Termduino

int completeByte = 13;
int backspaceByte = 127;

String getstr(){
  String complete;
  while(true){
    int currentChar = Serial.read();
    if(currentChar == completeByte){
       return complete;
    }else if(currentChar != -1){
      complete = complete + char(currentChar);
      Serial.print(char(currentChar));
    }
  }
}

void setup(){
  Serial.begin(250000);
  pinMode(13, OUTPUT);
}

void loop(){
  String st = getstr();
  if(st == "on"){
    digitalWrite(13, HIGH);
  }else if(st == "off"){
    digitalWrite(13, LOW);
  }
}