This module is designed for quick detection of water turbidity. Measurement results are transmitted digitally via UART interface. Turbidity refers to the cloudiness of water caused by suspended particles, commonly measured in NTU (Nephelometric Turbidity Units). The higher the value, the murkier the water.
BM25S4221-1 supports a detection range of 0 to 1000 NTU, making it suitable for home appliances or environmental water quality monitoring.
The module uses a digital output design and transmits data through a UART interface. Unlike traditional analog signals, digital transmission is more stable and less susceptible to interference—making development and system integration easier. The host device can directly read turbidity and temperature data via simple commands, with no need for additional analog-to-digital conversion.
After power-on or reset, the module initializes in about 600ms and begins normal operation. The host can send a command at any time to retrieve real-time turbidity and temperature values.
Main Features
- Turbidity Detection: Built-in infrared LED and photodiode, combined with turbidity algorithms, accurately detect changes in water turbidity caused by suspended particles.
- Temperature Compensation: High-precision NTC sensor automatically adjusts turbidity readings based on the environment, improving measurement stability.
- Low Power Consumption: Ideal for long-term water monitoring applications.
The module uses an infrared light source (940nm) internally, and the light intensity after passing through the water is captured by a receiver. The system automatically detects turbidity and temperature every 0.5 seconds.
Note: Prolonged exposure to high temperatures may speed up aging. Regular cleaning of the module surface is recommended to maintain accuracy.
How to Use
The module is calibrated before shipment and ready to use.
1. Make sure the wiring is correct (DC 5V power supply, avoid reversed polarity).
2. After powering on, the module initializes in about 600ms.
3. Wait about 1 second to allow the module to complete the first round of data collection.
4. Send a command from the host to retrieve the current turbidity (NTU) and temperature data.
5. Data is updated every 0.5 seconds. For the latest readings, be sure to read after each refresh.
⬥ For detailed protocol, please refer to the "Communication Protocol" section in the datasheet.
