Hi, When I test a device when system suspend/hibernate ~ resume, sometime I find on D+/D- a SE0 pulse between long suspend. The SE0 pulse is longer than 2.5us and shorter than 10ms, usually, it is 4ms. I think according the 7.1.7.5 of USB2.0 spec, SE0 which is longer than 2.5us should be a usb reset. And the reset signal must be longer than 10ms. So the 4ms SE0 is not a valid signal. Is it correct? And it seems the 4ms SE0 doesn't occur everytime during the resume process. Then what causes the 4ms SE0 happen? Thanks and best regards, Zhuxl -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.opencores.org/pipermail/usb/attachments/20050822/f695c231/attachment.html