Standalone Rpi source

Forum Digital source Standalone Rpi source

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    • #1744
      G600
      Participant

      Hi.

      I’m building a standalone Rpi source for the DAC, inspired by Andrea’s https://www.diyaudio.com/community/threads/the-well-synchronized-asynchronous-fifo-buffer-slaved-i2s-reclocker.348074/post-6495053

       

      I’ll be using Modushop Galaxy Maggiorato 3U GX288, with a windowed front panel for the official 7″ touchscreen, TWSAFB-RPI, and Andrea’s I2S LVDS transmittier-receiver solution.

      I’d be happy to share my DXF files for CNC, and I’d like to read what you did.

      For example I’m wondering how do you guys manage the Rpi on/off (especially the ON, because the OFF can be triggered by the player web interface).

      I suspect that the TWSAFB-RPI does not provide switch power management.

      I’ve read about Volumio’s GPIO button plugin https://community.volumio.org/t/adding-power-off-button-to-raspberry-pi-4-w-volumio/49588 which offers to power the machine using a momentary switch using the reset functionality.

    • #1903
      G600
      Participant

      Dear Andrea,

      I cannot make the Fifo to “lock”.

      I have finished my Rpi player, volumio configured to output “generic I2S”, transmitter & receiver HDMI boards.

      When I play various sample rate files, nothing happens: no relay click, nothing changes on the UI (it shows – – – 1 -).

      How to troubleshoot?

      By the way, is it possible to raise your TWSAFB-RPI current capacity? Under heavy load with a 2.5″ SSD, volumio sometimes shows low voltage alert (blinking lightning).

      Thanks.

    • #1904
      The Well Audio
      Participant

      You could try connecting the I2S output of the RPI interface directly to the FIFO Lite in order to understand the source of the issue. If it works so, the issue is related to the LVDS transmitter or receiver, otherwise the issue is related to the RPI.

      Sometimes I got the same problem of low voltage alert with the RPI. I measured 4.97V at the RPI DC supply.
      I’m not sure, but I remember I have read something about a Volumio issue. I’ll try a Google search.

    • #1909
      G600
      Participant

      Thanks for the tip, sounds very logical.

       

      Regarding the low voltage, I have read that RPI4 is far more finicky about this than RPI3.

      There is a software way to remove the warning, I’ll try it.

      Hope that it’s a fake alert and the device will not be throttled every now and then.

    • #1911
      G600
      Participant

      I’m afraid that the direct connection does not solve the problem.

      “Generic I2S DAC” is the right setting in Volumio?

    • #1913
      The Well Audio
      Participant

      I apologize but I don’t remember the correct settings in Volumio.
      If you own an oscilloscope you could test the I2S pins on the GPIO header and then the same I2S pins on the JST output connector (after the isolators).

    • #1914
      G600
      Participant

      Unfortunately I don’t have one, but I understand that it’ll be difficult to find the culprit without one…

      I’ll try a clean install, I may have made a software mistake by upgrading volumio (they say it could break some features).

      And maybe try another I2S source.

    • #1926
      G600
      Participant

      Dear Andrea,

      I have connected my good old WaveIO board as an i2s source.

      Attaching it to the FIFO triggers the x48 family clock, and the UI displays 48 as sample rate.

      No matter how I connect it and no matter the sample rate I’m playing (44.1 and 48 kHz tracks), nothing happens (the UI keeps displaying 48, and there is no relay click).

      Do you have an idea what could be wrong? Something malfunctioning in the FIFO?

    • #1930
      The Well Audio
      Participant

      Does the Windows app detect both oscillator when the FIFO is connected to computer by USB?

    • #1931
      G600
      Participant

      Yes, I don’t have any problem for configuring the FIFO.

    • #1933
      G600
      Participant

       

      Here is a screenshot of the software in plugged mode, and at the right you see the UI confirming the USB access.

    • #1939
      The Well Audio
      Participant

      It looks like the FIFO does not recognize the I2S input (x48 family is selected by default).
      Can you please check the I2S JST connector (DATA, BCK, LRCK and ground)?

    • #1942
      G600
      Participant

      Is there a specific thing I should check?

      I’ll take a deep look at it tonight (cold solder joint, etc…).

      I’m considering buying a scope, but apart than being sure that the I2S is there, it will not tell me if it’s a suitable I2S for the FIFO, and if it’s functionning correctly…

      • This reply was modified 2 months, 2 weeks ago by G600.
      • This reply was modified 2 months, 2 weeks ago by G600.
    • #1945
      The Well Audio
      Participant

      You can check if the I2S lines are connected correctly: DATA to DATA, BCK to BCK, LRCK to LRCK and ground to ground.

