Usb 3.0 Packets; Packet Direction - LeCroy USB Protocol Suite Advisor T3 User Manual

Chapter 5: Reading a Trace

5.1.1 USB 3.0 Packets

USB 3.0 has the following packet types:
• Link Commands (Flow Control)
• Link Training Sequences (TS1, TS2, TSEQ)
• Logical Idle Packets
• Upstream Packets
• Downstream Packets
• Skip Sequences
• ISO Time Stamp Packets
• Inter-Packet Symbols (unexpected packets)
• Link Commands (other than Flow Control)
• LMP Packets
• Electrical Idles
• LFPS Packets
• Termination Packets (Time stamped when termination is detected by Analyzer)

5.1.2 Packet Direction

The Packet Direction field displays the direction the packet or signal was traveling on the
bus: Downstream from a Host
In most cases, direction can be determined unambiguously. However, some signals and
situations, including protocol errors, cannot be determined with high confidence, since
either Host or Device might be responsible for them. Such cases are marked as
Question Marks
Rather than mis-identfying the signal, the software requires you to determine direction
(or note an error condition, which experience has shown is rare). In most cases, you can
assume the direction based on the sequence of events that occurred.
94
or Upstream from a Device
in the trace.
USB Protocol Suite User Manual
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