이산화 탄소 센서 사용법 알아보기(CO2 Sensor MG811)

이산화 탄소 센서(CO2 Sensor MG811)

http://mechasolution.com/shop/goods/goods_view.php?goodsno=8854&category=002015

메카솔루션 공식 쇼핑몰

 

 

CO2 이산화 탄소 센서에 대해 알아보기!

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생물이 호흡을 할때,

산소를 들이쉬고, 이산화 탄소를 내쉬게 된다.

 

이러한 이산화 탄소를 측정하기위해,

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다음과 같이 동작하게 된다.

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센서 내부에는 히터와 금속판이 있는데,

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히터로 공기를 가열하면, 공기의 입자가 금속판에 달라붙게 되는데

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입자가 달라붙는 정도에따라, 저항값이 변하게 된다.

 

 

 

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CO2 이산화 탄소 센서 특징 알아보기!

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동작전압 5V

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아날로그, 디지털 출력

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가열 회로가 내장되어 있다.

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가열될 시, 약 40도를 유지한다. 그리 높은 온도는 아니지만 오랫동안 닿아 있으면 화상을 입을 수 있다.

 

 

소스코드

/************************Hardware Related Macros************************************/
#define MG_PIN (2) //define which analog input channel you are going to use – A0 pin
#define BOOL_PIN (13)    // D9 – Dout pin
#define DC_GAIN (8.5) //define the DC gain of amplifier
/***********************Software Related Macros************************************/
#define READ_SAMPLE_INTERVAL (50) //define how many samples you are going to take in normal operation
#define READ_SAMPLE_TIMES (5) //define the time interval(in milisecond) between each samples in
//normal operation
/**********************Application Related Macros**********************************/
//These two values differ from sensor to sensor. user should derermine this value.

#define ZERO_POINT_VOLTAGE (0.185) //define the output of the sensor in volts when the concentration of CO2 is 400PPM

#define REACTION_VOLTGAE (0.010) //define the voltage drop of the sensor when move the sensor from air into 1000ppm CO2
/*****************************Globals***********************************************/

float CO2Curve[3] = {2.602, ZERO_POINT_VOLTAGE, (REACTION_VOLTGAE / (2.602 - 3))};
//two points are taken from the curve.
//with these two points, a line is formed which is
//"approximately equivalent" to the original curve.
//data format:{ x, y, slope}; point1: (lg400, 0.324), point2: (lg4000, 0.280)
//slope = ( reaction voltage ) / (log400 –log1000)

void setup()
{
  Serial.begin(115200); //UART setup, baudrate = 9600bps
  pinMode(BOOL_PIN, INPUT); //set pin to input
  digitalWrite(BOOL_PIN, HIGH); //turn on pullup resistor
  Serial.print("MG-811 Demostration\n");
}

void loop()
{
  int percentage;
  float volts;

  volts = MGRead(MG_PIN);
  Serial.print( "SEN-00007:" );
  Serial.print(volts);
  Serial.print( " V / before_amp : " );
  Serial.print(volts / DC_GAIN);
  Serial.print( " V " );

  percentage = MGGetPercentage(volts, CO2Curve);
  Serial.print("CO2:");
  if (percentage == -1) {
    Serial.print( "<400" );
  } else {
    Serial.print(percentage);
  }
  Serial.print( "ppm\n" );
  if (digitalRead(BOOL_PIN) ) {
    Serial.print( "=====BOOL is HIGH======" );
  } else {
    Serial.print( "=====BOOL is LOW======" );
  }
  Serial.print("\n");
  delay(200);
}
/***************************** MGRead *********************************************
  Input: mg_pin - analog channel
  Output: output of SEN-000007
  Remarks: This function reads the output of SEN-000007
************************************************************************************/
float MGRead(int mg_pin)
{
  int i;
  float v = 0;
  for (i = 0; i < READ_SAMPLE_TIMES; i++) {
    v += analogRead(mg_pin);
    delay(READ_SAMPLE_INTERVAL);
  }
  v = (v / READ_SAMPLE_TIMES) * 5 / 1024 ;
  return v;
}

/***************************** MQGetPercentage **********************************
  Input: volts - SEN-000007 output measured in volts
  pcurve - pointer to the curve of the target gas
  Output: ppm of the target gas
  Remarks: By using the slope and a point of the line. The x(logarithmic value of ppm)
  of the line could be derived if y(MG-811 output) is provided. As it is a
  logarithmic coordinate, power of 10 is used to convert the result to non-logarithmic
  value.
************************************************************************************/

int MGGetPercentage(float volts, float *pcurve)
{
  if ( pow(10, ((volts / DC_GAIN) - pcurve[1]) / pcurve[2] + pcurve[0] >= 0 ))
  {
    return pow(10, ((volts / DC_GAIN) - pcurve[1]) / pcurve[2] + pcurve[0]);
  } else {
    return -1;
  }
}

 

dm2468 센서

#include "CO2Sensor.h"

CO2Sensor co2Sensor(2, 0.99, 100);

void setup() {
  Serial.begin(115200);
  Serial.println("=== Initialized ===");
  co2Sensor.calibrate();
}

void loop() {
  int val = co2Sensor.read();
  Serial.print("CO2 value: ");
  Serial.print(val);
  Serial.println("ppm");
  delay(1000);
}

 

CO2센서 첨부파일

CO2Sensor-master.zip

0.32MB

 

 

 

 

위 공식을 그래프로 만들어 보면 다음과 같은 그래프가 나오게 된다.

 

위 소스코드가 동작하면

다음과 같이 출력된다.

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