#include <Arduino.h>

const int SENSOR_PIN = 4;  
const int RELAY_PIN = 2;   
void setup() {
  Serial.begin(9600);  
  Serial.println("Projects Planner");
  Serial.println("HC-SR501 sensor with relay");

  pinMode(SENSOR_PIN, INPUT); 
  pinMode(RELAY_PIN, OUTPUT); 
}

void loop() {
  int motion = digitalRead(SENSOR_PIN); 


  if (motion) {
    Serial.println("Motion detected");
    digitalWrite(RELAY_PIN, LOW); 
  } else {
    Serial.println("===nothing moves");
    digitalWrite(RELAY_PIN, HIGH); 
  }

  delay(500);
}