公开(公告)号：EP2432754A1

公开(公告)日：2012-03-28

申请号：EP10777231.1

申请日：2010-05-20

申请人： Chronologic Pty Ltd

发明人： FOSTER, Peter Graham

IPC分类号： C06F1/12

CPC分类号： G06F13/423 ,  G06F1/08 ,  G06F1/12 ,  G06F11/3027 ,  G06F13/10 ,  G06F13/4022 ,  G06F13/4027 ,  G06F13/405 ,  G06F13/4282 ,  G06F2213/0042 ,  H04L7/04 ,  H04L7/08

摘要： A method of determining the downstream propagation time of signals from a USB Host Controller across one or more USB cables and one or more USB Hubs to a Super Speed USB device, comprising: opening at least one Isochronous communication pipe between the Host Controller and the Super Speed USB device; ensuring that the Super Speed USB device is in link state U0 in preparation for receiving an ITP; controlling the USB Host Controller to send a plurality of ITPs across the Isochronous communication pipe, the ITPs containing respective first timestamps indicative of times at which the Host Controller generated the respective ITPs; locking a local clock of the Super Speed USB device to information that comprises the first timestamp, derived from one or more of the ITPs, the locking being in respect of frequency such that the local clock is syntonised to a timebase of the USB Host Controller and a notion of time of the local clock is substantially synchronised to a notion of time of the USB Host Controller but with a constant phase delay equal to an average downstream propagation time of the plurality of ITPs from the USB Host Controller to the Super Speed USB device; the Super Speed USB device transmitting a plurality of signals to the USB Host Controller, each of the signals containing a second timestamp indicative of a local time in the time domain of the Super Speed USB device when the respective signal was generated by the Super Speed device; the USB Host Controller creating a third timestamp indicative of a time of reception of the respective signals from the Super Speed USB device; the USB Host Controller determining a time period from one or more respective time differences between corresponding second and third timestamps, the time period being indicative of a sum of a downstream propagation time and an upstream propagation time; and determining the downstream propagation time from the time period.