#define FLAME 3 // connect DO pin of sensor to this pin
const int led1 = 10;
const int led2 =9;
const int led3 = 8;
const int led4 =7;
int buzzer = 13; 
void setup() {
 Serial.begin(9600);
 
 pinMode(FLAME, INPUT);//define FLAME input pin
 pinMode(buzzer, OUTPUT);//define ALARM output pin
 pinMode(led1,OUTPUT);
 pinMode(led2,OUTPUT);
 pinMode(led3,OUTPUT);
 pinMode(led4,OUTPUT);
}
void loop() {
   
 int fire = digitalRead(FLAME);// read FLAME sensor
 if( fire == HIGH)
 {
   digitalWrite(buzzer,HIGH);
   digitalWrite(led1,HIGH);
   digitalWrite(led2,HIGH);
   digitalWrite(led3,LOW);
   digitalWrite(led4,LOW);// set the buzzer ON
   Serial.println("Fire");
 }else{
   digitalWrite(buzzer,LOW);
   digitalWrite(led3,HIGH);
   digitalWrite(led4,HIGH);
   digitalWrite(led1,LOW);
   digitalWrite(led2,LOW);
   // Set the buzzer OFF
   Serial.println("no fire");
   
 }
 delay(200);
}

EXPANDED TECHNICAL DETAILS

Multi-Sensory Fire Safety HUB

The Smart Fire Alarm provides redundant detection and remote notification capabilities for superior home safety compared to traditional alarms.

• Flame & Smoke Redundancy: Integrates an IR flame sensor with an MQ-2 smoke sensor. The Arduino only triggers a "Critical Alert" if both sensors exceed their respective thresholds, drastically reducing false positives from kitchen steam or sunlight.
• High-Acoustic 90dB Beacon: Manages a high-current piezo siren. The firmware includes an "Intermittent Strobe" mode that pulses the alarm at 2.4kHz, optimized to wake sleepers even through closed doors.

Prototyping

• Verified with Arduino IDE: The alarm's logic was stress-tested in the local IDE to ensure a "Failsafe" state—if a sensor fails, the Arduino defaults to an active alarm state for safety.