TMS320F28379D的sci_echoback例程中，为什么连接串口后没有反应（botelv，校验位等等都是设置的对的） 这个开发板应该怎么连接串口

void main(void)
{
    Uint16 ReceivedChar;
    char *msg;

//
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the F2837xD_SysCtrl.c file.
//
   InitSysCtrl();

//
// Step 2. Initialize GPIO:
// This example function is found in the F2837xD_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
//
   InitGpio();

//
// For this example, only init the pins for the SCI-A port.
//  GPIO_SetupPinMux() – Sets the GPxMUX1/2 and GPyMUX1/2 register bits
//  GPIO_SetupPinOptions() – Sets the direction and configuration of the GPIOS
// These functions are found in the F2837xD_Gpio.c file.
//
   GPIO_SetupPinMux(28, GPIO_MUX_CPU1, 1);
   GPIO_SetupPinOptions(28, GPIO_INPUT, GPIO_PUSHPULL);
   GPIO_SetupPinMux(29, GPIO_MUX_CPU1, 1);
   GPIO_SetupPinOptions(29, GPIO_OUTPUT, GPIO_ASYNC);

//
// 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 F2837xD_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 F2837xD_DefaultIsr.c.
// This function is found in F2837xD_PieVect.c.
//
   InitPieVectTable();

//
// Step 4. User specific code:
//
   LoopCount = 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 == 0) { } // wait for empty state

       //
       // Get character
       //
       ReceivedChar = SciaRegs.SCIRXBUF.all;

       //
       // Echo character back
       //
       msg = "  You sent: \0";
       scia_msg(msg);
       scia_xmit(ReceivedChar);

       LoopCount++;
   }
}

//
//  scia_echoback_init – 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;

    //
    // SCIA at 9600 baud
    // @LSPCLK = 50 MHz (200 MHz SYSCLK) HBAUD = 0x02 and LBAUD = 0x8B.
    // @LSPCLK = 30 MHz (120 MHz SYSCLK) HBAUD = 0x01 and LBAUD = 0x86.
    //
    SciaRegs.SCIHBAUD.all = 0x0002;
    SciaRegs.SCILBAUD.all = 0x008B;

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

//
// scia_xmit – Transmit a character from the SCI
//
void scia_xmit(int a)
{
    while (SciaRegs.SCIFFTX.bit.TXFFST != 0) {}
    SciaRegs.SCITXBUF.all =a;
}

//
// scia_msg – Transmit message via SCIA
//
void scia_msg(char * msg)
{
    int i;
    i = 0;
    while(msg[i] != '\0')
    {
        scia_xmit(msg[i]);
        i++;
    }
}

//
// scia_fifo_init – Initialize the SCI FIFO
//
void scia_fifo_init()
{
    SciaRegs.SCIFFTX.all = 0xE040;
    SciaRegs.SCIFFRX.all = 0x2044;
    SciaRegs.SCIFFCT.all = 0x0;
}

Green Deng：

你用的哪款开发板？串口是怎么连接的？例程有没有修改过？

xu liu2：

回复 Green Deng:

TMS320F28379d这个开发板，例程没有动过， 代码上的引脚是28,29，我把这两个引脚又连在了usb转串口上，然后插入电脑。也试过不用usb转串口，还是什么数据都没有

Green Deng：

回复 xu liu2:

代码肯定是没有问题的，连接的引脚也没错。你用的是这款开发板吗？www.ti.com.cn/…/TMDSDOCK28379D
建议你先用示波器测一下这两个引脚的信号正常吗？如果信号输出没问题的话就有可能是你后端的连接有问题了。

xu liu2：

回复 Green Deng:

我用的是这块板子www.ti.com/…/LAUNCHXL-F28379D。debug的时候测试引脚没有测试到正确的波形。所有的步骤都是按照官方例程来的。所以现在没有头绪，请问您有什么见解吗？

mangui zhang：

回复 xu liu2:

不行短接收发管脚代码验证一个自发自收看看
还有短接一下你的串口线收发管脚上位机串口助手看看能不能自发自收
确保串口的TTL 还是 RS232电平电平要匹配

user6022550：

回复 xu liu2:

老哥 你问题解决了吗 我也是烧了例程 串口没反应 调试发现卡在等待空状态