Forum Discussion

dgr4it's avatar
dgr4it
Iron Contributor
Jun 25, 2020

Touchback not working with USB-C display (Surface Hub 2S)

We just got two Surface Hub 2S at work, but I've been unable to make touch-back work on a single USB-C cable.   https://docs.microsoft.com/en-us/surface-hub/surface-hub-2s-connect, it's supposed to...
cezarcretu's avatar
cezarcretu
Icon for Microsoft rankMicrosoft
Jun 29, 2020

Hello dgr4it,

 

Could you try with another USB-C cable or test with another device? 

If this returns the same behavior, kindly open a support case to investigate

 

Thank you,

Cezar 

dgr4it's avatar
dgr4it
Iron Contributor
Jul 03, 2020

cezarcretu One last question, on top of my previous question on the particular cable you linked.

 

I have noticed that the https://docs.microsoft.com/en-us/surface-hub/surface-hub-2s-connect website lists the maximum resolution being mailto:4K@30Hz, whereas all the devices are mentioned were outputing mailto:4k@60Hz through the USB-C connection.

 

Could it be that touch&pen back don't work when using 60Hz ?

  • cezarcretu's avatar
    cezarcretu
    Icon for Microsoft rankMicrosoft
    Jul 06, 2020

    Hello dgr4it,

     

    4K@60Hz is the output EDID from the Surface Hub to another device. Input is @30Hz .

    Are you connecting the USB-C cable in the compute module? What happens if you switch to one of the USB-C side ports? This won;t have 4K resolution but it would help to understand if it's related to 4K resolution.

    On the PC, can you see the Surface Hub in Device Manager?  

    • dgr4it's avatar
      dgr4it
      Iron Contributor
      Jul 10, 2020

      cezarcretu Actually, after so much testing on complicated scenarios, I have just discovered that Touch-back is simply not working at all.

      I always had the USB-C plugged when using Miracast, so I thought that's how I was getting pen & touchback, but I just didn't know Miracast could do that without USB.

       

      So in the end, I'll sum up my issue by:

      1. Touchback Host seems properly installed on the Hub2S (tried removing it and enabling it again)
      2. Touchback Guest properly installs on a wide array of devices, but only when using the Compute Module USB-C (none of the other ports react)
      3. There is no touch nor pen input no matter how I connect those devices. Tried :
        1. Both with the USB-C single cable and with HDMI display + USB-C for touchback on the compute module).
        2. A Surface Pro 7 on W10 1903, Lenovo T490S on 1909, and Intel NUK 10th gen on 2004
        3. A total of 3 different USB-C cables of the right spec.

      I'd guess there are only three possibilities left:

      1. There is an issue with both of the Hubs we got.
      2. Our IT guys applied some Group Policy which is blocking the touch functionality (probably unintended)
      3. The hub is missing some driver updates that might not be delivered because of WSUS policy)

       

      I'd love to know if there is an easy way to find out the cause.

      • cezarcretu's avatar
        cezarcretu
        Icon for Microsoft rankMicrosoft
        Jul 10, 2020

        Hello dgr4it,

         

        So to sum it up, you tried to use a single USB-C cable connected to the compute cartridge and to a laptop and touchback/inkback did not work. You also tried to use a HDMI cable and USB-C cable to another laptop and still no luck.

        It should work seamlessly so it does look like something is blocking it. Can you please open a case so we can address this in a remote session? If you're in EMEA time, I'd be happy to give you a call

         

        Thank you,

        Cezar

    • dgr4it's avatar
      dgr4it
      Iron Contributor
      Jul 07, 2020

      cezarcretu I tried quite a few more things on the Surface Pro 7 (W10 1903) today.

      Please see the attached screenshots but, in short:

      • Yes, I am connecting the USB-C cable on the Compute Module, since there is no video (at all) on any other connector.
      • I know the Hub 2S is supposed to be mailto:4K@30Hz, but using the recommended resolution which is automatically identified by any device I've tried (3672 x 2448), it sets up at 60Hz (and you can tell by the responsivity that it's indeed 60Hz)

      • When using the maximum available resolution (3840 x 2560) then it goes at 30Hz.

      • I can't get touch-pen to work no matter which resolution I use when using the USB-C Gen2 cables linked before, despite the Surface Hub being properly recognized (or so I believe, please check the attachments).

       

      • If I connect through Miracast, and then use the USB-C cable for Pen-Touch, then it works without problems.
      • On a very weird procedure, after connecting through Miracast + lateral USB-C I tried hot-unplugging the USB-C cable from a lateral connector and pugging it into the Compute Module, without disconnecting Miracast. In that case, it seemed that the screen switched to USB-C and I was finally getting Video+Touch&Pen, but settings became very unstable (resolution was not properly detected) and I'm not sure if it wasn't simply misreporting the input device.

      I'll try a bit more tomorrow on the Miracast-to-USB-C switch, out of curiosity, and even if this is certainly not how I expected the expensive Hub 2S to behave. It should really be plug & play for it to make sense.

       

      I keep wondering if there isn't any software/firmware update that our IT might be blocking out of ignorance... Would appreciate if you have any info on that area.

Resources