Question

我最近得到了Tiva C系列MCU，我想使用它的USB功能。

我的目标是通过USB向电路板发送电子邮件并收到回复信息（确认或错误报告）

命令以大写字母开头，后跟3位数字，如X123。

有一个示例代码我已经修改了一下，以便在RxBuffer中包含字母时获得某些响应。

static uint32_t
EchoNewDataToHost(tUSBDBulkDevice *psDevice, uint8_t *pui8Data,
                  uint32_t ui32NumBytes)
{
    uint32_t ui32Loop, ui32Space, ui32Count;
    uint32_t ui32ReadIndex;
    uint32_t ui32WriteIndex;
    tUSBRingBufObject sTxRing;

    //
    // Get the current buffer information to allow us to write directly to
    // the transmit buffer (we already have enough information from the
    // parameters to access the receive buffer directly).
    //
    USBBufferInfoGet(&g_sTxBuffer, &sTxRing);

    //
    // How much space is there in the transmit buffer?
    //
    ui32Space = USBBufferSpaceAvailable(&g_sTxBuffer);

    //
    // How many characters can we process this time round?
    //
    ui32Loop = (ui32Space < ui32NumBytes) ? ui32Space : ui32NumBytes;
    ui32Count = ui32Loop;

    //
    // Update our receive counter.
    //
    g_ui32RxCount += ui32NumBytes;

    //
    // Dump a debug message.
    //
    DEBUG_PRINT("Received %d bytes\n", ui32NumBytes);

    //
    // Set up to process the characters by directly accessing the USB buffers.
    //
    ui32ReadIndex = (uint32_t)(pui8Data - g_pui8USBRxBuffer);
    ui32WriteIndex = sTxRing.ui32WriteIndex;

    while(ui32Loop)
    {
        UARTprintf("\n" );
        //
        // Copy from the receive buffer to the transmit buffer converting
        // character case on the way.
        //

        //
        // Is this a lower case character?
        //
        if((g_pui8USBRxBuffer[ui32ReadIndex] == 'L'))
        {
            GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_3, GPIO_PIN_3);
            UARTprintf("LEFT" );

        }
        else if((g_pui8USBRxBuffer[ui32ReadIndex] == 'R'))
        {
            GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, GPIO_PIN_2);
            UARTprintf(" RIGHT " );

        }
        else
        {

            GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_3, 0);
            GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, 0);
            //
            // Is this an upper case character?
            //
            if((g_pui8USBRxBuffer[ui32ReadIndex] >= 'A') &&
               (g_pui8USBRxBuffer[ui32ReadIndex] <= 'Z'))
            {
                //
                // Convert to lower case and write to the transmit buffer.
                //
                g_pui8USBTxBuffer[ui32WriteIndex] =
                    (g_pui8USBRxBuffer[ui32ReadIndex] - 'Z') + 'z';
            }
            else
            {
                //
                // Copy the received character to the transmit buffer.
                //
                g_pui8USBTxBuffer[ui32WriteIndex] =
                    g_pui8USBRxBuffer[ui32ReadIndex];
            }
        }

        //
        // Move to the next character taking care to adjust the pointer for
        // the buffer wrap if necessary.
        //
        ui32WriteIndex++;
        ui32WriteIndex = (ui32WriteIndex == BULK_BUFFER_SIZE) ?
                         0 : ui32WriteIndex;

        ui32ReadIndex++;
        ui32ReadIndex = (ui32ReadIndex == BULK_BUFFER_SIZE) ?
                        0 : ui32ReadIndex;

        ui32Loop--;
    }

    //
    // We've processed the data in place so now send the processed data
    // back to the host.
    //
    USBBufferDataWritten(&g_sTxBuffer, ui32Count);

    DEBUG_PRINT("Wrote %d bytes\n", ui32Count);

    //
    // We processed as much data as we can directly from the receive buffer so
    // we need to return the number of bytes to allow the lower layer to
    // update its read pointer appropriately.
    //
    return(ui32Count);
}

但是我不知道如何将缓冲区中的下3位数作为数字，只需使用UARTprintf等单个命令将消息写回主机。

请你帮我一起走吧？

谢谢你们， Zoszko

TM4C123G6PMI USB设备通信

0 个答案: