Fire and Gas Leak Warning System Using Arduino, Flame Sensor, MQ2 and Buzzer

1// ANALOG
2int gasPin   = A0;   
3int flamePin = A1;   
4
5int gasThreshold   = 400;
6int flameThreshold = 350;
7
8// OUTPUT
9int buzzer = 8;
10int led    = 9;
11
12void setup() {
13  Serial.begin(9600);
14
15  pinMode(buzzer, OUTPUT);
16  pinMode(led, OUTPUT);
17
18  digitalWrite(buzzer, LOW);
19  digitalWrite(led, LOW);
20}
21
22void loop() {
23
24  int gasValue   = analogRead(gasPin);
25  int flameValue = analogRead(flamePin);
26
27  Serial.print("Gas: ");
28  Serial.print(gasValue);
29  Serial.print(" | Flame: ");
30  Serial.println(flameValue);
31  delay(200);
32
33  if (gasValue > gasThreshold || flameValue > flameThreshold) {
34    digitalWrite(buzzer, HIGH);
35
36    // LED
37    digitalWrite(led, HIGH);
38    delay(200);
39    digitalWrite(led, LOW);
40    delay(200);
41
42  } else {
43    digitalWrite(buzzer, LOW);
44    digitalWrite(led, LOW);
45  }
46}