Gas Ananlyser Using Arduino

1/*feel free to contact
2 * sreeramaj53@gmail.com
3 * www.youtube.com/ZenoModiff
4  * last updated - time 09:05 PM - date 20 may 2021
5 * Github Link :-- https://github.com/Zenomodiff/Atmospheric-Gas-Ananlyser-With-MQ-Series-Sensors-Dht-11
6  */
7
8#include <Wire.h> 
9#include <LiquidCrystal_I2C.h>
10#include "DHT.h"
11#define  DHTPIN 13     
12#define DHTTYPE DHT11 
13
14DHT dht(DHTPIN, DHTTYPE);
15LiquidCrystal_I2C  lcd(0x27, 16, 2);
16
17const int mq2 = A0;
18const int mq4 = A1;  
19const int  mq5 = A2; 
20const int mq135 = A3;
21
22float m = -0.6527; 
23float b = 1.30;  
24float R0 = 21.91;
25
26void setup() {
27
28  lcd.begin();
29  lcd.backlight();
30  lcd.print("Atmosphere");
31  lcd.setCursor(0,3);
32  lcd.print("Gas Analyser");
33  delay (3000);
34  lcd.clear();
35
36  lcd.print("By");
37  lcd.setCursor(0,3);
38  lcd.print("Zeno Modiff");
39  delay (3000);
40  lcd.clear();
41
42  pinMode(mq4,  INPUT); 
43  pinMode(mq135, INPUT); 
44  pinMode(mq5, INPUT); 
45  pinMode(mq2,  INPUT); 
46  
47  Serial.begin(9600);
48  dht.begin();
49}
50
51void loop()  {
52  
53  float h = dht.readHumidity();
54  float t = dht.readTemperature();
55  float f = dht.readTemperature(true);
56  if (isnan(h) || isnan(t) || isnan(f))  {
57  Serial.println(F("Failed to read from DHT sensor!"));
58  return;
59  float hif = dht.computeHeatIndex(f, h);
60  float hic = dht.computeHeatIndex(t,  h, false);
61  }
62  double mq4_value = analogToPPM(analogRead(mq4));
63  double  mq135_value = analogToPPM(analogRead(mq135));
64  double mq5_value = analogToPPM(analogRead(mq5));
65  double mq2_value = analogToPPM(analogRead(mq2));
66  
67  Serial.println("************************************");
68  Serial.print("MQ-4 Value: ");Serial.print(mq4_value, DEC);Serial.println("  PPM");
69  Serial.print("MQ-135 Value: ");Serial.print(mq135_value, DEC);Serial.println("  PPM");
70  Serial.print("MQ-5 Value: ");Serial.print(mq5_value, DEC);Serial.println("  PPM");
71  Serial.print("MQ-2 Value: ");Serial.print(mq2_value, DEC);Serial.println("  PPM");
72  Serial.print("DHT-Temp: ");Serial.print(t);Serial.println(" c");
73  Serial.print("DHT-Humi: ");Serial.print(h);Serial.println(" %");
74  Serial.println("************************************\
75\
76");
77
78  lcd.setCursor(0,0);
79  lcd.print("CNG Value");
80  lcd.setCursor(0,3);
81  lcd.println(mq4_value);
82  lcd.setCursor(7,7);
83  lcd.print("PPM");
84  delay(3000);
85  lcd.clear();
86
87  lcd.setCursor(0,0);
88  lcd.print("AQI  Value");
89  lcd.setCursor(0,3);
90  lcd.println(mq135_value);
91  lcd.setCursor(7,7);
92  lcd.print("PPM");
93  delay(3000);
94  lcd.clear();
95
96  lcd.setCursor(0,0);
97  lcd.print("LNG");
98  lcd.setCursor(0,3);
99  lcd.println(mq5_value);
100  lcd.setCursor(7,7);
101  lcd.print("PPM");
102  delay(3000);
103  lcd.clear();
104
105  lcd.setCursor(0,0);
106  lcd.print("SMOKE");
107  lcd.setCursor(0,3);
108  lcd.println(mq2_value);
109  lcd.setCursor(7,7);
110  lcd.print("PPM");
111  delay(3000);
112  lcd.clear();
113
114  lcd.setCursor(0,0);
115  lcd.print("DHT-11");
116  lcd.setCursor(0,3);
117  lcd.print("Temp  -");
118  lcd.setCursor(7,4);
119  lcd.println(t);
120  delay(3000);
121  lcd.clear();
122
123  lcd.setCursor(0,0);
124  lcd.print("DHT-11");
125  lcd.setCursor(0,3);
126  lcd.print("Humi  -");
127  lcd.setCursor(7,4);
128  lcd.println(h);
129  delay(3000);
130  lcd.clear();
131
132}
133  double analogToPPM(int aValue) {
134  float sensor_volt;
135  float RS_gas; 
136  float ratio;
137  int sensorValue = aValue;
138
139  sensor_volt = sensorValue*(5.0/1023.0);  
140  RS_gas = ((5.0*10.0)/sensor_volt)-10.0; 
141  ratio = RS_gas/R0; 
142  double  ppm_log = (log10(ratio)-b)/m;
143  return ppm_log;
144}