2011-10-03 12:54:56     Driver for daisy-chained AD1938 audio codecs?

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2011-10-03 12:54:56     Driver for daisy-chained AD1938 audio codecs?

Steve Strobel (UNITED STATES)

Message: 103699   

 

I am considering a hardware design which would need eight channels of audio input/output.  In the past I worked on a prototype that used two AD1938 chips on separate SPORT interfaces.  It worked, but having to deal with two ALSA sound devices made the software relatively complicated (error recovery, synchronization, etc).  It would be nice if all of the channels appeared as a single ALSA device.

 

I looked but haven't found a similar audio codec with more than six input channels, so I am considering chaining two AD1938 codecs as described in the datasheet so they can be interfaced to the same SPORT.  So for I haven't been able to find any Linux drivers for chained codecs. 

 

Suggestions for making such a driver or other options for getting eight channels of audio in/out would be greatly appreciated.

 

 

 

Steve

 

 

 

P.S.  I am currently using the AD1938 driver for a single codec that I wrote and posted here:    tinyurl.com/3f6j6mw   Now that a AD1938 driver has been mainlined, I would probably want to switch and use it as the basis for a driver supporting chained codecs.

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2011-10-10 02:23:00     Re: Driver for daisy-chained AD1938 audio codecs?

Aaron Wu (CHINA)

Message: 103762   

 

In my understanding the daisy-chained AD1938s share a single digital interface and hence represents a single software interface, only that each AD1938 is configured to diffrent modes, (LSB, MSB, righ-justified, left-justified etc to work in a TDM mode, response to some time slot and ignoring the other), so probably if you configure each of them fine, they work as you expected. Will this help?

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2011-10-10 02:31:58     Re: Driver for daisy-chained AD1938 audio codecs?

Aaron Wu (CHINA)

Message: 103763   

 

And if you are asking the daisy chain support in ALSA, you may get more help in ALSA mainline   www.alsa-project.org

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2011-10-11 14:23:33     Re: Driver for daisy-chained AD1938 audio codecs?

Steve Strobel (UNITED STATES)

Message: 103795   

 

I will ask there.  Thanks.

 

Steve

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