I2S1_SDOUT doesn't work, but the other pins do?

I’m trying to play audio out the I2S1 interface (or any interface for now), but the SDOUT pin doesn’t seem to send any data. I’m using aplay (with no arguments except for the source audio file). When aplay starts, I can see the MCLK start running, along with SRCLK and SFSYNC (all available on J21), however SOUT does not have any data. It just stays low. Running aplay with -vv clearly shows that it should be sending data.

Is this the expected behavior? Am I missing a step?

I’m running this on a virgin TX2 our of the box (after running the initial install script). I have tried the same command on a TX1 with the latest jetpack kernel and nothing at all happens on any of the I2S pins (no clock or data at all). I also tried this on a TX2 with the jetpack kernel, and it acted like the TX1 (no output at all).

Hi Brad
Thanks for your report. We will check it.

Thanks. I know that on the X1, you need to export then unexport the GPIO on those pins to make them work for I2S. I was going to try the same thing on my X2 just for the SDOUT pin, but I haven’t found the time.

(I stopped trying to get this to work on the dev kit for now, as I was having SI issues anyway. But I will be getting back to this after our custom hardware is built.)

Hi Brad
So you test is on the customize carrier board?
Does it have the same problem on the reference carrier board?

Could you provide step and any code modify is needed.

It sounds like he’s trying on the devkit, and his custom hardware isn’t even done yet.

Snarky is correct. It will be some time before I pick this up again, as I’m focused on other areas of the project right now.