//Original Program from Elena Cardiel, modified by Agonzalespi. FabAcademy 2021
//First, we need to include the serial communication library
#include <SoftwareSerial.h>
SoftwareSerial Serial_sonar(0, 2); // tx, rx . This is because RX in my FTDI connector corresponds to pin 2 of the ATTINY45. TX is not actually used

//Now we define variables and pin numbers. This may vary if your board is different to mine.
//My Echo pin is connected to PB3. My Trigger pin is connected to PB4. Use the ATTINY45 pinout from the datasheet to know where are your pins connected
#define echoPin 4 // echo conencted to PB3
#define trigPin 3 // trigger connected to PB4

//Now this is Elena Cardiel's program

long duration, distance; 

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

// the actual program loop
void loop() {
  //send the pulse
digitalWrite(trigPin, LOW); 
delayMicroseconds(4); //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; 


//send the information to the Serial Monitor
Serial_sonar.println(distance);
//Serial_sonar.println(" cm");
delay(200);
}