Breathalyzer-On-Wheels

1#define MQ3_PIN A0
2#define RELAY_PIN 8
3#define BUZZER_PIN 9
4#define LED_PIN 10
5
6const int samples = 20;       // High sensitivity sampling
7const int sampleDelay = 5;    // Fast response (ms)
8int thresholdOffset = 120;    // Sensitivity (lower = more sensitive)
9
10int baseline = 0;
11
12void setup() {
13  Serial.begin(9600);
14
15  pinMode(RELAY_PIN, OUTPUT);
16  pinMode(BUZZER_PIN, OUTPUT);
17  pinMode(LED_PIN, OUTPUT);
18
19  digitalWrite(RELAY_PIN, HIGH); // Engine ON
20
21  Serial.println("Calibrating MQ-3...");
22  delay(5000);  // Short warm-up for demo
23
24  baseline = calibrateBaseline();
25  Serial.print("Baseline Air Value: ");
26  Serial.println(baseline);
27}
28
29void loop() {
30  int alcoholValue = getAverageReading();
31  int alcoholLevel = alcoholValue - baseline;
32
33  Serial.print("Raw: ");
34  Serial.print(alcoholValue);
35  Serial.print(" | Alcohol Level: ");
36  Serial.println(alcoholLevel);
37
38  if (alcoholLevel > thresholdOffset) {
39    // Alcohol detected
40    digitalWrite(RELAY_PIN, LOW);   // Engine OFF
41    digitalWrite(BUZZER_PIN, HIGH);
42    digitalWrite(LED_PIN, HIGH);
43  } else {
44    digitalWrite(RELAY_PIN, HIGH);
45    digitalWrite(BUZZER_PIN, LOW);
46    digitalWrite(LED_PIN, LOW);
47  }
48
49  delay(100);
50}
51
52// ---------- FUNCTIONS ----------
53
54int getAverageReading() {
55  long total = 0;
56  for (int i = 0; i < samples; i++) {
57    total += analogRead(MQ3_PIN);
58    delay(sampleDelay);
59  }
60  return total / samples;
61}
62
63int calibrateBaseline() {
64  long total = 0;
65  for (int i = 0; i < 50; i++) {
66    total += analogRead(MQ3_PIN);
67    delay(50);
68  }
69  return total / 50;
70}