectations

    Power Tree and Power Budget

    Manufacturing and Assembly Expectations

    Firmware-Relevant Hardware Requirements

    Physical Design Expectations

    Important Design Decisions

    Assumptions

    Change Notes

Documents

    Project Specification

Assets

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USB-C WiFi BLE Sensor Node

USB-C WiFi BLE Sensor Node thumbnail
USB-C powered consumer environmental sensor node with ESP32-class Wi‑Fi/BLE connectivity, digital temperature/humidity sensing, protected 5 V input, and low-power 3.3 V electronics.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

Arrow

$3.66–$5.61

Digi-Key

$4.98–$5.10

HQonline

$7.77–$7.87

LCSC

$7.61–$7.73

Mouser

$14.48

TME

$0.00

Verical

$1.78–$4.21

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