char x;

void setup() {
Serial.begin(9600);
pinMode(5,OUTPUT);
}

void loop() 
{
 x=Serial.read();
if(Serial.available()>0)
{
  Serial.println("Enter");
 
  if(x=='r')
  digitalWrite(5, HIGH);
  Serial.println("HIGH");
  delay(300);
  digitalWrite(5, LOW);
  Serial.println("LOW");
}
delay(200);
}