To USB or Not to USB


USB Compliance and Labor Day

The first Monday in the U.S. is Labor Day

In China, it’s a regular work day, as my friend working for a China Corp told me.

The rigorousness and effort in authoring and executing the USB Certification program is likely the primary reason for the ubiquity of USB.  Companies use the USB Implementers Forum (USB-IF) procedures to test their products even if they don’t go for formal logo certification.  The procedures are free, the tools are (relatively) inexpensive.   (Okay, the electrical analyzers and protocol analyzers will set you back up to 100k for a set).  The USB Implementers Forum maintains multiple certification procedures including host systems and peripheral systems.

There are five components to achieving certification.

1) Protocol testing – The USB Command Verifier needs to be run for all speeds supported.

2) Gold tree testing – Test against a USB 2.0 and/or a USB 3.0 standard tree of peripherals as defined by the USB IF.  This includes 5 layers of hub that form the trunk, and peripherals forming the branches.  The peripherals are designed to test the different transfer types.

– A host needs to support the entire Gold Tree.

– A device needs to plug in at the highest branch of the tree.

USB 3.1 Host Gold Tree

3) Electrical testing – Important for PHYs so they can talk to other PHYs.  A good PHY can transmit over cables and sometimes even bad cables.  A bad PHY will transmit across shorter cables, and will be slower.   This is critical to the system really working well.

4) Certification checklist – The USB-IF provides a standard checklist. It has a range of questions with open fields for answers.  This helps guide product makers in designing their system properly for compliance.

5) Interoperability testing – In addition to gold tree testing a range of USB 3.0 and 2.0 peripherals. If being tested at a plugfest, it must pass testing with something like 90% of the peripherals brought to testing.

Once certified, a product goes on the USB Integrators List.  Only USB Members can see this list (it isn’t public).  This allows the manufacturer to use the USB Logo on the exact product that was certified.   In the case of IP, any product with the IP that gets certified, gets the IP certified.

In Synopsys’ case, the PHY and controller have been certified hundreds of times by Synopsys, and 1000s of times by customers.


I tried to use Siri to write part of this article.  This is the first sentence it recorded.

“The ubiquity of USB is quite probably due to thehigh quality of idiots.”


Also, I couldn’t find any safe for work Labor Day jokes so here are some quotes.

I can’t give you the source, but if you google “labor day jokes” you will find all five on one site.

  • Hard work never killed anybody, but why take a chance?  Edgar Bergen
  • Every day I get up and look through the Forbes list of the richest people in America. If I’m not there, I go to work.  Robert Orben
  • Whenever you are asked if you can do a job, tell ’em, “Certainly, I can!” Then get busy and find out how to do it.’  Theodore Roosevelt
  • One of the symptoms of an approaching nervous breakdown is the belief that one’s work is terribly important.  Bertrand Russell
  • Be regular and orderly in your life, so that you may be violent and original in your work. Gustave Flaubert


Share and Enjoy:
  • Digg
  • Facebook
  • Google Bookmarks
  • Print
  • Twitter
  • StumbleUpon
  • LinkedIn
  • RSS