USB 3.1 is here and it needs testing. From higher data rates (10 Mbps) to a new reversible connector (Type-C), to higher power deliver (100 W), USB will become truly universal. If you’ve seen (or have) a new MacBook, then you’ve seen the new connector, which is the only connector on the computer besides a headphone jack. As more devices shift to USB 3.1, engineers will have to design it in and test it.
In a series of three articles, Randy White of Tektronix explains what you need to know to get started testing USB 3.1. Keep in mind that the name USB 3.0 is no longer officially in use. What you know as USB 3.0 (5 Mbps) is now USB 3.1 Gen1. What have been called USB 3.1 (10 Mbps) is officially known as USB 3.1 Gen2.
USB 3.1 testing: Start to finish, part 1 charts the differences between USB 3.1 Gen1 and USB 3.1 Gen2. Those differences are not only data rate, but encoding, equalization, and eye height. The table below shows those differences. Part 1 also covers transmitter and receiver testing.
USB 3.1 testing part 2: Type-C cable assemblies explains what’s behind the new Type-C Connector. Finally, USB cables will be reversible in two ways, assuming you have Type-C connectors at both ends. That is, both ends of the cable have the same Type-C connector and both ends will work regardless of their orientation. How many times day do you have to reverse a USB Type-A or Micro-B USB connector to get it into the socket? Type-C does away with that. The article explains Alt Mode and that a Type-C cable can also carry DisplayPort video signals. Finally, the article discusses compliance testing, showing you waveforms and S-parameters.
USB 3.1 testing part 3: Power Delivery shows you test setups for USB PD (Power Delivery). You’ll see how PD can adapt so that either of two devices can provide power to the other as needed. PD Rev. 2.0, Version 1.1 was released in May 2015. It covers the Type-C cable with four power/ground pairs and a separate configuration channel (CC), which now hosts a DC coupled low-frequency BMC (Biphase Mark Code)-coded data channel that is intended to help reduce RF interference.
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