#define led 4
#define btn 2
int led_Ch = 0;
int Freq = 5000;
int Res = 8;
int DutyCycle;
int counter = 0;

void IRAM_ATTR Ext_INT1_ISR() {
  counter++;
  if (counter > 2) {
    counter = 0;
  }
}

void setup() {
  // put your setup code here, to run once:
  pinMode(led, OUTPUT);
  pinMode(btn, INPUT);
  ledcSetup(led_Ch,Freq,Res);
  ledcAttachPin(led,led_Ch);
  attachInterrupt(btn,Ext_INT1_ISR,RISING);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  while (counter == 0) {
    Serial.print("Pulse count = ");
    Serial.println(counter);
    for (DutyCycle=0;DutyCycle<=255;DutyCycle+=10) {
    ledcWrite(led_Ch,DutyCycle);
    delay(15);
    }
    for (DutyCycle=255;DutyCycle>=0;DutyCycle-=10) {
    ledcWrite(led_Ch,DutyCycle);
    delay(15);
    }
  }
  while (counter == 1) {
    Serial.print("Pulse count = ");
    Serial.println(counter);
    for (DutyCycle=0;DutyCycle<=255;DutyCycle+=20) {
    ledcWrite(led_Ch,DutyCycle);
    delay(15);
    }
    for (DutyCycle=255;DutyCycle>=0;DutyCycle-=20) {
    ledcWrite(led_Ch,DutyCycle);
    delay(15);
    }
  }
  while (counter == 2) {
    Serial.print("Pulse count = ");
    Serial.println(counter);
    for (DutyCycle=0;DutyCycle<=255;DutyCycle++) {
    ledcWrite(led_Ch,DutyCycle);
    delay(15);
    }
    for (DutyCycle=255;DutyCycle>=0;DutyCycle--) {
    ledcWrite(led_Ch,DutyCycle);
    delay(15);
    }
  }
}