Example Code for Arduino-Read VOC Index

Hardware Preparation

• DFRduino UNO R3 (or similar) x 1
• Gravity: SGP40 Air Quality Sensor x1
• Jumper wires

Software Preparation

• Arduino IDE
• Download and install the SGP40 Library and Sample Code. (About how to install the library?)

Wiring Diagram

Other Preparation Work

The sensor adopts easy-to-use standard Gravity I2C interface. Connect the sensor to your mainboard as the diagram. The product features short preheat time and 10s algorithms.

Note: The sensor will output more accurate and stable VOC data after using for 5 minutes.

Main API Function List

/**
   * @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);

Sample Code

/*!
 * @file getVocIndex.ino
 * @brief Read the environmental VOC index.  Range: 0-500;\
 * @n Experimental phenomena: read environmental VOC index once per second and print the value in serial port
 *
 * @copyright  Copyright (c) 2010 DFRobot Co.Ltd (http://www.dfrobot.com)
 * @licence     The MIT License (MIT)
 * @author [yangfeng]<[email protected]>
 * @version  V1.0
 * @date  2020-12-18
 * @get from https://www.dfrobot.com
 * @url  https://github.com/DFRobot/DFRobot_SGP40
 */
#include <DFRobot_SGP40.h>

/* 
 * Method 1: pass in the specified I2C object address 
 * #include <Wire.h>
 * DFRobot_SGP40    mySgp40(&Wire);

 * Method 2: use the default I2C object&Wire
 * I2C Default Address：0x59
 */

//#include <Wire.h>
//DFRobot_SGP40    mySgp40(&Wire);
DFRobot_SGP40    mySgp40;


void setup() {
  Serial.begin(115200);
  Serial.println("sgp40 is starting, the reading can be taken after 10 seconds...");
  /*
   * Sensor preheat time: 10s
   * duration: init wait time. Unit: ms. It is suggested: duration>=10000ms
   */
  while(mySgp40.begin(/*duration = */10000) !=true){
    Serial.println("failed to init chip, please check if the chip connection is fine");
    delay(1000);
  }
  Serial.println("----------------------------------------------");
  Serial.println("sgp40 initialized successfully!");
  Serial.println("----------------------------------------------");
  /* 
   * Set the relative humidity and temperature of current environment 
   * The sensor has internal temerpature & humidity calibration. For more accurate VOC index, please open the function setRhT().
   * relativeHumidity：ambient relative humidity, refer to the moisture content in air. Range：0-90, unit: %RH，e.g. 50%
   * temperatureC：ambient temperature. Range: -10~50, unit: °C, e.g. 20°C
   */
  //mySgp40.setRhT(/*relativeHumidity = */ 50, /*temperatureC = */ 20);

}

void loop() {
  /* 
   * Get VOC index 
   * VOC index can directly indicate the condition of air quality. The larger the value, the worse the air quality
   *    0-100，no need to ventilate,purify
   *    100-200，no need to ventilate,purify
   *    200-400，ventilate,purify
   *    400-500，ventilate,purify intensely
   * Return VOC index, range: 0-500
   */
  uint16_t index = mySgp40.getVoclndex();

  Serial.print("vocIndex = ");
  Serial.println(index);
  delay(1000);
}

Result

Additional Information

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.