#include <DHT.h>

#define DHTPIN 2       // DHT22 data pin
#define DHTTYPE DHT22  // DHT22 sensor

#define TRIG_PIN 3
#define ECHO_PIN 4

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  dht.begin();
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

void loop() {
  // Read temperature
  float tempC = dht.readTemperature();
  if (isnan(tempC)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Calculate speed of sound in cm/µs
  float speedOfSound = (331.4 + 0.6 * tempC) * 100 / 1000000; // cm/µs

  // Trigger ultrasonic sensor
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  long duration = pulseIn(ECHO_PIN, HIGH);
  
  // Calculate distance in cm
  float distance = (duration * speedOfSound) / 2.0;

  Serial.print("Temperature: "); Serial.print(tempC); Serial.print(" C, ");
  Serial.print("Distance: "); Serial.print(distance); Serial.println(" cm");

  delay(1000);
}