Design of Intelligent Fire Alarm System Based on Single Chip Microcomputer

Designing an Intelligent Fire Alarm System based on a Single Chip Microcomputer (SCM) involves integrating sensors, a microcontroller, and communication modules to detect fire hazards and alert users. Below is a detailed guide to designing such a system:

Key Components

1. Microcontroller:

   • Examples: STM32, ESP32, Arduino (ATmega328P), or PIC.

   • The microcontroller processes sensor data and controls the system.

2. Fire Detection Sensors:

   • Smoke Sensor: MQ-2 or MQ-135 (detects smoke and flammable gases).

   • Temperature Sensor: LM35 or DHT11/DHT22 (monitors ambient temperature).

   • Flame Sensor: Infrared (IR) flame sensor (detects fire flames).

3. Alerting Mechanisms:

   • Buzzer: For audible alerts.

   • LEDs: For visual alerts.

   • LCD/OLED Display: To show status and sensor readings.

4. Communication Modules (Optional):

   • Wi-Fi (ESP8266/ESP32): For sending alerts to a smartphone or cloud.

   • GSM Module (SIM800L): For sending SMS alerts.

5. Power Supply:

   • Battery or external power source (e.g., 5V USB or 12V adapter).

6. Additional Components:

   • Resistors, capacitors, and connectors.

   • Relay module (for controlling external devices like sprinklers).

System Design

1. Sensor Integration:

   • Connect smoke, temperature, and flame sensors to the microcontroller's analog/digital pins.

   • Use voltage dividers or signal conditioning circuits if necessary.

2. Data Acquisition:

   • The microcontroller reads data from the sensors at regular intervals.

   • Analog signals (e.g., from MQ-2) are converted to digital using the ADC.

3. Fire Detection Logic:

   • Implement algorithms to analyze sensor data:

     • Smoke concentration exceeds a threshold.

     • Temperature rises rapidly or exceeds a threshold.

     • Flame sensor detects IR radiation.

   • Trigger an alarm if any of these conditions are met.

4. Alerting Mechanisms:

   • Activate a buzzer and LEDs when fire is detected.

   • Display sensor readings and status on an LCD/OLED.

5. Communication (Optional):

   • Send alerts via Wi-Fi (e.g., to a smartphone app or cloud platform).

   • Send SMS alerts using a GSM module.

6. Control Actions (Optional):

   • Activate a relay to turn on a sprinkler system or exhaust fan.

Software Implementation

1. Microcontroller Firmware:

   • Write code to initialize sensors, read data, and implement fire detection logic.

   • Example pseudocode:

     c

      

     void loop() {
       int smokeValue = analogRead(SMOKE_SENSOR_PIN);
       float temperature = readTemperature();
       bool flameDetected = digitalRead(FLAME_SENSOR_PIN);
     
       if (smokeValue > SMOKE_THRESHOLD || temperature > TEMP_THRESHOLD || flameDetected) {
         triggerAlarm();
         sendAlert();
       }
       delay(1000); // Check every second
     }

2. Alerting Logic:

   • Use PWM to control buzzer volume or LED brightness.

   • Display messages on the LCD (e.g., "Fire Detected!").

3. Communication:

   • Use libraries like WiFi.h for ESP32 or TinyGSM for GSM modules.

   • Example: Send an HTTP request to a cloud server or an SMS using AT commands.

4. Optional Features:

   • Data logging to an SD card.

   • Self-test functionality to check sensor and system health.

Example Code (Arduino + MQ-2 + Buzzer)

#define SMOKE_SENSOR_PIN A0
#define BUZZER_PIN 8
#define SMOKE_THRESHOLD 300

void setup() {
  pinMode(BUZZER_PIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  int smokeValue = analogRead(SMOKE_SENSOR_PIN);
  Serial.println(smokeValue);

  if (smokeValue > SMOKE_THRESHOLD) {
    digitalWrite(BUZZER_PIN, HIGH); // Activate buzzer
    Serial.println("Fire Detected!");
  } else {
    digitalWrite(BUZZER_PIN, LOW); // Deactivate buzzer
  }
  delay(1000); // Check every second
}

Challenges

1. False Alarms:

   • Use multiple sensors and advanced algorithms to reduce false positives.

2. Power Consumption:

   • Optimize the system for low power if battery-operated.

3. Sensor Calibration:

   • Calibrate sensors for accurate detection.

Applications

• Residential and commercial fire safety.

• Industrial fire monitoring.

• Forest fire detection.

By combining the right hardware and software, you can build a reliable and intelligent fire alarm system.