//数字表示用ピン
const int pin7segA  = 5;
const int pin7segB  = 7;
const int pin7segC  = 12;
const int pin7segD  = 10;
const int pin7segE  = 9;
const int pin7segF  = 6;
const int pin7segG  = 13;
const int pin7segDP = 11;

//桁制御用ピン
const int pin7segDig1 = A5;
const int pin7segDig2 = A4;
const int pin7segDig3 = A3;
const int pin7segDig4 = A2;

//シリアル通信
char str[5]="0000"; //数字4桁+終端
char buf;
int i;

//7セグメントLED制御
int num;
int numDisp[4]={0, 1, 2, 3};             //LEDに表示する数字
int numDigit; //表示桁

//割り込み処理
volatile int sw = LOW;
volatile unsigned long time_prev = 0, time_now;
unsigned long time_chat = 20;

void setup()
{

  //各ピンの設定
  pinMode( pin7segA,  OUTPUT );
  pinMode( pin7segB,  OUTPUT );
  pinMode( pin7segC,  OUTPUT );
  pinMode( pin7segD,  OUTPUT );
  pinMode( pin7segE,  OUTPUT );
  pinMode( pin7segF,  OUTPUT );
  pinMode( pin7segG,  OUTPUT );
  pinMode( pin7segDP, OUTPUT );
  pinMode( pin7segDig1,  OUTPUT );
  pinMode( pin7segDig2,  OUTPUT );
  pinMode( pin7segDig3,  OUTPUT );
  pinMode( pin7segDig4,  OUTPUT );
  digitalWrite(pin7segDP  , LOW  );

  //シリアル通信の設定
  Serial.begin(9600);

  //割り込み処理の設定
  attachInterrupt(0, sendSW, CHANGE); //スイッチが変化したことをシリアル通信で通知


}

void loop()
{
  
  if (Serial.available() == 4) {  //数字4桁
    for( i=0; i<4; i++ )
      str[i] = Serial.read();
    num = atoi(str);
  }

  
  numDisp[0] = (num % 10);                                                                                                                                                                                                      //1秒単位
  numDisp[1] = (num/10) %10;  //10秒単位
  numDisp[2] = (num/100) % 10;  //1分単位
  numDisp[3] = (num/1000); //10分単位


  //7セグメントLED制御
  disp_7seg( -1 );  //残像対策として消灯
  if( numDigit == 3 ) numDigit = 0;  else numDigit++;  //桁移動
  dynamic_7seg( numDigit ); //桁移動
  disp_7seg( numDisp[numDigit] ); //数字表示

  delay(5);

}

//7セグメントLEDダイナミック点灯
void dynamic_7seg( int numDigit )
{
    switch(numDigit){
    case 1:
      digitalWrite(pin7segDig4  , LOW   );
      digitalWrite(pin7segDig3  , HIGH  );
      digitalWrite(pin7segDig2  , LOW   );
      digitalWrite(pin7segDig1  , LOW   );
      break;
  
    case 2:
      digitalWrite(pin7segDig4  , LOW   );
      digitalWrite(pin7segDig3  , LOW   );
      digitalWrite(pin7segDig2  , HIGH  );
      digitalWrite(pin7segDig1  , LOW   );
      break;
  
    case 3:
      digitalWrite(pin7segDig4  , LOW   );
      digitalWrite(pin7segDig3  , LOW   );
      digitalWrite(pin7segDig2  , LOW   );
      digitalWrite(pin7segDig1  , HIGH  );
      break;
  
   default :
      digitalWrite(pin7segDig4  , HIGH  );
      digitalWrite(pin7segDig3  , LOW   );
      digitalWrite(pin7segDig2  , LOW   );
      digitalWrite(pin7segDig1  , LOW   );
      break;
  }

