Wiring the Senserion SCD4X Photoacoustic (PA) Carbon Dioxide Sensor

This is the SCD4X produced and developed by SENSIRION, a next-generation of a Carbon Dioxide (CO2) Sensor . This sensor is based on photoacoustic NDIR ( Nondispersive Infrared ) sensing principle that offers high accuracy. In other words, this sensor works by an infrared (IR) lamp directing waves of light through a tube filled with a small amount of air. CO2 is a main chemical compound indicator for indoor air quality will be calculated. For instance, if the CO2 is high levels it will compromise mental performance and well-being.

This sensor enables a smart VAC system or ventilation system to regulate airflow in the most efficient way and can help maintain low CO2 concentrations indoors for a healthy productive atmosphere. The SCD4X high accuracy includes an integrated humidity and temperature sensor, it is in one sense for your indoor environment sensing. for more technical reading and specs please refer to the datasheet below.

Testing Requirements

Arduino IDE | PlatformIO
Test Boards :
- Note: The Diagram below is using Arduino NANO Microcontroller (please refer to your MCU’s respective pin-outs & bus configuration)
Resistors (See below diagram for required value)
Capacitor(See below diagram for required value)

Wiring Diagram & Schematics

Source Code

#include <Arduino.h> //Built-in Arduino IDE
#include <SensirionI2CScd4x.h> // This library can be downloaded below
#include <Wire.h> //Built-in Arduino IDE

SensirionI2CScd4x scd4x;

void printUint16Hex(uint16_t value) {
    Serial.print(value < 4096 ? "0" : "");
    Serial.print(value < 256 ? "0" : "");
    Serial.print(value < 16 ? "0" : "");
    Serial.print(value, HEX);
}

void printSerialNumber(uint16_t serial0, uint16_t serial1, uint16_t serial2) {
    Serial.print("Serial: 0x");
    printUint16Hex(serial0);
    printUint16Hex(serial1);
    printUint16Hex(serial2);
    Serial.println();
}

void setup() {

    Serial.print("14CORE | Testing SCD4X - CO2 SENSOR ...... ");
    delay(1000);

    Serial.begin(115200);
    while (!Serial) {
        delay(100);
    }

    Wire.begin();
    Serial.print("14CORE | Starting Serial Communication .... ");
    delay(2000);
    uint16_t error;
    char errorMessage[256];

    scd4x.begin(Wire);

    // stop potentially previously started measurement
    error = scd4x.stopPeriodicMeasurement();
    if (error) {
        Serial.print("14CORE | Error trying to execute stopPeriodicMeasurement(): ");
        errorToString(error, errorMessage, 256);
        Serial.println(errorMessage);
    }

    uint16_t serial0;
    uint16_t serial1;
    uint16_t serial2;
    error = scd4x.getSerialNumber(serial0, serial1, serial2);
    if (error) {
        Serial.print("14CORE | Error trying to execute getSerialNumber(): ");
        errorToString(error, errorMessage, 256);
        Serial.println(errorMessage);
    } else {
        printSerialNumber(serial0, serial1, serial2);
    }

    // Start Measurement
    error = scd4x.startPeriodicMeasurement();
    if (error) {
        Serial.print("14CORE | Error trying to execute startPeriodicMeasurement(): ");
        errorToString(error, errorMessage, 256);
        Serial.println(errorMessage);
    }

    Serial.println("14CORE | Waiting for first measurement... (5 sec)");
}

void loop() {
    uint16_t error;
    char errorMessage[256];

    delay(100);

    // Read Measurement
    uint16_t co2 = 0;
    float temperature = 0.0f;
    float humidity = 0.0f;
    bool isDataReady = false;
    error = scd4x.getDataReadyFlag(isDataReady);
    if (error) {
        Serial.print("14CORE | Error trying to execute readMeasurement(): ");
        errorToString(error, errorMessage, 256);
        Serial.println(errorMessage);
        return;
    }
    if (!isDataReady) {
        return;
    }
    error = scd4x.readMeasurement(co2, temperature, humidity);
    if (error) {
        Serial.print("14CORE | Error trying to execute readMeasurement(): ");
        errorToString(error, errorMessage, 256);
        Serial.println(errorMessage);
    } else if (co2 == 0) {
        Serial.println("14CORE | Invalid sample detected, skipping.");
    } else {
        Serial.print("Co2 :");
        Serial.print(co2);
        Serial.print("\t");
        Serial.print("Temperature:");
        Serial.print(temperature);
        Serial.print("\t");
        Serial.print("Humidity:");
        Serial.println(humidity);
    }
}

