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CONTENTS

UNIT CO2

SKU:U103

Description

UNIT CO2 is a photoacoustic Carbon Dioxide (CO2) Unit that will tell you the CO2 PPM (parts-per-million) composition of ambient air. With a built-in Sensirion SCD40 sensor, power by Buck converter circuitry, and I2C communication. It has a range of 400~2000 ppm with an accuracy of ±(50 ppm + 5% of reading). What's more, it supports with temperature and humidity measurement too. Perfect for environmental sensing, scientific experiments, air quality and ventilation studies, and more.

Product Features

  • CO2 concentration detection
  • Temperature and humidity measurement
  • I2C communication (Add: 0x62)
  • Integrated 5V -> 3.3V Buck converter
  • 2x Brick holes
  • HY2.0-4P interface

Include

  • 1x UNIT-CO2
  • 1x HY2.0-4P cable (20CM)

Applications

  • Environmental sensing
  • Air quality
  • Ventilation studies

Specification

Resources Parameter
CO2 Measurement range 400 ~ 2000 ppm
CO2 Sampling accuracy ±(50 ppm + 5% of reading)
Temperature range -10 - 60 °C
Humidity range 0 - 95 %RH
Communication protocol I2C: 0x62
Net weight 7.54g
Gross weight 13.13g
Product dimensions 48mm x 24mm x 16mm
Package size 134mm x 61mm x 16.3mm
Housing material Plastic ( PC )

PinMap

CO2 Unit SCL SDA 5V GND
M5Core(PORT A) GPIO22 GPIO21 5V GND
M5Core2(PORT A) GPIO22 GPIO21 5V GND
M5Atom(PORT A) GPIO32 GPIO26 5V GND
M5StickC/Plus(PORT A) GPIO33 GPIO32 5V GND
M5Station(PORT A1,A2) GPIO33 GPIO32 5V GND

Schematic

Example

#include <Arduino.h>
#include <Wire.h>

// SCD4x
const int16_t SCD_ADDRESS = 0x62;

void setup() {
    // check in your settings that the right speed is selected
    Serial.begin(115200);
    // wait for serial connection from PC
    // comment the following line if you'd like the output
    // without waiting for the interface being ready
    while (!Serial)
        ;

    // output format
    Serial.println("CO2(ppm)\tTemperature(degC)\tRelativeHumidity(percent)");

    // init I2C
    Wire.begin();

    // wait until sensors are ready, > 1000 ms according to datasheet
    delay(1000);

    // start scd measurement in periodic mode, will update every 5 s
    Wire.beginTransmission(SCD_ADDRESS);
    Wire.write(0x21);
    Wire.write(0xb1);
    Wire.endTransmission();

    // wait for first measurement to be finished
    delay(5000);
}

void loop() {
    float co2, temperature, humidity;
    uint8_t data[12], counter;

    // send read data command
    Wire.beginTransmission(SCD_ADDRESS);
    Wire.write(0xec);
    Wire.write(0x05);
    Wire.endTransmission();

    // read measurement data: 2 bytes co2, 1 byte CRC,
    // 2 bytes T, 1 byte CRC, 2 bytes RH, 1 byte CRC,
    // 2 bytes sensor status, 1 byte CRC
    // stop reading after 12 bytes (not used)
    // other data like  ASC not included
    Wire.requestFrom(SCD_ADDRESS, 12);
    counter = 0;
    while (Wire.available()) {
        data[counter++] = Wire.read();
    }

    // floating point conversion according to datasheet
    co2 = (float)((uint16_t)data[0] << 8 | data[1]);
    // convert T in degC
    temperature = -45 + 175 * (float)((uint16_t)data[3] << 8 | data[4]) / 65536;
    // convert RH in %
    humidity = 100 * (float)((uint16_t)data[6] << 8 | data[7]) / 65536;

    Serial.print(co2);
    Serial.print("\t");
    Serial.print(temperature);
    Serial.print("\t");
    Serial.print(humidity);
    Serial.println();

    // wait 5 s for next measurement
    delay(5000);
}

Arduino

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