PIR Night Security Light

1int relay = 8;
2volatile byte relayState = LOW;
3
4int PIRInterrupt  = 2;
5
6// LDR pin is connected to Analog 0
7int LDRPin = A0;
8// LDR value  is stored on LDR reading
9int LDRReading;
10// LDR Threshold value
11int LDRThreshold  = 300;
12
13// Timer Variables
14long lastDebounceTime = 0;  
15long debounceDelay  = 10000;
16
17void setup() {
18  // Pin for relay module set as output
19  pinMode(relay,  OUTPUT);
20  digitalWrite(relay, HIGH);
21  // PIR motion sensor set as an input
22  pinMode(PIRInterrupt, INPUT);
23
24  attachInterrupt(digitalPinToInterrupt(PIRInterrupt),  detectMotion, RISING);
25  // Serial communication for debugging purposes
26  Serial.begin(9600);
27}
28
29void  loop() {
30  // If 10 seconds have passed, the relay is turned off
31  if((millis()  - lastDebounceTime) > debounceDelay && relayState == HIGH){
32    digitalWrite(relay,  HIGH);
33    relayState = LOW;
34    Serial.println("OFF");
35  }
36  delay(50);
37}
38
39void  detectMotion() {
40  Serial.println("Motion");
41  LDRReading = analogRead(LDRPin);
42
43  if(LDRReading > LDRThreshold){
44    if(relayState == LOW){
45      digitalWrite(relay,  LOW);
46    }
47    relayState = HIGH;  
48    Serial.println("ON");
49    lastDebounceTime  = millis();
50  }
51}