将默认视觉通信换为usb虚拟串口，修复视觉发送roll错误；增加了attach调试支持

Src/usbd_cdc_if.c

@@ -31,7 +31,8 @@
 
 /* USER CODE BEGIN PV */
 /* Private variables ---------------------------------------------------------*/
-
+static USBCallback tx_cbk = NULL;
+static USBCallback rx_cbk = NULL;
 /* USER CODE END PV */
 
 /** @addtogroup STM32_USB_OTG_DEVICE_LIBRARY
@@ -263,6 +264,10 @@ static int8_t CDC_Receive_FS(uint8_t* Buf, uint32_t *Len)
   /* USER CODE BEGIN 6 */
   USBD_CDC_SetRxBuffer(&hUsbDeviceFS, &Buf[0]);
   USBD_CDC_ReceivePacket(&hUsbDeviceFS);
+
+  if(rx_cbk)
+    rx_cbk(*Len);
+
   return (USBD_OK);
   /* USER CODE END 6 */
 }
@@ -311,12 +316,19 @@ static int8_t CDC_TransmitCplt_FS(uint8_t *Buf, uint32_t *Len, uint8_t epnum)
   UNUSED(Buf);
   UNUSED(Len);
   UNUSED(epnum);
+  if(tx_cbk)
+    tx_cbk(*Len);
   /* USER CODE END 13 */
   return result;
 }
 
 /* USER CODE BEGIN PRIVATE_FUNCTIONS_IMPLEMENTATION */
-
+uint8_t* CDCInitRxbufferNcallback(USBCallback transmit_cbk,USBCallback recv_cbk)
+{
+  tx_cbk = transmit_cbk;
+  rx_cbk = recv_cbk;
+  return UserRxBufferFS;
+}
 /* USER CODE END PRIVATE_FUNCTIONS_IMPLEMENTATION */
 
 /**