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Support Question of the Week: How Do I Attach a Beagle USB Protocol Analyzer to Monitor an Embedded USB Link?

I have a question about using the Beagle USB 480 Protocol Analyzer. In our latest designs, many of the USB links are embedded – chips are interconnected on the same circuit board. My question: How do we attach the analyzer to an embedded USB link?

Thanks for your question! You can cut a USB and use the individual wires to tap onto to any leads on the board or solder the wires to the USB lines. This information is available in section 2.2 of the Beagle Protocol Analyzer User Manual and the knowledge base article Monitoring an embedded USB with a Beagle USB Protocol Analyzer.

In section 3.1.1 of the Beagle Protocol Analyzer User Manual, Figure 40 shows the four  main architectures for connecting devices to the Beagle protocol analyzer. Item (d) of Figure 40 shows connecting the Beagle protocol analyzer to an embedded system. Refer to Figure 1 below. In this case, you can use a parallel connector to tap off the lines, and then plug the tapped off cable to either the Target Host or the Target Device port of the Beagle analyzer (the ports are equivalent).

Monitoring an Embedded System with a Beagle USB 480 Protocol Analyzer Figure 1: Monitoring an Embedded System

More information is provided in the knowledge base article Monitoring an embedded USB with a Beagle USB Protocol Analyzer.  A summary follows:

  • The D+/D- signal path of a USB does not have to be broken to be monitored by a Beagle USB protocol analyzer.
  • The VBUS, GND, D+, and D- lines can be connected to either the Type A or Type B connector on the Beagle analyzer using "T" connections.
  • The method of connecting the Beagle analyzer to the embedded bus will vary depending on how accessible the signals are on the target system. A USB cable may need to be cut open to connect the wires directly to the target system.

    • If the signal lines are accessible through a header or test pads, then the connection to the Beagle protocol analyzer is straightforward.
    • If the signals are not easily accessible, the wires may need to be soldered directly to IC pins or to copper traces on the printed circuit board, and then connect to the Beagle protocol analyzer.

For more information, please refer to the following documents:

Beagle Protocol Analyzer User Manual

Monitoring an embedded USB with a Beagle USB Protocol Analyzer

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We hope this answers your question. If you have other questions about our Beagle protocol analyzers or other Total Phase products, feel free to email us at sales@totalphase.com or submit a request for technical support.