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Air Quality Sensor

Introduction​

The Air Quality Sensor Module consists of the CCS811 sensor. This sensor is designed to monitor indoor air quality by measuring the concentration of carbon dioxide (CO₂) and total volatile organic compounds (TVOCs).

What is the CCS811?​

The CCS811 is a digital gas sensor that provides reliable measurements of air quality. It is primarily used to assess the levels of CO₂ and TVOCs, which are important for maintaining good indoor air quality.

  • CO₂ (Carbon Dioxide): Elevated levels can indicate poor ventilation, leading to discomfort and reduced cognitive function.
  • TVOCs (Total Volatile Organic Compounds): Organic chemicals found in everyday products like paints and cleaning supplies, which can have adverse health effects.

How the CCS811 Works:​

  • Measurement Process: Uses MEMS technology to detect gas concentrations and requires a short warm-up time for accurate readings.
  • Data Output: Communicates via I2C, reporting CO₂ in ppm and TVOCs in µg/m³.

Key Features:​

  • Digital Output: Easy integration with microcontrollers via I2C.
  • Low Power Consumption: Suitable for battery-powered devices.
  • Built-in Temperature and Humidity Compensation: Ensures accuracy in varying conditions.
  • Calibration: Automatic calibration after a period of operation.

Real-World Applications:​

  • Indoor Air Quality Monitoring: Used in homes, offices, and schools.
  • HVAC Systems: Optimizes climate control based on air quality.
  • Smart Home Devices: Integrated into smart systems for automatic monitoring and control.

Pinout for CCS811 Module:​

  • VCC: Power supply (3.3V to 5V).
  • GND: Ground.
  • SCL: Clock line for I2C communication.
  • SDA: Data line for I2C communication.

Refer to the CCS811 Datasheet for detailed specifications.

Code Guide​

Library and Sensor Setup​

  • Library Name: AirQuality.h
  • I2C address of the sensor: 0x5B

Code Flow​

#include <AirQuality.h>  // Include the library
AirQuality sensor;       // Create an object of the class

void setup() {
  Serial.begin(115200);  // Initialize serial communication
  Wire.begin();          // Initialize I2C communication
  if (sensor.begin()) {
    Serial.println("Sensor connected");
  } else {
    Serial.println("Sensor not connected");
  }
}

void loop() {
  if (sensor.ping()) {
    Serial.println("Sensor connected");
    // Display data
  } else {
    Serial.println("Sensor disconnected");
  }
}

Code Breakdown:​

  1. Include the Library: Import the required library for interacting with the sensor.
  2. Create a Sensor Object: Enable communication between the microcontroller and the sensor.
  3. Initialize Serial and I2C: Set up communication in the setup() function.
  4. Check Sensor Connection: Ensure the sensor is connected and proceed with actions based on connection status.
  5. Monitor the Sensor: Continuously check the connection and fetch data in the loop().

Available Functions in AirQuality.h​

The AirQuality library offers a variety of useful functions to retrieve data and interact with the sensor.

Class Creation and Initialization Functions​

These functions are foundational and should be used when setting up the sensor.

Create an Object of the Class:​

AirQuality();

Initialize the Sensor:​

CCS811_STATUS_t begin();

This function performs the necessary setup for the sensor and returns a status code indicating if the sensor is connected properly.

Connection Status Function​

This function checks whether the sensor is connected.

Ping the Sensor:​

bool ping(void);

It returns true if the sensor is connected; otherwise, it returns false. If a disconnection occurs, it also attempts to re-establish the connection.

Air Quality Measurement Functions​

These functions allow you to retrieve air quality measurements, including TVOCs and CO₂ levels.

Get TVOC Levels:​

uint16_t getTVOC();

This function returns the total volatile organic compounds (TVOC) level in parts per billion (ppb).

Get CO₂ Concentration:​

uint16_t getCO2();

This function returns the carbon dioxide (CO₂) concentration in parts per million (ppm).

Get Temperature Readings:​

float getTemperature();

This function returns the temperature in degrees Celsius (°C), which can be used for air quality reading compensation.

Advanced Features​

The library also provides advanced functions for sensor calibration and performance optimization. Example code can be found in Arduino IDE under File -> Examples -> AirQuality_Demo.