How Can I View and Analyze USB Traffic for a Composite High Speed Device?

Question from the Customer: I’m using the Beagle USB 12 Protocol Analyzer and I haven’t been able to view the USB traffic for a composite device: an HID keyboard and an Audio device connected to the USB hub. What do I need to look into? Do I need to make any changes to this setup? Response from Technical Support: Thanks for your questions! There are three modes (speeds) of USB traffic, and our USB protocol analyzers support various ranges of speed. We have two recommendations for monitoring the USB traffic. First, we’ll go over the modes of USB traffic.

USB Traffic Modes

The USB 2.0 standard is broadly divided into 3 different modes based on the speed, also known as the maximum transfer rate, of the devices:

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

How to Check Device Speeds

An easy way to check the speed of a device is using the USB Device Tree Viewer. When you run the USB Device Tree Viewer, you will see a list of USB Host Controllers. You could cycle through each port of the USB Root Hubs attached to these controllers to see what is connected to that port. The USB Device Tree viewer will display each USB device connected to your computer (mouse, WiFi or Bluetooth adapter, webcam, etc.) on the hub ports. It will also display the Device Bus Speed as shown below. This first image shows the left window of the viewer, which displays the USB device per port. In this window, a mass storage device is selected.

USB tree view of mass storage device

This second image, the right window of the viewer, shows the details of the device that was selected above.  The three modes of speed are indicated as follows:

Detailed USB tree view of high speed mass storage device Detailed USB tree view of high speed mass storage device
  • 0x01 (Full-Speed)
  • 0x02 (High-Speed)
  • 0x03 (SuperSpeed)

As you can see in the pictures, the selected device is a High Speed device.

Beagle USB Protocol Analyzer Models

The Beagle USB 12 Protocol Analyzer is a Low-Speed/Full-Speed device – it tracks Low Speed and Full Speed USB traffic. The Beagle USB 12 analyzer is an excellent tool for a variety of HID devices such as mice and keyboards, but its speed does not work for the USB devices that operate in High-Speed. For High-Speed traffic, we recommend using one of the following Total Phase analyzers:

Using Data Center Software, here is an example of what you can  capture and analyze with the a High-Speed protocol analyzer: 164487-beagle-data For a quick overview of the features of our protocol analyzers, please take a look at this chart.

Configuring the Speed During Setup

For an immediate solution, you could configure the speed of your devices to operate with the range of the Beagle USB 12 analyzer, Full or Low Speed. However, to fully test your system, we recommend using a protocol analyzer that captures the maximum speed at which your system is expected to operate. We hope this answers your questions. Additional resources that you may find helpful include the following

More questions? You can contact us for questions about the Beagle protocol analyzers and other Total Phase products. You can also request a demo that applies to your application.

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