#include <TinyWire.h>

#define TRIG_PIN 3
#define ECHO_PIN 4

long duration;
int distance;

void setup() {
  // put your setup code here, to run once:

  TinyWire.begin(8);
  TinyWire.onRequest(requestEvent);
  pinMode(TRIG_PIN, OUTPUT); // Sets the trigPin as an Output
  pinMode(ECHO_PIN, INPUT);

}

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

  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
   // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(ECHO_PIN, HIGH);
  // Calculating the distance
  distance= duration*0.034/2;

}

void requestEvent() {
  if(distance>20){
    TinyWire.send("1");
  }else{
    TinyWire.send("0");
  }
  
}