Integrating a CO2 Sensor into Arduino and ESP32 Projects

In this post, I explain how to use a CO₂ sensor – specifically the Sensirion SCD30 – with an Arduino or an ESP32. This sensor is particularly versatile because it can measure not only CO₂ but also temperature and humidity.

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Why the Sensirion SCD30?

The SCD30 from :contentReference[oaicite:0]{index=0} is a precise and reliable sensor that communicates via an I²C interface. This makes it relatively easy to connect to most microcontrollers.

You just need to identify the I²C pins of your microcontroller.
For the ESP32 Dev Kit, which I use in this example, these are typically:

• Pin 21 → SDA
• Pin 22 → SCL

Additionally, the sensor requires power supply:

• 3V or 5V → VCC
• GND → microcontroller ground

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Required Components

The following components are needed for this project:

• Sensirion SCD30 CO₂ sensor
• Microcontroller (e.g., Arduino or ESP32)
• Jumper wires
• USB cable for programming and power supply

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The Code

The following code works for Arduino boards from :contentReference[oaicite:1]{index=1} as well as ESP32 boards from :contentReference[oaicite:2]{index=2}.

First, include the necessary libraries:

#include 
#include "SparkFun_SCD30_Arduino_Library.h" 

SCD30 airSensor;

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setup()

In setup(), the I²C communication, serial interface, and the sensor are initialized:

void setup()  
{
  Wire.begin();           // Start I2C communication
  Serial.begin(9600);     // Start serial communication
  airSensor.begin();      // Initialize the sensor
}

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loop()

The actual measurement work takes place in the loop() function:

void loop()  
{
  if (airSensor.dataAvailable()) 
  {
    Serial.print("CO2 (ppm): ");
    Serial.print(airSensor.getCO2());

    Serial.print(", Temp (C): ");
    Serial.print(airSensor.getTemperature(), 1);

    Serial.print(", Humidity (%): ");
    Serial.print(airSensor.getHumidity(), 1);

    Serial.println();
  }
  else
  {
    // Serial.println("Waiting for data..."); // Optional
  }

  delay(500); // Short pause between measurements
}

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Complete Code

#include 
#include "SparkFun_SCD30_Arduino_Library.h" 

SCD30 airSensor;

void setup()  
{
  Wire.begin();                 // Start I2C communication
  Serial.begin(9600);           // Serial communication at 9600 baud
  airSensor.begin();            // Initialize the SCD30 sensor
}

void loop()  
{
  if (airSensor.dataAvailable()) // Check if new sensor data is available
  {
    Serial.print("CO2 (ppm): ");
    Serial.print(airSensor.getCO2());

    Serial.print(", Temp (C): ");
    Serial.print(airSensor.getTemperature(), 1);

    Serial.print(", Humidity (%): ");
    Serial.print(airSensor.getHumidity(), 1);

    Serial.println();
  }
  else
  {
    // Optional: output if no data is available
    // Serial.println("Waiting for data...");
  }

  delay(500); // 500 ms pause until the next measurement
}

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Conclusion

With this simple setup, you can transform your Arduino or ESP32 into a compact environmental monitoring station. The Sensirion SCD30 is excellent for projects requiring reliable measurements of CO₂, temperature, and humidity.