How do Beagle USB Protocol Analyzers Control the VBUS to the Target Device?

Question from the Customer:

I have the Total Phase Beagle USB 480 Protocol Analyzer and am testing some bus-powered devices. Is it possible to use the Beagle Software API to disconnect and connect the VBUS (and thereby disable the  USB signals from the target device) to simulate manually unplugging and then plugging in the cable? If not, do you have more advanced protocol analyzers that can support this simulation?

Response from Technical Support:

Thanks for your question! The Beagle 480 analyzer does not support the simulation of disconnecting and reconnecting the VBUS. However, we do have USB analyzers that can do that job for you. The Beagle USB 480 Power Protocol Analyzer series (Standard Edition and Ultimate Edition) and the Beagle USB 5000 v2 Protocol Analyzer series (USB 2.0 Edition, SuperSpeed - Standard Edition and SuperSpeed -Ultimate Edition) provide the options of connecting and disconnecting the VBUS.

beagle480power_200  Beagle5000_200
Fig 1: Beagle USB 480 Power Protocol Analyzer - Standard Edition Fig 2: Beagle USB 5000 v2 Protocol Analyzer - USB 2.0 Edition

Controlling VBUS via API:

For both the Beagle USB 480 Power analyzers and the Beagle USB 5000 analyzers, a Beagle API function, bg_usb_target_power, can be used to control the VBUS that is provided to the target device, or to disconnect the target VBUS to/from the host VBUS. For more information about the Beagle Software API, please refer to section 6 of the Beagle Protocol Analyzer User Manual.

Controlling VBUS via Manual Control:
In addition to controlling the VBUS via API, the Beagle USB 5000 analyzers have a Target Power indicator that controls VBUS and shows if the VBUS is connected or disconnected, with:

  • A large white circular button, which can be pressed to disconnect and pressed again to reconnect the VBUS between the target host and the target device.
  • An LED (located in the upper right corner of the button) that is illuminated when the VBUS is present. Alternatively, the LED turns off when the button is pressed to disconnect the VBUS.

For additional information about this feature, please refer to section 2.1 of the Beagle Protocol Analyzer User Manual.

Additional resources that you may find helpful include the following:

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 sales@totalphase.com, or if you already own one of our devices and have a technical question, please submit a request for technical support.

Leave a Reply