#define LED 12
#define SLIDE 13

// definire la periodcità del mio segnale
#define C_TIME 100 // PWM period

// how much il led deve rimanere acceso (duty cycle)
volatile int pwm_value = 0; // volatile perchè cambia spesso valore
hw_timer_t *Mytimer = NULL; //timer for triggering the led

// funzione che parte se il timer finisce 
void IRAM_ATTR timer_function(){
  bool led_status = digitalRead(LED);

  if(led_status && pwm_value != C_TIME){
    digitalWrite(LED, !led_status);
    timerWrite(Mytimer, pwm_value);
  }
  else if(!led_status && pwm_value != 0){
    digitalWrite(LED, !led_status);
    timerWrite(Mytimer, C_TIME - pwm_value);
  }

}


void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT); // define led
  pinMode(SLIDE, INPUT); // define slide

  Mytimer = timerBegin(0, 80, true); // startare il timer
  // 0 is for timer index in the controller
  // 80 is the divider for defining the timer tick rate 
  // true is increment

  // attach the interrupt when timer fires
  timerAttachInterrupt(Mytimer, &timer_function, true);

  timerAlarmWrite(Mytimer, C_TIME, true);
  // C_TIME is when to fire 
  // true is for starting again timer or not 

  //start timer
  timerAlarmEnable(Mytimer);

}

void loop() {
  // put your main code here, to run repeatedly:

  // la funzione map permette di creare una proporzione tra quello che gli diamo in input e l'altra roba
  // quindi lo slide che originariamente va da 0 a 4096, andrà da 0 a C_TIME
  pwm_value = map(analogRead(SLIDE), 0, 4096, 0, C_TIME); 
}