Could I Use a Low/Full-Speed USB Protocol Analyzer with High-Speed USB Traffic?

Question from the Customer:

I just purchased a Beagle USB 12 Protocol Analyzer.  I am using it to debug and sniff USB 2.0 Flash drives. I installed the drivers and the Data Center Software, but I am having problems. When I start a capture and insert a USB Flash drive, I only see the following:

Trying to Monitor a Full-Speed Device with a Low/High-Speed Analyzer Trying to Monitor a Full-Speed Device with a Low/High-Speed Analyzer

I can see no signals and no packets. I only see "Target Connected" and "Target Disconnected". When I plug in another type of USB device, such as a mouse or a USB-to-serial converter, I can capture and view signals and packet information, which is what I expect.  Also, I have tried the Beagle USB 12 analyzer on three different computers, and for each setup, the results are the same.

What am I doing wrong? For budget reasons, I really want to make this work.

Response from Technical Support

Thanks for your question! The Beagle USB 12 Protocol Analyzer is a Low-Speed/Full-Speed device that only tracks Low-Speed and Full-Speed USB traffic. Here are the three speeds of USB 2.0 devices:

  • High-Speed: 480 Mbit/s
  • Full-Speed: 12 Mbit/s
  • Low-Speed: 1.5 Mbit/s

Which USB Protocol Analyzer Do You Need for Which Target Device?

The devices that you successfully monitored are Low/Full-Speed USB devices. A USB 2.0 Flash memory, however, operates at High-Speed USB, which is beyond the parameters of the Beagle USB 12 analyzer. The Beagle USB 12 Protocol Analyzer is really great for a variety of HID devices such as mice and keyboards, but it does not work for the USB devices that operate in High-Speed mode.

To monitor and capture High-Speed data traffic, you could use one of the following USB protocol analyzers:

Of these protocol analyzers, the Beagle USB 480 Power Protocol Analyzer could be your “go-to” tool. It offers class-decoding, triggers, and filtering with the deepest USB 2.0 High Speed hardware buffer in our tools. For an easy comparison, take a look at our product guide, which summarizes the features of our USB protocol analyzers and other devices.

If you really need to use the Beagle USB 12 Protocol Analyzer for High-Speed devices, there is a way to see the traffic. However, it will be without the benefits of full class-level decoding, triggering, and other advanced features provided by our High-Speed USB protocol analyzers.

The class-level decoding feature of the Data Center Software does provide real-time USB descriptor decoding for data captured with a Beagle USB 12 Protocol Analyzer. However, full class-level decoding is only available with the Beagle USB 480/5000 protocol analyzers.

What Is the Speed of Your Target Device?

If you are uncertain of the speed of the target device, the easiest method to find the device speed is using the USB Device Tree Viewer. When you run the USB Device Tree Viewer, you will see a list of USB Host Controllers. By cycling through each port of the USB Root Hubs attached to the controllers, you will see what is connected to that port. Each USB device that is connected to your computer (mouse, Wi-Fi or Bluetooth adapter, webcam, and so on) will be displayed on one of those ports. It will also show the Device Bus Speed.

The speed values can be displayed as follows:

  • 0x01 (Full-Speed)
  • 0x02 (High-Speed)
  • 0x03 (SuperSpeed)

Monitoring High-Speed Data with Low/Full -Speed Analyzer

If necessary, there is a short-term workaround that could work for you. To buffer and slow down the data traffic to where the Beagle USB 12 Protocol Analyzer could capture the data, place a Full-Speed USB 1.1 hub between the target device and the Beagle USB 12 analyzer. For extended periods of work and detailed analysis, you may find using one of our High-Speed USB protocol analyzers more effective and more efficient.

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

If you want more information, feel free to contact us with your questions, or request a demo that applies to your application.