//for the master unit 
//Wire lib is for using the I2C bus
#include <Wire.h>

//define slave address
#define SLAVE_ADDR 9

//define Slave answer size 
#define ANSWERSIZE 5
//The above expects that the slave gives us 5 bytes

void setup(){
  //initialize the I2C communication for the master
  Wire.begin();
  Serial.begin(9600);
  
}

void loop(){
  delay(500);
  Serial.println("Write Data to slave");
  //write charecters to the slave 
  Wire.beginTransmission(SLAVE_ADDR);
  Wire.write(0);
  Serial.println("recieve data");

  //Read response for the slave
  //Read 5 charecters back
  Wire.requestFrom(SLAVE_ADDR,ANSWERSIZE);
  
  //the string that is read from slave
  String response = "";
  while (Wire.available()){
    char b = Wire.read();
    response += b;
  }
  //print to serial monitor
  Serial.print(response);
}