Support Question of the Week - USB Power Management

Q:  I have a Beagle USB 480 Protocol Analyzer. I need to know if it does support LPM-L1 and, if it does not, which product of yours would support it.

A: LPM-L1 is one level (LPM-L2 is the other) of the power management aspect of the USB 2.0 specification.  We do decode LPM packets and will show the suspend/resume events for USB 2.  The real-time decoding applies to the Beagle USB 480 analyzer and Beagle USB 5000 series (all models) analyzers.

The table below, excerpted from a white paper by Intel entitled "energy-efficient-platforms-white-paper.pdf", details the differences between the L1 (sleep) and L2 (suspend) states.

Comparison of LPM-L1 and LPM-L2 for USB 2.0 Comparison table of LPM-L1 and LPM-L2 for USB 2.0.
Excerpted from Intel White Paper

The equivalent for USB 3.0 is called LTSSM (Link Training Status State Machine).  It is fully supported in any of our Beagle USB 5000 v2 Protocol Analyzers (standard feature on the 'Standard' and 'Ultimate' models, upgrade required to enable this feature on the USB 2.0 model).

There's a great video on our website which shows how the LTSSM view in Data Center can be used for USB 3.0 debugging.

Power management is becoming more important across all the protocols we serve - I2C, SPI, USB and CAN.  Whether it's lower voltage for your I2C bus or SPI bus, or power management features for your USB bus, our tools are designed to help provide visibility into your bus level transactions.

Do you have a question about your Total Phase products, other protocols, or suggestions for new protocols – let us know here.

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