//based on Elena Cardiel FabAcademy 2019
//FabAcademy 2019 - Jesús López
//include the serial communication library
#include <SoftwareSerial.h>
SoftwareSerial Serial_sonar(0, 1); // tx, rx

//define variables and pin numbers
#define echoPin 9 // echo conencted to PB1
#define trigPin 10 // trigger connected to PB0

long duration, distance;
boolean abierto;


//serial communication and pins for input and output
void setup()
{
  Serial_sonar.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  abierto = false;
}

// the actual program loop
void loop() {
  //send the pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(1000); //each 1 sec we send a pulse
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  //we measuse the time
  duration = pulseIn(echoPin, HIGH);

  //formula for cm feedback. The sound speed is 340m/s = 29us/cm.
  //we divide the pulse time by 58, the time that the pulse takes to go and come back.
  distance = duration / 58;
  int msg;

  if (distance < 10) {
    if (!abierto) {
      msg = 1;
      Serial_sonar.write(msg);
      abierto = true;
    }
  } else {
    if (abierto) {
      msg = 0;
      Serial_sonar.write(msg);
      abierto = false;
    }
  }




  //send the information to the Serial Monitor
  //Serial_sonar.write(distance);
  delay(100);
}