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Powered USB hubs and webcams with Modern Robotics electronics

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  • Powered USB hubs and webcams with Modern Robotics electronics

    The recent update to Game Manual Part 1 allows powered USB hubs that connect to a REV Expansion Hub, to better power and support USB webcams.

    Are there any comparable legal configurations for using a powered USB hub with the Modern Robotics electronics? If not, is there any supported hardware that allows USB webcams to be powered and used reliably with the Modern Robotics electronics, or must teams use the REV electronics if they wish to use USB webcams?

    [Note: I also asked a similar question on the official Q&A forum as it isn't clear whether there needs to be a rule change to support powered hubs with MR electronics or if there are just creative, tested solutions that may work with MR electronics that are within the current rules.]

  • #2
    The USB hub on the Modern Robotics Core Power Distribution Module is powered.


    • #3
      As noted here, "The Modern Robotics Core Power Distribution Module only supports USB 2 'full' speed (12Mbps) not 'high' speed (480Mbps); full speed is insufficient to support video streaming." If true, this would imply that a separate powered hub would be needed from the RC phone to both the webcam and the MRI CPDM.

      The possible MRI configuration that may or may not be legal is:

      RC Phone -> USB Hub (powered by external battery RE14 c iii. i.???) -> USB camera on one port and MRI CPDM on another port.

      Would this work and is this legal?

      RE14 c iii describes a USB hub connected to a REV hub and then says if a powered hub is used it can get its energy from a commercial USB battery or the REV hub itself.

      The issue is that a USB hub connected to a built-in input port of the CPDM (as per RE14 c. i.) would also need to be powered if it were to also support a webcam as in the configuration described above. But RE14 c iii as written appears to only apply to hubs connected to the REV hub.

      I wonder if a "newline" were placed between the two sentences currently in RE14 c iii, then the powered hub description would appear to apply to all options in RE14 c. But as written, the regarding powering appears to only apply to RE14 c iii.


      • #4
        Ok thanks... If you are going to ask for a rule change, then I suggest a rule change that would allow the use of a powered USB 3.X hub in lieu of the USB hub on the CPDM. Use one hub or the other but not both. You want to minimize points of failure by way of minimizing USB hubs and USB cables.


        • #5
          But having multiple hubs might make wiring easier (in the same way that having 2 REV hubs makes wiring easier compared to having 1 REV mega-hub that everything would need to be plugged into).

          I'd still hope that you could use the configuration I described in post #3 so all the wiring would be the same as a "usual" MR-based robot, but you just introduce a small powered hub between the RC phone and the CPDM for the webcam.

          Giving teams the flexibility to do it however they want is usually preferable, IMHO, especially if it can be done while providing rookies with a template wiring diagram to get them going.