Thursday, November 22, 2012

Dexter's USB port is too slow with the Raspberry Pi

Well, after writing some new code to bypass the /dev/ttyUSB0 path on the Raspberry Pi and instead use the direct method of http://www.intra2net.com/en/developer/libftdi/ , I have sadly observed the same problem exists for both methods; performance goes down the drain and the Pi cannot play the video at the full speed.  So for now, the only method that exists for getting the video playing full speed on the Pi is using the pin headers on the Pi.  This actually works great BUT I am wondering how this solution could possibly work for a consumer version of Dexter.  This will have to be something to think about.

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5 comments:

  1. hyperfanNovember 22, 2012 at 9:46 AM

    Hi Matt

    Just been told about this project and am really interested in it, any ideas when a version will be for sale?

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  2. lord_victorinoNovember 22, 2012 at 2:47 PM

    Hi Matt,

    So, let me see if I understand what you are saying. So, to be able to use the Raspberry PI with DEXTER, the DEXTER Board will need to be modified so not to use the USB port, but instead have some sort of Hard Wired Connector to connect between both boards. Is this Right? Would this include extra components besides a connector? Would be a major modification? Would you need to make some sort of in between I/O board between the two boards?

    In any case, I do believe that the Final DEXTER System should be as user friendly as possible. Plug and Play. With no soldering involved. And I do understand cost effective. With more components, connectors, boards, and ect... means more costs. But we do need a stable Working Model above all else.

    Yours Truly,

    Tony M. Victorino


    Maybe we should make a Raspberry PI Thread on the Dexter Discussion Board to discuss this further.

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  3. Shaun WoodNovember 23, 2012 at 9:45 AM

    Hi Matt,
    Can you describe the problem in more detail. Maybe hardware guys like myself can help out.
    -Shaun

    ReplyDelete
  4. Matt OwnbyNovember 23, 2012 at 11:01 AM

    hi Shaun,

    See my posts (and the replies) in this thread:

    http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=12097&start=425

    I have one reply on the next page after the one in that link.

    The problem according to Dom: "It seems the device generates a continuous stream of NAKs which causes a very high interrupt rate (about 44k/s)."

    I suppose it might be worthwhile to see if there is another USB->serial convertor that does not have this issue.

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  5. Matt OwnbyNovember 23, 2012 at 11:16 AM

    Oh also see this thread:

    http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=16280

    ReplyDelete

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