const int S1=14, S2=27, ledPin = 12;  // 16 corresponds to GPIO16


// setting PWM properties
const int freq = 5000;
const int ledChannel = 0;
const int resolution = 8;
 
void setup(){

  ledcSetup(ledChannel, freq, resolution);
  pinMode(S1, INPUT);
  pinMode(S2, INPUT);
  
  // attach the channel to the GPIO to be controlled
  ledcAttachPin(ledPin, ledChannel);
}
 
void loop(){
  main:
  if( digitalRead(S1)==1 & digitalRead(S2)==0){
    goto on1;   
  }
  else{
    goto main;
  }
  goto main;

  on1:
    // increase the LED brightness
    for(int dutyCycle = 0; dutyCycle <= 255; dutyCycle++){   
      ledcWrite(ledChannel, dutyCycle);
       if(digitalRead(S2)==1& digitalRead(S1)==0){
          ledcWrite(0,0);
          goto main;
       }
      delay(10);
  }
    // decrease the LED brightness
    for(int dutyCycle = 255; dutyCycle >= 0; dutyCycle--){
      ledcWrite(ledChannel, dutyCycle);   
       if(digitalRead(S2)==1& digitalRead(S1)==0){
          ledcWrite(0,0);
          goto main;
       }
      delay(10);
  }
  goto on1;
}