void sio3_init(void)
{
  __disable_interrupt();
  /*------------------------------------------------------------------------\
  | SI/O3 Control register (protect off before writing to this register)    |
  |//Sout3 output, Input-output-port, MSB first, external clock, high output|
  \------------------------------------------------------------------------*/
  // setting up configuration  ----------------------------------------------
  
  
  //PROTECT OFF
  PRCR = 7;

  S3C |= 0xA0;
  //S3BRG must not be set, Transfer Bitrate is determined by ext. clk from ECK Chip !

  //Interrupt control register  (polarity select bit: rising edge, Interrupt Level 6)
  S3IC |= 0x16;
  S3IC &= 0xDE;

  //in Interrupt cause select register: select SI/O3
  IFSR &= 0xBF0;

  //reset Interrupt request bit for SI/O3
   S3IC &= 0xF7;

  //PROTECT ON
  PRCR = 0x00;


  puts("SI/O3 initialized.\n");

  __enable_interrupt();

}



/*------------------------------------------------------------------------
  SIO3 ISR added/changed by Simon Bauernfeind
  Interrupt Request Bit in S3IC is set by the rising edge of last transfer clock !
  ----------------------------------------------------------------------*/
#pragma vector = SIO3
__interrupt void sio3_handler(void)
{
  //only for testing
  printf("SIO3 int %d\n", data_counter);

  //save S3TRR content in daten Array
  daten[data_counter] = S3TRR;

  //increment counter
  data_counter++;

  //reset Interrupt Request bit to 0
  S3IC &= ~(1<<3);
}