HOW to Detect Flame With ESP32

Description

In daily life, it is often seen that a fire broke out without any precaution. It will cause great economic and human loss. So how can we avoid this situation? Right, install a flame sensor and a speaker in those places that easily break out a fire. When the flame sensor detects a fire, the speaker will alarm people quickly to put out the fire.

So in this project, you will learn how to use a flame sensor and an active buzzer module to simulate the fire alarm system.

Working Principle

This flame sensor can be used to detect fire or other light sources with wavelength stands at 700nm ~ 1000nm. Its detection angle is about 60°. You can rotate the potentiometer on the sensor to control its sensitivity. Adjust the potentiometer to make the LED at the critical point between on and off state. The sensitivity is the best.

From the below figure, power up. When detecting fire, the digital pin outputs low levels, the red LED2 will light up first, the digital signal terminal D0 outputs a low level, and the red LED1 will light up. The stronger the external infrared light, the smaller the value; the weaker the infrared light, the larger the value.

Required Components

Connection Diagram

Test Code

//**********************************************************************************
/*  
 * Description : Read the basic usage of Digital，ADC，DAC and Voltage
 * Auther      : http//www.keyestudio.com
*/
//Flame sensor two pins 13, 34, respectively
#define PIN_ANALOG_IN  34 
int digitalPin = 13;

//The following two variables hold the digital signal and adc values respectively
int analogVal = 0;
int adcVal = 0;

void setup() {
  Serial.begin(9600);
  pinMode(digitalPin, INPUT); //Digital pin 13 is set to input mode
}

//In loop()，the digitalRead()function is used to obtain the digital value,
//the analogRead() function is used to obtain the ADC value. 
//the map() function is used to convert the value into an 8-bit precision DAC value. 
//The input and output voltage are calculated according to the previous formula, and the information is finally printed out.
void loop() {
  int digitalVal = digitalRead(digitalPin);  //Read digital signal;
  int adcVal = analogRead(PIN_ANALOG_IN);
  int dacVal = map(adcVal, 0, 4095, 0, 255);
  double voltage = adcVal / 4095.0 * 3.3;
  Serial.printf("digitalVal: %d, \t ADC Val: %d, \t DAC Val: %d, \t Voltage: %.2fV\n",digitalVal, adcVal, dacVal, voltage);
  delay(200);
}
//**********************************************************************************

Code Explanation

Two pins we use are defined as GPIO13 and GPIO34 according to the wiring-up diagram, and print digital signals and analog signals respectively.

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. Rotating the potentiometer on the sensor, we can adjust the red LED bright and not bright critical point. The red LED2 on the sensor module is lit, while the red LED1 is not. Open the monitor and set baud rate to 9600. The “Shell” window will display the digital value, ADC value, DAC value and voltage value of the flame sensor. When fire is detected, the LED1 will be on. the digital value will change from 1 to 0, and the analog value will become smaller, as shown below.