Plan For Successful USB Compliance Testing (Part III)

Figure 1: In USB 3.0 link-layer compliance test,
all logical states of the LTSSM come into play

In Part I and Part II of this series on USB compliance test, we've looked at some of the basic information on compliance testing and at some aspects of physical-layer test, respectively. In this third part of the series, we'll turn our attention to USB 3.0 link-layer testing.

Plan For Successful USB Compliance Testing (Part II)

Figure 1: A representative transmitter
compliance test setup

In the first post in this series, we looked at some of the basics of USB 3.0 and 3.1 compliance test and covered the USB-IF's role in overseeing the protocol. Now, let's look into some aspects of physical-layer test.

Plan For Successful USB Compliance Testing (Part I)

Figure 1: The coveted SuperSpeed USB logo

Certifying a device's implementation of a serial protocol standard is a fairly complex process involving a number of levels: electrical test, interoperability, backward compatibility, link layer, and so on. Generally, some organization oversees a given protocol, managing the revision process for the protocol itself as well as the testing process that a product must undergo. Passing the relevant compliance test suite and having a valid Trademark License Agreement on file bestows the prized right to display the protocol's logo on the product's box (Figure 1). That logo's presence tells the product's users that their device's serial interface operates within parameters set by the overseeing organization.