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Using a Beagle USB Protocol Analyzer, How Do I Trigger and Capture VBUS Measurements and USB Data?
Rena Ayeras

Question from the Customer:

We are working to reverse engineer a mobile phone. We analyze the USB traffic to figure out what the tool does on the device. However, the tool that we are using often “realizes” that we’re analyzing USB traffic and “halts” – it stops us from working on this project.

In addition to the data traffic, we also need to track the USB VBUS voltage and current draw. Which of your Total Phase tools do you recommend for this project?

Response from Technical Support:

Thank you for your question! For your usage, we recommend the Beagle USB 480 Power Protocol Analyzer - Ultimate Edition, which supports the following features:

  • USB 2.0 Advanced Triggering Capabilities
  • Create state-based and flexible trigger conditions based on data patterns, packet types, error types, events, and other criteria
  • Hardware packet filtering
  • Up to eight independent states and six matches per state for USB 2.0 captures
  • Track current drawn from the USB bus and VBUS voltage
Beagle USB 480 Power Protocol Analzyer - Ultimate Edition

Capture and View Data with Complex Matching

Here is a video that shows you how to set up and use Complex Matching. For more information, please refer to the sections Triggering a Capture, Capture Control and Device Settings in the Data Center Software User Manual.

More information about capturing data is available in this article, Using a Beagle USB Protocol Analyzer, How Do I Trigger and Capture Data? Additional information is provided in the article, including how to work with the Digital I/O and the Hardware Filter.

Trigger and Capture Current and Voltage Readings

The Beagle USB 480 Power Protocol Analyzer - Ultimate Edition can be used to track the USB VBUS voltage and the current draw by the target device. Using the Beagle USB 480 Power analyzer and Data Center Software together supports Complex Matching. This feature can be used to monitor VBUS voltage or current.

  • The pre-set threshold can be included in any state of the Complex Matching state machine and each state can vary the edge(s) of the threshold it detects. This feature is effective for complex debugging and optimizing the power consumption profile of target devices.
  • You can configure the analyzer to trigger on the rising and/or falling edge(s) of a pre-set voltage or current threshold of VBUS; it can trigger on a rise or drop in VBUS current or voltage.

Example of Monitoring Current and Voltage

To see an example of monitoring current and voltage readings, take a look at the Data Center Software.

  1. Install and open Data Center Software.
  2. Press the F4 key on your keyboard. The Example Captures dialog window will open.
  3. In that dialog window, scroll down and select the PD trace file usb480-fs-power.tdc. Click the OK
  4. On the Menu bar, click the option Current/Voltage monitor.
  5. The Current/Voltage monitor graph will be displayed in the left and lower corner of the Data Center Window.


View of Current Voltage graph in Data Center Software


For more information, please refer to the Current/Voltage Monitoring sub-section in the Data Center Software User Manual.

We hope this answers your questions. Additional resources that you may find helpful include the following:

Do you have more questions? Please send us an email at sales@totalphase.com. You can also request a demo that applies to your application.