ESPHome USB Temperature & Humidity Sensor with SHT40, ESP32-C3 Wi-Fi and BLE Proxy
 
Smart Environmental Monitoring for Home Assistant
 
Turn any standard USB power source into a compact smart temperature and humidity monitoring point. This ESPHome-based sensor combines the high-performance SHT40 temperature and humidity sensor with an ESP32-C3 Wi-Fi chip, providing reliable environmental data and convenient integration with Home Assistant.
The default firmware also supports ESPHome Bluetooth Low Energy Proxy, helping extend Bluetooth coverage for compatible BLE devices around your home.
 
Key Features
• Built-in Sensirion SHT40 temperature and humidity sensor
• Built-in ESP32-C3 Wi-Fi and Bluetooth Low Energy chip
• ESPHome-based firmware
• Compatible with Home Assistant through the ESPHome integration
• BLE Proxy enabled by default
• 2.4 GHz Wi-Fi connectivity
• Direct USB-A power supply
• Compact plug-and-play hardware design
• Local control with no mandatory cloud service
• Supports OTA firmware updates after network configuration
• Suitable for smart homes, server rooms, storage areas, greenhouses and more
 
High-Quality SHT40 Sensor
The integrated SHT40 sensor provides responsive and stable temperature and relative humidity measurements. Its exposed sensing area allows better contact with the surrounding air, making the device suitable for continuous indoor environmental monitoring.
 
ESP32-C3 Wi-Fi Connectivity
Powered by the ESP32-C3, the sensor connects directly to your 2.4 GHz Wi-Fi network. Once added to ESPHome and Home Assistant, temperature and humidity readings can be used in dashboards, history charts, alerts and automations.
 
Examples:
• Turn on a humidifier when humidity is too low
• Start a ventilation fan when humidity rises
• Send a warning when room temperature exceeds a set value
• Monitor storage, equipment or plant-growing conditions
• Create temperature and humidity history charts in Home Assistant
 
Built-In BLE Proxy
BLE Proxy is enabled in the default firmware. The device can forward data from compatible Bluetooth Low Energy devices to Home Assistant through ESPHome, extending BLE coverage in areas where the Home Assistant host cannot receive a strong Bluetooth signal.
Please note: BLE Proxy is intended for compatible Bluetooth Low Energy devices. It does not function as a general-purpose Bluetooth audio or Bluetooth Classic adapter.
 
Simple USB Power
Simply connect the sensor to a powered USB-A port, USB charger, power bank or other compatible 5V USB power source. No battery replacement is required, making it ideal for continuous monitoring.
 
Home Assistant Integration
The sensor is designed for use with ESPHome and Home Assistant. After Wi-Fi configuration, it can be discovered and added through the ESPHome integration.
Depending on the installed firmware and setup method, initial Wi-Fi configuration may require an ESPHome-compatible provisioning process. Basic knowledge of ESPHome and Home Assistant is recommended.
 
Product Specifications
Specification
Details
Product Type
USB Temperature and Humidity Sensor
Firmware Platform
ESPHome
Temperature & Humidity Sensor
SHT40
Main Controller
ESP32-C3
Wireless Connection
2.4 GHz Wi-Fi
Bluetooth
Bluetooth Low Energy
Default Bluetooth Feature
ESPHome BLE Proxy
Power Input
5V USB
Connector Type
USB-A
Cloud Service
Not required for local Home Assistant operation
Main Applications
Indoor environmental monitoring and BLE coverage extension
 
Typical Applications
• Home Assistant environmental monitoring
• Bedroom, living room and office monitoring
• Server cabinet and equipment room monitoring
• Greenhouse and indoor plant monitoring
• Storage room, wardrobe and basement monitoring
• Humidifier, dehumidifier and ventilation automation
• Extending Home Assistant Bluetooth Low Energy coverage
Installation Recommendations
For more representative measurements, install the device in an open, well-ventilated location.
 
Avoid placing it:
• In direct sunlight
• Directly beside a heater or air conditioner outlet
• Near steam, water droplets or condensation
• Inside a closed cabinet without airflow
• Next to equipment that generates significant heat
Heat from some USB chargers, computers or hubs may influence temperature readings. For improved measurement placement, a short USB extension cable can be used to position the sensor away from the heat source.
 
Package Contents
• 1 × ESPHome USB Temperature and Humidity Sensor
USB charger, extension cable, Home Assistant server and other accessories are not included unless specifically selected in the product options.
 
GPIO
SDA:GPIO10
SCL:GPIO8
WS2812:GPIO21
Button:GPIO9
 
Important Notes
• Only 2.4 GHz Wi-Fi networks are supported.
• This product does not connect directly to 5 GHz-only Wi-Fi networks.
• Home Assistant and ESPHome are open-source third-party platforms and are not included as physical products.
• BLE Proxy compatibility depends on the Bluetooth device and its Home Assistant integration.
• This device is intended for general indoor environmental monitoring and smart-home automation. It is not certified for medical, laboratory, safety-critical or industrial metrology applications.
• Actual measurements may be affected by installation location, airflow, nearby heat sources and environmental conditions.
 
Frequently Asked Questions
Q: Does it work with Home Assistant?
A: Yes. It is designed to connect to Home Assistant through the ESPHome integration.
Q: Does it require a cloud account?
A: No mandatory cloud service is required for local ESPHome and Home Assistant operation.
Q: Does it support 5 GHz Wi-Fi?
A: No. The ESP32-C3 uses 2.4 GHz Wi-Fi.
Q: Is Bluetooth Proxy enabled?
A: Yes, ESPHome BLE Proxy is enabled in the default firmware.
Q: Can it control Bluetooth speakers or headphones?
A: No. The proxy is intended for compatible Bluetooth Low Energy devices, not Bluetooth audio or general Bluetooth Classic devices.
Q: Does it need a battery?
A: No. The device is powered continuously through its USB-A connector.
Q: Can the firmware be customized?
A: The ESP32-C3 platform is compatible with ESPHome. Firmware customization should be performed by users familiar with ESPHome configuration and flashing. Changing or replacing the original firmware is at the user’s own risk.