const int P_LED = 3;
const int P_TASTO = 2;

int stato = 0;

void setup() {
  pinMode(P_LED, OUTPUT);
  pinMode(P_TASTO, INPUT_PULLUP);
}
void loop() {

  switch (stato) {
    case 0:
      digitalWrite(P_LED, LOW);
      if (!digitalRead(P_TASTO)) {
        delay(300);
        stato = 1;
      }
      break;
    case 1:
      fadeLed();
      if (!digitalRead(P_TASTO)) {
        delay(300);
        stato = 2;
      }
      break;
    case 2:
      blinkLed();
      if (!digitalRead(P_TASTO)) {
        delay(300);
        stato = 0;
      }
      break;
  }
}


void fadeLed() {
  const int POT = analogRead(A0);
  int convert = map(POT, 0, 1023, 0, 255);
  analogWrite(P_LED, convert);
}

void blinkLed() {
  int POT = analogRead(A0);
  int flash = map(POT, 0, 1023, 0, 500);
  digitalWrite(P_LED, !digitalRead(P_LED));
  delay(flash);
}