Stephen

#include <Keypad.h>
#include <LiquidCrystal_I2C.h>

// LCD setup
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Pin assignments
const int buzzerPin = A0;
const int pirPin = 2;

// PIN code (fixed for now)
String storedPIN = "1234";
String inputCode = "";

// System states
bool isArmed = false;
bool disarmCountdown = false;
bool exitDelayActive = false;

unsigned long entryStartTime;
unsigned long exitStartTime;
const int entryDelay = 15000; // 15 seconds
const int exitDelay = 10000;  // 10 seconds

// Timing for buzzer
unsigned long lastBeepTime = 0;

// Keypad setup
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS] = {10, 9, 8, 7};
byte colPins[COLS] = {6, 5, 4, 3};
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void beep(int duration = 100) {
  tone(buzzerPin, 1000);
  delay(duration);
  noTone(buzzerPin);
}

void setup() {
  Serial.begin(9600);
  pinMode(pirPin, INPUT);
  pinMode(buzzerPin, OUTPUT);

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Enter PIN:");
}

void loop() {
  char key = keypad.getKey();

  if (key) {
    beep();
    handleKeyInput(key);
  }

  // Exit delay logic
  if (exitDelayActive) {
    unsigned long elapsed = millis() - exitStartTime;
    if (elapsed >= exitDelay) {
      isArmed = true;
      exitDelayActive = false;
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("System ARMED");
    } else {
      lcd.setCursor(0, 0);
      lcd.print("Arming: ");
      lcd.print((exitDelay - elapsed) / 1000);
      lcd.print("s    ");

      if (millis() - lastBeepTime >= 1000) {
        lastBeepTime = millis();
        beep(100);
      }
    }
  }

  // Entry delay logic
  if (disarmCountdown) {
    unsigned long elapsed = millis() - entryStartTime;
    int remaining = (entryDelay - elapsed) / 1000;

    if (elapsed >= entryDelay) {
      disarmCountdown = false;
      soundAlarm();
    } else {
      lcd.setCursor(0, 0);
      lcd.print("Motion Detected! ");
      lcd.setCursor(0, 1);
      lcd.print("Disarm: ");
      lcd.print(remaining);
      lcd.print("s    ");

      if (millis() - lastBeepTime >= 1000) {
        lastBeepTime = millis();
        beep(100);
      }
    }
  }

  // PIR detection when armed
  if (isArmed && digitalRead(pirPin) == HIGH && !disarmCountdown) {
    disarmCountdown = true;
    entryStartTime = millis();
    lastBeepTime = 0;
    lcd.clear();
  }
}

void soundAlarm() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("!! ALARM !!");
  for (int i = 0; i < 10; i++) {
    tone(buzzerPin, 2000);
    delay(200);
    noTone(buzzerPin);
    delay(200);
  }
}

void handleKeyInput(char key) {
  if (key == '#') {
    checkPIN();
  } else if (key == '*') {
    inputCode = "";
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("PIN cleared");
  } else if (inputCode.length() < 4 && isDigit(key)) {
    inputCode += key;
    lcd.setCursor(0, 0);
    lcd.print("Code: ");
    lcd.print(inputCode);
    lcd.print("    ");
  }
}

void checkPIN() {
  if (inputCode == storedPIN) {
    // Disarm system in any state
    if (disarmCountdown || exitDelayActive || isArmed) {
      disarmCountdown = false;
      exitDelayActive = false;
      isArmed = false;
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("System DISARMED");
    } else {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Arming in 10s...");
      exitDelayActive = true;
      exitStartTime = millis();
      lastBeepTime = 0;
    }
  } else {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Wrong PIN!");
  }

  inputCode = "";
}