arduino和MG111二氧化碳传感器采集co2

原文地址：http://wiki.dfrobot.com.cn/index.php/(SKU:SEN0159)CO2_二氧化碳传感器模块_V1#.E6.A0.B7.E4.BE.8B.E4.BB.A3.E7.A0.81.E4.BA.8C

(SKU:SEN0159)CO2 二氧化碳传感器模块 V1

简介

温室效应、废气排放、冰川融化、岛国淹没，这一切的罪魁祸首就是CO2的过度排放。是时候家中常备一款CO2监测装置，来知道我们的环境危机是多么的紧迫。它还可以告诉你室内空气的质量，及时开窗降低CO2浓度。DFRobot为您带来这款CO2传感器。CO2浓度越高，输出的电压值就越小。通过我们的说明书和样例代码，用户可以轻松的读取CO2数值。

用户还可以用板子上的电位器直接设置阈值，当CO2浓度高达一定程度时，探头旁边的3P针头会输出一个信号（数字量）。

该模块采用工业级的MG-811 CO2探头，对CO2极为敏感，同时还能排除酒精和CO的干扰。该探头对环境温湿度的依赖小，性能稳定，快速恢复响应。模块自带信号放大电路，进一步提高灵敏度。另外，板子上的加热电路直接把5V转换成稳定6V，为探头加热供电，提高模块适应性。

产品参数

• 传感器探头工作电压：6v
• 内置升压电路，支持3.7~5v DC电源输入,电源电流大于500mA
• 兼容蜂鸣器，通过调节板载金属电位器，可快速实现CO2超标蜂鸣器警报功能
• 高品质接头，耐反复插拔
• 沉金工艺，金色质感
• 板子上带有模拟传感图标“A”和明显的电位器标识
• 尺寸：32*42mm

• 模块数据曲线表

数据曲线表

使用教程

连线图

SEN0159 Diagram

注意:使用二氧化传感器时，Arduino必须外接供电（7.5V-9V），否则会造成数据不准确。另外，样例2中需要更改代码，具体看#define 部分Application Related Macros
细节说明:电位器用来设置阀值，当设置的阀值小于测得的数值时，数字输出口便输出一个高电平。你可以在数字输出口接蜂鸣器模块或者LED模块用作报警显示。

样例代码一

void setup(){
   
  Serial.begin(9600);
   
}
 
void loop(){
  Serial.print("Sample value:");
  Serial.println(analogRead(0));
  delay(100);
}

样例代码二

/*******************Demo for MG-811 Gas Sensor Module V1.1*****************************
Author:  Tiequan Shao: tiequan.shao@sandboxelectronics.com
         Peng Wei:     peng.wei@sandboxelectronics.com
         
Lisence: Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)

Note:    This piece of source code is supposed to be used as a demostration ONLY. More
         sophisticated calibration is required for industrial field application. 
         
                                                    Sandbox Electronics    2012-05-31
************************************************************************************/

/************************Hardware Related Macros************************************/
#define         MG_PIN                       (0)     //define which analog input channel you are going to use
#define         BOOL_PIN                     (2)
#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           (0.324) //define the output of the sensor in volts when the concentration of CO2 is 400PPM
#define         REACTION_VOLTGAE             (0.020) //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(9600);                              //UART setup, baudrate = 9600bps
    pinMode(BOOL_PIN, INPUT);                        //set pin to input
    digitalWrite(BOOL_PIN, HIGH);                    //turn on pullup resistors

   Serial.print("MG-811 Demostration\n");                
}

void loop()
{
    int percentage;
    float volts;
    
   
    volts = MGRead(MG_PIN);
    Serial.print( "SEN0159:" );
    Serial.print(volts); 
    Serial.print( "V           " );
    
    percentage = MGGetPercentage(volts,CO2Curve);
    Serial.print("CO2:");
    if (percentage == -1) {
        Serial.print( "<400" );
    } else {
        Serial.print(percentage);
    }
    Serial.print( "ppm" );  
    Serial.print( "       Time point:" );
    Serial.print(millis());
    Serial.print("\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 SEN0159
Remarks: This function reads the output of SEN0159
************************************************************************************/ 
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 ((volts/DC_GAIN )>=ZERO_POINT_VOLTAGE) {
      return -1;
   } else { 
      return pow(10, ((volts/DC_GAIN)-pcurve[1])/pcurve[2]+pcurve[0]);
   }
}

结果

打开串口监视器，大约五分钟后，你会得到你周围二氧化碳浓度的数据。