//define the pins

#define PIR 2
#define Buzzer 3


#define TRIG 4
#define ECHO 5

#define RedLED 8
#define GreenLED 9

#define Switch 11
#define RedButton 12
#define GreenButton 13

// The LCD display you have is I2C with 4 wires
// Connect Vcc and 0V as normal - SCL and SDA as per device - on UNO:
// SCL - pin A5
// SDA - pin A4 

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

// set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27,16,2); 


void setup() {
  // put your setup code here, to run once:

  //Set the right pin modes for our i/o devices
  pinMode(Switch, INPUT_PULLUP);
  pinMode(RedButton, INPUT_PULLUP);
  pinMode(GreenButton, INPUT_PULLUP);
  pinMode(RedLED, OUTPUT);
  pinMode(GreenLED, OUTPUT);
  pinMode(PIR, INPUT);
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);

  

  // initialize the lcd 
  lcd.init();                      
  
  // Turn on backlight
  lcd.backlight();

  
 lcd.setCursor(0, 0);
 lcd.print("SYSTEM OFF");

  digitalWrite(GreenLED, HIGH);


}

void loop() {
  // put your main code here, to run repeatedly:

// Only enter the armed loop when the green button gets pressed, otherwise just loop until


if(digitalRead(RedButton)==LOW){ 
  
    // Add a 10-second countdown to the LCD display
    lcd.setCursor(0, 1);
    lcd.print("Countdown: ");
    for(int i=10; i>=0; i--){
      lcd.setCursor(11, 1);
      lcd.print(i);
      delay(1000);
    }
    lcd.setCursor(0, 1);
    lcd.print("                ");
  
  lcd.setCursor(0, 0);
  lcd.print("SYSTEM ON       ");
  digitalWrite(GreenLED, LOW);
  digitalWrite(RedLED,HIGH);
  delay(1000);
 

  //show system is armed on the LED and light the Red LED (turn off the green also)
  
 digitalWrite(GreenLED, LOW);
 digitalWrite(RedLED,HIGH);
 lcd.setCursor(0, 0);
 lcd.print("SENSING...       ");
 

  //the code below will keep looping until the green button is pressed (stays HIGH until pressed)
  while (digitalRead(GreenButton) == HIGH) {

      digitalWrite(TRIG, HIGH);
      delayMicroseconds(10);
      digitalWrite(TRIG, LOW);

      // Read the resulting pulse duration on Echo pin
      // the distance in cm is the pulse length (in ms) divided by 58
      int distance = (pulseIn(ECHO, HIGH) / 58);

      // Check to see if the PIR sensor senses motion and goes HIGH
      if (digitalRead(PIR) == HIGH) {
        // Sound the alarm!
        lcd.setCursor(0, 0);
        lcd.print("Motion Detected!  ");
        lcd.setCursor(0, 1);
        lcd.print("                ");
        digitalWrite(Buzzer, HIGH);
        delay(5000);
      } else if (distance < 20) {

        
        // Sound the alarm!
        lcd.setCursor(0, 0);
        lcd.print("DOOR OPEN         ");
        lcd.setCursor(0, 1);
        lcd.print("                ");
        digitalWrite(Buzzer, HIGH);
        delay(5000);
      
    
    }


  
  //return to armed state after alarm
  lcd.setCursor(0, 0);
  lcd.print("SENSING...       ");

  }


  //disarm
  lcd.setCursor(0, 0);
  lcd.print("SYSTEM OFF        ");

  digitalWrite(RedLED, LOW);
  digitalWrite(GreenLED, HIGH);

}
}