Hello @D.Botelho , Now that I have solved the problem with having multiple CDC interfaces working at the same time I would also like to add a DFU interface so that the firmware can be updated without having to reset the microcontroller and controllin...

Hello @D.Botelho,The issue was the use of USBD_malloc during the USBD_CDC_Init. It assigned the same memory address for the two interfaces. Modifying USBD_CDC_Init in the following way solved it (I attach only the modified part)USBD_CDC_HandleTypeDef...

Hello @D.Botelho, I think I have found the problem. Right now, my code is very similar to the one you sent. I do not use neither a circular buffer nor a UART interface. I just want to send periodically to the two CDC interfaces. In the following way:...

Thank you @D.Botelho ! It helped a bit but I am using a H5 microcontroller so I was using the middleware mentioned in this guide. With the help of the tutorial on the link you posted, I was able to create the USB device with two CDC interfaces. Howev...

Hello @D.Botelho I am trying to implement a similar composite device but with several CDC interfaces and no HID interfaces.Is there any example I could use or could you point me to some useful resources? Thank you.