HOW to Build a Fire Alarm with ESP32

Description

In this experiment, we will make a fire alarm system. Just use a flame sensor to control an active buzzer to emit sounds.

Required Components

Connection Diagram

Test Code

/*  
 * Description : Controlling the buzzer by flame sensor.
 * Auther      : http//www.keyestudio.com
*/
int item = 0;
void setup() {
  Serial.begin(9600);
  pinMode(4, INPUT);//Flame sensor digital pin is connected to GPIO4
  pinMode(15, OUTPUT);//Buzzer pin is connected to GPIO15
}

void loop() {
  item = digitalRead(4);//Read the digital level output by the flame sensor
  Serial.println(item);//Newline print level signal
  if (item == 0) {//Flame detected
    digitalWrite(15, HIGH);//Turn on the buzzer
  } else {//Otherwise, turn off the buzzer
    digitalWrite(15, LOW);
  }
  delay(100);//Delay 100ms
}

Code Explanation

This flame sensor uses an analog pin and a digital pin. When a flame is detected, the digital pin outputs a low level. In this experiment we will use the digital port.

Test Result

Connect the wires according to the experimental wiring diagram, compile and upload the code to the ESP32. After uploading successfully，we will use a USB cable to power on. When the sensor detects the flame, the external active buzzer will emit sounds, otherwise the active buzzer will not emit sounds.