#include <Wire.h>

void setup()
{
 Wire.begin(9);
 Wire.onRequest(requestEvent);
 Wire.onReceive(receiveEvent);
 Serial.begin(9600); // Serial 0 interface for PC
 Serial1.begin(9600); // Serial 1 interface for Bluetooth module
}
void loop(){}

void receiveEvent(int howMany){
  Serial1.write(Wire.read());
}

void requestEvent(){
  if (Serial1.available()){
    Wire.write(Serial1.read());
  }
}