Code for Arduino based Door Monitoring System using Reed Switch.

Arduino_based_Door_Monitoring_System.ino

#include <LiquidCrystal.h>

const int reedPin = 8;
const int ledPin = 13;
const int RS = 7, EN = 6, D4 = 5, D5 = 4, D6 = 3, D7 = 2;

bool switchState = HIGH;

LiquidCrystal lcd(RS, EN, D4, D5, D6, D7);

void setup() 
{
  lcd.begin(16,2);
  //Serial.begin(9600);
  pinMode(reedPin, INPUT);
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);
  lcd.print("Electronics  Hub");
  lcd.setCursor(0,1);
  lcd.print("    Presents    ");
  delay(3000);
  lcd.setCursor(0,0);
  lcd.print("Door Monitoring ");
  lcd.setCursor(0,1);
  lcd.print("   System       ");
  delay(3000);
}

void loop() 
{
 switchState = digitalRead(reedPin);
 if(switchState == LOW)
  {
    digitalWrite(ledPin, LOW);
    //lcd.clear();
    lcd.setCursor(0,0);
    lcd.print(" Door is closed ");
    lcd.setCursor(0,1);
    lcd.print("   No Worries   ");
  }
  else
  {
    digitalWrite(ledPin, HIGH); 
    lcd.setCursor(0,0);
    lcd.print("  Door is Open  ");
    lcd.setCursor(0,1);
    lcd.print("  BREACH BREACH" );
  }
}