int led=2;
int buz=3;
int rx;
void setup()
{
  pinMode(led, OUTPUT);
  pinMode(buz, OUTPUT);
  Serial.begin(9600);
}
void loop()
{
if(Serial.available()>0)
{
  rx=Serial.read();
}
if(rx=='T')
{
  digitalWrite(led, HIGH);
  digitalWrite(buz, LOW);
}
else if(rx=='F')
{
  digitalWrite(led, LOW);
  digitalWrite(buz, HIGH);
}
}