请问为啥28335的SCIA的TI官方例程无法和串口调试工具通信啊？

void main(void)

{

    Uint16 ReceivedChar;

    char *msg;



// Step 1. Initialize System Control:

// PLL, WatchDog, enable Peripheral Clocks

// This example function is found in the DSP2833x_SysCtrl.c file.

   InitSysCtrl();



// Step 2. Initialize GPIO:

// This example function is found in the DSP2833x_Gpio.c file and

// illustrates how to set the GPIO to it's default state.

   // InitGpio(); Skipped for this example



// For this example, only init the pins for the SCI-A port.

// This function is found in the DSP2833x_Sci.c file.

   InitSciaGpio();



// Step 3. Clear all interrupts and initialize PIE vector table:

// Disable CPU interrupts

   DINT;



// Initialize PIE control registers to their default state.

// The default state is all PIE interrupts disabled and flags

// are cleared.

// This function is found in the DSP2833x_PieCtrl.c file.

   InitPieCtrl();



// Disable CPU interrupts and clear all CPU interrupt flags:

   IER = 0x0000;

   IFR = 0x0000;



// Initialize the PIE vector table with pointers to the shell Interrupt

// Service Routines (ISR).

// This will populate the entire table, even if the interrupt

// is not used in this example.  This is useful for debug purposes.

// The shell ISR routines are found in DSP2833x_DefaultIsr.c.

// This function is found in DSP2833x_PieVect.c.

   InitPieVectTable();



// Step 4. Initialize all the Device Peripherals:

// This function is found in DSP2833x_InitPeripherals.c

// InitPeripherals(); // Not required for this example



// Step 5. User specific code:



    LoopCount = 0;

    ErrorCount = 0;



    scia_fifo_init();           // Initialize the SCI FIFO

    scia_echoback_init();  // Initialize SCI for echoback



    msg = "\r\n\n\nHello World!\0";

    scia_msg(msg);



    msg = "\r\nYou will enter a character, and the DSP will echo it back! \n\0";

    scia_msg(msg);



        for(;;)

    {

       msg = "\r\nEnter a character: \0";

       scia_msg(msg);



       // Wait for inc character

       while(SciaRegs.SCIFFRX.bit.RXFFST !=1) { } // wait for XRDY =1 for empty state

       //while(SciaRegs.SCIRXST.bit.RXRDY !=1) { }



       // Get character

       ReceivedChar = SciaRegs.SCIRXBUF.all;



       // Echo character back

       msg = "  You sent: \0";

       scia_msg(msg);

       scia_xmit(ReceivedChar);



       LoopCount++;

    }

}



// Test 1,SCIA  DLB, 8-bit word, baud rate 0x000F, default, 1 STOP bit, no parity

void scia_echoback_init()

{

    // Note: Clocks were turned on to the SCIA peripheral

    // in the InitSysCtrl() function



         SciaRegs.SCICCR.all =0x0007;   // 1 stop bit,  No loopback

                                   // No parity,8 char bits,

                                   // async mode, idle-line protocol

        SciaRegs.SCICTL1.all =0x0003;  // enable TX, RX, internal SCICLK,

                                   // Disable RX ERR, SLEEP, TXWAKE

        SciaRegs.SCICTL2.all =0x0003;

        SciaRegs.SCICTL2.bit.TXINTENA =1;

        SciaRegs.SCICTL2.bit.RXBKINTENA =1;

        #if (CPU_FRQ_150MHZ)

              SciaRegs.SCIHBAUD    =0x0001;  // 9600 baud @LSPCLK = 37.5MHz.

              SciaRegs.SCILBAUD    =0x00E7;

        #endif

        #if (CPU_FRQ_100MHZ)

      SciaRegs.SCIHBAUD    =0x0001;  // 9600 baud @LSPCLK = 20MHz.

      SciaRegs.SCILBAUD    =0x0044;

        #endif

        SciaRegs.SCICTL1.all =0x0023;  // Relinquish SCI from Reset

}



// Transmit a character from the SCI

void scia_xmit(int a)

{

    while (SciaRegs.SCIFFTX.bit.TXFFST != 0) {}

   // while (SciaRegs.SCICTL2.bit.TXRDY == 0) {}

    SciaRegs.SCITXBUF=a;

}



void scia_msg(char * msg)

{

    int i;

    i = 0;

    while(msg[i] != '\0')

    {

        scia_xmit(msg[i]);

        i++;

    }

}



// Initialize the SCI FIFO

void scia_fifo_init()

{

    SciaRegs.SCIFFTX.all=0xE040;

    SciaRegs.SCIFFRX.all=0x204f;

    SciaRegs.SCIFFCT.all=0x0;

}