问Xilinx:通过UART将数据发送到ZedBoard

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    XUartPs_SetInterruptMask(UartInstPtr, IntrMask);

XUartPs_SetOperMode(UartInstPtr, XUARTPS_OPER_MODE_LOCAL_LOOP);

#WHAT IS LOCAL LOOPBACK MODE?? DOES THIS PREVENT THE BOARD FROM RECEIVING 
DATA COMING FROM MY PC?

/*
 * Set the receiver timeout. If it is not set, and the last few bytes
 * of data do not trigger the over-water or full interrupt, the bytes
 * will not be received. By default it is disabled.
 *
 * The setting of 8 will timeout after 8 x 4 = 32 character times.
 * Increase the time out value if baud rate is high, decrease it if
 * baud rate is low.
 */
XUartPs_SetRecvTimeout(UartInstPtr, 8);


/*
 * Initialize the send buffer bytes with a pattern and the
 * the receive buffer bytes to zero to allow the receive data to be
 * verified
 */
for (Index = 0; Index < TEST_BUFFER_SIZE; Index++) {

    SendBuffer[Index] = (Index % 26) + 'A';

    RecvBuffer[Index] = 0;
}

/*
 * Start receiving data before sending it since there is a loopback,
 * ignoring the number of bytes received as the return value since we
 * know it will be zero
 */
XUartPs_Recv(UartInstPtr, RecvBuffer, TEST_BUFFER_SIZE);

/*
 * Send the buffer using the UART and ignore the number of bytes sent
 * as the return value since we are using it in interrupt mode.
 */
XUartPs_Send(UartInstPtr, SendBuffer, TEST_BUFFER_SIZE);

#HOW DOES THIS ACTUALLY WORK? WHY DO WE START RECEIVING BEFORE WE SEND ANY 
BYTES?

/*
 * Wait for the entire buffer to be received, letting the interrupt
 * processing work in the background, this function may get locked
 * up in this loop if the interrupts are not working correctly.
 */
while (1) {
    if ((TotalSentCount == TEST_BUFFER_SIZE) &&
        (TotalReceivedCount == TEST_BUFFER_SIZE)) {
        break;
    }
}

/* Verify the entire receive buffer was successfully received */
for (Index = 0; Index < TEST_BUFFER_SIZE; Index++) {
    if (RecvBuffer[Index] != SendBuffer[Index]) {
        BadByteCount++;
    }
}

/* Set the UART in Normal Mode */
XUartPs_SetOperMode(UartInstPtr, XUARTPS_OPER_MODE_NORMAL);

#WHAT DOES SETTING THE UART IN NORMAL MODE MEAN??