I'm trying to get Toslink PCM audio into the RPI. This is the entire reason I purchased two of these cards. This is for capturing TV audio for distribution using snapcast and/or Linux based audio filters run outside of the DSP.
I have Sigma Studio up and running and have successfully written a profile to the DSP using it.
Responses to the second question of this post mentions a 'hifiberry-dacplusdsp' dtoverlay which supports reading data from the DSP to the RPI, but does not expand further. https://support.hifiberry.com/hc/en-us/community/posts/360006995438-HifiBerry-DAC-DSP-192k-Processing-Path-and-SPDIF-input
I'm guessing perhaps I need ASRCout, but don't know much beyond that. I'm an electrical engineer by degree, took some DSP classes in school, have been studying ALSA, but I2S is foreign to me.
A kick in the right direction would be very helpful here. What outputs in the DSP must I route the signal to? Where am I looking for the data in the RPI? Approximate steps to get the data into a named pipe/mkfifo appreciated.