MQ-7 โมดูลตรวจจับคาร์บอนมอนอกไซด์ MQ7 SNP-00052

1int sensor = 7;
2int val = 0;
3void setup() {
4  Serial.begin(9600);
5}
6void loop() {
7  val = digitalRead(sensor);
8  if (val == 0) {
9    Serial.println("MQ-7 Detected");
10  }
11  delay(500);
12}

1int sensor = A0;
2int val = 0;
3void setup() {
4  Serial.begin(9600);
5}
6void loop() {
7  val = analogRead(sensor);
8  Serial.println(val);
9  delay(500);
10}

1/*******************Demo for MQ-7 Gas Sensor Module*****************************
2  Support:  Tiequan Shao: support[at]sandboxelectronics.com
3  Lisence: Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)
4  Note:    This piece of source code is supposed to be used as a demonstration ONLY.
5           More sophisticated calibration is required for industrial field application.
6                                                    Sandbox Electronics    2011-04-25
7************************************************************************************/
8
9/************************Hardware Related Macros************************************/
10#define         MQ_PIN                       (0)     //define which analog input channel you are going to use
11#define         RL_VALUE                     (5)     //define the load resistance on the board, in kilo ohms
12#define         RO_CLEAN_AIR_FACTOR          (27.0)  //RO_CLEAR_AIR_FACTOR=(Sensor resistance in clean air)/RO, for MQ-7
13
14/***********************Software Related Macros************************************/
15#define         CALIBARAION_SAMPLE_TIMES     (50)    //define how many samples you are going to take in the calibration phase
16#define         CALIBRATION_SAMPLE_INTERVAL  (500)   //define the time interval(in milisecond) between each samples in the calibration phase
17#define         READ_SAMPLE_INTERVAL         (50)    //define the time interval(in milisecond) between each samples in normal operation
18#define         READ_SAMPLE_TIMES            (5)     //define how many samples you are going to take in normal operation
19
20/**********************Application Related Macros**********************************/
21#define         GAS_CO                       (0)
22
23/*****************************Globals***********************************************/
24float           COCurve[3]  =  {2.3, 0.72, -0.34};  // MQ-7 curve for CO
25float           Ro           =  10;                 //Ro is initialized to 10 kilo ohms
26
27void setup()
28{
29  Serial.begin(9600);                                //UART setup, baudrate = 9600bps
30  Serial.print("Calibrating...\n");
31  Ro = MQCalibration(MQ_PIN);                        //Calibrating the sensor. Please make sure the sensor is in clean air
32  Serial.print("Calibration is done...\n");
33  Serial.print("Ro=");
34  Serial.print(Ro);
35  Serial.print("kohm");
36  Serial.print("\n");
37}
38
39void loop()
40{
41  Serial.print("CO:");
42  Serial.print(MQGetGasPercentage(MQRead(MQ_PIN) / Ro, GAS_CO) );
43  Serial.print( "ppm" );
44  Serial.print("\n");
45  delay(200);
46}
47
48float MQResistanceCalculation(int raw_adc)
49{
50  return ( ((float)RL_VALUE * (1023 - raw_adc) / raw_adc));
51}
52
53float MQCalibration(int mq_pin)
54{
55  int i;
56  float val = 0;
57
58  for (i = 0; i < CALIBARAION_SAMPLE_TIMES; i++) {
59    val += MQResistanceCalculation(analogRead(mq_pin));
60    delay(CALIBRATION_SAMPLE_INTERVAL);
61  }
62  val = val / CALIBARAION_SAMPLE_TIMES;                 
63  val = val / RO_CLEAN_AIR_FACTOR;                      
64  return val;
65}
66
67float MQRead(int mq_pin)
68{
69  int i;
70  float rs = 0;
71
72  for (i = 0; i < READ_SAMPLE_TIMES; i++) {
73    rs += MQResistanceCalculation(analogRead(mq_pin));
74    delay(READ_SAMPLE_INTERVAL);
75  }
76
77  rs = rs / READ_SAMPLE_TIMES;
78  return rs;
79}
80
81int MQGetGasPercentage(float rs_ro_ratio, int gas_id)
82{
83  if ( gas_id == GAS_CO ) {
84    return MQGetPercentage(rs_ro_ratio, COCurve);
85  }
86
87  return 0;
88}
89
90int MQGetPercentage(float rs_ro_ratio, float *pcurve)
91{
92  return (pow(10, ( ((log(rs_ro_ratio) - pcurve[1]) / pcurve[2]) + pcurve[0])));
93}
94