Fire alarm system

1int gasSensor = A0;
2
3int ledPins[] = {2, 3, 4, 5, 6, 7, 8};
4int buzzer = 9;
5
6int gasValue = 0;
7
8void setup() {
9  Serial.begin(9600);
10
11  for (int i = 0; i < 7; i++) {
12    pinMode(ledPins[i], OUTPUT);
13  }
14
15  pinMode(buzzer, OUTPUT);
16}
17
18void loop() {
19  gasValue = analogRead(gasSensor);
20  Serial.println(gasValue);
21
22  // Turn OFF all LEDs first
23  for (int i = 0; i < 7; i++) {
24    digitalWrite(ledPins[i], LOW);
25  }
26
27  // LED bar based on gas level
28  if (gasValue > 100) digitalWrite(ledPins[0], HIGH);
29  if (gasValue > 200) digitalWrite(ledPins[1], HIGH);
30  if (gasValue > 300) digitalWrite(ledPins[2], HIGH);
31  if (gasValue > 400) digitalWrite(ledPins[3], HIGH);
32  if (gasValue > 500) digitalWrite(ledPins[4], HIGH);
33  if (gasValue > 600) digitalWrite(ledPins[5], HIGH);
34  if (gasValue > 700) digitalWrite(ledPins[6], HIGH);
35
36  // Buzzer alert (high gas)
37  if (gasValue > 600) {
38    digitalWrite(buzzer, HIGH);
39  } else {
40    digitalWrite(buzzer, LOW);
41  }
42
43  delay(200);
44}