Temperature and Humidity Sensor Node Design

Thought

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

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.

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

Firmware Pin Map — ESP32-S3 Environmental Node

MCU

ESP32-S3-WROOM-1-N16R8, powered from 3V3.

Pin assignments

Table

Function	ESP32-S3 pin	Net	Notes
I2C SDA	IO8	I2C_SDA	SHT31 SDA, 4.7 kΩ pull-up to 3V3
I2C SCL	IO9	I2C_SCL	SHT31 SCL, 4.7 kΩ pull-up to 3V3
SHT31 ALERT	IO5	SHT_ALERT	Optional interrupt input
eFuse FAULT	IO4	EFUSE_FAULT	Active-low open-drain fault input, 10 kΩ pull-up to 3V3
USB D-	IO19	USB_DN	ESP32-S3 USB Serial/JTAG / USB device
USB D+	IO20	USB_DP	ESP32-S3 USB Serial/JTAG / USB device
UART0 TX	TXD0	UART0_TX	Debug header J2 pin 3
UART0 RX	RXD0	UART0_RX	Debug header J2 pin 4
Reset/enable	EN	ESP_EN	Debug header J2 pin 5, 10 kΩ pull-up, 1 µF delay capacitor
Boot mode	IO0	ESP_BOOT_IO0	Debug header J2 pin 6, 10 kΩ pull-up; pull low for download boot

Firmware initialization outline

Configure I2C on SDA=IO8, SCL=IO9 at 100 kHz or 400 kHz.
Initialize SHT31 at default address with ADDR tied low.
Configure IO4 and IO5 as inputs with internal pull-ups disabled or enabled only if needed; external pull-ups are present for FAULT.
Enable Wi-Fi 2.4 GHz and BLE 5.x services as required by application firmware.
Use light sleep/deep sleep between measurements for low-power operation; keep USB power policy simple because the node is USB powered.
Use USB Serial/JTAG or UART0 header for manufacturing programming and debug.