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USB2.0 LPM L1 Compatibility | Cypress Semiconductor

USB2.0 LPM L1 Compatibility

Summary: 2 Replies, Latest post by dadeur on 03 Aug 2016 11:35 PM PDT
Verified Answers: 0
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dadeur's picture
30 posts

Hi all,

I'm dealing with USB-IF certification for a device build using a FX3S. The test performed with USB 3 Gen X Command Verifier (Chapter 9 Tests) goes smooth for the USB3.0 part but, if I put an USB2.0 hub in the middle and attempt the USB2.0 part there is a fail:


Now Starting Test: L1Suspend/Resume Test (Configuration Index 0)
Start time: Mon Aug  1 14:54:36 2016

Checking Device Under Test for LPM L1 Compatibility...
USB version of device is 2.10.
DUT IS compatible with LPM.
LPM IS required for DUT
USB 2.0 Extension Descriptor bmAttributes:
    LPM Capable = 1
    BESL and Alternate HIRD Supported = 1
    Baseline BESL Valid = 0
    Deep BESL Valid = 0
    Baseline BESL: 0d
    Deep BESL:  0d
Device Under Test is LPM Compatible.
Upstream port is LPM Compatible.
Parent port of DUT does not support L1C.
Test failed

Stop time: Mon Aug  1 14:54:37 2016
Duration:  1 second.
Stopping Test [ L1Suspend/Resume Test (Configuration Index 0):
     Number of: Fails (1); Aborts (1); Warnings (0) ]

Does somebody know what "L1C" means (above sentence "Parent port of DUT does not support L1C") ?

Is there some FX3 fw example on how to correctly manage USB2.0 LPM L1 compatibility?


Thanks a lot,


mady's picture
Cypress Employee
964 posts

When you use a different 2.0 hub and when you do not use a 2.0 hub (And making Fx3 to work in 2.0 mode alone in the firmware), do you face this issue? Also, you can use any of our example projects for compliance testing. (typically USBBulkLoopAuto, USBBulkSourceSink


-Madhu Sudhan

dadeur's picture
30 posts

Hi Madhu, thanks for your reply.

It seems that the problem was caused by the hub. Many USB2.0 hubs (expecially the old ones) don't support the new L1 LPM, and this makes the test fail.

If I use a USB2.0 cable to connect the device and the USB3.0 host's port, the test passes.



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