#include <Servo.h>

Servo myServo;
volatile bool reset = false; 
int res = 2;

void setup() {
  myServo.attach(9);           
  pinMode(2, INPUT_PULLUP);    
  attachInterrupt(digitalPinToInterrupt(2), resetServo, FALLING); 
  Serial.begin(9600);
}

void loop() {
  if (reset && res % 2 == 0) {
    myServo.write(0);          
    if(digitalRead(2) == HIGH)
      res++;       
  } 
  else if(reset && res % 2 == 1){
    if(digitalRead(2) == LOW){
      reset = false; 
      res--;
    }
  }
  else if(!reset){
    int pot = analogRead(A0);   
    int spomalenie = map(pot, 0, 1023, 10, 50);  

    for (int i = 0; i <= 180; i++) {
      if (reset) 
        break;
      myServo.write(i);
      analogWrite(9, map(spomalenie, 10, 50, 0, 255)); 
      delay(spomalenie);
    }

    for (int i = 180; i >= 0; i--) {
      if (reset) 
        break; 
      myServo.write(i);
      analogWrite(9, map(spomalenie, 10, 50, 0, 255));
      delay(spomalenie);
    }
  }
}


void resetServo() {
  reset = true;
}