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Thread: change I2S BCK ratio ?

  1. #26
    Senior Member PaulStoffregen's Avatar
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    Since you have a scope, I'd recommend using it to watch LRCLK, BCLK and DATA. Set your scope to trigger on LRCLK.

    My guess is you'll see the bits immediately after LRCLK flickering wildly. If there isn't a consistent logic low for 1 BCLK cycle after LRCLK changes, that's a sure sign the PCM1802 is transmitting left justified data rather than I2S.

    Click image for larger version. 

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    It should look like that waveform above, with always logic low for 7 cycles before LRCLK changes (the yellow part) and 1 cycle after LRCLK changes (the green part).

  2. #27
    Senior Member DD4WH's Avatar
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    My recommendation: try to spend a little more time on digesting and reading than on replying to posts.
    here is the requested connection of the PCM1808 that works with the T4:
    https://forum.pjrc.com/threads/57167...l=1#post212640
    Try to go through all the connections and compare them with the connections of your PCM1802
    Most important: be aware that the T4 has aggressive signals on MCLK and other relevant pins which means zhat it is impossible to use long wires for wiring and even if you use short (< 3cm) wires without a good ground plane, this can ruin your audio.
    I had the T4 set up with 2cm wires connected to the audio shield and this did not work properly because of a missing ground plane!

  3. #28
    sorry mate, I admit I have a negative attitude, but I wrote a game engine, once, well in the end, after 2 years of hard work, I still had no game

    I don't want to dig in something I bought, who's supposed to help me and do the work for me

    it's like asking a concept artist to debug photoshop, it's not his job, he already have a lot to achieve

    I misunderstood the DS ? Ia m not the only one apprently, and at least I tried, as I said [bold] I am not an english person [/bold], and I have zero XP with I2S

    I am not even supposed to deal with this

    sorry you guys dont get it, I gave all the infos I could put on this forum to get help

    sorry I am not as mature and open minded as Frank B

  4. #29
    Quote Originally Posted by DD4WH View Post
    My recommendation: try to spend a little more time on digesting and reading than on replying to posts.
    here is the requested connection of the PCM1808 that works with the T4:
    https://forum.pjrc.com/threads/57167...l=1#post212640
    Try to go through all the connections and compare them with the connections of your PCM1802
    Most important: be aware that the T4 has aggressive signals on MCLK and other relevant pins which means zhat it is impossible to use long wires for wiring and even if you use short (< 3cm) wires without a good ground plane, this can ruin your audio.
    I had the T4 set up with 2cm wires connected to the audio shield and this did not work properly because of a missing ground plane!
    yeah I thought about doing that too
    thanks

  5. #30
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by phil123456 View Post
    sorry you guys dont get it, I gave all the infos I could put on this forum to get help
    Use your scope to view LRCLK, BCLK and DATA, as I tried to explain in msg #26. If you need more help to do that, just ask.

    I have a hunch the waveforms are going to turn out to be left justified format, because the wrong analog waveforms on msg #15 look pretty much like too much non-clipping gain applied, causing integer overflow.

  6. #31
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    Quote Originally Posted by PaulStoffregen View Post
    Look, this isn't the first time. Over and over this same conversation has come up on this forum, where someone misreads the datasheet and believes their chip expects exactly 24 BCLK clocks per phase of LRCLK. It's a common misunderstanding, because these parts of the diagrams (highlighted yellow and green) aren't always clearly explained.
    And, it seems like every manufacturer that makes an I2S device puts that same picture in their datasheet, many times with no further explanation. It would be so much easier if they just put in tabular form all possible combinations of:
    • Sample Rate
    • Number of (significant) bits per sample
    • MCLK Freq
    • BCLK Freq


    Be that as it may, it doesn't excuse a bad attitude and hostility directed at those providing correct information.

    If you don't like working on this project, stop whining about it and find something else to work on.
    Last edited by gfvalvo; 02-15-2020 at 05:55 PM.

  7. #32
    Senior Member PaulStoffregen's Avatar
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    I ordered one of these PCM1802 boards. But it's coming from China. Estimate is 30 to 50 days for delivery!

    If @phil123456 returns, and I hope he does so we can fully resolve this issue, I'd like to ask everyone to please remain focused on the technical problem at hand. These sorts of problems can be really frustrating. Sometimes human reactions only make things harder rather than better. Let's work to get this problem figured out.

  8. #33
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    Quote Originally Posted by PaulStoffregen View Post
    But it's coming from China. Estimate is 30 to 50 days for delivery!
    That's literally taking a slow boat from China. May they arrive Coronavirus-free

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