Internet of
Things (IoT)

// Arduino: Temperature sensor controls a fan LED

const int tempPin = A0;    // Analog pin for sensor
const int fanPin  = 9;     // Digital pin for fan/LED
const int threshold = 30;  // Degrees Celsius

void setup() {
  pinMode(fanPin, OUTPUT);  // Set pin as output
  Serial.begin(9600);       // Start serial monitor
}

void loop() {
  int rawVal  = analogRead(tempPin);
  float volts = rawVal * (5.0 / 1023.0);
  float temp  = (volts - 0.5) * 100.0;

  Serial.print("Temp: ");
  Serial.println(temp);

  if (temp >= threshold) {
    digitalWrite(fanPin, HIGH); // Fan ON
  } else {
    digitalWrite(fanPin, LOW);  // Fan OFF
  }
  delay(1000);  // Wait 1 second
}