topic Re: Error Priming USB Endpoints in LPC Microcontrollers

Error Priming USB Endpoints

lpcware — Wed, 15 Jun 2016 18:13:21 GMT

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,
Federico

Re: Error Priming USB Endpoints

lpcware — Wed, 15 Jun 2016 18:13:22 GMT

Content originally posted in LPCWare by Daniel Widyanto on Mon Oct 15 20:11:01 MST 2012
Hi,

Are you connecting the MCU to the high speed port at PC side ?

I've seen several cases, where the data/request from PC is not intact due to cable issues. Shortening the cable, using USB certified cable, or even using external USB hub to buffer the signal from PC may help.

Re: Error Priming USB Endpoints

lpcware — Wed, 15 Jun 2016 18:13:22 GMT

Content originally posted in LPCWare by dsidlauskas on Mon Feb 09 19:26:35 MST 2015
I'm seeing a very similar thing. Did you ever get this figured out?

Thanks,
Dave

Re: Error Priming USB Endpoints

lpcware — Wed, 15 Jun 2016 18:13:23 GMT

Content originally posted in LPCWare by dsidlauskas on Mon Feb 09 19:27:02 MST 2015
I'm seeing a very similar thing. Did you ever get this figured out?

Thanks,
Dave