int buzzer=2; 

void setup() {
  // put your setup code here, to run once:
pinMode(buzzer, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
int i=0;
do{
i++;
tone(buzzer,450);
delay(200);
noTone(buzzer);
delay(200);
} while(i<2);
delay(3000);
}