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Support for Botic Linux driver

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francolargo

francolargo

Member
Joined 2007
Paid Member
twluke said:
Yes we do. Actually, I found that the similar noise did occur for a tenth of second, very short, at the beginning of track even on my prototype system with either 22/24 or 45/49 clocks, which has been otherwise mostly immune to this noise for long playing.
Click to expand...

I'm wondering if/how the comparison between users and circuits would change if all parameters re B3se other than sync/async are identical. I'm curious if DPLL bandwidth can be set to "no bandwidth" on both rigs? ...and perhaps "slow roll off" for the fir filter plus the same IIR bandwidth? :)
 
nautibuoy

nautibuoy

Member
Joined 2010
miero, I've been thinking about the clicks I'm experiencing with DSD playback when I use Start or Stop on on HQPlayer. This is a common issue with DSD playback and is often fixed with a mute device, such as a relay, triggered by a pin going 'high' when there is no DSD signal - that is how my JLSounds I2S to USB board does it.

Does, or could, BBB/Botic expose a header pin with a mute trigger like this? I did check the documentation but couldn't immediately see anything about this.

Thanks

Ray
 
nautibuoy

nautibuoy

Member
Joined 2010
miero said:
A mute signal could be generated from the BBB, but you might want to isolate it galvanically before connecting it to a DAC.

Maybe your DAC does have I2C control that allows to trigger Mute. Then it could be done in a software
Click to expand...

miero, a mute option would be very handy; apart from exploring more with the B3SE I'm looking to use BBB/Botic with Hermes/Cronus as the front end to a Signalyst DSC1 DAC, which will need a mute trigger as it doesn't have I2C control. I'm sure there are other scenarios where it would be useful.

I have some PCBs that will do the muting with an option for isolation, however this isn't essential, it just depends on your muting arrangement.

If it helps, on the JLSounds USB board the mute trigger goes high at Codec change, opening the relay contacts, here's a link;

http://jlsounds.com/uploads/Specifications.pdf

Thanks

Ray
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
Regarding the high sample rate DSD initial noise issue a few users were experiencing - it boils down to this... Just remember to turn of the automatic SPDIF detector on the B3SE. The SPDIF detector should always be disabled when you know you will be playing high rate DSD or PCM. Disabling the SPDIF detector has solved this problem every time I have ever seen it. :)

Cheers!
Russ
 
nautibuoy

nautibuoy

Member
Joined 2010
As I don't yet have the isolator/reclocker hardware (not currently available) I plan to experiment with my DSD-only DAC project by plugging directly into the P9 header of a BBB. Can someone please just check the pin mappings that I've put together from reading through the documentation - remember, this is DSD only.

P9-24 - Clock Select Flag
P9-25 - External Clock Input
P9-26 - DSD Date On Flag output
P9-30 - DSD Data1 Output (is this left or right?)
P9-31 - DSD Clock Output (BCK)
P9-41 - DSD Data2 Output (is this left or right?)

I believe that it will be appropriate to configure the Botic serializer settings to 'DD--'?

Until a codec-change mute function becomes available on Botic I will have to be careful to use the volume control to mute output to avoid the bumps that can be a feature of DSD playback.

Thanks

Ray
 
T

twluke

Member
Joined 2012
nautibuoy said:
P9-24 - Clock Select Flag
P9-25 - External Clock Input
P9-26 - DSD Date On Flag output
P9-30 - DSD Data1 Output (is this left or right?)
P9-31 - DSD Clock Output (BCK)
P9-41 - DSD Data2 Output (is this left or right?)

I believe that it will be appropriate to configure the Botic serializer settings to 'DD--'?

Until a codec-change mute function becomes available on Botic I will have to be careful to use the volume control to mute output to avoid the bumps that can be a feature of DSD playback.
Click to expand...

Hi Ray, as long as keeping with the pin mapping above, you can be almost free from such bumps and, from my experience, I believe that you can enjoy DSD512 play with a much less burden than with the use of Hermes/Cronus boards.

Regards,
 
B

bern

Member
Joined 2010
Right Justified Data Format and Botic?

