const int lm35Pin = 34;  // Pin where the LM35 sensor is connected
const int buzzerPin = 19;  // Pin where the buzzer is connected
const int ledPin = 23;  // Pin where the LED is connected

// Temperature thresholds
const float tempLow = 19.0;
const float tempHigh = 25.0;

// Time tracking variables
unsigned long outOfRangeStartTime = 0;
const unsigned long thresholdTime = 10000;  // 10 seconds

void setup() {
  Serial.begin(115200);  // Initialize serial communication
  pinMode(lm35Pin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  digitalWrite(buzzerPin, LOW);  // Turn off buzzer initially
  digitalWrite(ledPin, LOW);  // Turn off LED initially
}

void loop() {
  float temperature = readTemperature();  // Read the temperature from the LM35 sensor
  Serial.print("Temperature: ");
  Serial.println(temperature);

  if (temperature < tempLow || temperature > tempHigh) {
    if (outOfRangeStartTime == 0) {
      outOfRangeStartTime = millis();  // Start the timer if it wasn't already running
    }
    if (millis() - outOfRangeStartTime >= thresholdTime) {
      digitalWrite(ledPin, HIGH);  // Turn on LED
      tone(buzzerPin, 1000);  // Turn on buzzer with 1kHz tone
    }
  } else {
    outOfRangeStartTime = 0;  // Reset the timer
    digitalWrite(ledPin, LOW);  // Turn off LED
    noTone(buzzerPin);  // Turn off buzzer
  }

  delay(1000);  // Wait for a second before next reading
}

float readTemperature() {
  int analogValue = analogRead(lm35Pin);  // Read the analog value from the LM35 sensor
  float voltage = analogValue * (5.0 / 4095.0);  // Convert the analog value to voltage
  float celsius = voltage * 100.0;  // Convert voltage to temperature in Celsius (LM35 provides 10mV per degree Celsius)
  return celsius;
}