The next-generation USB “Type C” standard that became available to manufacturers last month will also offer a “DisplayPort Alternate Mode”, enabling the new USB cables to “deliver full DisplayPort audio/video (A/V) performance, driving monitor resolutions of 4K and beyond, SuperSpeed USB (USB 3.1) data and up to 100 watts of power–over a single cable.” That means new USB cables that adopt the new slimmer Type-3 standard can essentially also work as a full-fledged DisplayPort cable. The announcement was made today by The Video Electronics Standards Association (VESA), which worked with the USB 3.0 Promoter Group to offer the functionality:
The result is manufacturers might be able to remove DisplayPort, VGA, and HDMI ports from their devices and offer power, USB data, audio, and video over the single USB Type C cable. Although you’ll also still be able to use USB Type C to drive DisplayPort, HDMI, DVI or VGA displays using an adaptor. Reports claim a rumored 12-inch MacBook Air will arrive next year with USB Type C only for its USB ports and that would make DisplayPort Alt Mode quite important for new MacBook owners in 2015. “By leveraging USB Type-Cs flexibility, the DisplayPort Alt Mode can choose to transmit on just one or two of the four available lanes, so that the other two lanes can be used for SuperSpeed USB data at the same time. In a docking station connection, for example, the use of two lanes for DisplayPort at 8.1 Gbps per lane would allow simultaneous transfer of SuperSpeed USB data (up to 10 Gbps in each direction) while also supporting a 4K UHD (3840 x 2160) DisplayPort monitor.”
VESA utilized the Alternate Mode functional extension of the USB Type-C specification in the development of this new Standard. The DisplayPort Alt Mode repurposes some or all of the four existing SuperSpeed USB lanes to deliver full DisplayPort performance, and uses other signaling available in the USB Type-C connector for DisplayPorts AUX channel and HPD (Hot Plug Detection) function. This enables computers, tablets, smartphones, displays, and docking stations to implement the new USB Type-C connector at both ends while using the DisplayPort Standard over USB Type-C to transmit high-resolution A/V along with USB data and power.
VESA says initial DisplayPort Alt Mode USB Type-C devices will use the current DisplayPort 1.2a, which supports 5.4 Gbps per lane and up to 4K (4096 x 2160) resolutions at a 60Hz frame rate. That means we’ll likely see USB Type C also support the recently announced DisplayPort 1.3 standard that offers a higher 8.1 Gbps per-lane link rate and as a result support for next-gen 5K displays.
