stm32 usb device dual

[DJung.3]

Hello. I'm using EVM board with STM32F407ZGT.

I set up the USB as below to use it as a USB Device. (CDC)

But only one COM port can be found in the device manager on the PC.

I want to know if I can't set 2 usb device or if it's a problem with setting.

Please help me!!

[FBL · Accepted solution]

Hello @DJung.3 

You need to register two instances with USBD_RegisterClassComposite.

  /* Init Device Library */
  USBD_Init(&USBD_Device, &COMPOSITE_Desc, 0);

  /* Register CDC class first instance */
  USBD_RegisterClassComposite(&USBD_Device, USBD_CDC_CLASS, CLASS_TYPE_CDC, CDC_EpAdd_Inst1);

  /* Register CDC class second instance */
  USBD_RegisterClassComposite(&USBD_Device, USBD_CDC_CLASS, CLASS_TYPE_CDC, CDC_EpAdd_Inst2);

  /* Add CDC Interface Class */
  if (USBD_CMPSIT_SetClassID(&USBD_Device, CLASS_TYPE_CDC, 0) != 0xFF)
  {
    USBD_CDC_RegisterInterface(&USBD_Device, &USBD_CDC_fops);
  }

  /* Add CDC Interface Class */
  if (USBD_CMPSIT_SetClassID(&USBD_Device, CLASS_TYPE_CDC, 1) != 0xFF)
  {
    USBD_CDC_RegisterInterface(&USBD_Device, &USBD_CDC_fops);
  }
  /* Start Device Process */
  USBD_Start(&USBD_Device);

[Mrli110]

Hello, for a USB composite device with two CDC, both CDC eventually call the same CDC_Init_FS function and thus share a single buffer. When both CDCs are transmitting data simultaneously, is there a risk of data loss due to sharing the same buffer?

[FBL]

Hi @Mrli110 

Have you checked this article How to implement a dual CDC ACM USB device using t... - STMicroelectronics Community  If still having issues, I suggest you starting a new thread.