Ｐｉａｎｏ-arduino側

const int dobutton = 6;
const int rebutton = 7;
const int mibutton = 8;
const int fabutton = 9;
const int sobutton = 10;
const int rabutton = 11;
const int sibutton = 12;
const int ddobutton = 13;
int leftbuttonState = LOW;

void setup(){
  pinMode(dobutton,OUTPUT);
  pinMode(rebutton,OUTPUT);
  pinMode(mibutton,OUTPUT);
  pinMode(fabutton,OUTPUT);
  pinMode(sobutton,OUTPUT);
  pinMode(rabutton,OUTPUT);
  pinMode(sibutton,OUTPUT);
  pinMode(ddobutton,OUTPUT);
  Serial.begin(9600) ;
}

void loop(){
 
  leftbuttonState = digitalRead(dobutton);
   if(leftbuttonState == HIGH){
     Serial.println("do");
   }
   leftbuttonState = digitalRead(rebutton);
   if(leftbuttonState == HIGH){
     Serial.println("re");
   }
   leftbuttonState = digitalRead(mibutton);
   if(leftbuttonState == HIGH){
     Serial.println("mi");
   }
   leftbuttonState = digitalRead(fabutton);
   if(leftbuttonState == HIGH){
     Serial.println("fa");
   }
   leftbuttonState = digitalRead(sobutton);
   if(leftbuttonState == HIGH){
     Serial.println("so");
   }
   leftbuttonState = digitalRead(rabutton);
   if(leftbuttonState == HIGH){
     Serial.println("ra");
   }
   leftbuttonState = digitalRead(sibutton);
   if(leftbuttonState == HIGH){
     Serial.println("si");
   }
   leftbuttonState = digitalRead(ddobutton);
   if(leftbuttonState == HIGH){
     Serial.println("t");
   }
  delay(300);
}