Slaving BBB to Buffalo III, possible?

[giulio]

Hi,

is there a way to slave a BBB to the Buffalo III clock using a /4 divider?

I plan to upsample with sox to 384k (on my server running LMS) so I do not need a dual clock plus one would want the master clock to be as close to the dac as possible and jitter should be minimized if the BBB is slaved to the DAC clock.

TIA,
Giulio

 

[miero]

It should be already possible if you have 98.304MHz clock.

Just set the snd_soc_botic.ext_masterclk=2 in uEnv.txt. Or ...=6 if you want to have clock inverted.

The next version of BBB driver will support also non standard sample rates, e.g. 312.5kHz that can be derived from 80MHz clock.

For more info check the http://bbb.ieero.com/

And also the support thread for this driver http://www.diyaudio.com/forums/twisted-pear/258254-support-botic-linux-driver.html

 

[giulio]

Miroslav,

thanks for your reply and for taking care of the software side ;->

On the hardware side, I need to replace the standard 100M clock on the Buffalo, built a divider and some kind of isolator to avoid frying the BBB.

Would the Amanero/Ackdac isolator boards work (I have a spare one at home) for that purpose?

Giulio

 

[nautibuoy]

Miroslav,

thanks for your reply and for taking care of the software side ;->

On the hardware side, I need to replace the standard 100M clock on the Buffalo, built a divider and some kind of isolator to avoid frying the BBB.

Would the Amanero/Ackdac isolator boards work (I have a spare one at home) for that purpose?

Giulio

If you've got a spare Acko SO3 board, if you equip it with good clock modules it can provide clock signals to the BBB and to the Buffalo III, as well as isolation and reclocking of the digital signal - I've purchased an SO3 myself to do just that using miero's software. Acko seems to be operating in the same space as Twisted Pear so it might be politic to ask any specific questions you might have about the SO3 over on Acko's thread in the Group Buy section; there's already a lot of info on using the SO3in this way on there.

Ray

 

[giulio]

Hi Ray,

thanks for your reply.

I did not want to step on anyone's toes, but I thought that be it the SO3 or the Hermes-Cronus would both. e redundant if I just use 192k or 384k sample rates. And the right way to do I2s is to have the clock at the dAc and slave the source to it. Hence my original question. Were it not for the bad design of the BBB, i would not worry about isolators.

Bottom line I need to replace the Buffalo clock as miero suggested and have some board that provides dividing and isolation. I think the Hermes should that (or the SO3 fed from the Dac clock signal). Slaving should be better than reclocking.

 

[miero]

At least that unsafe design of BBB forces to use proper solution with isolators.

Without isolators you would not be able to use BBB as high-end USB DAC (later when drivers will be implemented).

The Hermes-BBB will provide at least 2 features unavailable on other solutions:
- I2S/DSD switching
- I2C isolation (for configuring DAC directly from BBB)

Also you do not need to replace Buffalo clock. It will be good enough just to remove power from it and then use clock signal from Cronus instead

And IMHO it is acceptable to discuss Acko's products here if they are relevant to the topic.