STEMMA QT AS7331 UV/UVA/UVB/UVC Sensor - module with AS7331 UV sensor

Description

Adafruit AS7331 Sensor is a precise ultraviolet radiation sensor module capable of measuring three main UV ranges: UVA, UVB, and UVC. Unlike many simple UV sensors that measure only the total radiation intensity or are limited to the UVA band, the AS7331 chip can distinguish between individual ultraviolet wavelength ranges. This enables more accurate measurements and detailed analysis of UV radiation sources. Separate measurement channels for UVA, UVB, and UVC allow the sensor to be used in many fields such as UV radiation monitoring for human safety, precision agriculture, UV warning systems, UVC sterilization process control, material curing, and specialized lighting analysis. As a result, the module is suitable for both research projects and environmental monitoring devices as well as automation systems.

The sensor offers extensive configuration options via the I²C interface, allowing adjustment of gain and conversion parameters to suit different measurement conditions. With a gain of 1×, the sensor can measure radiation levels up to 349 mW/cm² in the UVA channel, 386 mW/cm² in the UVB channel, and 169 mW/cm² in the UVC channel. The high sensitivity of the sensor enables detection of extremely low radiation levels—down to 2.38 nW/cm² per measurement step (LSB). The module also allows the I²C address to be changed using two solder jumpers on the board, enabling up to four sensors to operate on the same I²C bus. Additionally, the board exposes a READY pin that signals the completion of a measurement and a SYNC pin that allows measurement synchronization with an external pulse signal.

The sensor is mounted on a convenient STEMMA QT breakout board equipped with logic-level shifting circuitry and connectors compatible with the Qwiic ecosystem. This allows the module to be easily connected to a microcontroller without soldering. The device works with platforms such as Arduino, Raspberry Pi, and boards supporting CircuitPython. The manufacturer provides ready-to-use libraries for Arduino and CircuitPython, simplifying sensor configuration and measurement data acquisition. Thanks to this, the module provides a convenient solution for building UV radiation monitoring systems, scientific and educational projects, and industrial applications requiring precise ultraviolet detection.

Features

• Ultraviolet radiation sensor: AS7331
• Measured radiation ranges: UVA, UVB, UVC
• Independent measurement channels for UVA, UVB, and UVC
• Communication interface: I²C
• Default I²C address: 0x74
• Adjustable I²C address via two solder jumpers
• Maximum number of sensors on a single I²C bus: 4
• Maximum measurement range at gain 1×:
  • UVA: up to 349 mW/cm²
  • UVB: up to 386 mW/cm²
  • UVC: up to 169 mW/cm²
• Measurement sensitivity: from 2.38 nW/cm² per LSB
• Configurable gain and conversion parameters
• READY signal output indicating conversion completion
• SYNC input for synchronization with an external signal
• Board format: STEMMA QT
• Connectors: 2 × STEMMA QT / Qwiic
• Logic level shifting for compatibility with 3.3 V and 5 V systems
• Compatible platforms: Arduino, Raspberry Pi, CircuitPython
• Available software libraries: Arduino and CircuitPython