suoni

#include "pitches.h"
byte a = 0;
byte a1 = 0;
int noteDuration;

// notes in the melody:
int melody[] = {
  NOTE_C4, NOTE_G3, NOTE_G3, NOTE_A3
};
int melody1[] = {
  NOTE_E5, NOTE_E5, NOTE_E5, NOTE_E5
};
int noteDurations[] = {
  4, 8, 8, 4
};
int noteDurations1[] = {
  4, 1, 1, 4
};
unsigned long previousMillis = 0;
unsigned long pauseBetweenNotes;
int thisNote = 10;

void setup() {
  Serial.begin(9600);
}

void loop() {
  if (Serial.available() > 0) {
    char state = Serial.read();
    if (state == '+' ) {
      Serial.print("+ ");
      a = 2;
    }
    if (state == '-' ) {
      Serial.print("- ");
      a = 1;
    }
  }
  unsigned long currentMillis = millis();
  if (a != 0 &&  a != a1) {
    thisNote = 0;
    Serial.println(" cambio  ");
  }
  a1 = a;
  if (thisNote < 4 && currentMillis - previousMillis >= pauseBetweenNotes) {
    Serial.println(" Note  ");
    previousMillis = currentMillis;
    if (a == 1) {
      noteDuration = 1000 /  noteDurations[thisNote];
      tone(8, melody1[thisNote], noteDuration);
    }
    if (a == 2) {
      noteDuration = 1000 /  noteDurations1[thisNote];
      tone(8, melody[thisNote], noteDuration);
    }
    pauseBetweenNotes = noteDuration * 1.30;
    thisNote++;

  }
  if (thisNote >= 4 ) {
    a = 0;
  }

}