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Old 20th March 2014, 05:03 AM   #381
pfdavid is offline pfdavid  United States
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Default Bitclock Inversion Thing

Russ and Miero,

I noticed you're grappling with a 'bitclock inversion thing'. This has also been discussed in a blog by Shabaz over on element14.com. The blog is entitled "BBB -- Building-a-DAC". Shabaz extracts I2S signals from his BBB and feeds a DAC, apparently successfully. In the comments section at the end of Part 2 Shabaz claims that (as 22 February 2014):

"I checked a recent-ish Debian test build (BBB-eMMC-flasher-debian-7.3-2014-01-22-2gb.img from Robert Nelson) and the problem persists, so the driver code has not been fixed yet. Data changed on the rising edge, which is the opposite of what the I2S specification requires. So, the inverter is still needed for now."

You may be aware of this already, or perhaps this is helpful. Unfortunately I am ignorant and can be of no assistance. The link is:

BeagleBone Black: BBB - Building a DAC - part 2 | element14

- David
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Old 20th March 2014, 08:56 AM   #382
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I just finished reading that entire thread myself. Excellent, work over there at element14! John Rhoades breakdown of the issues, realization of their causes and concise implementation guide is a must read.
I learned more than I thought I ever would on the subject:
The goal of an embeded BBB player .... hopefully, direct sourced to the BIII.
Impressive, element14
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I'm kinda curious about that myself........
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Old 20th March 2014, 11:41 AM   #383
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Yes that is good info - we actually had read it previously. Miero has already been working at the "bitclock" fix. I believe he has already applied the correction in his latest code, but it seems that perhaps there is more to be done...
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Old 20th March 2014, 12:21 PM   #384
miero is offline miero  Czech Republic
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Yes, bitclock inversion is already fixed in the driver code.

Verified also by I2S timing diagrams posted in #382
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Old 20th March 2014, 11:44 PM   #385
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Fantastic work guys!
I just finished the BBB image I promised you:
1- MPD 18.9
2- Alsa-DSD Player included
3- Miero's i2s driver included (fantastic work mate!).

However, the kernel is the 3.8.13bone20. Seems there is something not working... But I cannot be sure, since I don't have any DAC for testing purposes... So please report if this works or not...

I will however make another image version with the kernel of bbbdebian, replicating the optimization I got with mine.

I also set up a volumio repo, where you could find latest MPD (both for PI and for other platforms, and the Alsa-dsd player.

To use that just add this to your /etc/apt/sources.list

deb index styled with h5ai 0.24.0 (http://larsjung.de/h5ai/) all main contrib non-free

(for BBB, UDOO, Cubox, Utilite and so on)

and

deb index styled with h5ai 0.24.0 (http://larsjung.de/h5ai/) pi main contrib non-free

for the little pi. Please note that repos are not signed yet, so just ignore the warnings and install.

To install alsa-dsd-player:

sudo apt-get update
sudo apt-get install alsa-dsd

The syntax is:

alsa-dsd-player namefile

You can find the image, as usual, here:
Get Started - Volumio

Enjoy and keep up the good work! Congrats to everyone involved, and please let me know if I can do any further!
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Old 21st March 2014, 08:25 AM   #386
Goto is offline Goto  United Kingdom
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Quote:
Originally Posted by mikelangeloz View Post
Fantastic work guys!
I just finished the BBB image I promised you:
1- MPD 18.9
2- Alsa-DSD Player included
3- Miero's i2s driver included (fantastic work mate!).

However, the kernel is the 3.8.13bone20. Seems there is something not working... But I cannot be sure, since I don't have any DAC for testing purposes... So please report if this works or not...

I will however make another image version with the kernel of bbbdebian, replicating the optimization I got with mine.

I also set up a volumio repo, where you could find latest MPD (both for PI and for other platforms, and the Alsa-dsd player.

To use that just add this to your /etc/apt/sources.list

deb index styled with h5ai 0.24.0 (http://larsjung.de/h5ai/) all main contrib non-free

(for BBB, UDOO, Cubox, Utilite and so on)

and

deb index styled with h5ai 0.24.0 (http://larsjung.de/h5ai/) pi main contrib non-free

for the little pi. Please note that repos are not signed yet, so just ignore the warnings and install.

To install alsa-dsd-player:

sudo apt-get update
sudo apt-get install alsa-dsd

The syntax is:

alsa-dsd-player namefile

You can find the image, as usual, here:
Get Started - Volumio

Enjoy and keep up the good work! Congrats to everyone involved, and please let me know if I can do any further!
Hi Mikelangeloz

I will download the new beta for BBB and try it out over the next day or so. I have been using Volumio on the RPi for a few weeks now and it works great.

Yesterday I got I2S and Squeezelite working on the BBB with BBBDebian and Miero's driver - haven't got it plumbed into my dac yet, but the scope makes the right waveforms!

Thanks for the great efforts.

Mark
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Old 21st March 2014, 08:46 PM   #387
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Mikelsngeloz,

Did you consider the I2C volume control option I proposed you via PM?
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Old 22nd March 2014, 01:53 AM   #388
wlowes is offline wlowes  Canada
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Default Great progress

Might be early to ask, but how does it sound?

BBB vs other linux embedded processors that use USB? I am currently using ALIX to WaveIO to I2S 1541A DAC.
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Old 22nd March 2014, 12:50 PM   #389
jrling is offline jrling  United Kingdom
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Quote:
Originally Posted by nyc_paramedic View Post
Hi Russ,

I had posted on your forums a while back about the Technologic Systems ARM boards. (Link:
Single Board Computers, Computer-on-Modules, Touch Panel Computers, PC/104 Peripherals, Enclosures, and Carrier Boards for Embedded Systems - Technologic Systems) You mentioned that they looked very interesting and would have no issued connecting I2S to on of your DACs.

Have you looked at any of these of late? They're more expensive than a Pi but seem much better designed. They offer a range of boards and support Debian out of the box. Their engineering team told me that modifications to their existing designing are possible with with low costs engineering charges, should a custom audiophile SBC be popular for a group buy. But they do offer single quantities, which is rare in the industrial SBC world

I've recently purchased the TS-7700, TS-7700 Ultra-compact Format with High Performance - Technologic Systems, but haven't had time to put it through its paces.

Click the image to open in full size.
Hi - must say that board does look to have great potential - did you get a chance to try it out?

Cheers
Jonathan
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Old 22nd March 2014, 01:50 PM   #390
Goto is offline Goto  United Kingdom
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Miero

I have the Botic driver working on the BBB with Debian and Squeezelite. It plays faultlessly using 44.1/16 flac files as source material (though I am guessing it's upsampling to 48k?).

It sounds very organic and clean and powerful.

When I try hires files (88/24, 96/24, 192/24) the Buffalo seems to lose lock sporadically leading to dropouts. I don't see this issue with the Rpi, so it's unlikely a bandwidth issue between server and BBB. My first thought is to try to change the Squeezelite buffer settings. I copied the ones ChrisMmm posted a few days ago to get it working.

On a more general level I have found I need to open a SSH session, load the Botic driver, manually start Squeezelite and leave the Putty window open or the Squeezelite session drops. This is nothing to do with the driver, but I guess means I have work to do on my Squeezelite installation on the BBB.

I haven't managed to get wifi working yet so am running on Ethernet. More work to do, but it sounds good as is - very good in fact.

Mark
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