14 Mar
2018
14 Mar
'18
11:33 p.m.
Hi Pepijn,
Thanks for the advice so far.
Based on this post, I managed to make my own I2S overlay.
https://www.raspberrypi.org/forums/viewtopic.php?t=189152
However, still only two channels.
I found that the Pi can in fact understand TDM, but the SoC can only get 2
of the channels for some reason.
https://github.com/raspberrypi/linux/pull/1982
Yep, two channels only for Pi. It's after all a consumer SoC designed
for mobile phones.
I am not sure how the Audioinjector Octo works but this has eight channels.
It uses a gate array with some kind of strange multiplexing. I have
added Matt, he will be able to explain more on the design ;-).
For the Beagle Bone, I also found someone who makes a
cape with a lot of
inputs and outputs.
There are some forum post scattered here and there with references to McASP,
as you mentioned.
This overlay seems a good starting point, potentially:
https://github.com/ctag-fh-kiel/ctag-face-2-4/blob/master/device-tree-overl…
So to sum it up, I2S works on the Pi for 2 channels, Beagle Bone is
something to look at more closely.
We are working with a university who have designed a Beaglebone cape
and I have written kernel driver for soundcard with up to 6
input/output channels designed for hearing aid research.
Please wait kindly and I will post a link to the Github page in coming
days with full hardware layout and kernel patch.
BR,
Chris