Example Code for Arduino-Period Measurement

Hardware Preparation

• DFRduino UNO R3 (or similar) × 1
• Gravity: SCD41 Infrared CO2 Sensor - I2C × 1
• M-M/F-M/F-F Jumper wires

Software Preparation

• Arduino IDE
• Download and install the SCD4X Library. (About how to install the library?)

Wiring Diagram

Other Preparation Work

The actual compensation and calibration parameter should be changed according to the operating environment.

Sample Code

/*!
 * @file  periodMeasure.ino
 * @brief  This sample shows how to configure period measurement mode, compensation and calibration.
 * @note  The actual compensation and calibration parameter should be changed according to the operating environment
 * @copyright  Copyright (c) 2010 DFRobot Co.Ltd (http://www.dfrobot.com)
 * @license  The MIT License (MIT)
 * @author  [qsjhyy]([email protected])
 * @version  V1.0
 * @date  2022-05-11
 * @url  https://github.com/DFRobot/DFRobot_SCD4X
 */
#include <DFRobot_SCD4X.h>

/**
 * @brief Constructor
 * @param pWire - Wire object is defined in Wire.h, so just use &Wire and the methods in Wire can be pointed to and used
 * @param i2cAddr - SCD4X I2C address.
 */
DFRobot_SCD4X SCD4X(&Wire, /*i2cAddr = */SCD4X_I2C_ADDR);

void setup(void)
{
  Serial.begin(115200);

  // Init the sensor
  while( !SCD4X.begin() ){
    Serial.println("Communication with device failed, please check connection");
    delay(3000);
  }
  Serial.println("Begin ok!");

  /**
   * @brief set periodic measurement mode
   * @param mode - periodic measurement mode:
   * @n       SCD4X_START_PERIODIC_MEASURE : start periodic measurement, signal update interval is 5 seconds.
   * @n       SCD4X_STOP_PERIODIC_MEASURE : stop periodic measurement command
   * @n       SCD4X_START_LOW_POWER_MEASURE :  start low power periodic measurement, signal update interval is approximately 30 seconds.
   * @return None
   * @note The measurement mode must be disabled when configuring the sensor; after giving the stop_periodic_measurement command, the sensor needs to wait 500ms before responding to other commands.
   */
  SCD4X.enablePeriodMeasure(SCD4X_STOP_PERIODIC_MEASURE);

  /**
   * @brief set temperature offset
   * @details T(offset_actual) = T(SCD4X) - T(reference) + T(offset_previous)
   * @n T(offset_actual): the calculated actual temperature offset that is required
   * @n T(SCD4X): the temperature measured by the sensor (wait for a period of time to get steady readings)
   * @n T(reference): the standard reference value of the current ambient temperature
   * @n T(offset_previous): the previously set temperature offset
   * @n For example : 32(T(SCD4X)) - 30(T(reference)) + 2(T(offset_previous)) = 4(T(offset_actual))
   * @param tempComp - temperature offset value, unit ℃
   * @return None
   * @note When executing the command, the sensor can't be in period measurement mode
   */
  SCD4X.setTempComp(4.0);

  /**
   * @brief get temperature offset
   * @return The current set temp compensation value, unit ℃
   * @note When executing the command, the sensor can't be in period measurement mode
   */
  float temp = 0;
  temp = SCD4X.getTempComp();
  Serial.print("The current temperature compensation value : ");
  Serial.print(temp);
  Serial.println(" C");

  /**
   * @brief set sensor altitude
   * @param altitude - the current ambient altitude, unit m
   * @return None
   * @note When executing the command, the sensor can't be in period measurement mode
   */
  SCD4X.setSensorAltitude(540);

  /**
   * @brief get sensor altitude
   * @return The current set ambient altitude, unit m
   * @note When executing the command, the sensor can't be in period measurement mode
   */
  uint16_t altitude = 0;
  altitude = SCD4X.getSensorAltitude();
  Serial.print("Set the current environment altitude : ");
  Serial.print(altitude);
  Serial.println(" m");

