Server Room Security System

#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_Fingerprint.h>
#include <DHT.h>
#include <LiquidCrystal_I2C.h>


// Forward declarations
void setTransient(const String &message, unsigned long durationMs);
void pulseDoorLatch();
void pulseWindowLatch();
void updateLatches();
void pollKeypad();
bool fingerprintMatched();
void showStatus(float temperature, float humidity, int smoke, bool emergency, bool intrusion);

const uint8_t FINGERPRINT_RX_PIN = 0;
const uint8_t FINGERPRINT_TX_PIN = 1;
const uint8_t DOOR_RELAY_PIN = 4;
const uint8_t WINDOW_RELAY_PIN = 5;
const uint8_t FAN_RELAY_PIN = 6;
const uint8_t PIR_PIN = 7;
const uint8_t DHT_PIN = 8;
const uint8_t FLAME_DIGITAL_PIN = 9;
const uint8_t BUZZER_PIN = 10;
const uint8_t RED_LED_PIN = 11;
const uint8_t GREEN_LED_PIN = 12;
const uint8_t MQ2_PIN = A0;
const uint8_t FLAME_ANALOG_PIN = A1;

const uint8_t KEYPAD_ADDRESS = 0x20;
const uint8_t LCD_ADDRESS = 0x27;
const char ACCESS_CODE[] = "1234"; // Change this before displaying the model.
const int SMOKE_THRESHOLD = 450;
const float FAN_ON_C = 30.0;
const float FAN_OFF_C = 28.0;
const unsigned long LATCH_PULSE_MS = 800;
const unsigned long DISPLAY_PERIOD_MS = 1000;

// Most small relay boards are active-low.
const uint8_t RELAY_ON = LOW;
const uint8_t RELAY_OFF = HIGH;

// Use the Uno hardware UART for the R307. This avoids the ESP-only serial
// implementation that is incompatible with the browser simulator.
Adafruit_Fingerprint finger(&Serial);
DHT dht(DHT_PIN, DHT22);
LiquidCrystal_I2C lcd(LCD_ADDRESS, 16, 2);

const char keyMap[4][4] = {{'1','2','3','A'}, {'4','5','6','B'}, {'7','8','9','C'}, {'*','0','#','D'}};
char enteredCode[5] = "";
uint8_t enteredLength = 0;
bool armed = true;
bool fanOn = false;
bool releasedForThisAlarm = false;
unsigned long doorPulseUntil = 0;
unsigned long windowPulseUntil = 0;
unsigned long lastDisplay = 0;
String transientMessage = "Starting...";
unsigned long transientUntil = 0;

void setTransient(const String &message, unsigned long durationMs) {
  transientMessage = message;
  transientUntil = millis() + durationMs;
}

void pulseDoorLatch() {
  doorPulseUntil = millis() + LATCH_PULSE_MS;
  setTransient("Door unlocked", 1500);
}

void pulseWindowLatch() {
  windowPulseUntil = millis() + LATCH_PULSE_MS;
}

void updateLatches() {
  // These miniature 5 V latches are intermittent-duty parts: pulse them briefly only.
  digitalWrite(DOOR_RELAY_PIN, millis() < doorPulseUntil ? RELAY_ON : RELAY_OFF);
  digitalWrite(WINDOW_RELAY_PIN, millis() < windowPulseUntil ? RELAY_ON : RELAY_OFF);
}

void pollKeypad() {
  for (uint8_t row = 0; row < 4; row++) {
    uint8_t pattern = 0xFF;
    bitClear(pattern, row);
    Wire.beginTransmission(KEYPAD_ADDRESS); Wire.write(pattern); Wire.endTransmission();
    delayMicroseconds(80);
    Wire.requestFrom(KEYPAD_ADDRESS, (uint8_t)1);
    if (!Wire.available()) continue;
    uint8_t reading = Wire.read();
    for (uint8_t col = 0; col < 4; col++) {
      if (!bitRead(reading, col + 4)) {
        char key = keyMap[row][col];
        while (true) {
          Wire.beginTransmission(KEYPAD_ADDRESS); Wire.write(pattern); Wire.endTransmission();
          Wire.requestFrom(KEYPAD_ADDRESS, (uint8_t)1);
          if (!Wire.available() || bitRead(Wire.read(), col + 4)) break;
          delay(10);
        }
        Wire.beginTransmission(KEYPAD_ADDRESS); Wire.write(0xFF); Wire.endTransmission();
        if (key == '*') {
          enteredLength = 0; enteredCode[0] = '\0'; setTransient("Code cleared", 1000);
        } else if (key == '#') {
          if (strcmp(enteredCode, ACCESS_CODE) == 0) pulseDoorLatch();
          else setTransient("Access denied", 2000);
          enteredLength = 0; enteredCode[0] = '\0';
        } else if (key == 'A') {
          armed = !armed; setTransient(armed ? "System armed" : "System disarmed", 1500);
        } else if (key >= '0' && key <= '9' && enteredLength < 4) {
          enteredCode[enteredLength++] = key; enteredCode[enteredLength] = '\0';
          setTransient("Code: " + String(enteredLength) + " digits", 700);
        }
        return;
      }
    }
  }
  Wire.beginTransmission(KEYPAD_ADDRESS); Wire.write(0xFF); Wire.endTransmission();
}

