Temperature and Humidity Sensor Node Design
Thought for 2 mins 56 sec
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
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.
- ✅ 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.
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
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Project Specification
Goal
Consumer-grade low-power temperature and humidity sensor node powered from USB-C 5 V default power. The node uses an ultra-low-power dual-radio MCU module supporting 2.4 GHz 802.11 b/g/n Wi-Fi and BLE 5.x, plus a digital I2C temperature/relative-humidity sensor.
Architecture
- USB-C receptacle configured as a 5 V sink with CC pull-downs.
- Protected 5 V input path with reverse blocking, over-voltage protection, under-voltage lockout, and over-current protection for 0.5–3 A source capability.
- 3.3 V rail generated from protected 5 V for MCU and sensor.
- ESP32-S3-WROOM module provides Wi-Fi/BLE and USB/UART programming/debug.
- SHT31-DIS digital T/RH sensor connected by I2C.
- UART debug/programming header and boot/reset support.
Key implementation choices
- MCU: ESP32-S3-WROOM-1-N16R8 module to simplify RF certification/layout and provide dual radio.
- Sensor: Sensirion SHT31-DIS on I2C.
- Regulator: AP2112K-3.3 LDO for simple, low-noise 3.3 V rail; adequate for USB-powered consumer sensor node.
- Protection: 5 V eFuse stage used as protected power-path controller with enable, current-limit, and fault signaling.
- PCB: compact 50 mm × 50 mm 4-layer board with continuous ground reference for RF/EMI performance.
Firmware pin map
- I2C SDA: ESP32-S3 IO8 to SHT31 SDA
- I2C SCL: ESP32-S3 IO9 to SHT31 SCL
- SHT31 ALERT: ESP32-S3 IO5
- USB D+: ESP32-S3 IO20
- USB D-: ESP32-S3 IO19
- UART TXD0/RXD0 routed to debug header
- EN and IO0 include reset/boot biasing for programming support
Layout requirements
- USB-C at board edge for cable access.
- ESP32-S3 module at board edge with antenna facing outward and copper/component keepout under antenna.
- Power protection and regulator grouped near USB-C.
- SHT31 placed away from regulator/MCU heat sources and near board air exposure.
- 5 V path sized for up to 3 A using wide traces/copper pours; 3.3 V rail sized for MCU peak current.
Goal
Architecture
Key implementation choices
Firmware pin map
Layout requirements
