Stacking Audio Capes for Multichannel Audio Input

So I’m thinking about using the BeagleBoneBlack for multichannel audio DSP, but there are still some questions I have about it.

Since the audio capes are stackable, and you can assign each one a unique address, and the AM335X uses McASP, I should
be able to process multiple channel input separately on the board, but choose to output the resultant signal on only use one of the capes?

-Jeff

You could make a stackable TDM cape I guess?
Each codec/cape board could pick off its own channel from the McASP/TDM port…

I like that idea…

We were considering that, but were concerned if we could find a fast enough mux to do 6 channels at 48kHz, and that plus clock issues.
Thanks for the idea, though! I will check out how the Am335x fares in TDM.

I think I tested 8 or 16 CH TDM at 48k and it worked fine.

ooh that’s pretty cool! Hopefully it will work for me as well.

Did you have to build your own TDM cape, or could you just stack them and use the Am335x to do the multiplexing

We just used a proto cape to expose the McASP pins we needed, then ran wires over to a set of TI SmartAmp boards which supported TDM at the time.

Picture:
https://dl.dropboxusercontent.com/u/82765462/BBB/4channel_audioCape.jpg

Ah, I see. Thanks for the help!

My general idea so far is to stack 3 audio capes to receive 6 channel input, then process and output probably stereo (or 6 channel out for feedback); I guess I’ll see how the multiplexing will fit in once I understand the board more.

Since the audio capes are stackable, and you can assign each one a unique address, and the AM335X uses McASP, I should
be able to process multiple channel input separately on the board, but choose to output the resultant signal on only use one of the capes?

Interesting. Are you keen to avoid soldering?

I've got some Cirrus 6in/8out codecs* mounted on LQFP=>DIP adaptor boards** which I'm hoping to eventually wire up to a Bone proto cape. Given that these devices have a TDM mode and some kernel driver support I reckoned it should not be too hard to do.

If anyone else is especially interested in multi-channel Bone audio please do get in touch.

BR

Jerry.

* http://www.cirrus.com/en/products/cs42448.html
** http://www.proto-advantage.com/store/product_info.php?products_id=2200113 These guys will also order the part(s) and do the soldering! Ace.

Wait, that’s pretty cool. I will forward this to my group, and see what they think.
Thanks for the suggestion/idea!

Hi,

I’ve been trying to work with the CS42448 audio codec as a peripheral for the STM32F405 Discovery Board, but with little success. I’m also very interested in porting the codec over to the BB and the Raspberry Pi (any ARM processors, really). If you have any information or code you’d be willing to share, I’d be eternally grateful. I would also be happy to share board layouts I’ve been using for the codec.

Cheers,
Colin

Hi Colin,

I have decided to forgo the CS42448 board for now, as its Evaluation board a codec board, and instead I am going to see if I can figure out stacking the audio capes with the BBB, and how the BBB does multichannel audio… and if that doesn’t work, I might have to try the external board.

I’ll let you know what happens!

Jeff

I have decided to forgo the CS42448 board for now, as its Evaluation board a codec board, and instead I am going to see if I can figure out stacking the audio capes with the BBB, and
how the BBB does multichannel audio... and if that doesn't work, I might have to try the external board.

Suggest a quick scan of the Rev B audio cape schematics. There might be one or two issues arising :slight_smile:

Is it because the cape only uses one of the I2C ports and one of the audio in/out ports?