// PIR Motion Detection with Arduino Uno

int ledPin = 13;
int pirPin = 2;
int state = LOW;
unsigned long startTime, responseTime;
int motionCount = 0;

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(pirPin, INPUT);
  Serial.begin(115200);
  Serial.println("Arduino PIR Motion Detection - Response Time Test");
}

void loop(){
  startTime = micros();
  
  int pirValue = digitalRead(pirPin);
  
  if (pirValue == HIGH) {
    digitalWrite(ledPin, HIGH);
    responseTime = micros() - startTime;
    
    if (state == LOW) {
      motionCount++;
      Serial.print("Motion #");
      Serial.print(motionCount);
      Serial.print(" - Response Time: ");
      Serial.print(responseTime);
      Serial.println(" μs");
      state = HIGH;
    }
  } 
  else {
    digitalWrite(ledPin, LOW);
    if (state == HIGH){
      Serial.println("Motion stopped");
      state = LOW;
    }
  }
  
  delay(500);
}