SEN0394 SGP40 Reference: API, Protocol & Pinout

This article serves as a detailed reference for the SGP40 Air Quality Sensor, covering library installation, communication protocols, and API functionalities essential for air quality monitoring and management.

Library

Download and install the SGP40 Library and Sample Code. (About how to install the library?)
SGP40 Air Quality Sensor Python Library

Communication Protocol Description

Communication: I2C
I2C Address: 0x59

API Description

/**
   * @brief  Initialization function
   * @param duration Warm-up time
   * @return return true succeed ;return false failed.
   */
  bool begin(uint32_t duration = 10000);

  /**
   * @brief  Set the temperature and humidity
   * @param  relativeHumidityRH  Current environmental relative humidity value, range 0-90, unit: %RH
   * @param  temperatureC  Current ambient temperature, range -10~50, unit: °C
   */
  void setRhT(float relativeHumidity = 50,float temperatureC=25);

  /**
   * @brief  Measure VOC index after humidity compensation
   * @note   VOC index can indicate the quality of the air directly. The larger the value, the worse the air quality.
   * @note       0-100，no need to ventilate, purify
   * @note       100-200，no need to ventilate, purify
   * @note       200-400，ventilate, purify
   * @note       400-500，ventilate, purify intensely
   * @return The VOC index measured, ranged from 0 to 500
   */
  uint16_t getVoclndex(void);

Principle

VOC Index	Air Quality	Suggested Action
0-100	Excellent	No measures needed
100-200	Good	No measures needed
200-300	Lightly Polluted	Ventilation suggested
300-400	Moderately Polluted	Increase ventilation with clean air
400-500	Heavily Polluted	Optimize ventilation

The sensor provides the change of air quality trend, and the algorithm will continuously adjust the baseline of typical air according to historical data. The longer the sensor is used, the better the sensitivity and accuracy of trend and change.
In the normal air environment, the sensor can obtain the accurate VOC index immediately after use; in the heavily-polluted environment, the sensor can obtain the accurate VOC index after use for about 1 hour. It is recommended to integrate it into the long-term indoor projects.
For more information about VOC index, please refer to: SGP40 VOC Index for Experts.pdf

Other Supplementary Information

SGP40 VOC Index