Standalone Alarm with PIR Sensor and Responsive RGB Strip

1#include <Wire.h>
2#include <LiquidCrystal_I2C.h>
3
4LiquidCrystal_I2C lcd(0x27, 16, 2);
5
6const int buttonPin = 8;       // arm/disarm
7const int panicButton = 2;    // panic trigger
8const int buzzerPin = 9;
9const int pirPin = 10;
10
11const int greenLed = 5;
12const int blueLed = 6;
13const int redLed = 11;
14
15bool alarmEnabled = false;
16bool alarmTriggered = false;
17bool panicMode = false;
18
19int lastButtonState = HIGH;
20int lastPanicState = HIGH;
21
22bool lcdState = true;
23
24void setup() {
25  pinMode(buttonPin, INPUT_PULLUP);
26  pinMode(panicButton, INPUT_PULLUP);
27  pinMode(buzzerPin, OUTPUT);
28  pinMode(pirPin, INPUT);
29
30  pinMode(greenLed, OUTPUT);
31  pinMode(blueLed, OUTPUT);
32  pinMode(redLed, OUTPUT);
33
34  lcd.init();
35  lcd.backlight();
36  lcd.print("Alarm Disabled");
37
38  digitalWrite(greenLed, HIGH);
39}
40
41void loop() {
42
43  int buttonState = digitalRead(buttonPin);
44  int panicState = digitalRead(panicButton);
45
46  // ARM / DISARM BUTTON
47  if (lastButtonState == HIGH && buttonState == LOW) {
48    alarmEnabled = !alarmEnabled;
49    alarmTriggered = false;
50    panicMode = false;
51
52    lcd.clear();
53    lcd.print(alarmEnabled ? "Alarm Enabled" : "Alarm Disabled");
54
55    digitalWrite(redLed, LOW);
56
57    // Short beep on toggle
58    tone(buzzerPin, 1500);
59    delay(120);
60    noTone(buzzerPin);
61
62    delay(250);
63  }
64
65  // PANIC BUTTON
66  if (lastPanicState == HIGH && panicState == LOW) {
67    alarmTriggered = true;
68    panicMode = true;
69    lcd.clear();
70  }
71
72  lastButtonState = buttonState;
73  lastPanicState = panicState;
74
75  // PIR MOTION
76  if (alarmEnabled && digitalRead(pirPin) == HIGH) {
77    alarmTriggered = true;
78    panicMode = false;
79  }
80
81  // NORMAL STATUS
82  if (!alarmTriggered) {
83    noTone(buzzerPin);
84    digitalWrite(redLed, LOW);
85
86    if (!alarmEnabled) {
87      digitalWrite(greenLed, HIGH);
88      digitalWrite(blueLed, LOW);
89    } else {
90      digitalWrite(greenLed, LOW);
91      digitalWrite(blueLed, HIGH);
92    }
93  }
94
95  // ALARM ACTIVE
96  if (alarmTriggered) {
97    // FLASH LEDs
98    digitalWrite(greenLed, HIGH);
99    digitalWrite(blueLed, HIGH);
100    digitalWrite(redLed, HIGH);
101
102    // HIGHER WAILING ALARM SOUND
103    tone(buzzerPin, 1600);  // high tone
104    delay(100);
105    tone(buzzerPin, 1000);  // lower tone
106    delay(100);
107
108    // LCD blinking message
109    lcd.clear();
110    if (lcdState) {
111      lcd.print(panicMode ? "PANIC!" : "MOTION!");
112      lcd.setCursor(0,1);
113      lcd.print("Press button");
114    }
115    lcdState = !lcdState;
116
117    // Turn off LEDs briefly
118    digitalWrite(greenLed, LOW);
119    digitalWrite(blueLed, LOW);
120    digitalWrite(redLed, LOW);
121    noTone(buzzerPin);
122    delay(100);
123  }
124}