Simple Alarm System

1#include <Keypad.h>
2#include <LiquidCrystal_I2C.h>
3
4// LCD setup
5LiquidCrystal_I2C lcd(0x27, 16, 2);
6
7// Pin assignments
8const int buzzerPin = A0;
9const int pirPin = 2;
10
11// PIN code (fixed for now)
12String storedPIN = "1234";
13String inputCode = "";
14
15// System states
16bool isArmed = false;
17bool disarmCountdown = false;
18bool exitDelayActive = false;
19
20unsigned long entryStartTime;
21unsigned long exitStartTime;
22const int entryDelay = 15000; // 15 seconds
23const int exitDelay = 10000;  // 10 seconds
24
25// Timing for buzzer
26unsigned long lastBeepTime = 0;
27
28// Keypad setup
29const byte ROWS = 4;
30const byte COLS = 4;
31char keys[ROWS][COLS] = {
32  {'1','2','3','A'},
33  {'4','5','6','B'},
34  {'7','8','9','C'},
35  {'*','0','#','D'}
36};
37byte rowPins[ROWS] = {10, 9, 8, 7};
38byte colPins[COLS] = {6, 5, 4, 3};
39Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
40
41void beep(int duration = 100) {
42  tone(buzzerPin, 1000);
43  delay(duration);
44  noTone(buzzerPin);
45}
46
47void setup() {
48  Serial.begin(9600);
49  pinMode(pirPin, INPUT);
50  pinMode(buzzerPin, OUTPUT);
51
52  lcd.init();
53  lcd.backlight();
54  lcd.setCursor(0, 0);
55  lcd.print("Enter PIN:");
56}
57
58void loop() {
59  char key = keypad.getKey();
60
61  if (key) {
62    beep();
63    handleKeyInput(key);
64  }
65
66  // Exit delay logic
67  if (exitDelayActive) {
68    unsigned long elapsed = millis() - exitStartTime;
69    if (elapsed >= exitDelay) {
70      isArmed = true;
71      exitDelayActive = false;
72      lcd.clear();
73      lcd.setCursor(0, 0);
74      lcd.print("System ARMED");
75    } else {
76      lcd.setCursor(0, 0);
77      lcd.print("Arming: ");
78      lcd.print((exitDelay - elapsed) / 1000);
79      lcd.print("s    ");
80
81      if (millis() - lastBeepTime >= 1000) {
82        lastBeepTime = millis();
83        beep(100);
84      }
85    }
86  }
87
88  // Entry delay logic
89  if (disarmCountdown) {
90    unsigned long elapsed = millis() - entryStartTime;
91    int remaining = (entryDelay - elapsed) / 1000;
92
93    if (elapsed >= entryDelay) {
94      disarmCountdown = false;
95      soundAlarm();
96    } else {
97      lcd.setCursor(0, 0);
98      lcd.print("Motion Detected! ");
99      lcd.setCursor(0, 1);
100      lcd.print("Disarm: ");
101      lcd.print(remaining);
102      lcd.print("s    ");
103
104      if (millis() - lastBeepTime >= 1000) {
105        lastBeepTime = millis();
106        beep(100);
107      }
108    }
109  }
110
111  // PIR detection when armed
112  if (isArmed && digitalRead(pirPin) == HIGH && !disarmCountdown) {
113    disarmCountdown = true;
114    entryStartTime = millis();
115    lastBeepTime = 0;
116    lcd.clear();
117  }
118}
119
120void soundAlarm() {
121  lcd.clear();
122  lcd.setCursor(0, 0);
123  lcd.print("!! ALARM !!");
124  for (int i = 0; i < 10; i++) {
125    tone(buzzerPin, 2000);
126    delay(200);
127    noTone(buzzerPin);
128    delay(200);
129  }
130}
131
132void handleKeyInput(char key) {
133  if (key == '#') {
134    checkPIN();
135  } else if (key == '*') {
136    inputCode = "";
137    lcd.clear();
138    lcd.setCursor(0, 0);
139    lcd.print("PIN cleared");
140  } else if (inputCode.length() < 4 && isDigit(key)) {
141    inputCode += key;
142    lcd.setCursor(0, 0);
143    lcd.print("Code: ");
144    lcd.print(inputCode);
145    lcd.print("    ");
146  }
147}
148
149void checkPIN() {
150  if (inputCode == storedPIN) {
151    // Disarm system in any state
152    if (disarmCountdown || exitDelayActive || isArmed) {
153      disarmCountdown = false;
154      exitDelayActive = false;
155      isArmed = false;
156      lcd.clear();
157      lcd.setCursor(0, 0);
158      lcd.print("System DISARMED");
159    } else {
160      lcd.clear();
161      lcd.setCursor(0, 0);
162      lcd.print("Arming in 10s...");
163      exitDelayActive = true;
164      exitStartTime = millis();
165      lastBeepTime = 0;
166    }
167  } else {
168    lcd.clear();
169    lcd.setCursor(0, 0);
170    lcd.print("Wrong PIN!");
171  }
172
173  inputCode = "";
174}