int pirPin = 8;
const int ledPin = 13;
unsigned long previousMillis = 0;
const long interval = 20000;  
 
void setup()
{
pinMode(pirPin, INPUT);
pinMode(ledPin, OUTPUT);
digitalWrite(pirPin, LOW);
digitalWrite(ledPin, LOW);
}
 
void loop()
{
  unsigned long currentMillis = millis();
  if(currentMillis - previousMillis >= interval) 
  {
    previousMillis = currentMillis;
  }
  if(digitalRead(pirPin)==HIGH) 
  {
   digitalWrite(ledPin, HIGH);
  }
   else 
   {
   (digitalRead(pirPin)==LOW);
   digitalWrite(ledPin, LOW);
   }
 
}