I2S audio and SPDIF at the same time

Showcase builds, discuss cases, embedding MiSTer into existing computer cases.
deadsnare
Posts: 4
Joined: Wed Jun 23, 2021 11:56 am
Been thanked: 3 times

I2S audio and SPDIF at the same time

Unread post by deadsnare »

Hi there, I am currently in the works of designing my own I/O board and would like to incorporate a DAC IC fed by an I2S stream to circumvent the poor analog audio of the MiSTer. At the same time, I would like to keep SPDIF functionality should I ever want to connect the MiSTer to an AVR. However, official documentation does not seem to exist or I have been unable to find it. From several disjunct forum posts here and there, I was able to gather the following:

The rightmost big metal switch on the DE-10 Nano switches the functions of GPIO1's pins 2, 7 and 9 from left/right analog audio and SPDIF stream to I2s stream (see pinout I've sketched below). So this means you can feed a DAC I2S, but you will lose SPDIF, since it won't be output anymore. Am I right about this?

Consider this: Antonio Villenas IOUSB is able to circumvent this limitation, and the Ironclad also seems able to use both I2S and SPDIF. What am I missing here? Are some of the Arduino header pins used for this which are unconnected on the official IO board? (On a side note: How is Antonio able to output full 24-bit RGB over VGA instead of the official IO board's 18-bit output?)

MiSTer_pinout.png
You do not have the required permissions to view the files attached to this post.
Post Reply