int pinA = 2;
int pinB = 3;
int pinC = 4;
int pinD = 5;

int stop = 0;
int VarSign = 1;
int SerIn = -1;        
long VarN[9] = {  
  0, 0, 0, 0, 0, 0, 0, 0, 0 };  
int PosN = -1;    
char VarHandlerChar = '@';  

// SERIAL PARSER **********************************
void SerialParser(void) {
  while (Serial.available()) {
    SerIn = '@';
    SerIn = Serial.read();
    // debugging CODE
    // Serial.print(' ');
    // Serial.print(SerIn);
    if ((SerIn >= 65) && (SerIn <= 90)) {          // if ASCII 'A' - 'Z'
      VarHandlerChar = SerIn;  
      for (PosN = 0; PosN < 9; PosN++) {           // clean up
        VarN[PosN] =  0;                           // reset Var array
      }  
      PosN = -1;                              
    }
    if (SerIn == 45) {
      VarSign = -1;
    }
    if ((SerIn >= 48) && (SerIn <= 57)) {          // if ASCII numeric '0' - '9'
      VarN[PosN] = VarN[PosN] * 10 + (SerIn - 48);
    }
    if (SerIn == ' ') {                            // if ASCII " " detected
      if (PosN > -1) {
        VarN[PosN] = VarSign * VarN[PosN];           // assign sign 
        VarSign = 1;
      }
      PosN++;
    }
    if (SerIn == 33 || SerIn == 10 || SerIn == 13) {  // '!' or CR or LF ends all this spooky things ...
      VarN[PosN] = VarSign * VarN[PosN];           // assign sign 
      VarSign = 1;
      CallHandler();                               // Call funktion by first Char
    }   // IfEND CR spooky things
  }
}
//*************************************

void CallHandler(void) {
  switch(VarHandlerChar) {
  case 'A': 
    LED(pinA, VarN[0]);
    break;    
  case 'B':  
    LED(pinB, VarN[0]);
    break;
  case 'C':   // 
    LED(pinC, VarN[0]);
    break;
  case 'D':  // 
    LED(pinD, VarN[0]);
    break;           
  } // Switch END
}



void LED(int ledNr, int OnOff){
  if (OnOff <= 0 ){
    digitalWrite(ledNr, LOW);
  }
  else {
    digitalWrite(ledNr, HIGH);
  }
}


void setup(void) {
  Serial.begin(115200);  
  pinMode(pinA, OUTPUT);
  pinMode(pinB, OUTPUT);
  pinMode(pinC, OUTPUT);
  pinMode(pinD, OUTPUT);
}

void loop(void) {
  SerialParser();

}