      With a two channel oscilloscope you could check if the I2S input is correct.
      Trigger on LRCK and then you can see DATA and BCK.

    • #1950
      G600
      Participant

      This is a new behaviour I had tonight with the Rpi streamer connected through HDMI, but shutdown.

       

      And a small scary video : https://drive.google.com/file/d/1wljBrWCdFfDgjJ-9W14uUdBb2n2qJbH3/view?usp=drivesdk

    • #1952
      G600
      Participant

      I’ll explore a possible grounding and PSU issue thie evening.

      I’ll let the whole I2S stream “float”, and change the FIFO PSU.

      If it’s a failure, could I send the FIFO back for competent inspection?

    • #1953
      The Well Audio
      Participant

      Of course, if you don’t fix the issue you can send me the board back and I’ll check it.
      Please, send an e-mail to sales@thewellaudio.com.

    • #1955
      lasercut
      Participant

      Have you made sure reflecktor d is providing stable power or tested a different reg?

       

      I have had difficultly powering high current digital circuits with UltraBiB, the bib could not provide enough current during startup sequence despite having 100mA surplus current to the device’s listed current requirement.

    • #1956
      lasercut
      Participant

      When I look at your photos on Diyaudio I see yellow, purple, gold (4.7r) for R1 on reflecktor D.
      If that’s correct then that is your problem, only 130mA shunt current.

      Unless I’m missing something

      • This reply was modified 2 months, 2 weeks ago by lasercut.
    • #1957
      The Well Audio
      Participant

      We have not tested Salas shunt regulators.
      Anyway the Vref current consumption of the DAC Lite is very low (less than 20mA).

    • #1959
      lasercut
      Participant

      Sorry, I was talking about G600 issue

    • #1960
      lasercut
      Participant

      Oh it was the old Ultrabib, not reflecktor D, but same applies.

    • #1962
      G600
      Participant

      Yes, it’s an old 1.1 Ultrabib, set for about 400 mA dissipation (I have bypassed the 4.7r with a parallel 10r since I made the picture, so the 1.3v drop divided by 3.2 Ohm = 407 mA).

      But with 4.7r I had almost the same drop of 1.3v, so I’m not in line with the dissipation you wrote, it must have been 270 mA.

      But I will try another reg tonight, one of my assumption is that it’s oscillating / not supplying the fast transients that may be needed by the FIFO.

      The other idea is a grounding problem. Let me test that and report back, thank you very much for brainstorming with me!

      • This reply was modified 2 months, 2 weeks ago by G600. Reason: typo
      • This reply was modified 2 months, 2 weeks ago by G600.
      • This reply was modified 2 months, 2 weeks ago by G600.
    • #1969
      lasercut
      Participant

      Yeah, disregard that, it was WRT reflecktor D which has different current calculation.

       

       

    • #1967
      G600
      Participant

      We have not tested Salas shunt regulators.
      Anyway the Vref current consumption of the DAC Lite is very low (less than 20mA).

      My DAC lite is powered, but not possible to test it because the FIFO is not functioning, and I need a longer u.fl cable for Drn, it’s almost 25 cm away in my situation.

      Will source one while I’m working the FIFO.

    • #2042
      G600
      Participant

      Gents,

      An update here: the system works!

      My FIFO board had no problem, this was confirmed by Andrea’s inspection.

      I’m not sure what the problem was, maybe a bad connector or a cold solder joint.

      Pics, or it did not happen! (The Well Audio logo hijacked with Andrea’s permission)

      [URL=https://www.imagebam.com/view/MEHVBKV][IMG]https://thumbs4.imagebam.com/b3/ce/95/MEHVBKV_t.jpg[/IMG][/URL]

      [URL=https://www.imagebam.com/view/MEHVBKZ][IMG]https://thumbs4.imagebam.com/ea/79/c7/MEHVBKZ_t.jpg[/IMG][/URL]

    • #2044
      Kazuma
      Participant

      Beautiful build.

      I also plan to do something like this, supercap reference etc.

      I have a question, what is the voltage source for clean side of fifo there? Isn’t it should be literally the same, as vref for DAC to avoid DC bias?

       

    • #2045
      G600
      Participant

      Thanks.

      I messed with the pics

      FIFO clean part is powered by it’s own lt3042 reg, set to 3.8v like the two I use for DAC digital side.

      They are not balanced to the last mV, but very tight.

       

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