8051 Probleme mit UART Kommunikation

#include <at89c5131.h>            

void Uart_Init(crystal_t systemCrysal)

{

    // init uart

    SCON |= 0x50;        // SM1 (2^6) = 1; REN (2^4) = 1;

//-------------------------------------------------

    // Timer2 init

    T2CON |= 0x30;    // TCLK (2^4) = 1; RCLK (2^5) = 1;

    TR2 = 1;          // Timmer2 run T2CON 2^2

    if(systemCrysal == _12MHz)

    {

        // Reloadwert fuer 12MHz Quarz

        RCAP2H = 0xFF;

        RCAP2L = 0xB2;

    }

    else if  (systemCrysal == _24MHz)

    {

        // Reloadwert fuer 24MHz Quarz

        RCAP2H = 0xFF;

        RCAP2L = 0x66;

    }

    else {}

//-------------------------------------------------

    TI = 1;        // SCON; Ermoeglicht das Benutzen von printf()

}

void serial_send(unsigned char dat){

  while(!TI);

  TI = 0;

  SBUF = dat;

}

  unsigned char serial_read(){

  while(!RI);

  RI = 0;

  return SBUF;

}

void main (void){

  Uart_Init (_12MHz);

  serial_send (0x02);

  serial_send (0x01);

  serial_send (0xF0);

  while(1){

    serial_read();

  P2_0 = RI;

  P2_1 = TI;

  }}