RK002 Pitchbend on a key

int pd=0;
int tpd=0;
void RK002_onHeartBeat() // we use heartbeat for button debouncing
{
  if(tpd!=pd){
    tpd+=(pd-tpd)/4;
    RK002_sendPitchBend(0,tpd);
  }
}
boolean RK002_onNoteOn(byte channel, byte key, byte velocity)
{
  bool retval=true;
  if (key==49){pd=-8173;retval=false;}
  if (key==51){pd=8174;retval=false;}
  return retval;
}

boolean RK002_onNoteOff(byte channel, byte key, byte velocity)
{
  bool retval=true;
  if (key==49){pd=0;retval=false;}
  if (key==51){pd=0;retval==false;}
  return retval;
}
void setup()
{
}

void loop()
{
}