}


//7セグメントLED数字表示
void disp_7seg( int numDisp )
{
      switch(numDisp){
      case 1:
        digitalWrite(pin7segA  , LOW  );
        digitalWrite(pin7segB  , HIGH );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , LOW  );
        digitalWrite(pin7segE  , LOW  );
        digitalWrite(pin7segF  , LOW  );
        digitalWrite(pin7segG  , LOW  );
        break;
    
      case 2:
        digitalWrite(pin7segA  , HIGH );
        digitalWrite(pin7segB  , HIGH );
        digitalWrite(pin7segC  , LOW  );
        digitalWrite(pin7segD  , HIGH );
        digitalWrite(pin7segE  , HIGH );
        digitalWrite(pin7segF  , LOW  );
        digitalWrite(pin7segG  , HIGH );
        break;
    
      case 3:
        digitalWrite(pin7segA  , HIGH );
        digitalWrite(pin7segB  , HIGH );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , HIGH );
        digitalWrite(pin7segE  , LOW  );
        digitalWrite(pin7segF  , LOW  );
        digitalWrite(pin7segG  , HIGH );
        break;
    
      case 4:
        digitalWrite(pin7segA  , LOW  );
        digitalWrite(pin7segB  , HIGH );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , LOW  );
        digitalWrite(pin7segE  , LOW  );
        digitalWrite(pin7segF  , HIGH );
        digitalWrite(pin7segG  , HIGH );
        break;
    
      case 5:
        digitalWrite(pin7segA  , HIGH );
        digitalWrite(pin7segB  , LOW  );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , HIGH );
        digitalWrite(pin7segE  , LOW  );
        digitalWrite(pin7segF  , HIGH );
        digitalWrite(pin7segG  , HIGH );
        break;
    
      case 6:
        digitalWrite(pin7segA  , HIGH );
        digitalWrite(pin7segB  , LOW  );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , HIGH );
        digitalWrite(pin7segE  , HIGH );
        digitalWrite(pin7segF  , HIGH );
        digitalWrite(pin7segG  , HIGH );
        break;
    
      case 7:
        digitalWrite(pin7segA  , HIGH );
        digitalWrite(pin7segB  , HIGH );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , LOW  );
        digitalWrite(pin7segE  , LOW  );
        digitalWrite(pin7segF  , HIGH );
        digitalWrite(pin7segG  , LOW  );
        break;
    
      case 8:
        digitalWrite(pin7segA  , HIGH );
        digitalWrite(pin7segB  , HIGH );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , HIGH );
        digitalWrite(pin7segE  , HIGH );
        digitalWrite(pin7segF  , HIGH );
        digitalWrite(pin7segG  , HIGH );
        break;
    
      case 9:
        digitalWrite(pin7segA  , HIGH );
        digitalWrite(pin7segB  , HIGH );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , HIGH );
        digitalWrite(pin7segE  , LOW  );
        digitalWrite(pin7segF  , HIGH );
        digitalWrite(pin7segG  , HIGH );
        break;
    
      case -1:  //消灯
        digitalWrite(pin7segA  , LOW  );
        digitalWrite(pin7segB  , LOW  );
        digitalWrite(pin7segC  , LOW  );
        digitalWrite(pin7segD  , LOW  );
        digitalWrite(pin7segE  , LOW  );
        digitalWrite(pin7segF  , LOW  );
        digitalWrite(pin7segG  , LOW  );
        break;
    
      default :  //0
        digitalWrite(pin7segA  , HIGH );
        digitalWrite(pin7segB  , HIGH );
        digitalWrite(pin7segC  , HIGH );
        digitalWrite(pin7segD  , HIGH );
        digitalWrite(pin7segE  , HIGH );
        digitalWrite(pin7segF  , HIGH );
        digitalWrite(pin7segG  , LOW  );
        break;
    }
}

//割り込み処理
//前回のエッジ発生から20ms(time_chat)超過かつ、エッジ発生前の状態がLOW（=立ち上がりエッジが発生）の時に割り込み処理を実行
void sendSW()
{
  time_now = millis();
  if( time_now-time_prev > time_chat){
    if( sw == LOW ) {
      //実行する割り込み処理
      Serial.write(65);
    }
    sw = !sw;
  }
  time_prev = time_now;

}