Arduino Keypad Password Lock System with Servo, LCD & Indicator Alerts

1#include <Wire.h>
2#include <LiquidCrystal_I2C.h>
3#include <Servo.h>
4#include <Keypad.h>
5
6// --- LCD Configuration ---
7LiquidCrystal_I2C lcd(0x27, 16, 2);
8
9// --- Servo ---
10Servo lockServo;
11
12// --- Keypad Configuration ---
13const byte ROWS = 4;
14const byte COLS = 4;
15char keys[ROWS][COLS] = {
16  {'1','2','3','A'},
17  {'4','5','6','B'},
18  {'7','8','9','C'},
19  {'*','0','#','D'}
20};
21byte rowPins[ROWS] = {2, 3, 4, 5};
22byte colPins[COLS] = {6, 7, 9, 8};  // Note: matches first code's pin order
23
24Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
25
26// --- Pin Definitions ---
27#define RED_LED    12
28#define GREEN_LED  13
29#define SERVO_PIN  10
30#define BUZZER     11
31
32// --- Password Logic ---
33String correctPassword = "1234";
34String enteredPassword = "";
35
36void setup() {
37  Serial.begin(9600);
38
39  // Initialize LCD
40  lcd.init();
41  lcd.backlight();
42
43  // Initialize pins
44  pinMode(RED_LED,   OUTPUT);
45  pinMode(GREEN_LED, OUTPUT);
46  pinMode(BUZZER,    OUTPUT);
47
48  // Initialize Servo
49  lockServo.attach(SERVO_PIN);
50  lockServo.write(90);  // Locked position
51
52  // Default state: locked
53  digitalWrite(RED_LED,   HIGH);
54  digitalWrite(GREEN_LED, LOW);
55
56  // --- Startup Test (from first code) ---
57  lcd.print("System Testing");
58
59  // LED Test
60  lcd.setCursor(0, 1);
61  lcd.print("Testing LEDs... ");
62  digitalWrite(RED_LED, HIGH);  delay(500);
63  digitalWrite(RED_LED, LOW);
64  digitalWrite(GREEN_LED, HIGH); delay(500);
65  digitalWrite(GREEN_LED, LOW);
66
67  // Buzzer Test
68  lcd.clear();
69  lcd.print("Buzzer: BEEP");
70  digitalWrite(BUZZER, HIGH); delay(150);
71  digitalWrite(BUZZER, LOW);
72
73  // Servo Test
74  lcd.clear();
75  lcd.print("Servo: Testing");
76  lockServo.write(0); delay(1000);
77  lockServo.write(90);  delay(1000);
78
79  lcd.clear();
80  lcd.print("Test Complete!");
81  delay(1000);
82
83  // Set locked state and show prompt
84  digitalWrite(RED_LED, HIGH);
85  resetSystem();
86
87  Serial.println("--- System Online: Waiting for Input ---");
88}
89
90void loop() {
91  char key = keypad.getKey();  // Uses Keypad library (no manual scan needed)
92
93  if (key) {
94    Serial.print(key);
95
96    if (key == '#') {
97      Serial.println("\n--- SUBMIT BUTTON PRESSED ---");
98      processPassword();
99    }
100    else if (key == '*') {
101      Serial.println("\n--- CLEAR BUTTON PRESSED ---");
102      resetSystem();
103    }
104    else {
105      if (enteredPassword.length() < 8) {
106        enteredPassword += key;
107
108        // Show asterisk for each character
109        lcd.setCursor(enteredPassword.length() - 1, 1);
110        lcd.print('*');
111
112        Serial.print("Typed: ");        Serial.print(key);
113        Serial.print(" | Buffer: ");    Serial.println(enteredPassword);
114
115        // Key press beep
116        digitalWrite(BUZZER, HIGH); delay(50);
117        digitalWrite(BUZZER, LOW);
118      }
119    }
120  }
121}
122
123void processPassword() {
124  Serial.print("Entered: [");   Serial.print(enteredPassword); Serial.println("]");
125  Serial.print("Expected: [");  Serial.print(correctPassword); Serial.println("]");
126
127  lcd.clear();
128  enteredPassword.trim();
129
130  if (enteredPassword == correctPassword) {
131    Serial.println(">>> RESULT: MATCH FOUND! <<<");
132    lcd.print("Access Granted!");
133
134    digitalWrite(RED_LED,   LOW);
135    digitalWrite(GREEN_LED, HIGH);
136
137    lockServo.write(0);  // Unlock
138    delay(3000);
139    lockServo.write(90);   // Lock again
140
141    digitalWrite(GREEN_LED, LOW);
142    digitalWrite(RED_LED,   HIGH);
143  }
144  else {
145    Serial.println(">>> RESULT: NO MATCH! <<<");
146    lcd.print("Wrong Password!");
147
148    for (int i = 0; i < 4; i++) {
149      digitalWrite(BUZZER, HIGH); delay(150);
150      digitalWrite(BUZZER, LOW);  delay(150);
151    }
152  }
153
154  resetSystem();
155}
156
157void resetSystem() {
158  enteredPassword = "";
159  lcd.clear();
160  lcd.print("Enter Password:");
161  lcd.setCursor(0, 1);
162}