spdif out

Discussion in 'UDOO X86' started by Triodefreak, Mar 22, 2017.

  1. Triodefreak

    Triodefreak Active Member

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    Is it coax or toslink?
     
  2. Laura

    Laura UDOOer

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    I believe it's routed to the TRRS (Tip Ring Ring Sleeve) audio jack
     
  3. Triodefreak

    Triodefreak Active Member

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    Thanks again Laura.
     
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  4. GourouLubrik

    GourouLubrik New Member

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    Edit:
    I forgot that there are optical + trrs combo connector, so I guess it's optical mini toslink output :)
     
    Last edited: Mar 23, 2017
  5. Triodefreak

    Triodefreak Active Member

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    Looks like we'll just have to wait and see. Though that would be the obvious choice. Just like the Chromecast Audio.
     
  6. Laura

    Laura UDOOer

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    There's no optical out as far as I'm aware. Just the coaxial SPDIF connection on the TRRS jack, and most likely via a header pin as well.

    If you require optical output, you can either get an adapter like: https://www.amazon.co.uk/Cable-Mountain-Digital-Coaxial-Converter/dp/B001U7GW68 (though not this particular one, just using as an example of a converter).
    Or make a shield with an optical transmitter on it. There seems to be a range of these on distributor websites like Mouser and Digikey, though I'm not sure how you would choose a particular model, so will not link to any particular one.

    Edited to add: I vaguely remember reading the jack and a header pin will expose SPDIF. I cannot find where it was mentioned for the jack, but for the header, it's mentioned in the following linked comment: https://www.kickstarter.com/project...ver/comments?cursor=13755409#comment-13755408
     
    Last edited: Mar 23, 2017
  7. GourouLubrik

    GourouLubrik New Member

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    The thing is, like my edited posted stated first, you cannot have coaxial spdif through a TRRS jack.
    Since the TRRS output of the udoo x86 is a stereo output + microphone input, pinout of the TRRS is Left / Right / Ground / Microphone
    there is no pin left for a coaxial output. And you don't really want to mux spdif ouput and microphone input...

    If you plug a 3 pins headphones or cable, you'd have a 0.5v-pp squared wave signal right to the ground !
    So no, I don't believe it's the good answer. If it is, i'd be a bad design :/
     
    Last edited: Mar 23, 2017
  8. Laura

    Laura UDOOer

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    @GourouLubrik For the coaxial jack, the switching between the microphone and SPDIF will be configured by the user through the operating systems sound playback options.
    If you prefer a dedicated non switchable SPDIF output, I'd suggested using the header pin.

    As your knowledge of audio is much better than mine, please share in the forum what you discover about the audio when we start receiving the boards. I would like to learn more on this topic :)
     
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  9. GourouLubrik

    GourouLubrik New Member

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    I found out that camcorders used TRRS to 3 RCA in order to pass composite video + stereo. It would do the job.
    [​IMG]
    [​IMG]
    But the color scheme would be wrong in our case.
    Spdif would be the red one, right would be the yellow and left white one.

    Maybe the udoo team could stock few cable of this type for those who whould like to use s/pdif without much hassle ?

    About reporting, yeah, I will,
    My project with udoo will have an audio side, but... I'm not sure yet of what i'll do exactly, I guess the s/pdif output would be of good use.
    My final project will probably imply this already done "DIY" stuff (quoting the DIY, because it's not my design, just soldering and/or plugin things together): https://goo.gl/photos/RzHv5Swwrk3Y2r2L9
    DAC: Soekris dam1021 r2r modded rev 1 with normundss rev1.1 input board. powered by a Diyinhk bipolar 12v PSU.
    Amanero 384 usb to i2s interface (hidden under the input board)
    Headphoner amplifier: opc the wire bal bal (in SE-BAL mode), powered by 2 opc the wire psu)
     
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  10. Triodefreak

    Triodefreak Active Member

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    Cool...another diy audio person. :)
    For my main system I have the dddac connected with hifiberry digi+pro through i2s. Picoreplayer running on the rpi.
     
  11. GourouLubrik

    GourouLubrik New Member

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    In fact, everything was already documented :)
    https://udooboard.github.io/X86-Docs/Hardware_Reference/Pinout_Braswell.html

    This image show that spdif out is pin 47 on CN12 - if comes directly from Realtek ALC, it should be TTL level, not consumer level, so it would need something like a murata (DA101C) transformer and few resistors to galvanically isolate it and set it to consumer spdif level
    [​IMG]
     
    Last edited: Mar 24, 2017
  12. Andrea Rovai

    Andrea Rovai Well-Known Member

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    It is not routed to the TRRS (Tip Ring Ring Sleeve) audio jack as suggested by Laura.
    The spdif is exposed on pin 47 of the external pinout. By using this pin together with a ground pin you can connect an RCA or toslink female connector.
     
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  13. GourouLubrik

    GourouLubrik New Member

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    Thanks for the update, so it's TTL level (3.3v), not consumer level (0.5Vp-p) ?
     
  14. Andrea Rovai

    Andrea Rovai Well-Known Member

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    The external pinout logic is 1.8v.
    This is an example of how to connect the spdif out to a toslink connector.
    unnamed.png
    We will add it to the documentation.
     
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  15. GourouLubrik

    GourouLubrik New Member

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    damn, it's not usual to see 1.8v logic level for spdif. I wonder if it will compatible with all usual transceiver or module.

    good old (and obsolete) TOTX147 doesn't seem to like < 2.1v logic as per datasheet.
     
  16. Sjonno

    Sjonno New Member

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    Anyone who has connected a toslink output onto the X86 yet who can confirm if this works?
    My audio set only has optical in, so by using that I can prevent having to buy a receiver with HDMI ;-)
     
  17. ccs_hello

    ccs_hello UDOOer

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    It needs
    (1) Toslink E-to-O transmitter module w/ driver (3.3V TTL input compatible), e.g.,
    http://www.ebay.com/itm/5pcs-Toslin...nal-16-Mbps-TTL-Compatible-Jack-/122531023964
    5pcs $7.44 shipped

    (2) TXB0108 1.8V to 3.3V voltage level shifter module, e.g.,
    http://www.ebay.com/itm/8-Channel-8...rter-Module-TXB0108-for-Arduino-/141976894663
    1 pcs $1.03 shipped

    UDOO x86's SPDIF output is in electrical (1.8V ULV TTL) format, straight out of Braswell SoC.
    Optical SPDIF suitable for fiber optics cable is in "optical" format.

    (2) does 1.8V --> 3.3V signal conversion
    (1) does electrical to optical conversion (with its built-in driver to drive the LED)

    ccs_hello
     
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  18. ccs_hello

    ccs_hello UDOOer

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    Coaxial version (a single RCA jack) of the SPDIF:
    http://sound.whsites.net/p85-f6.gif

    Note the diagram assumes 5V TTL thus 5V TTL part is used.
    Now that Braswell is 1.8V ULV level, an adjustment on the buffer circuit is required.
     
  19. Paede

    Paede New Member

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    To confirm:
    I need part nr.2 (logic level shifter) to connect the udoo x86 to a logitech Z-5500 coax spdif input?
     
  20. ccs_hello

    ccs_hello UDOOer

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    For COAX version of SPDIF, under the Braswell's 1.8V output signal level,
    I'd recommend this design with the following changes:
    http://radiopages.ru/wp-content/uploads/2013/03/spdif_c.gif

    IC will be SN74LVC04 (to make it 1.8V friendly) and
    use supply voltage of 1.8V Vcc (not the 5V as in that picture.)
    ccs_hello
     
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