I2S: Relationship between SCK and Fs (targeting SRC4192) - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st September 2010, 08:25 PM   #1
afo is offline afo  Germany
diyAudio Member
 
Join Date: Feb 2008
Default I2S: Relationship between SCK and Fs (targeting SRC4192)

Hi,

I plan to feed a SRC4192 from a MCU with I2S.
My master clock for the audio part is currently planned to be 24.576MHz. I chose this to be able to run the DAC with 128fs on the 192 kHz upsampled signal from the SRC4192.
Now I am wondering how I should clock the I2S signal that goes into the SRC4192 from the MCU. Does the SCK on I2S have to be a multiple (or even a 2^n factor) of the signals sampling rate (Fs). This would be a problem when having 44.1kHz Fs and only having a 24.576MHz clock.
Would I have to add a second clock just to create the SCK for the I2S->SRC4192 line in case of 44.1kHz playback?

Regards
  Reply With Quote
Old 1st September 2010, 09:54 PM   #2
glt is offline glt  United States
diyAudio Member
 
Join Date: Oct 2004
Yes, the 4192 will generate a new clock based on the on-board clock. So for the 44.1K family you will need a 22.xxxx clock. The 24.576 is only good for the 48K family.

You can feed any sample rate and the asrc will resample into the new sample rate...
__________________
www.hifiduino.wordpress.com
  Reply With Quote
Old 2nd September 2010, 10:49 AM   #3
afo is offline afo  Germany
diyAudio Member
 
Join Date: Feb 2008
So it's common to have two seperate clock circuits to support all common sampling frequencies?

Also one more question: When I take a 22.xx MHz clock for the 44.1kHz and I would want to use a SCK of 64fs, how would I do the clock division ideally?
  Reply With Quote
Old 2nd September 2010, 05:07 PM   #4
afo is offline afo  Germany
diyAudio Member
 
Join Date: Feb 2008
One more thing: When I install an additional 22.5792 MHz oscillator on my board and I want to do a 64fs bitclock on I2S when running 44,1 kHz, would I use a binary divider to generate the bitclock, or are there any better choices?
Actually I might even be able to install a 2,8224 MHz oscillator which matches exactly the bitclock for 44.1 kHz transfers.
What do you think would be the better choice?
  Reply With Quote
Old 2nd September 2010, 07:28 PM   #5
glt is offline glt  United States
diyAudio Member
 
Join Date: Oct 2004
It is probably not common to have two clocks, but it is a requirement if you want to support both 44.1 and 48K families. I don't know how fs is generated (you will have to look at the data sheet to figure this out). I only have experience with the Metronome module from twistedpearaudio.

Since you are familiar with microprocessors, why not use the 4193 which has a s/w interface? And then use dual frequency clocks where you can choose the frequency with a pin.

Also, according the asrc theory (the little I know) converting to an integer multiple of the sample frequency would not be any different than converting to fractional multiple of the sample frequency...
__________________
www.hifiduino.wordpress.com
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
I2S: Master Clock relationship with BCLK and LRCLK mahen.jnk Digital Line Level 0 27th August 2010 06:05 PM
FS: TDA1541 twin DAC, USB/I2S receiver, more nl Swap Meet 6 30th April 2010 10:02 PM
FS:USB-SPDIF/I2S Converter $45 bbp Swap Meet 13 7th February 2010 01:55 AM
SRC4192 Use... MWP Digital Source 33 26th April 2005 08:17 PM


New To Site? Need Help?

All times are GMT. The time now is 09:38 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2