Wednesday, September 24, 2014

USB Type-C connector will also support DisplayPort: Finally, one cable will fit every hole

Every single one

The USB Promoters Group and VESA have announced that the new reversible USB Type-C connector, along with supporting power delivery of up to 100 watts, will also support the simultaneous transport of DisplayPort 1.3 — and thus HDMI 2.0 and DVI will also work, with an adapter. Yes, it’s looking like USB 3.1 with the Type-C connector will finally be a workable all-in-one cabling solution. Thunderbolt, we hardly knew you.

It has been a busy few weeks for the USB Promoters Group — the consortium of tech companies that develop the USB standards. Last month, it announced that the long-sought-after reversible Type-C connector was finally ready for mass production — and then last week, it announced that the USB Power Delivery 2.0 spec had been finalized. The Power Delivery 2.0 spec didn’t appear to be very exciting at first glance, except for a rather mysterious new feature called “Alternate Modes.” Alternate Modes allows other, non-USB data to be carried over the USB 3.1 Type-C connector. At the time, it wasn’t clear what these Alternate Modes might be.

Now, VESA — the Video Electronics Standards Association — is announcing that it has developed a DisplayPort Alternate Mode standard for the USB Type-C connector. In short, with adequate support from device makers, this now means that dedicated display ports are no longer needed. Instead of having a range of DisplayPorts, HDMI ports, DVI ports, and USB ports, your device could simply have a bunch of USB Type-C ports.

USB Type-C connector, with DisplayPort using some of the Superspeed lanes

On the technical side of things, it just so happens that DisplayPort has a very similar physical layer to USB 3.1. USB 3.1 has four lanes — eight wires/pins — for differential Superspeed transport, along with the standard four pins for legacy USB 2.0 connections. The DisplayPort protocol also uses four lanes/eight wires. In VESA’s DisplayPort Alternate Mode, DisplayPort would simply take over some or all of USB 3.1′s Superspeed lanes. One lane — 10Gbps — would be more than enough for most display output scenarios, leaving plenty of bandwidth available for other applications.

The only feature of DisplayPort that won’t work over the Type-C Alternate Mode is Dual-Mode DisplayPort (DP++), which means you’ll need to use active adapters if you want to plug the Type-C connector into an HDMI, DVI, or VGA socket.

USB Type-C connector, with DisplayPort and Power Delivery possibilities

USB Type-C connector with DisplayPort legacy modes to DVI/HDMI/etc.

Moving forward, VESA says the first devices with USB Type-C connectors that also support DisplayPort Alternate Mode will arrive in 2015. Mobile devices will probably be the primary focus, where having a few tiny Type-C ports is much more desirable than cramming a MHL or DisplayPort socket p into the design. Presumably desktop motherboard makers and discrete graphics card vendors will follow suit at some point in 2015/2016, too.

USB Type-C connector, cable (Click to zoom in)

The addition of Alternate Modes to the USB standard is a very big deal. Don’t forget, all of this is in addition to the tthe USB Power Delivery spec, which will allow for up to 100 watts to be carried over the Type-C connector. A future version of Thunderbolt may also have many of the same features of USB 3.1, including higher-wattage power delivery — but under Apple’s auspices it will never, ever reach ubiquity in the same way that USB has done. With the Type-C connector, we now have a single cable/socket that can attach peripherals like mice and digital cameras, your laptop to the power brick, or your smartphone to a desktop monitor. The Type-C connector is the same on both ends, too – you can quite literally grab any USB Type-C cable, plug both ends into just about any kind of device, peripheral, or power outlet… and it’ll just work.

Yes, in the not-so-distant future, you may live in a world where every cable fits every hole. Take a moment out of your busy day and just think about that for a few minutes. Personally, if I never again have to reach behind my PC and try to blindly plug in a DVI connector, I will die happy.

Source: ExtremeTech

The Chief Technomancer
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