Subscribe to feed Viewing entries tagged USB Compliance Testing

How USB 3.0 Host Controller Certification Works

Posted by Terry Moore
Terry Moore
User is currently offline
on Tuesday, 16 October 2012
in USB 3

As we announced today, MCCI's customer ASMedia received certification for their xHCI 1.0 host controller.

I thought it would be interesting to summarize how the USB-IF host controller certification process works in practice.

The process starts when the host controller vendor (ASMedia in this case) books a week-long slot at the USB-IF SuperSpeed USB Platform Interoperability Lab (or "PIL"). This lab is located in Portland, Oregon. ASMedia is a USB-IF member company, which is good: slots are only available to member companies.

Slot availability is limited, and demand is high -- this is the only place where you can currently certify SuperSpeed host controllers and hubs. Recently, the lead time seems to be about four to six weeks.

When the scheduled time arrives, companies typically send hardware, software, and system engineers to the PIL to perform testing and debug problems. A number of different tests are performed.  

  • Electrical and low-level tests check the performance of the USB 3.0 PHY.  These are low-level analog tests; they check eye diagrams, bit error rates, and other functions that are handled by low-level hardware.
  • Device functionality tests check the ability to operate specific reference devices correctly. These tests are not limited to plugging in the device and verifying function; they also exercise the devices and the system in various power management scenarios (suspend, hibernate, reboot, shut down).
  • Gold Tree tests check the performance of the host controller when operating a referece tree of hubs and known devices. Again, these tests are not merely functional, but also include power management.

The device functionality tests, and the gold tree tests, require that a Windows-compatible host stack be supplied by the host-controller vendor. This is where MCCI comes in. Standard class drivers from Microsoft and third parties are used over the vendor stack (which we provided to ASMedia). Everything has to work exactly as they work on the reference stack and reference host controller. For high-speed (USB 2.0) devices, the reference host controllers is the EHCI controller; for full-speed and low-speed devices, the reference is the UHCI controller. The reference stack in either case is the Microsoft USB stack.

The point of doing this testing is two fold: it proves that the ASMedia host controller can generate the appropriate bus traffic in response to the many different patterns generated by the devices and their associated class drivers. It also proves that the MCCI stack will operate successfully in all these scenarios, and will emulate the Microsoft USB stack well enough that the class drivers will operate without problems.

A consequence, however, is that the software and hardware are co-tested. Whenever a problem arises, the software developers and hardware developers must work together to determine if the problem is in hardware or software. Then the teams must collaborate to determine the best resolution. Sometimes special software versions must be built to highlight the bug for the hardware team and to make it easier to reproduce. In this case (as at previous PIL tests by our customers), MCCI sent an engineer to work on-site with ASMedia's engineers throughout the PIL process.

Of course, not every test passes initially. The process of getting certification for early hardware and software was frustratingly slow. We'd test for a week, then return to our labs, while we waited for the next available slot. When we returned, we often found that the PIL engineers had improved their tests. This is good for the industry, but frustrating for the engineers; we'd return thinking that all was well, only to learn that new tests were finding new problems.

On the other hand, it means that passing the test is a real accomplishment, both for ASMedia's team and for MCCI's team. Congratulations to all the engineers involved!

Hits: 2397 0 Comments
0 votes

MCCI Authorized to Perform USB 3.0 SuperSpeed Certification Testing

Posted by Terry Moore
Terry Moore
User is currently offline
on Tuesday, 12 June 2012
in USB 3

MCCI has been authorized to perform USB 3.0 SuperSpeed certification testing, as part of the independent test lab program organized by USB-IF.

The full details are in our press release:  2012-06-11-superspeed-testing.pdf.

For a sample of the press-release "as run", check out PRnewswire or Yahoo finance.

We updated our USB test FAQ and our compliance overview pages.

Congratulations to our hard-working USB test team!


Hits: 2406 0 Comments
0 votes
Legal and Copyright Information