void setup() {
 
  pinMode(3, OUTPUT);   //set pin as output , blue led
  pinMode(4, OUTPUT);   //set pin as output , red led
  pinMode(A5, OUTPUT);   //set pin as output , yellow led
 
  Serial.begin(9600);  //start serial communication @9600 bps
  }
 
void loop(){
 
  if(Serial.available()){  //id data is available to read
 
  char val = Serial.read();
 
  if(val == 'r'){     //if r received
    digitalWrite(4, HIGH); //turn on red led
    }
  if(val == 'b'){     //if b received
    digitalWrite(3, HIGH); //turn on blue led
    }
  if(val == 'y'){     //if y received
    digitalWrite(A5, HIGH); //turn on yellow led
    }
  if(val == 'f'){     //if f received
    digitalWrite(4, LOW); //turn off all led
    digitalWrite(A5, LOW);
    digitalWrite(3, LOW);
    }   
    }
  }