VirtualLink

{{short description|Failed USB-C alternate mode proposal, intended to connect virtual reality headsets to computers}}

VirtualLink was a proposed USB-C Alternate Mode that was historically intended to allow the power, video, and data required to power virtual reality headsets to be delivered over a single USB-C cable instead of a set of three different cables as it was in older headsets.{{cite web|url=https://www.theverge.com/2018/7/17/17583362/virtuallink-vr-headsets-oculus-valve-microsoft-connect-usb-c-cable|title=The next generation of VR headsets will connect over a single USB-C cable|date=17 July 2018 |publisher=The Verge}}{{cite web|url=https://www.forbes.com/sites/moorinsights/2018/08/17/virtuallink-everything-usb-type-c-is-supposed-to-be/|title=VirtualLink: Everything USB Type-C Is Supposed To Be|work=Forbes|date=2018-08-17}} The standard was supported by Nvidia, AMD, HTC Vive, Oculus VR, Valve, and Microsoft.{{Cite web |url=https://www.anandtech.com/show/13088/virtuallink-announced-standardized-connector-for-vr-headsets |title=VirtualLink USB-C Alt Mode Announced: Standardized Connector for VR Headsets |last=Smith |first=Ryan |date=July 17, 2018 |website=AnandTech |access-date=2018-08-21}} The VirtualLink Consortium was chaired by Rambo Jacoby representing Nvidia.{{Citation needed|date=December 2021}}

VirtualLink specifications

According to its specifications, the VirtualLink cable consisted of:

DisplayPort:
4 × DisplayPort balanced pair data path
DisplayPort HPD (hot-plug detection pin) as a single wire.
DisplayPort AUX signal as a balanced pair
USB 3.1 signals
A USB TX balanced pair for USB 3.0 data
A USB RX balanced pair for USB 3.0 data
I2C wire to control the USB Billboard interface, in case the cable is plugged into an unsupported interface.
VBUS carrying power to HMD visor
GND ground

The USB-C plug pinout specified:{{Citation needed|date=December 2021}}

class="wikitable" !A12 !A11 !A10 !A9 !A8 !A7 !A6 !A5 !A4 !A3 !A2 !A1
GND \|DP[0]+ \|DP[0]− \|V{{sub\|BUS}} \|CC1 \|USBTX+ \|USBTX− \|DP[AUX]+ \|V{{sub\|BUS}} \|DP[2]− \|DP[2]+ \|GND
GND \|DP[1]+ \|DP[1]− \|V{{sub\|BUS}} \|DP[AUX]− \|USBRX− \|USBRX+ \|VCONN \|V{{sub\|BUS}} \|DP[3]− \|DP[3]+ \|GND
B1 !B2 !B3 !B4 !B5 !B6 !B7 !B8 !B9 !B10 !B11 !B12

class="wikitable"

!A12

!A11

!A10

!A9

!A8

!A7

!A6

!A5

!A4

!A3

!A2

!A1

GND

|DP[0]+

|DP[0]−

|V{{sub|BUS}}

|CC1

|USBTX+

|USBTX−

|DP[AUX]+

|V{{sub|BUS}}

|DP[2]−

|DP[2]+

|GND

GND

|DP[1]+

|DP[1]−

|V{{sub|BUS}}

|DP[AUX]−

|USBRX−

|USBRX+

|VCONN

|V{{sub|BUS}}

|DP[3]−

|DP[3]+

|GND

!B2

!B3

!B4

!B5

!B6

!B7

!B8

!B9

!B10

!B11

!B12

Unlike most alt-modes this remapped A7, A6, B6, B7 to carry a USB 3.0 signal, instead of the usual passive USB 2.0 signal. This means that one would not be able to extend the cable using a standard USB-C 3.0 cable, which has these pins mapped only for unshielded USB 2.0 signals. Also this required the VirtualLink port to also detect the correct orientation of the USB-C plug to ensure that the USB 3.0 TX and RX lanes are correctly connected.

In VirtualLink mode, there were six high-speed lanes active in the USB-C connector and cable: four lanes transmit four DisplayPort HBR 3 video streams from the PC to the headset while two lanes implement a bidirectional USB 3.1 Gen 2 channel between the PC and the headset. Unlike the classic DisplayPort USB-C alternate mode, VirtualLink has no USB 2.0 channels active, instead providing a higher speed USB 3.1 Gen 2 (SuperSpeed+) over the same A6, A7, B7, B6 pins. VirtualLink also required the PC to provide 15 to 27 watts of power.{{cite web|title=Virtual reality giants unveil VirtualLink as a standardized cable that may simplify VR rigs|url=https://www.pcworld.com/article/3290466/virtual-reality/virtual-reality-giants-unveil-virtuallink-as-a-standardized-cable-that-may-simplify-vr-rigs.html|work=PCWorld}} No information pertaining to VirtualLink alternate mode compatibility with USB4 (and so Thunderbolt 3 alternate mode) had been published.

