Wowki file

Information on mq2 is from this source. DAC pins are analog output.

The mq2 will need a 5v, gnd, and an analog output pin for my application. The 2 ESP32 pins that are analog output are GPIO 25 & 26 (info on pinout from here).

Basic gas sensor code:

        
          #define MQ2pin 25 // or 26, either is fine

          float sensorValue;  //variable to store sensor value
          
          void setup() {
            Serial.begin(9600);  // sets the serial port to 9600
            Serial.println("MQ2 warming up!");
            delay(20000);  // allow the MQ2 to warm up
          }
          
          void loop() {
            sensorValue = analogRead(MQ2pin);  // read analog input pin 0
          
            Serial.print("Sensor Value: ");
            Serial.println(sensorValue);
          
            delay(2000);  // wait 2s for next reading
          }
        
      

Basic buzzer code. All the buzzer needs is a random pin for power (any PWM pin, which means any pin except 34-39) and a GND pin.

        
          #define Buzzer 4 // (can be any except 34-39)

void setup(){
    Serial.begin(115200);
    Serial.println("Hello Buzz!");
    pinMode(Buzzer, OUTPUT);
}

void loop(){
    delay(1000);
    digitalWrite(Buzzer, HIGH);
    delay(1000);
    digitalWrite(Buzzer, LOW);
}
        
      

Both code integrated to buzz when a high value is reached (for immediate danger):

        
          #define MQ2pin 25 // or 26, either is fine
#define Buzzer 4 // can be any

float sensorValue;  //variable to store sensor value
int dangerValue = 800; // arbitrary
          
void setup() {
    Serial.begin(9600);  // sets the serial port to 9600
    Serial.println("MQ2 warming up!");
    pinMode(Buzzer, OUTPUT);
    delay(20000);  // allow the MQ2 to warm up
}
          
void loop() {
    sensorValue = analogRead(MQ2pin);  // read analog input pin 0
          
    Serial.print("Sensor Value: ");
    Serial.println(sensorValue);
    if (sensorValue >= dangerValue ) {
      digitalWrite(Buzzer, HIGH); // buzzer on 
      delay(20000); // buzzer on for 20 s to allow the miner to react
    }
          
    delay(2000);  // wait 2s for next reading
}


        
      

Wowki wiring diagram:

Schematic