Teledyne LeCroy USB Protocol Suite User Manual (Voyager_Advisor T3_Mercury) - Manual (Page 128)

Teledyne LeCroy Corporation Display 2 Only
128 USB Protocol Suite User Manual
Figure 5.29: Un-stacked View
Figure 5.30: Stacked View
Note:
Items are grouped regardless of any intervening Skip Sequence, Electrical Idle, or Logical Idle
symbols. If any of these occur during a stream of the repeating stacking item, they are not
displayed.
Note on unexpected 3.0 Idle times in traces which include Logical Idle and/or SKPs:
There will occasionally be "Idle" fields (typically 8ns) between packets which do not seem
to make sense within a continuous set of captured data, such as amongst idles and SKPS.
These are a by‐product of the mechanism which compensates for timestamp / event rate
matching between the various time bases. There are 3 clock domains (Rx, Tx, and our
precision timestamp) that need to be represented in the trace. The nominal 2nSec /
symbol Transmit and Receive clocks can vary up to 500ppm per the USB Specification,
whereas the Analyzer is accurate to 3ppm. The small idle time at the end of a packet is
there to compensate for this clock drift difference between the protocol clocks and our
precision clock, and to try to maintain the most accurate relationship amongst these
clocks. The Timestamp field is always based on our 3ppm clock timestamp.
5.11 Display 2 Only
Click the button to display only USB 2.0 traffic.