Hi,
Finally I've launched my new DIY NOS Dac based on 4xPCM1704 (mentioned in this post).
Yesterday I connected it into the Cronus/Hermes.
I relay enjoy the sound (full of details and alive) of this NOS multibit DAC. :)

However one issue concern me... There is a little noise from the left channel.
IT is not loud but audible. It intensifies at the beginning of playback and then weakens.
What is interesting when I switched off my default player (squeezelite) and enter commands into terminal (putty) this strange noise appears for a while when I execute any command.
In the botic configuration I've set Right Justified data format, BCLK/LRCLK ratio=64 (32 didn't want to play) and in my squeezelite 24bit output.
Code: 
root@botic:~# uname -a
Linux botic 4.5.0-botic7-rc1 #1 PREEMPT Tue May 17 00:51:35 CEST 2016 armv7l GNU/Linux
root@botic:~# grep . /sys/module/snd_soc_botic/parameters/*
/sys/module/snd_soc_botic/parameters/blr_ratio:64
/sys/module/snd_soc_botic/parameters/clk_44k1:22579200
/sys/module/snd_soc_botic/parameters/clk_48k:24576000
/sys/module/snd_soc_botic/parameters/dai_format:16386
/sys/module/snd_soc_botic/parameters/dsd_format_switch:1
/sys/module/snd_soc_botic/parameters/ext_masterclk:3
/sys/module/snd_soc_botic/parameters/pinconfig:default
/sys/module/snd_soc_botic/parameters/serconfig:MMMM
I've also mapped data D2 as R channel and D3 as Left channel. My asound.conf is:
Code: 
pcm.botic-split {

    type route;
    slave.pcm "hw:0,0";
    slave.channels 4;
    ttable.0.2 1;
    ttable.1.3 1;
    ttable.0.0 1;
    ttable.1.1 1;

}

ctl.botic-split {

    type hw;
    card 0;

}
I regret that I do not have a scope. I would measure a waveform.
PCM1704 should work fed by native Right Justified format.
See this and this post.
Any hint appreciated. :)

PS. Some photos
An externally hosted image should be here but it was not working when we last tested it.



An externally hosted image should be here but it was not working when we last tested it.
 
Last edited:
francolargo

francolargo

Member
Joined 2007
Paid Member
bern said:
Hi,
Finally I've launched my new DIY NOS Dac based on 4xPCM1704 (mentioned in this post).
Yesterday I connected it into the Cronus/Hermes.
I relay enjoy the sound (full of details and alive) of this NOS multibit DAC. :)

However one issue concern me... There is a little noise from the left channel.
IT is not loud but audible. It intensifies at the beginning of playback and then weakens.
What is interesting when I switched off my default player (squeezelite) and enter commands into terminal (putty) this strange noise appears for a while when I execute any command.
Click to expand...

Lovely build, Bern!

This is merely a 'shot in the dark', but what happens if you gently manipulate the U.Fl connectors with something like a pencil eraser? Others have reported noise from U.Fl connections:
http://www.diyaudio.com/forums/twis...tic-cape-beaglebone-black-42.html#post4549094

Best,

Frank


Sent from my iPad using Tapatalk HD
 
B

bern

Member
Joined 2010
francolargo said:
Lovely build, Bern!

This is merely a 'shot in the dark', but what happens if you gently manipulate the U.Fl connectors with something like a pencil eraser? Others have reported noise from U.Fl connections:
http://www.diyaudio.com/forums/twis...tic-cape-beaglebone-black-42.html#post4549094

Best,

Frank


Sent from my iPad using Tapatalk HD
Click to expand...
Thanks Frank:)
I have manipulated Cronus <->Dac u.fl connectors
I started with Cronus's D2 as left and D3 as right channel then I changed D2 as right and D3 as left. The result was still the same: some little noise (scratching/crackle) from the left channel.
I suspect that this is rather software issue since this noise appears during execution of any command from the terminal even with player switched off
PCM1704s accept slightly different waveform than Right Justified (RJ) format (CLK continues for two additional times before stopped) although others reported that native RJ works well with PCM1704.
Normally PCM1704s works in tandem with DF1706 (Digital filter chip) and accepts signals from DF1706 described on page 8 of DF1706 manual in 'Audio Output Interface' section.
Maybe there is a magic combination of Botic variables of DAI format for PCM1704. :scratch2: I don't know...
Regards, B
 
Last edited:
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