Ethernet and I2S: I2S does not work as soon as 50MHz clock is fed to GPIO0

[philippe_44]

Hi - I'm trying to add ethernet to my audio project and need a precise audio clock, so I use APLL. Most of DAC that can be used do not need an MCLK and in case they need it, I set GPIO0 as an output of CLK_OUT1 which is I2S0_CLK. All that works fine.

Problem happens with the ethernet. I know that, as I want to use APLL for audio, I need to provide a 50MHz clock and ethernet also works fine (using a 8270 and a 50MHz oscillator) used standalone

The issue is that as soon as a 50MHz clck is connected to GPIO0, the esp32 I2S system seems to stop working properly, all I have is white noise. If I just disconnect the 50MHz wire, all is good. So it seems that this 50MHz clock finds its way in the I2S clock system but I can't find how.

I've read that post viewtopic.php?t=10674 but I does not seem to help

[philippe_44]

Solved ... it was a ground loop / power supply issue. Really interesting that the *external* DAC totally did "freak out" and produced white noise as soon as the 50 MHz pin was connected to GPIO0