const int GAS_PIN     = A1;       // Pin Sensor Gas (harusnya pakai MQ-2 Gas Sensor ke pin digital, tapi di wokwi gaada, jadi pakai LDR ke pin analog)
const int RELAY_PIN   = 12;       // Pin relay
const int BUZZER_PIN  = 11;       // Pin buzzer

int kondisiRelay = 0; 
int ambangGas = 210;
int nilaiGas;  
bool gasBahaya;

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

void loop() {
nilaiGas    = analogRead(GAS_PIN);
gasBahaya   = nilaiGas > ambangGas;
Serial.print("konsenterasi gas : ");
Serial.println(nilaiGas);

if(gasBahaya){
  tone(BUZZER_PIN, 523, 200);
  digitalWrite(RELAY_PIN, HIGH);
  kondisiRelay = HIGH;
  delay(300);
  tone(BUZZER_PIN, 523, 200);
  digitalWrite(RELAY_PIN, LOW);
  kondisiRelay = LOW;
  delay(300);
}
}