int relay = 4; //// choose the pin for the RELAY int ledPin = 13; // choose the pin for the LED int inputPin = 2; // choose the input pin (for PIR sensor) int pirState = LOW; // we start, assuming no motion detected int val = 0; // variable for reading the pin status void setup() { pinMode(ledPin, OUTPUT); // declare LED as output pinMode(relay, OUTPUT); //declare RELAY as output pinMode(inputPin, INPUT); // declare sensor as input Serial.begin(9600); } void loop(){ val = digitalRead(inputPin); // read input value if (val == HIGH) { // check if the input is HIGH digitalWrite(ledPin, LOW); // turn LED ON digitalWrite(relay, LOW); // turn RELAY ON if (pirState == LOW) { // we have just turned on Serial.println("Motion detected!"); // We only want to print on the output change, not state pirState = HIGH; } } else { digitalWrite(ledPin, HIGH);// turn LED OFF digitalWrite(relay, HIGH);// turn RELAY OFF if (pirState == HIGH){ // we have just turned of Serial.println("Motion ended!"); // We only want to print on the output change, not state pirState = LOW; } } }