CO2 Sensor

The SCD30 is a precise CO₂ sensor from the Swiss manufacturer Sensirion. The sensor board has a JST PHR4 connector, suitable for operation with the senseBox MCU. It is also equipped with the Qwiic Connect System.

In addition to CO₂ detection, a high-quality Sensirion humidity and temperature sensor is used on the same sensor module. Thanks to the applied dual-channel principle for measuring carbon dioxide concentration, the sensor is designed to automatically compensate for long-term drifts.

warning

The CO₂ sensor should not be used permanently outdoors.

CO2 Sensor

Technical Information

• CO₂ measurement range: 0 - 40,000 ppm
• Accuracy: ± (30 ppm + 3% MV) (25 °C, 400 - 10,000 ppm)
• Repeatability: 10 ppm
• Temperature stability: 2.5 ppm / °C (0-50 °C)
• Response time: 20s
• Humidity measurement range: 0 - 100 % RH
• Accuracy: ±3% RH (0-100% RH)
• Repeatability: 0.1% RH
• Response time: 8s
• Temperature measurement range: -40 °C - 70 °C
• Accuracy (°C): ± (0.4 °C + 0.023 x (T [°C] - 25°C))
• Repeatability (°C): 0.1 °C
• Response time: >10s

Connection

Die Komponente wird am I2C Port angeschlossen.

Programmierung (Arduino)

Dieser Sketch liest die CO₂-Konzentration und gibt sie im Seriellen Monitor aus.

Software Library

To program the sensor in Arduino, you need to install the software library SparkFun SCD30 Arduino Library.

Code

#include <senseBoxIO.h>
#include <SparkFun_SCD30_Arduino_Library.h> // http://librarymanager/All#SparkFun_SCD30_Arduino_Library

SCD30 airSensor;

void setup() {
  Serial.begin(9600);
  Wire.begin();
  if (airSensor.begin() == false)
  {
    while (1)
      ;
  }
  airSensor.useStaleData(true);
}
void loop()
{
 Serial.println(airSensor.getCO2());
 delay(500);
}

Programming (Blockly)

You can read the CO₂ sensor with the following block.

Calibrating the CO₂ Sensor (Auto Calibration)

As a rule, the CO₂ sensor comes pre-calibrated. Rough handling, shipping, or soldering can reduce the accuracy of the sensor, making calibration necessary. For this sketch, you need the display. If you don't have a display, you can delete the display-related parts, this does not affect the calibration of the sensor!

To calibrate the CO₂ sensor, it must be exposed to fresh air with a CO₂ concentration of 400ppm for at least 7 days, each day for at least one hour. As long as the sensor is not set up in the immediate vicinity of a CO₂ source (e.g., your own breath, combustion process, etc.), we can assume that the atmosphere has a concentration of about 400ppm tendency increasing.

Install the Board Support Package of the senseBox and additionally the SparkFun_SCD30_Arduino_Library via the library manager in the Arduino IDE. Then you can upload the following sketch to the MCU.

Alternatively, the compiled .bin file can be downloaded here.

#include <SPI.h>
#include <Wire.h>

#include "SparkFun_SCD30_Arduino_Library.h"

// DISPLAY_PART_START
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);
// DISPLAY_PART_ENDE
SCD30 airSensor;


void setup() {
  // DISPLAY_PART_START
  senseBoxIO.powerI2C(true);
  delay(2000);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3D);
  display.display();
  delay(100);
  display.clearDisplay();
  // DISPLAY_PART_ENDE
  if (airSensor.begin(Wire, true) == false)
  {
    while (1)
      ;
  }
  airSensor.getAutoSelfCalibration();
}


void loop() {

  // DISPLAY_PART_START
  long time_elapsed = millis();
  time_elapsed = time_elapsed / 1000;
  time_elapsed = time_elapsed / 60;

  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextColor(WHITE, BLACK);
  display.setTextSize(1);
  display.println("Sensor eine Stunde an der frischen Luft lassen!");
  display.println();
  display.println();
  display.println();
  display.print("Zeit vergangen: ");
  display.print(time_elapsed);
  display.println(" min");
  display.display();
  // DISPLAY_PART_ENDE

  if (airSensor.dataAvailable())
  {
    airSensor.getCO2();
    airSensor.getTemperature();
    airSensor.getHumidity();
  }
   delay(500);
}

After uploading the sketch, take the CO₂ sensor outside to fresh air for at least 1 hour daily over a period of 7 days. The display will show you how much time has passed since the upload. For optimal calibration of the sensor, repeat this process for 7 days. Please note that the senseBox must not be turned off during this period, otherwise the calibration must be restarted!

Calibrating the CO₂ Sensor (Manual Calibration)

In contrast to the automatic calibration of the CO2 sensor, which takes at least 7 days, you can alternatively perform manual calibration. An excellent guide has been written in the senseBox forum.

The compiled .bin file can be downloaded here.

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