  /**
   * @brief set automatic self calibration enabled
   * @param mode - automatic self-calibration mode:
   * @n       true : enable automatic self-calibration
   * @n       false : disable automatic self-calibration
   * @return None
   * @note When executing the command, the sensor can't be in period measurement mode
   */
  // SCD4X.setAutoCalibMode(true);

  /**
   * @brief get automatic self calibration enabled
   * @return Automatic self-calibration mode:
   * @n        true : enable automatic self-calibration
   * @n        false : disable automatic self-calibration
   * @note When executing the command, the sensor can't be in period measurement mode
   */
  // if(SCD4X.getAutoCalibMode()) {
  //   Serial.println("Automatic calibration on!");
  // } else {
  //   Serial.println("Automatic calibration off!");
  // }

  /**
   * @brief persist settings
   * @details Configuration settings such as the temperature offset, sensor altitude and the ASC enabled/disabled 
   * @n  parameter are by default stored in the volatile memory (RAM) only and will be lost after a power-cycle.
   * @return None
   * @note To avoid unnecessary wear of the EEPROM, the persist_settings command should only be sent 
   * @n  when persistence is required and if actual changes to the configuration have been made. 
   * @n  The EEPROM is guaranteed to endure at least 2000 write cycles before failure.
   * @note Command execution time : 800 ms
   * @n When executing the command, the sensor can't be in period measurement mode
   */
  // SCD4X.persistSettings();

  /**
   * @brief reinit reinit
   * @details  The reinit command reinitializes the sensor by reloading user settings from EEPROM.
   * @return None
   * @note Before sending the reinit command, the stop measurement command must be issued.
   * @n  If the reinit command does not trigger the desired re-initialization, 
   * @n  a power-cycle should be applied to the SCD4x.
   * @n  Command execution time : 20 ms
   * @n When executing the command, the sensor can't be in period measurement mode
   */
  //SCD4X.moduleReinit();

  /**
   * @brief set periodic measurement mode
   * @param mode - periodic measurement mode:
   * @n       SCD4X_START_PERIODIC_MEASURE : start periodic measurement, signal update interval is 5 seconds.
   * @n       SCD4X_STOP_PERIODIC_MEASURE : stop periodic measurement command
   * @n       SCD4X_START_LOW_POWER_MEASURE :  start low power periodic measurement, signal update interval is approximately 30 seconds.
   * @return None
   * @note The measurement mode must be disabled when changing the sensor settings; after giving the stop_periodic_measurement command, the sensor needs to wait 500ms before responding to other commands.
   */
  SCD4X.enablePeriodMeasure(SCD4X_START_PERIODIC_MEASURE);

  Serial.println();
}

void loop()
{
  /**
   * @brief get data ready status
   * @return data ready status:
   * @n        true : data ready
   * @n        false : data not ready
   */
  if(SCD4X.getDataReadyStatus()) {
    /**
     * @brief set ambient pressure
     * @param ambientPressure - the current ambient pressure, unit Pa
     * @return None
     */
    // SCD4X.setAmbientPressure(96000);

    /**
     * @brief Read the measured data
     * @param data - sSensorMeasurement_t, the values measured by the sensor, including CO2 concentration (ppm), temperature (℃) and humidity (RH)
     * @n  typedef struct {
     * @n    uint16_t   CO2ppm;
     * @n    float   temp;
     * @n    float   humidity;
     * @n  } sSensorMeasurement_t;
     * @return None
     * @note CO2 measurement range: 0~40000 ppm; temperature measurement range: -10~60 ℃; humidity measurement range: 0~100 %RH.
     */
    DFRobot_SCD4X::sSensorMeasurement_t data;
    SCD4X.readMeasurement(&data);

    Serial.print("Carbon dioxide concentration : ");
    Serial.print(data.CO2ppm);
    Serial.println(" ppm");

    Serial.print("Environment temperature : ");
    Serial.print(data.temp);
    Serial.println(" C");

    Serial.print("Relative humidity : ");
    Serial.print(data.humidity);
    Serial.println(" RH");

    Serial.println();
  }
  delay(1000);
}

Result