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#include <Arduino.h> //Built-in Arduino IDE

#include <SensirionI2CScd4x.h> // This library can be downloaded below

#include <Wire.h> //Built-in Arduino IDE

SensirionI2CScd4x scd4x;

void printUint16Hex(uint16_t value) {

Serial.print(value < 4096 ? "0" : "");

Serial.print(value < 256 ? "0" : "");

Serial.print(value < 16 ? "0" : "");

Serial.print(value, HEX);

}

void printSerialNumber(uint16_t serial0, uint16_t serial1, uint16_t serial2) {

Serial.print("Serial: 0x");

printUint16Hex(serial0);

printUint16Hex(serial1);

printUint16Hex(serial2);

Serial.println();

}

void setup() {

Serial.print("14CORE | Testing SCD4X - CO2 SENSOR ...... ");

delay(1000);

Serial.begin(115200);

while (!Serial) {

delay(100);

}

Wire.begin();

Serial.print("14CORE | Starting Serial Communication .... ");

delay(2000);

uint16_t error;

char errorMessage[256];

scd4x.begin(Wire);

// stop potentially previously started measurement

error = scd4x.stopPeriodicMeasurement();

if (error) {

Serial.print("14CORE | Error trying to execute stopPeriodicMeasurement(): ");

errorToString(error, errorMessage, 256);

Serial.println(errorMessage);

}

uint16_t serial0;

uint16_t serial1;

uint16_t serial2;

error = scd4x.getSerialNumber(serial0, serial1, serial2);

if (error) {

Serial.print("14CORE | Error trying to execute getSerialNumber(): ");

errorToString(error, errorMessage, 256);

Serial.println(errorMessage);

} else {

printSerialNumber(serial0, serial1, serial2);

}

// Start Measurement

error = scd4x.startPeriodicMeasurement();

if (error) {

Serial.print("14CORE | Error trying to execute startPeriodicMeasurement(): ");

errorToString(error, errorMessage, 256);

Serial.println(errorMessage);

}

Serial.println("14CORE | Waiting for first measurement... (5 sec)");

}

void loop() {

uint16_t error;

char errorMessage[256];

delay(100);

// Read Measurement

uint16_t co2 = 0;

float temperature = 0.0f;

float humidity = 0.0f;

bool isDataReady = false;

error = scd4x.getDataReadyFlag(isDataReady);

if (error) {

Serial.print("14CORE | Error trying to execute readMeasurement(): ");

errorToString(error, errorMessage, 256);

Serial.println(errorMessage);

return;

}

if (!isDataReady) {

return;

}

error = scd4x.readMeasurement(co2, temperature, humidity);

if (error) {

Serial.print("14CORE | Error trying to execute readMeasurement(): ");

errorToString(error, errorMessage, 256);

Serial.println(errorMessage);

} else if (co2 == 0) {

Serial.println("14CORE | Invalid sample detected, skipping.");

} else {

Serial.print("Co2 :");

Serial.print(co2);

Serial.print("\t");

Serial.print("Temperature:");

Serial.print(temperature);

Serial.print("\t");

Serial.print("Humidity:");

Serial.println(humidity);

}

PCB Board Milling / Gerber File

Download PCB Milling File | Gerber
Download Gerber Viewer | Windows | Linux

Downloads

Download Senserion SCD4X Datasheet | PDF
Download Senserion SCD4X Arduino Code Library | ZIP

Wiring the Senserion SCD4X Photoacoustic (PA) Carbon Dioxide Sensor

Testing Requirements

Wiring Diagram & Schematics

Source Code

PCB Board Milling / Gerber File

Downloads

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