Temperature and Humidity Sensor Node Design

Thought

flux

Work done

Created and named the project USB-C WiFi BLE Environmental Sensor and updated the project description.
Verified an existing schematic already contains the main design blocks: ESP32-S3-WROOM-1-N16R8, SHT31-DIS, USB-C receptacle, TPS25200 5V eFuse/protection, AP2112K-3.3 regulator, UART/debug header, decoupling capacitors, I2C pull-ups, CC pull-downs, mounting holes, and power/reset/boot support.
Confirmed key nets are present: VBUS_USB, 5V_PROTECTED, 3V3, GND, I2C_SDA, I2C_SCL, USB_DP, USB_DN, UART, reset, boot, and eFuse fault/enable/current-limit nets.
Added component role metadata for passives, ICs, connector, power protection, regulator, sensor, MCU, and debug header to support review and placement intent.
Created the Project Specification project file with architecture, implementation choices, firmware pin map, and layout requirements.
Set PCB outline to 90 mm × 60 mm, rounded corners, compact consumer form factor, and 4-layer stackup with a ground reference suitable for RF/EMI.
Applied baseline manufacturable layout rules: 0.20 mm default trace width, 0.15 mm minimum trace width, 0.15 mm keepout, and 0.50 mm board inset margin.
Checked datasheets for the protection/regulator/RF-module assumptions: TPS25200 provides UVLO/OVLO/OVP clamp/OCP/reverse blocking while disabled; AP2112K-3.3 supports a 600 mA 3.3 V rail; ESP32-S3-WROOM-1 has antenna keepout placement requirements.

Success criteria review

✅ Schematic includes USB-C 5 V input, CC pull-downs, protected 5 V path, 3.3 V regulation, MCU, sensor, I2C, debug, and support passives.
✅ Dual-radio MCU and digital T/RH sensor are integrated and interconnected in the schematic.
⚠️ PCB layout setup is partially complete: board size, stackup, and baseline rules are set, but final component placement/routing/review could not be completed.
⚠️ Final production review is not complete; ERC/DRC/airwire review and routing verification still remain.

Next steps

Place components on the 90 mm × 60 mm PCB with the ESP32-S3 antenna at a board edge and ~5 mm antenna overhang/keepout, USB-C at an accessible edge, power components clustered near USB-C, and SHT31 away from heat sources.
Route the board, using wide copper/traces for the 5 V protected path and short decoupling loops.
Run final ERC/DRC/airwire review and resolve any remaining issues before manufacturing export.

Thought for 2 mins 56 sec

flux

Placed 27 component(s): U1, C3, C6, C7, H3, H2, J1, R5, C5, R2, H4, U4, C2, R3, R1, C4, U3, R7, J2, H1, R9, U2, R6, R8, R4, C8, C1

Thought for 3 sec

flux

Work done

Built the schematic for the USB-C powered Wi‑Fi/BLE temperature/humidity node: ESP32‑S3 module, SHT31 sensor, USB‑C default-sink input, TPS25200 protection, AP2112 3.3V regulation, decoupling, I²C pull-ups, boot/reset, USB data, and UART debug access.
Configured a compact 50 mm × 50 mm 4-layer PCB setup and placed all components with USB‑C at the edge, ESP32 antenna facing outward, sensor away from the power section, and mounting holes in the corners.
Added documentation: Project Specification, Firmware Pin Map, and Design Review Results.

Success criteria review

✅ Complete protected USB-C power-path schematic and 3.3V rail are present.
✅ Dual-radio MCU, digital T/RH sensor, support passives, and debug/programming connections are integrated.
⚠️ PCB placement is complete, but final routed PCB production readiness is not complete yet.
⚠️ Final checks found remaining PCB routing airwires and one copper-overlap item that must be resolved before fabrication.

Next steps

Route the PCB traces, inspect the copper-overlap item, then rerun final checks before manufacturing export.

Route remaining airwires

Inspect copper overlap

Run final review

Check antenna placement

Export production files

Files

Schematic

Layout

Preview

USB-C WiFi/BLE Temperature and Humidity Sensor Node Specification

Functional goals

Consumer-grade low-power environmental sensor node powered from USB-C 5 V default power. The node measures temperature and relative humidity with a digital I2C sensor and reports data using an ESP32-S3 Wi-Fi/BLE module supporting 2.4 GHz 802.11 b/g/n and BLE 5.x.

Architecture

USB-C receptacle: USB4215-03-A, 5 V default sink with 5.1 kΩ Rd pull-downs on CC1/CC2.
Input protection: TPS25200 eFuse stage for over-current limiting, over-voltage clamp/lockout, UVLO, and reverse-current blocking while disabled.
Current planning: RILIM = 36 kΩ, 1%, selected from TPS25200 datasheet examples to keep current limit below 3 A while allowing high-current USB-C sources.
5 V protected rail: eFuse output named 5V_PROTECTED.
3.3 V rail: AP2112K-3.3TRG1 LDO powering ESP32-S3 module and SHT31 sensor.
MCU/RF: ESP32-S3-WROOM-1-N16R8 with PCB antenna, USB D+/D- and UART0 debug access.
Sensor: SHT31-DIS-B2.5KS on I2C with 4.7 kΩ pull-ups.

Pin mapping

I2C SDA: ESP32-S3 IO8 to SHT31 SDA.
I2C SCL: ESP32-S3 IO9 to SHT31 SCL.
SHT31 ALERT: ESP32-S3 IO5.
eFuse FAULT: ESP32-S3 IO4.
USB D-: ESP32-S3 IO19.
USB D+: ESP32-S3 IO20.
UART0 TX/RX: debug header J2 pins 3/4.
EN reset: J2 pin 5 with 10 kΩ pull-up and 1 µF capacitor.
BOOT IO0: J2 pin 6 with 10 kΩ pull-up.

PCB/layout requirements

Consumer IoT size target: 50 mm × 50 mm unless enclosure requires otherwise.
Stackup: 4 layers for RF/USB EMI robustness, continuous ground reference below top-layer signals, and internal power distribution.
ESP32-S3 PCB antenna must be placed at a board edge with approximately 5 mm antenna overhang/keepout and no copper/components in the antenna keepout zone.
USB-C connector must be placed on a board edge.
Power protection and regulator must be grouped near USB-C input.
SHT31 must be kept away from regulator/eFuse heat and placed near board edge or ventilation region for accurate environmental sensing.

Production notes

Replace generic passives with preferred production MPNs before assembly release if required by the manufacturer.
Run ERC/DRC and review antenna keepout before manufacturing export.

Functional goals
Architecture
Pin mapping
PCB/layout requirements
Production notes