Светодиодное пианино

Самое простое пианино, которое воспроизводит заданную мелодию:

диоды - ноты от ДО до СИ

#define DO 7  // high/low
#define RE 8  // high/low
#define MI 9  // ~
#define FA 10 // ~
#define SO 11 // ~
#define LA 12 // high/low
#define SI 13 // high/low
int pol = 1000;
int chet = 500;

void setup() {              
  for (int x=7; x==13; x++) {
  pinMode(x, OUTPUT);
  }
}


void loop() {
  analogWrite(MI, 0);
  digitalWrite(LA, HIGH);
  delay(pol);

  digitalWrite(LA, LOW);
  analogWrite(FA, 255);
  delay(chet);

  analogWrite(FA, 0);
  digitalWrite(LA, HIGH);
  delay(chet);

  digitalWrite(LA, LOW);
  analogWrite(SO, 255);
  delay(chet);

  analogWrite(SO, 0);
  analogWrite(FA, 255);
  delay(chet);

  analogWrite(FA, 0);
  analogWrite(MI, 255);
  delay(pol);

  analogWrite(MI, 0);
  digitalWrite(LA, HIGH);
  delay(chet);

  digitalWrite(LA, LOW);
  digitalWrite(LA, HIGH);
  delay(chet);

  digitalWrite(LA, 0);
  analogWrite(FA, 255);
  delay(chet);

  analogWrite(FA, 0);
  digitalWrite(LA, HIGH);
  delay(chet);

  digitalWrite(LA, LOW);
  analogWrite(SO, HIGH);
  delay(chet);

  analogWrite(SO, LOW);
  analogWrite(FA, 255);
  delay(chet);

  analogWrite(FA, 0);
  analogWrite(MI, 255);
  delay(pol);

}