WiFi & Bluetooth Sensor Node

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Project Specification — USB-C WiFi BLE TH Sensor

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Status: Draft schematic in progress. A consumer USB-C powered temperature and relative humidity sensor node with Wi-Fi and Bluetooth Low Ene...

flux

Architecture review agrees with a USB-C sink plus real VBUS protection and a buck regulator; I’m selecting a low-power certified Wi‑Fi/BLE module rather than a hot LDO-based ESP32-style power tree.
Worked for 45 sec
Thought for 18 sec — Choosing components for low-power MCU
Found 3 results for Find Flux library USB input eFuse or protection switch IC for 5 V USB-C sink with adjustable/current limit around 0.75 to 1 A, overvoltage protection threshold above normal USB 5.25 V and below 9 V, undervoltage lockout, reverse current blocking, soft-start/inrush control, active SMD part. Prefer TI TPS2595 TPS2596 TPS2594 AP2265 AP22802 style eFuse..
Found 10 results for TPS2595.
Found 10 results for TPS2596.
Found 2 results for AP22652.
Found 4 results for NCP361.
Thought for 19 sec
Thought for 16 sec
Reading SIWG917Y111MGABAR, SHT41-AD1B-R2, USB4105-GF-A, TPS259621DDAR, MP28301GG-Z, USBLC6-2SC6, ESD5341N datasheets.
Thought for a moment
Assessing developer requirements
I need to follow the developer's instructions exactly. However, it seems the results are missing the pinout or footprint, which likely means the drawing isn't capturing the details properly—it's probably not using OCR. I should search more thoroughly to find information about GF-A. It's clear that I need to dig deeper to ensure I get the right information and meet the requirements correctly. Let's stay focused on that!

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Project Specification — USB-C WiFi BLE TH Sensor
Project Overview
Status: Draft schematic in progress.
A consumer USB-C powered temperature and relative humidity sensor node with Wi-Fi and Bluetooth Low Energy connectivity. The board uses a protected USB-C 5 V sink input, local 3.3 V regulation, a low-power Wi-Fi/BLE MCU module, and a digital I2C T/RH sensor.
Intended Use
  • Indoor consumer environmental monitoring node.
  • Powered from USB-C 5 V chargers, hubs, or ports.
  • Designed for prototype-to-production learning; not medical, industrial safety, or outdoor/weatherproof use unless later specified.
What the Device Should Do
  • Measure ambient temperature and relative humidity.
  • Connect over 2.4 GHz 802.11 b/g/n Wi-Fi.
  • Support BLE 5.x provisioning or local telemetry.
  • Power from USB-C default 5 V sources.
  • Survive common consumer input faults with reverse-current, overvoltage, undervoltage, and overcurrent protection.
Main Features
  • USB-C receptacle configured as sink-only with independent CC1/CC2 5.1 kΩ Rd resistors.
  • Protected 5 V input sized for 0.5–3 A capable sources, while the node itself is expected to draw well below 500 mA average.
  • 3.3 V logic rail for MCU and sensor.
  • Native USB data/programming path where supported by the selected MCU.
  • Boot/reset controls, debug/programming access, and status LED.
System Architecture
Diagram



  
    
  
  
    
  









I2C

USB D+/D-






USB-C Receptacle node_5V Sink
VBUS Protection OVP UVLO OCP Reverse Blocking
3.3V Regulator
WiFi/BLE MCU Module
Digital T/RH Sensor
Status LED
Hardware Subsystems
  • Power input: USB-C receptacle, CC pull-downs, VBUS ESD/TVS, protected power switch/eFuse or load switch with OVP/UVLO/OCP/reverse-current blocking.
  • Regulation: 5 V to 3.3 V rail sized for Wi-Fi transmit current peaks.
  • Compute/radio: certified ESP32-family module preferred to avoid custom RF matching and simplify regulatory work.
  • Sensor: digital I2C temperature/humidity sensor with local decoupling and one shared I2C pull-up pair.
  • User/debug: reset and boot controls, status LED, USB programming, optional exposed test/debug header.
Interfaces and Connections
  • External: USB-C 5 V power and USB 2.0 D+/D- for programming/debug.
  • Internal: 3.3 V rail, GND, I2C SDA/SCL, boot/reset, status LED GPIO.
  • RF: integrated 2.4 GHz antenna module; PCB layout must provide the module antenna keepout.
Power and Runtime Expectations
  • Source: USB-C 5 V default power only; no battery in this revision.
  • Source capability planning: tolerate 0.5 A, 1.5 A, and 3 A capable USB-C sources. Do not assume the device may draw 3 A unless CC current advertisement is measured/implemented.
  • Low-power behavior: firmware should sleep between samples and radio transmissions, but USB-powered operation makes absolute sleep current less critical than thermal and regulatory behavior.
Power Tree and Power Budget

Table

RailLoadSleepTypical activePeak
3.3 VWi-Fi/BLE MCU module~10–100 µA deep sleep~80–240 mA radio active~500 mA short Wi-Fi TX burst
3.3 VT/RH sensor<1 µA standby~0.5–1 mA measuring~1 mA
3.3 VStatus LED0 mA off~2 mA on~5 mA configured max
3.3 VPull-ups/leakage~1–2 mA worst when lines lownegligible average~1.4 mA for two 4.7 kΩ pull-ups low
Estimated 3.3 V rail sizing target: 250 mA typical active, 510 mA transient peak. For an LDO from 5 V, input current is approximately output current; thermal at 250 mA is about (5.25 V - 3.3 V) × 0.25 A = 0.49 W, so a small SOT-23 LDO may be marginal during sustained Wi-Fi. Preferred choices are a high-current low-Iq regulator in a thermally capable package or a quiet buck regulator if sustained radio current/thermal limits demand it.
Manufacturing and Assembly Expectations
  • Default assembly: SMD, production-intent consumer PCB.
  • Use stocked, non-EOL parts where available.
  • Add test points for 5 V protected rail, 3.3 V, GND, reset/boot, and I2C if space permits.
Firmware-Relevant Hardware Requirements
  • Define actual GPIO pins for I2C SDA/SCL and status LED.
  • Provide USB programming or serial/JTAG path.
  • Support Wi-Fi + BLE provisioning, periodic sensor reads, and telemetry output.
  • Include boot/reset access for field recovery.
Physical Design Expectations
  • ESP32 module antenna must be placed at board edge with no copper/traces/components in the keepout on all layers.
  • Sensor should be isolated from regulator/MCU heat sources and exposed to ambient airflow.
  • USB-C connector should be board-edge mounted and mechanically reinforced.
Important Design Decisions
  • Use an ESP32-family certified module rather than a bare RF SoC.
  • Use a digital I2C humidity/temperature sensor.
  • Use USB-C sink-only 5 V; no USB-PD negotiation in this revision.
  • Include a protected VBUS front end instead of relying on a fuse alone.
Assumptions
  • Indoor consumer use, ambient operating range roughly 0–50 °C unless later expanded.
  • No enclosure dimensions or board size provided yet.
  • No cloud protocol specified; firmware examples will print readings and include Wi-Fi/BLE placeholders.
Change Notes
  • Initial requirements captured from user request on 2026-07-17.

  • 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

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USB-C WiFi BLE TH Sensor

USB-C WiFi BLE TH Sensor thumbnail
Consumer USB-C powered environmental sensor node with Wi-Fi, BLE 5.x, digital temperature/humidity sensing, protected 5 V input, and a 3.3 V low-power MCU/sensor rail.

Properties

WiFi

USB-C

Consumer IoT

5

V

Bluetooth

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