#include <DHT.h>

#define DHTPIN 7 // DHT 22 output pin connection
#define DHTTYPE DHT22 // DHT type (22)

DHT dht(DHTPIN, DHTTYPE);

int triggerPin_1= 9;
int echoPin_1= 10;
float distance_1;
float duration_1;

int triggerPin_2= 11;
int echoPin_2= 6;
float distance_2;
float duration_2;

float hum;
float temp;

float sound_m_s;
float sound_cm_ms;

void setup() {
  // put your setup code here, to run once:
  Serial.begin (9600);
  pinMode (triggerPin_1, OUTPUT);
  pinMode (echoPin_1, INPUT);
  pinMode (triggerPin_2, OUTPUT);
  pinMode (echoPin_2, INPUT);
  dht.begin();
}

void loop() {
  // put your main code here, to run repeatedly


    // delay (2000); in case DHT needs to be stablized
    hum= dht.readHumidity();
    temp= dht.readTemperature();

    sound_m_s= 331.4+ (0.606* temp)+ (0.0124* hum); //speed of sound (meter per second)
    sound_cm_ms= sound_m_s/ 10000; //speed of sound (centimeter per millisecond)


    digitalWrite (triggerPin_1, LOW);
    delayMicroseconds (2);
    digitalWrite (triggerPin_1, HIGH);
    delayMicroseconds (10);
    digitalWrite (triggerPin_1, LOW);

    duration_1= pulseIn(echoPin_1, HIGH);
    
    delay(200);

    digitalWrite (triggerPin_2, LOW);
    delayMicroseconds (2);
    digitalWrite (triggerPin_2, HIGH);
    delayMicroseconds (10);
    digitalWrite (triggerPin_2, LOW);

    duration_2= pulseIn(echoPin_2, HIGH);
    
    delay(200);
    
    distance_1= (duration_1/2) * sound_cm_ms;
    distance_2= (duration_2/2) * sound_cm_ms;

  if (distance_1> 400 || distance_1< 2){
    Serial.println("Distance1= Out of range !");
  }
  else{
    Serial.print("Distance1= ");
    Serial.print(distance_1);
    Serial.print(" cm, ");
    
  }

  if (distance_2> 400 || distance_2< 2){
    Serial.println("Distance2= Out of range !");
  }
  else{
    Serial.print("Distance2= ");
    Serial.print(distance_2);
    Serial.println(" cm");
  }
  
}