To achieve six high-speed lanes over USB-C, VirtualLink required special cables that conformed to version 1.3 of the USB-C standard and used shielded differential pairs for both USB 2.0 pairs.{{cite web|date=7 August 2018|title=VirtualLink Removes Tangles from VR Goggles|url=https://www.eejournal.com/article/virtuallink-removes-tangles-from-vr-goggles/|work=EEJournal}}

The available bandwidth was estimated to be equivalent to DisplayPort 1.4 (32.4 Gbit/s, up to 4K @ 120 Hz with 8 bpc color) for video and 10 Gbit/s of USB 3.1 Gen 2 data.

Implementation in graphics cards and devices

As of March 2023 Sony PSVR2 has a single 5m USB Type-C cable connection to PS5 which seems to be working with Nvidia GeForce 20 series cards as well; because, unlike most ports, VirtualLink must also provide the required 12V via USB Power Delivery, an uncommon voltage, and they additionally support standard two-lane DisplayPort alt-mode, but the PSVR2 headset does not use the actual four-lane VirtualLink alt-mode, pinout or special shielded cable.{{Cite web |title=INFO: Hardware required for PSVR2 :: iVRy Driver for SteamVR PSVR2 |url=https://steamcommunity.com/app/992490/discussions/17/3879344463500344882/ |access-date=2024-01-18 |website=steamcommunity.com |language=en}}{{Cite web |last=iVRy_VR |date=2023-09-28 |title=Author of the PSVR2 PC driver on Reddit |url=http://www.reddit.com/r/PSVR/comments/16tmzmz/no_usbc_on_gpu/k2jtxac/ |access-date=2024-01-18 |website=r/PSVR}}

Nvidia GeForce 20 series cards, initially released in 2018, implemented a single VirtualLink port in all RTX Founders Edition (FE) cards (2060, 2070, 2080, 2080 Ti).{{cite web|last=Lang|first=Ben|date=20 August 2018|title=GeForce RTX Cards Announced with VirtualLink VR Connector|url=https://www.roadtovr.com/nvidia-geforce-rtx-virtuallink-vr-connector/|publisher=Road to VR}} This port was also made available on Quadro RTX cards.{{cite web|title=NVIDIA Unveils Quadro RTX, World's First Ray-Tracing GPU|url=https://nvidianews.nvidia.com/news/nvidia-unveils-quadro-rtx-worlds-first-ray-tracing-gpu|publisher=NVIDIA}}

As of Nvidia's GeForce 30 series cards announcement, all of Nvidia's new Founders Edition GPUs, alongside the partner boards announced so far, lacked a VirtualLink port due to its discontinuation.{{Cite web|last=Smith|first=Ryan|title=NVIDIA Announces the GeForce RTX 30 Series: Ampere For Gaming, Starting With RTX 3080 & RTX 3090|url=https://www.anandtech.com/show/16057/nvidia-announces-the-geforce-rtx-30-series-ampere-for-gaming-starting-with-rtx-3080-rtx-3090|access-date=2020-09-03|website=www.anandtech.com}} By contrast, the AMD Radeon RX 6000 series, announced in October 2020, implemented a VirtualLink port for the first time.{{Cite web|last=Lang|first=Ben|date=2020-10-28|title=AMD Announces Radeon RX 6000-series GPUs with USB-C "for a modern VR experience"|url=https://www.roadtovr.com/amd-radeon-rx-6900-xt-6800-xt-price-release-date-specs/|access-date=2020-11-09|website=Road to VR}}

Discontinuation & abandonment

As of August 2020, the VirtualLink standard had failed to propagate into the virtual reality headset market. The Valve Index had initially developed a VirtualLink accessory, but it was canceled due to technical signaling and reliability issues.{{cite web|title=Valve Cancels VirtualLink Adapter Accessory for Index, Cites Technical Issues & Laptop Adoption|date=3 August 2019 |url=https://www.roadtovr.com/valve-index-virtuallink-adapter-canceled/|publisher=RoadtoVR}} By September of that year, it had been abandoned by its consortium, and the website now redirects to its Wikipedia page.{{Cite web|last=Lang|first=Ben|date=2020-09-03|title=The VirtualLink Single-cable VR Headset Connection Standard Has Been Abandoned|url=https://www.roadtovr.com/virtuallink-connection-standard-abandoned/|access-date=2021-12-11|website=Road to VR|language=en-US}}

References

External links

[https://web.archive.org/web/20200601115559/http://sites.google.com/view/virtuallink-consortium/home?authuser=1 VirtualLink Consortium website]
http://www.virtuallink.org/

Category:USB

Category:Virtual reality headsets

Category:Defunct technology companies

Category:Technology consortia