现已经实现host通过cdc驱动ch340正常收发通信  波特率是默认的19200 按照网上的资料修改波特率

static USBH_StatusTypeDef SetLineCoding(USBH_HandleTypeDef *phost,

                                        CDC_LineCodingTypeDef *linecoding)

{

  phost->Control.setup.b.bmRequestType = USB_H2D | USB_REQ_TYPE_CLASS |

                                         USB_REQ_RECIPIENT_INTERFACE;

  phost->Control.setup.b.bRequest = CDC_SET_LINE_CODING;

  phost->Control.setup.b.wValue.w = 0U;

  phost->Control.setup.b.wIndex.w = 0U;

  phost->Control.setup.b.wLength.w = LINE_CODING_STRUCTURE_SIZE;

  phost->Control.setup.d8[0] = 0x000ca140;

  phost->Control.setup.d8[1] = 0x0000cc03;

  return USBH_CtlReq(phost, linecoding->Array, LINE_CODING_STRUCTURE_SIZE);

}

一直返回usb_busy

 波特率没有任何改变  usb转串口芯片是ch340g  有人知道是啥问题吗