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USB - Details on electrical requirements

MerlinC
Protege
After recently upgrading my graphics card to GTX1080 (worked well with my GTX780 but with performance limitations) and not paying attention to what USB 3.0 port I used for the specific devices I had recurring sensor and HDMI failures. The only way to get around the issue I was able to find by trial and error is to plug the sensor to a USB 2.0 port.

Reading all the issues with regard to USB connection of the rift I assume that my USB 3.0 Ports are not able to provide the power/current required by the sensor and/or headset. According to the motherboard  manufacturer the USB ports are according to USB 3.0 standard.

Due to not having had any issue with other USB devices I assume that the current drawn by my rift is either n the edge or over the rated power for USB 3.0 ports. Was not able to find any information what maximum current is specified for the sensor and headset.

Could you please provide this information?
45 REPLIES 45

Nick_Bb
Explorer

I found that using USB2 for sensors are very prone to poor tracking quality errors when there are sunlight in their way. My 3rd sensor is partially facing the window, works well during the evening, I never used the rift during the day so I never encountered this problem till now. The errors went away after I changed to a USB3 extension.

As for the hmd's usb is only 200mA. Maybe the hmd's panels got its power from hdmi with some type of mhl.




MerlinC
Protege

Nick_Bb said:


...The errors went away after I changed to a USB3 extension. ...

What do you mean with USB3 extension? An active USB 3.0 extension cable?

P.S.: Most people (including myself) do have the issues just connecting the original cable of the sensor to an USB 3.0 port.

Nick_Bb
Explorer

MerlinC said:


Nick_Bb said:


...The errors went away after I changed to a USB3 extension. ...

What do you mean with USB3 extension? An active USB 3.0 extension cable?

P.S.: Most people (including myself) do have the issues just connecting the original cable of the sensor to an USB 3.0 port.

I used 4 AmazonBasics USB 3.0 Extension Cable for all 3 sensors and the hmd.
2 sensors are connected to a USB3 hub that is connected to the MSI G45 motherboard.
3rd sensor and hmd is connected to Inateck Superspeed 4 Ports




TwoHedWlf
Expert Trustee
I tried turning on the hmd and then refreshing,  no change to the power mode.  Wonder if even if the power mode is 100ma it can still draw 1000ma or whatever the max the port can provide? 

I could see this causing problems if some chipsets enforce the limit and some don't. 

kojack
MVP
MVP
The idea is that usb devices can define multiple configurations for different uses, the host can choose which one to use. For example a device could say it has both a low current mode that is self powered (uses a power adapter or batteries) or a high current one that is host powered. The host can then decide which mode the device should use (a laptop on batteries could say to use the low power mode, while a laptop on wall power could use the high power one).

This is the interesting bit though, from http://www.beyondlogic.org/usbnutshell/usb5.shtml
If a device loses external power, then it must not drain more than
indicated in bMaxPower. It should fail any operation it cannot perform
without external power.
That talks about external power, but I think it's generally applicable.
What if the sensors are reporting a bMaxPower lower than they need, then disconnecting/glitching rather than going over that value. Or maybe some motherboard chipsets are providing slightly less than the requested max current.

I had a western digital portable hard drive. It only worked on really short usb cables, on a slightly longer one it just couldn't get enough current (usb hard drives were notorious for trying to pull more than usb was supposed to support).

The other interesting thing is that USBPcap (usb packet sniffing) can see my rift sensors on my laptop (it's usb3 is fully rift friendly) and on my desktop's usb2 ports. But on the desktop's usb3 ports that are glitchy (frequent disconnects, when it decides to work), it can't see them at all. Everything else is there, just not the rift.



Author: Oculus Monitor,  Auto Oculus Touch,  Forum Dark Mode, Phantom Touch Remover,  X-Plane Fixer
Hardware: Threadripper 1950x, MSI Gaming Trio 2080TI, Asrock X399 Taich
Headsets: Wrap 1200VR, DK1, DK2, CV1, Rift-S, GearVR, Go, Quest, Quest 2, Reverb G2

kojack
MVP
MVP
I saw a thread on reddit about tracking issues, and two people have both claimed that turning motherboard XMP on or off reliably controlled if their sensors glitched. XMP on gave frequent glitches, XMP off and everything worked fine. Tested multiple times with no other changes.

XMP does auto configure of ram based on profiles embedded in the ram modules. It includes power settings.
If XMP is cranking up the voltage more than default, that could negatively affect the usb host I guess?

I can't even get into my bios at the moment, it has stopped accepting my K95 keyboard during bios start.


Author: Oculus Monitor,  Auto Oculus Touch,  Forum Dark Mode, Phantom Touch Remover,  X-Plane Fixer
Hardware: Threadripper 1950x, MSI Gaming Trio 2080TI, Asrock X399 Taich
Headsets: Wrap 1200VR, DK1, DK2, CV1, Rift-S, GearVR, Go, Quest, Quest 2, Reverb G2

Hornet_F4C
Adventurer
If power supply is an issue I wonder if they could provide a powered break-out box for people with more than two sensors? On the PC side the break-out box could even have two USB connectors along the HDMI connector, thus could be connected to two indpendend USB controllers if desired. And of course it could get power from an ac adaptor. Further it would easily give another meter of cable length and could also provide some intelligent connector system to protect the ports from pulling the cable...
Of course it should offer a rock steady 4 sensor setup to justify itself.
Would certainly be a welcome addition, no?

stevieh
Honored Guest
I had my Oculus replaced for black screen issue just received the new one today and have the same issue, gutted!

MerlinC
Protege

stevieh said:

I had my Oculus replaced for black screen issue just received the new one today and have the same issue, gutted!


Sorry to hear that a replaced device did not solve the issue.

On the other hand it's not a big surprise to me because fixing an issue requires to accept that there is currently a design issue.

All feedback from Oculus I received so far is more in the direction that they are assuming that the root cause is not at there device (e.g MS windows, USB cards although certified by USB.org not compatible, etc).

But I have not seen that Oculus either acknowledged that there is an issue or provided evidence that there device can't be the root cause.

Let's start with the USB interface and cabeling. Why is it that difficult to provide the current drawn from the devices sensor/HMD? If they are in the limits specified by USB standard I do have something in my hands to get either back to my motherboard or USB card vendor. 

Next would be USB cabeling. Carefully reading USB 3.0 articles you can figure out that there is no maximum cable length - but due to the higher bandwidth - there must certain specification met that USB 3.0 works reliable. Thus cables a lot of high quality (higher priced) cables starting with a cable length are having an amplifier integrated to guarantee sufficient signal quality.

Furthermore you can read that meeting this requirements will increase the cost and effort on the cable side if cable length is greater 3m - and we get a cable which 5 m and can't be replaced with a shorter standard cable. Thus Oculus please do us and yourself a favor and execute the USB 3.0 compliance tests and get it certified by USB.org (or provide the technical data to your customers).

You might want to consider a revised design providing standard USB and HDMI connectors than people can choose there preference of cable length and supplier. And spare cables would be no issue anymore.

MerlinC
Protege


Further it would easily give another meter of cable length and could also provide some intelligent connector system to protect the ports from pulling the cable...


On the USB side I don' think that higher output current will simple enable higher cable length - enabler (and challenge) is meeting the USB electrical cable requirements independent of length.