bool fingerprintMatched() {
  if (finger.getImage() != FINGERPRINT_OK) return false;
  if (finger.image2Tz() != FINGERPRINT_OK) { setTransient("Print not read", 1500); return false; }
  if (finger.fingerFastSearch() == FINGERPRINT_OK) { setTransient("Fingerprint OK", 1500); return true; }
  setTransient("Print denied", 1500);
  return false;
}

void showStatus(float temperature, float humidity, int smoke, bool emergency, bool intrusion) {
  if (millis() - lastDisplay < DISPLAY_PERIOD_MS && millis() > transientUntil) return;
  lastDisplay = millis();
  lcd.setCursor(0, 0);
  String upper;
  if (emergency) upper = "FIRE/SMOKE ALERT";
  else if (intrusion) upper = "INTRUSION ALERT ";
  else if (millis() < transientUntil) upper = transientMessage;
  else upper = "T:" + String(temperature, 1) + "C H:" + String(humidity, 0) + "%";
  upper += "                ";
  lcd.print(upper.substring(0, 16));
  lcd.setCursor(0, 1);
  String lower = "S:" + String(smoke) + (armed ? " ARMED" : " DISARMED") + "       ";
  lcd.print(lower.substring(0, 16));
}

void setup() {
  pinMode(DOOR_RELAY_PIN, OUTPUT); pinMode(WINDOW_RELAY_PIN, OUTPUT); pinMode(FAN_RELAY_PIN, OUTPUT);
  pinMode(PIR_PIN, INPUT); pinMode(FLAME_DIGITAL_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT); pinMode(RED_LED_PIN, OUTPUT); pinMode(GREEN_LED_PIN, OUTPUT);
  digitalWrite(DOOR_RELAY_PIN, RELAY_OFF); digitalWrite(WINDOW_RELAY_PIN, RELAY_OFF);
  digitalWrite(FAN_RELAY_PIN, RELAY_OFF); digitalWrite(BUZZER_PIN, LOW);
  digitalWrite(RED_LED_PIN, LOW); digitalWrite(GREEN_LED_PIN, HIGH);
  Wire.begin();
  lcd.init(); lcd.backlight(); lcd.clear(); lcd.print("Mini server room"); lcd.setCursor(0, 1); lcd.print("Starting sensors");
  dht.begin();
  Serial.begin(57600); finger.begin(57600); delay(300);
  if (!finger.verifyPassword()) setTransient("Finger sensor err", 3000);
  Wire.beginTransmission(KEYPAD_ADDRESS); Wire.write(0xFF); Wire.endTransmission();
}

void loop() {
  pollKeypad();
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();
  if (isnan(humidity)) humidity = 0;
  if (isnan(temperature)) temperature = 0;
  int smoke = analogRead(MQ2_PIN);
  bool flame = digitalRead(FLAME_DIGITAL_PIN) == LOW;
  bool emergency = flame || smoke >= SMOKE_THRESHOLD || temperature >= 55.0;
  bool intrusion = armed && digitalRead(PIR_PIN) == HIGH && !emergency;

  if (temperature >= FAN_ON_C) fanOn = true;
  if (temperature <= FAN_OFF_C) fanOn = false;
  digitalWrite(FAN_RELAY_PIN, fanOn ? RELAY_ON : RELAY_OFF);

  if (emergency) {
    // Model-only response: momentarily open both small latches once per alarm event.
    if (!releasedForThisAlarm) { pulseDoorLatch(); pulseWindowLatch(); releasedForThisAlarm = true; }
    digitalWrite(RED_LED_PIN, HIGH); digitalWrite(GREEN_LED_PIN, LOW); tone(BUZZER_PIN, 1800);
  } else {
    releasedForThisAlarm = false;
    digitalWrite(RED_LED_PIN, intrusion ? HIGH : LOW); digitalWrite(GREEN_LED_PIN, intrusion ? LOW : HIGH);
    if (intrusion) tone(BUZZER_PIN, 1200); else noTone(BUZZER_PIN);
    if (millis() >= doorPulseUntil && fingerprintMatched()) pulseDoorLatch();
  }
  updateLatches();
  showStatus(temperature, humidity, smoke, emergency, intrusion);
  delay(50);
}