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.[1][2] The standard was supported by Nvidia, AMD, HTC Vive, Oculus VR, Valve, and Microsoft.[3] The VirtualLink Consortium was chaired by Rambo Jacoby representing Nvidia.[citation needed].
VirtualLink specifications
editAccording 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]
| A12 | A11 | A10 | A9 | A8 | A7 | A6 | A5 | A4 | A3 | A2 | A1 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| GND | DP[0]+ | DP[0]− | VBUS | CC1 | USBTX+ | USBTX− | DP[AUX]+ | VBUS | DP[2]− | DP[2]+ | GND |
| GND | DP[1]+ | DP[1]− | VBUS | DP[AUX]− | USBRX− | USBRX+ | VCONN | VBUS | DP[3]− | DP[3]+ | GND |
| B1 | 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.[3][4] 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.[3][5]
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.[3]
Implementation in graphics cards and devices
editAs 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.[6][7]
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).[8] This port was also made available on Quadro RTX cards.[9]
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.[10] By contrast, the AMD Radeon RX 6000 series, announced in October 2020, implemented a VirtualLink port for the first time.[11]
Discontinuation & abandonment
editAs 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.[12] By September of that year, it had been abandoned by its consortium, and the website now redirects to its Wikipedia page.[13]
References
edit- ^ "The next generation of VR headsets will connect over a single USB-C cable". The Verge. 17 July 2018.
- ^ "VirtualLink: Everything USB Type-C Is Supposed To Be". Forbes. 2018-08-17.
- ^ a b c d Smith, Ryan (July 17, 2018). "VirtualLink USB-C Alt Mode Announced: Standardized Connector for VR Headsets". AnandTech. Retrieved 2018-08-21.
- ^ "Virtual reality giants unveil VirtualLink as a standardized cable that may simplify VR rigs". PCWorld.
- ^ "VirtualLink Removes Tangles from VR Goggles". EEJournal. 7 August 2018.
- ^ "INFO: Hardware required for PSVR2 :: iVRy Driver for SteamVR PSVR2". steamcommunity.com. Retrieved 2024-01-18.
- ^ iVRy_VR (2023-09-28). "Author of the PSVR2 PC driver on Reddit". r/PSVR. Retrieved 2024-01-18.
- ^ Lang, Ben (20 August 2018). "GeForce RTX Cards Announced with VirtualLink VR Connector". Road to VR.
- ^ "NVIDIA Unveils Quadro RTX, World's First Ray-Tracing GPU". NVIDIA.
- ^ Smith, Ryan. "NVIDIA Announces the GeForce RTX 30 Series: Ampere For Gaming, Starting With RTX 3080 & RTX 3090". www.anandtech.com. Retrieved 2020-09-03.
- ^ Lang, Ben (2020-10-28). "AMD Announces Radeon RX 6000-series GPUs with USB-C "for a modern VR experience"". Road to VR. Retrieved 2020-11-09.
- ^ "Valve Cancels VirtualLink Adapter Accessory for Index, Cites Technical Issues & Laptop Adoption". RoadtoVR. 3 August 2019.
- ^ Lang, Ben (2020-09-03). "The VirtualLink Single-cable VR Headset Connection Standard Has Been Abandoned". Road to VR. Retrieved 2021-12-11.