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Old 18th March 2014, 06:11 AM   #361
TBM is offline TBM  Norway
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Looking good!

Just want to make a point that I am also NOT interested in making this cape "low end" and save a few bucks. PLEASE make it "high end" with the best clocks, power, isolation,... for interfacing to the Buffalo

IMO after this is done, then an other cape with features like included "low end" DAC, cheaper clocks, no reclocking etc can be developed, IF time and interest is there...

Please be aware of the "scope creep monster"...

Cheers
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Higher end!

Last edited by TBM; 18th March 2014 at 06:16 AM.
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Old 18th March 2014, 07:21 AM   #362
miero is offline miero  Czech Republic
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Default Roll off issues with I2S

I've measured HUGE difference of ES9018 filter roll off when using I2S.

Any idea? Bad settings?

White noise signal on SPDIF generated by onboard sound card and ARTA.
White noise signal on I2S generated by following command on BBB:

$ dd if=/dev/urandom | aplay -r 48000 -c 1 -f S24_3LE -

For 16bit it looks similar, but for 32bit the roll off is even more strange and roll-of is moved to 48kHz instead of 24kHz.

EDIT: first two images are for SPDIF input and the other two (with much noise) are for I2S input.
Attached Images
File Type: png b3-white-48k-sharp-spdif.png (39.7 KB, 618 views)
File Type: png b3-white-48k-slow-spdif.png (39.9 KB, 586 views)
File Type: png b3-white-48k-sharp-i2s.png (39.3 KB, 568 views)
File Type: png b3-white-48k-slow-i2s.png (39.5 KB, 557 views)

Last edited by miero; 18th March 2014 at 07:23 AM. Reason: added comment for images
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Old 18th March 2014, 10:42 AM   #363
DQ828 is offline DQ828  Australia
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Quote:
Originally Posted by TBM View Post
Looking good!

Just want to make a point that I am also NOT interested in making this cape "low end" and save a few bucks.
Cheers
Is it possible to have both? your cake & eat it to
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Old 18th March 2014, 12:34 PM   #364
peufeu is offline peufeu  France
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Quote:
Originally Posted by miero View Post
I've measured HUGE difference of ES9018 filter roll off when using I2S.

Any idea? Bad settings?
Check frequency of BCLK, WCLK of your I2S, using oscilloscope. Check ALSA settings. It may perform some oversampling or other processing.
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Old 18th March 2014, 12:45 PM   #365
Russ White is offline Russ White  United States
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Quote:
Originally Posted by miero View Post

For 16bit it looks similar, but for 32bit the roll off is even more strange and roll-of is moved to 48kHz instead of 24kHz.
It looks like either bit clock and/or the word clock are double the expected rate.
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Old 18th March 2014, 01:15 PM   #366
miero is offline miero  Czech Republic
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OK, I'll check the I2S output with logic analyzer soon.
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Old 18th March 2014, 02:36 PM   #367
peufeu is offline peufeu  France
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If you use a scope and proper probing you can also check for ugly looking clock signals, which can cause all kinds of trouble (ringing -> double clocking), etc
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Old 18th March 2014, 04:20 PM   #368
clivem is offline clivem  United Kingdom
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Quote:
Originally Posted by Adrian View Post
Default settings work on a pi so should be ok for BBB. They also work well on a wandboard which is what we are using for CSOS.
Pi doesn't have the horse-power (CPU bound) to resample on-the-fly to >96k. Not sure how the BBB compares, hardware wise. ISTR, upsample was fine up to 192k with the original BB I have. Not used that for a couple of months, though. (And not sure if the BBB uses the same processor as the BB.)

I'm building the latest CSOS F20 kernel with a bunch of patches for the BBB. Not sure this is going to happen anytime soon, but I'll add miero's BBB I2S patches to the next build, assuming they apply to the latest mainline. Then, maybe Chris can try my CSOS F20 test image on the BBB.

Miero, your code, are you using recent kernels and device tree for initialisation?
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Old 18th March 2014, 04:45 PM   #369
miero is offline miero  Czech Republic
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Miero, your code, are you using recent kernels and device tree for initialisation?
Yes, it is developed for kernel 3.8.13 and it uses device tree for initialization.

I've not tried it with the 3.12.x yet.
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Old 18th March 2014, 06:58 PM   #370
clsidxxl is offline clsidxxl  France
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I have this issue with alot of attention,but if I understand I2S output Raspi and BeagleBone Black are not bitperfect is the current state?
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