Error Priming USB Endpoints

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by fiosca on Thu Oct 11 02:17:55 MST 2012
We're facing a very strange situation developing a USB CDC driver for LPC1850.
As a standard CDC Virtual COM port, our driver can handle Bulk IN/OUT transfers
on Endpoint 2.

In case of heavy traffic, USB peripheral seems not to be able to prime the Bulk OUT endpoint.
Setting dTD and dQH correctly, and writing to the correspondent ENDPTPRIME bit, the endpoint
is not primed and bit still remains set forever.

There's no way to have the endpoint primed again and the only solution is an hardware reset.
We're experiencing this strange behavior in many different boards, so it's not something specific or
an hardware problem, and this problem seems to disappear if we connect the board to a PC
using an USB Hub.

We're using LPC1850 hw revision 'A'.
Does anybody know if there're condition that can avoid and endpoint to be primed?

Best Regards,