#include <Wire.h>

#define SLAVE_ADDRESS 0x02
#define TRIG_PIN 2
#define ECHO_PIN 3

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  Wire.begin(); // Initialize as master
}

void loop() {
  // Measure distance
  long duration, distance;
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2; // Convert to cm

  // Send distance to slave
  Wire.beginTransmission(SLAVE_ADDRESS);
  Wire.write(distance);
  Wire.endTransmission();
  delay(100);