USB C WiFi BLE Sensor Node

Created 4 project docs

Design Notes — USB-C WiFi BLE Environmental Node

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Input: USB-C receptacle J1, 5 V sink-only, USB 2.0 D+/D- routed to ESP32-C3 native USB Serial/JTAG. USB-C configuration: R1/R2 = 5.1 kΩ Rd f...

Firmware Starter — ESP32-C3-WROOM-02-N4

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MCU/module: ESP32-C3-WROOM-02-N4 Framework: Arduino on PlatformIO

Board Bring-Up Plan — USB-C WiFi BLE Environmental Node

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Equipment: current-limited 5 V USB supply or USB power meter, multimeter, oscilloscope, USB-C cable, ESD-safe workstation, PlatformIO firmwa...

Technical Construction File — USB-C WiFi BLE Environmental Node

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Draft, schematic-stage. FCC Part 15 intentional radiator integration using pre-certified module conditions.

flux

Implemented the schematic for the USB-C powered Wi‑Fi/BLE temperature/humidity node and created the supporting project files:
Open items:
  • PCB layout has not been started yet; airwires are expected until placement/routing.
  • Generic passives/testpoints still need production MPN assignment before manufacturing export.
  • Layout must enforce ESP32 antenna keepout and keep the SHT40 away from heat sources.
Suggested next steps:
  1. Set board size/stackup and antenna/sensor placement constraints.
  2. Place components with the ESP32 antenna at the board edge.
  3. Route USB, buck power, and I2C nets.
  4. Assign production MPNs for generic passives and test pads.
Create layout constraints
Assign passive MPNs
Run schematic review
Start PCB placement
Prepare layout intent
Sign up to send

Files

Schematic

Layout

Preview

U4
D1
U3
J1
Technical Construction File — USB-C WiFi BLE Environmental Node
Status
Draft, schematic-stage.
Applicable Regulations
  • FCC Part 15 intentional radiator integration using pre-certified module conditions.
  • FCC Part 15B unintentional radiator testing for the final product.
  • CE RED for EU wireless product placement.
  • ISED/UKCA may apply depending on target markets.
  • RoHS/REACH material compliance for consumer sale.
Product Description
USB-C powered consumer temperature and humidity node using an ESP32-C3-WROOM-02-N4 Wi-Fi/BLE module and SHT40 digital sensor.
Wireless Technology Summary

Table

ModuleMPNTechnologyFrequency BandAntennaNotes
U3ESP32-C3-WROOM-02-N4Wi-Fi 802.11 b/g/n + BLE 5.x2.4 GHz ISMIntegrated PCB antennaFollow Espressif module integration and antenna keepout rules
Required Documentation Checklist
  • Project specification created.
  • Schematic-stage BOM available in Flux.
  • Firmware starter created.
  • Bring-up/test plan created.
  • Final PCB layout/Gerbers after placement/routing.
  • RF module certificate/grant evidence attached for the exact ordered module variant.
  • EMC/RF lab test reports for the finished product.
  • Final user manual and product labels.
RF Design Notes
  • Place U3 at a board edge with the ESP32-C3-WROOM-02 PCB antenna facing outward.
  • Keep the antenna keepout free of copper, traces, vias, components, batteries, USB cable routing, and enclosure metal unless Espressif explicitly allows otherwise.
  • Keep the buck converter, inductor, USB-C connector shell, and USB cable path away from the antenna area.
  • Configure firmware regulatory domain/channel plan for the intended market.
EMC/ESD Notes
  • D2 protects VBUS_RAW; D1 protects USB D+/D−. Place both close to J1 with low-inductance ground return.
  • U2 buck layout is the primary conducted/radiated EMI risk. Keep SW loop compact and avoid routing SW near USB D+/D−, SHT40, and antenna.
  • USB-C shield should be tied to board ground near the connector with stitching vias in the layout stage.
Draft Declaration of Conformity Placeholder
We, [Company Name], declare that the product USB-C WiFi BLE Environmental Node is designed for conformity with applicable FCC Part 15, CE RED, RoHS, and EMC requirements when manufactured and tested in its final enclosure.
Authorized signatory: ____________________ Date: ____________________
User Manual Safety/Compliance Outline
  • Indoor use only unless enclosure is later rated for outdoor use.
  • Use only compliant USB-C 5 V power sources.
  • Do not cover or contaminate the humidity sensor opening.
  • This device contains a 2.4 GHz Wi-Fi/Bluetooth radio module.
  • Include required FCC/CE/ISED statements after module grant review and final product testing.
Open Items
  • Attach exact Espressif certification documents for ESP32-C3-WROOM-02-N4.
  • Complete PCB layout with antenna keepout and EMI controls.
  • Perform pre-scan EMC/ESD testing before production release.

  • Status

  • Applicable Regulations

  • Product Description

  • Wireless Technology Summary

  • Required Documentation Checklist

  • RF Design Notes

  • EMC/ESD Notes

  • Draft Declaration of Conformity Placeholder

  • User Manual Safety/Compliance Outline

  • Open Items