To USB or Not to USB


Relationships Between USB Specs, Part Two & Where to Learn more about Type-C and DisplayPort alt mode

Recently I blogged on the relationships between USB Type-C, USB 3.1, Power Delivery and DisplayPort specifications. In my last blog I simplified the view focusing on the important and latest specifications. I think the simplified view answer most designer’s questions but there are still a few that like to see the full history and complex interactions. The below image, click to enlarge, provides a more detailed view of the different specifications, timeline representation and relationships.

USB Spec Relationship in full

BC = Battery Charging

PD = Power Delivery

HSIC = High Speed Inter Chip

SSIC = Super Speed inter Chip

DP = DisplayPort

USB = Well if you don’t know what this means why are you reading my blog?

A little commentary on the above representation focusing on the more recent changes. The USB 2.0 specification included everything from the USB 1.1 specification. When the SuperSpeed USB aka USB 3.0 specification was published in 2008, this covered SuperSpeed only so both USB 2.0 and USB 3.0 specs needed to be referenced. The USB 3.0 specification was updated to USB 3.1 in 2013, adding SuperSpeedPlus or USB SuperSpeed 10Gbps capability. In 2014, multiple ECNs (Engineering Change Notices or spec changes and/or clarifications) for USB 3.1 were published. The avid reader would also find two additional specifications; USB Type-C and USB Power Delivery 2.0, a significant update of USB Power Delivery 1.0. Both these specs also received significant updates in 2015, and a new USB Debug Device Class specification was added at the same time. The Debug Device specification ties in and relates to multiple new specifications and updates that were recently published by MIPI, including Gigabit Debug for USB, Trace Wrapper Protocol, SneekPeek Protocol and System Trace Protocol. Surprisingly for most readers, the USB Debug Device Class does not relate to the USB Debug Accessory appendix that was added to the USB 3.1 spec in 2016.

Both USB Type-C and Power Delivery specs have already been updated in 2016, along with a new appendix for USB 3.1 repeaters. Synopsys is a USB-IF contributor. The 2016 spec bundle also includes USB Type-C Authentication specification that ties into both the USB Type-C and Power Delivery specifications, with future implications for USB 2.0 and USB 3.1 devices and hosts.

Did you find this interesting, then Subscribe (oh and read on, I’m not finished.)

To subscribe, click on this link:

To add to the spec ensemble, the Type-C Port Controller Interface spec was published in 2015. The final pieces of the puzzle can be found in the USB Type-C DisplayPort Alternate Mode specification. However, this specification was not published by USB-IF. DisplayPort Alternate mode spec is owned and published by VESA in 2014 and updated in 2015. DisplayPort 1.2a, 1.3 and 1.4 in addition to Display Stream Compression specs are required reading in addition to the DisplayPort Alt Mode spec.

The above represents a flood of specs that add up to thousands of pages where misinterpreting even a single comma, number or part of a sentence can mean the difference between compliance or not. Worst case even between working or not. This is why I simplified the view in the previous blog and why I recommend the DesignWare USB IP as then you don’t have to worry about any of this as we do.

Do you want to know more about USB Type-C and DisplayPort Alt mode?

If yes I highly recommend the recent web seminar on Successful SoC Implementation of USB Type-C and DisplayPort Alt Mode. USB Type-C is the fastest adopted USB standard to date. Designers are busy adding Type-C capability to existing products and requesting SoC designers to add native USB Type-C support in next-generation SoCs. The main advantage for users of the USB Type-C connector is the flippability of the connector. One small and robust connector for data, video and power is advantageous for portable products, and appreciated by end-users if implemented properly. However, USB Type-C implementation is non-trivial and specification updates are frequent.


This webinar discusses how to integrate USB Type-C and DisplayPort controllers and PHY IP in your next SoC. This includes solving the hardware and software partitioning challenges for an efficient, flexible and successful USB Type-C implementation. We will also provide a brief overview of Synopsys’ DesignWare® USB-C/DisplayPort IP solution which integrates USB Type-C, USB 3.1 and DisplayPort 1.3 interfaces with High-bandwidth Digital Content Protection (HDCP) 2.2.

Attend this webinar to learn about:

  • How Alt Mode affects SoC design
  • How to implement the Type-C Port Controller to address multiple SoC design challenges
  • Effective software partitioning for the Type-C Port Manager
  • Challenges and solutions to implementing the USB and DisplayPort datapath switch
  • Creating a cost, power, area and performance-optimized USB Type-C design

Who should attend?

Design engineers, design managers, and system architects who are interested in implementing USB Type-C in their next SoC

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