// 1. Include the necessary library for the DHT sensor
#include <DHT.h>
// 2. Define hardware connections and sensor type
#define DHTPIN 4 // GPIO pin connected to the DHT22 DATA pin
#define DHTTYPE DHT22 // Specify the sensor type (DHT22/AM2302)
// 3. Instantiate the DHT sensor object
DHT dht(DHTPIN, DHTTYPE);
void setup() {
 // Initialize serial communication for debugging output
 Serial.begin(115200);

 // Initialize the DHT sensor hardware
 dht.begin();

 Serial.println("Smart Campus: DHT22 Sensor Initialized");
 Serial.println("--------------------------------------");
}
void loop() {
 // 4. Read temperature (Celsius) and humidity (Percentage)
 float temperature = dht.readTemperature();
 float humidity = dht.readHumidity();

 // 5. CRITICAL: Data Validation (Error Checking)
 // If the sensor disconnects or fails, it returns NaN (Not a Number).
 // We MUST catch this to prevent feeding garbage data to our future AI models
 if (isnan(temperature) || isnan(humidity)) {
 Serial.println("ERROR: Sensor read failure! Check wiring.");
 return; // Exit the current loop iteration and try again
 }

 // 6. Display valid data
 Serial.print("Temp: ");
 Serial.print(temperature);
 Serial.print(" °C | Humidity: ");
 Serial.print(humidity);
 Serial.println(" %");

 // 7. Blocking delay (Wait 2 seconds before next reading)
 delay(2000);
}