int ir= 12;
int buzzer = 10;
void setup()
{
 pinMode(ir, INPUT);
 pinMode(buzzer, OUTPUT);
Serial.print("Person In Room:");
 Serial.begin(9600);
}
void loop()
{ 
if(digitalRead(ir)==0)
 {
 digitalWrite(buzzer, HIGH);
 Serial.println("Person In Room");
 Serial.println("Buzzer Is ON");
 delay(200);
 }
 else
 {
 digitalWrite(buzzer, LOW);
 Serial.println("Nobody In Room");
 }
}