Security Access System with LCD Display

1#include <LiquidCrystal.h>
2
3// Initialize the LiquidCrystal library with the LCD pins
4LiquidCrystal lcd(7, 8, 9, 10, 11, 12); // RS, E, D4, D5, D6, D7
5
6// Define pins for LEDs
7const int greenLedPin = A3;
8const int yellowLedPin = A4;
9const int redLedPin = A5;
10
11// Define pins for buttons
12const int buttonAPin = 2;
13const int buttonBPin = 3;
14const int buttonCPin = 4;
15const int buttonDPin = 5;
16
17// Code sequence to disarm the alarm (press 'A' four times)
18const char disarmCode[] = "AAAA";
19const int disarmCodeLength = 4;
20int disarmCodeIndex = 0;
21
22// Countdown timer variables
23unsigned long previousMillis = 0;
24const long interval = 1000; // 1 second
25int seconds = 15; // Change to 15 seconds
26boolean alarmActive = true;
27
28// Delay between button 'A' presses
29unsigned long buttonDelayMillis = 500; // Adjust as needed
30
31void setup() {
32  // Initialize the LCD with 16 columns and 2 rows
33  lcd.begin(16, 2);
34
35  // Display initial time on the LCD
36  lcd.print("TIME: 15");
37
38  // Set the pinMode for LEDs and buttons
39  pinMode(greenLedPin, OUTPUT);
40  pinMode(yellowLedPin, OUTPUT);
41  pinMode(redLedPin, OUTPUT);
42  pinMode(buttonAPin, INPUT_PULLUP);
43  pinMode(buttonBPin, INPUT_PULLUP);
44  pinMode(buttonCPin, INPUT_PULLUP);
45  pinMode(buttonDPin, INPUT_PULLUP);
46}
47
48void loop() {
49  // Check for button presses
50  if (digitalRead(buttonAPin) == LOW) {
51    checkButton('A');
52  }
53  if (digitalRead(buttonBPin) == LOW) {
54    checkButton('B');
55  }
56  if (digitalRead(buttonCPin) == LOW) {
57    checkButton('C');
58  }
59  if (digitalRead(buttonDPin) == LOW) {
60    checkButton('D');
61  }
62
63  // Update the countdown timer
64  unsigned long currentMillis = millis();
65  if (alarmActive && currentMillis - previousMillis >= interval) {
66    previousMillis = currentMillis;
67    seconds--;
68
69    // Check if seconds is negative
70    if (seconds < 0) {
71      // Timer expired, activate red LED and display "DENIED"
72      alarmActive = false;
73      digitalWrite(redLedPin, HIGH);
74      lcd.clear();
75      lcd.setCursor(0, 0);
76      lcd.print("Access DENIED");
77      delay(2000); // Display "Access DENIED" for 2 seconds
78      lcd.clear();
79      lcd.setCursor(0, 0);
80      lcd.print("TIME: 15"); // Reset timer to 15 seconds
81      seconds = 15;
82      disarmCodeIndex = 0; // Reset code input
83    }
84  }
85
86  // Display countdown and code on LCD
87  lcd.setCursor(6, 0);
88  lcd.print(seconds < 10 ? " " : ""); // Add a leading space if seconds is single-digit
89  lcd.print(seconds);
90
91  // Check if the correct code was entered
92  if (disarmCodeIndex == disarmCodeLength) {
93    alarmActive = false;
94    digitalWrite(greenLedPin, HIGH);
95    lcd.clear();
96    lcd.setCursor(0, 0);
97    lcd.print("Access GRANTED");
98    delay(2000); // Display "Access GRANTED" for 2 seconds
99    lcd.clear();
100    lcd.setCursor(0, 0);
101    lcd.print("TIME: 15"); // Reset timer to 15 seconds
102    seconds = 15;
103    disarmCodeIndex = 0; // Reset code input
104  }
105}
106
107void checkButton(char button) {
108  if (button == disarmCode[disarmCodeIndex]) {
109    disarmCodeIndex++;
110    if (disarmCodeIndex == disarmCodeLength) {
111      // Correct code entered, grant access
112      alarmActive = false;
113      digitalWrite(greenLedPin, HIGH);
114      lcd.clear();
115      lcd.setCursor(0, 0);
116      lcd.print("Access GRANTED");
117      delay(2000); // Display "Access GRANTED" for 2 seconds
118      lcd.clear();
119      lcd.setCursor(0, 0);
120      lcd.print("TIME: 15"); // Reset timer to 15 seconds
121      seconds = 15;
122      disarmCodeIndex = 0; // Reset code input
123    } else {
124      // Delay between button presses
125      delay(buttonDelayMillis);
126    }
127  } else {
128    // Incorrect code, reset code input
129    disarmCodeIndex = 0;
130    digitalWrite(yellowLedPin, HIGH);
131    delay(1000); // Display "Incorrect" for 1 second
132    digitalWrite(yellowLedPin, LOW);
133  }
134}