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Building an open embedded audio applicance.

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I've compiled info how to control onboard oscillator on Angstrom ...

Currently this is usable only if one has external 24.576MHz oscillator ...

For frequencies other than 48kHz new kernel will be needed.
It appears complicated to implement dual clocks. And if the clock is also referenced by the CPU, will a switchover from one clock to another cause a problem?

I just read about I2S output from the CubieTruck here -
CUBIEBOARD FOR AUDIO? | H i F i D U I N O
The CubieTruck has a 24MHz system clock, from which a PLL derives clock frequencies to suit both the 44.1kHz and 48kHz families.

While maybe not as technically elegant as a system with dual clocks at dedicated audio frequencies, would the simplicity of the CubieTruck's clock regime be a better (easier) foundation from which to work?
 
It's actually not that complicated, we are just discussing angstrom development effort. Once it's done there will be a distro you can simply install. Like Volumio.

CubbieTruck is using the same technique as the rpi. A PLL from a single clock. You might as well use an rpi. :)

I would much prefer two clocks. Also the cape allows us to optimize for audio in other ways. I want a solution that is directed toward high quality audio to start. :)
 
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I would much prefer two clocks. Also the cape allows us to optimize for audio in other ways. I want a solution that is directed toward high quality audio to start. :)

Couldn't agree more, no point in a solution that doesn't go as far as is possible towards best quality audio that can be achieved (within reasonable cost constraints of course ;) ).
 
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What are the difference between the default I2S settings and the one suggested by Russ ?

Russ
snd_soc_bcm2708
snd_soc_bcm2708_i2s
bcm2708_dmaengine
snd-soc-pcm1794a
snd_soc_rpi_dac





Default

snd_soc_bcm2708
snd_soc_bcm2708_i2s
bcm2708_dmaengine
snd_soc_pcm5102a
snd_soc_hifiberry_dac
snd_soc_hifiberry_digi
snd_soc_rpi_dac

Any hint on where to experiment to get rid of the pops between songs ?

Thanks,

Davide
 
I'm using piCorePlayer on its hifiberry settings for i2s output and it works with the Buffalo 2. How many variations of i2s are there?

john

I am doing the same with an ES9023 DAC. My belief is that only one driver would be required to cover I2S for any DAC. The one in use for PiCoreplayer was developed by the HifiBerry crowd I believe hence its name.

Would my assumption be the more knowledgeable peoples understanding?
 
I tried this little experiment with my pi->i2s->sabre dac using volumio os, but didn't work.
I didn't do any changes in the software like Russ suggested, because at the volumio website it is stated that volumio works with i2s. So i just enabled it in the settings.
But unfortunately it didn't work.

Besides the three i2s pins do I need to connect anything else? There is a 5V pin on the P5 header and I also noticed that right next to it there is a regulator. Do I need to supply 5v at that pin?
 
I tried this little experiment with my pi->i2s->sabre dac using volumio os, but didn't work.
I didn't do any changes in the software like Russ suggested
Try hand editing /etc/modules and putting in the modules Russ suggested, in that order, replacing whatever volumio put in there. On mine the first module in his list is not found, but it still works. You also need the ground connection from the rpi I think (in addition to the three bck, fsck and data lines)? I didn't try this on the Buffalo because I broke mine, but it worked on Doede's dac with volumio 1.2b.
 
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