I'm creating an application which needs up to four virtual COM ports from the USB on BF707. This application is using uC/OS + uC/USB CDC + uC/USB ACM Serial. I can only get up to 2 virtual COM ports working properly, the 3rd one hangs on data RX and the 4th one crashes in the DMA handler on connection. I traced the crash to this location: \usb\controller\musbmhdrc\adi_usb_dev_musbmhdrc_intrpt.c line 127. It looks like pEpCurURB is NULL.
I attached a sample application which reproduces the problem on Windows 10 (I haven't tested other versions).
We understand that you have already contacted our private support.
Please continue the discussion there. We will post the final response here for others to benefit
The response from the private support was that it isn't possible to support the number of endpoints required for 3 USB CDC ACM serial instance because there are not enough DMA channels available. The driver fails to check this.