// feito na cadeira de Fundamentos de automação - IFRS - Campus Restinga
// Igor B. Farias

// reference: https://randomnerdtutorials.com/esp32-hc-sr04-ultrasonic-arduino/

#define echo 35
#define trigger 25

int response = 0;
int distanceCm = 0;
int duration = 0;
#define soundSpeed 0.034

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(trigger, OUTPUT);
  pinMode(echo, INPUT);
  
}

void loop() {
  //int response = 0;
  // Clears the trigPin
  digitalWrite(trigger, LOW);
  delayMicroseconds(2);
  // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigger, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigger, LOW);
  
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echo, HIGH);
  
  // Calculate the distance
  distanceCm = duration * soundSpeed/2;

  
  // Prints the distance in the Serial Monitor
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);

  
  delay(1000);
 
}