Hello,
I apologize in advance that this is not an issue with your code, but I have found no other way to contact you for assistance in I2S programming.

I am an undergraduate computer engineering student at Louisiana State University. I am currently in the process of planning a design project for a studio speaker controller which will be able to receive input and output multiple digital formats as well as analog, which includes the use of I2S on the Raspberry Pi. After reading through the code you have on RPi stereo microphone setups, I see that you are quite knowledgeable in implementing I2S on the RPi. After tirelessly searching the internet over the past month, I can't seem to find any concrete info on what I am trying to do with the RPi so my last resort is to attempt to personally contact someone who is skilled in I2S/RPi implementation, like yourself. I understand you may be busy with your own personal matters and if so please read no further, but if you wouldn't mind sharing your knowledge of I2S with me, I would be forever grateful.

So here is what I am trying to do:
Our speaker controller will have two microprocessors, the first being a Raspberry Pi 3 Model B, the second being an XMOS xCore-200 Multichannel Audio Platform. The XMOS board, being designed for all sorts of audio formats, has built in libraries of functions to easily implement I2S, so that is not the problem. What I wish to program the RPi to do is to receive audio input from a USB sound card (via a 3.5mm analog audio plug) and send it to the XMOS board via I2S. Additionally, the RPi must be programmed to receive I2S audio signal from the XMOS and send it out via the USB sound card (also 3.5mm analog audio jack). The USB sound card has one analog audio input and one analog audio output jack on it and is supposedly automatically configured to the RPi (does not require drivers).

So my first question would be, is this possible? I have seen several implementations of RPis sending I2S audio out to DACs but never seen one where the RPi receives I2S audio. Though the RPi has a DIN and a DOUT pin (38 and 40 respectively), I assume there is some way to do it.

And if there is a way to do it, how would you think I should go about it? Would a simple modification to your code suffice? Would this also be implemented as a module?

Additional info: the XMOS board in this case is the Master device and the RPi is the slave device, thus the XMOS generates the clock signal to be sent to the device. Also, these signals will not be routed at the same time, the RPi will be programmed to either send audio out or receive audio in, not both at the same time.

Thank you in advance for considering helping me,
If you wish to discuss further, either post here or, if you don't mind, email me at [email protected]