Support Question of the Week: Suspend-Resume Sequence Analysis with Beagle USB Protocol Analyzer and Data Center Software

Q: I am trying to analyze a Suspend-Resume sequence using the Total Phase Data Center Software with a Beagle USB 5000 V2 Protocol Analyzer. Our device under test is a USB 2.0 high-speed device and the test is being driven by the USB20CV tool. The screen shot below shows the trace from a successful test run.

Suspend-Resume Captures using Data Center and Beagle USB Protocol Analyzer Figure 1: Suspend-Resume Captures via Data Center and Beagle USB Protocol Analyzer

I have some questions about the timestamp/durations of some of the events - are my interpretations correct?

  1. Index 7, suspend event. Did the idle state start at 0:02.657.066 and continue for 164ms?
  2. Index 10, resume event.  The duration is the K-portion of resume signaling, according to the information panel, but is the time stamp the beginning of the K-state? This does not match the duration of the suspend event.
  3. Index 11 shows a reset (which did not seem to occur) and then the trace switches to FS (full speed)  mode. However, the bus is still in HS (high speed); the start of frame (SOF) occurs every 125us. These readings appear to be HS micro frames.

To have data presented in time-order (sequential), we used Packet View for the Data Center Software view of the captures.

Thanks for the question! Following are the interpretations of each capture. One capture, index 12, shows you may need to set the Beagle Protocol Analyzer and the Data Center Software specifically to high speed mode (instead of using the default mode of auto speed).

In the beginning of index 6 the bus has 5224 SOF for 652 ms starting at 0:02.001. Then, in the end of index 6, the bus in idle state for 3 ms starting at 0:02:653. Then, in index 7, the bus is in suspend state for 164 ms.

The details of the readings:

  • Index 6 a: 0:02.001, 652 ms, 5224 SOF
  • Index 6 b: 0:02:653, 3 ms, idle state
  • Index 7 0:02.657: 164 ms, suspend state
  • Index 10 the bus is in Resume state for 65.2 ms starting at 0:02.966.
  • Index 10 the bus is in K state for 65.2 ms starting at 0:02.966.
  • Index 10 0:02.966: 65.2 ms, resume state (K state).
  • Index 11 the bus is in target disconnect state for 1.10 µs starting at 0:03.029.
  • Index 12 the Beagle analyzer and Data Center software show that the bus entered to full speed (FS), although the Bus is in high speed (HS)

This behavior shown for Index 12 may be related to the speed detection mechanism. To correct this reading,  set up the Beagle analyzer and Data Center software for high speed mode. (The default mode is auto detect.)

  1. Click Device Setting
  2. Select USB
  3. Select USB 2.0 Bus Speed: High (480 Mbps)

For more information about our products, guidelines and manuals, please refer to the following:

USB Protocol Analyzers
Data Center Software
Total Phase Products
Product Selector Guide

We hope this answers your question. If you have other questions about our Protocol Analyzers or other Total Phase products, feel free to email us at or

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