1 usb 3.0 packets, 2 packet direction, 1 usb 3.0 packets 5.1.2 packet direction – Teledyne LeCroy USBTracer_Trainer - Users Manual User Manual

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Chapter 5: Reading a Trace

USB Protocol Suite User Manual

94

LeCroy Corporation

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

or Upstream from a Device

.

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

in the trace.

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.

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