何かアレ

gistfile1.c

int speaker=11;

#define Do 523
#define Re 587
#define Mi 659
#define Fa 698
#define So 783
#define Ra 880
#define Si 987
#define DoU 1046
#define ReU 1174

int m[9] = {Do, Re, Mi, Fa, So, Ra, Si, DoU, ReU};

void sound(int tone_delay) {
  digitalWrite(speaker, HIGH);
  delayMicroseconds((float)1000000/tone_delay/2);
  digitalWrite(speaker, LOW);
  delayMicroseconds((float)1000000/tone_delay/2);
}

void setup()
{
  pinMode(speaker, OUTPUT);
  int i;
  for (i=2; i<=9; i++) {
    pinMode(i, INPUT);
    digitalWrite(i, HIGH); 
  }
}

void loop()
{
  int i;
  for (i=2; i<=9; i++) {
    if(digitalRead(i) == LOW) sound(m[i-2]);
  }
}