ADAU1701 + ESP32 + I2S connectivity

Hello Mayuresh,

This is one of our older processors and has this unusual setup. If the clocks coming into the serial port are not synchronous with the master clock coming into the PLL, then it mutes all the outputs. So either the DSP has to be the master for the serial port clocking or the master clock coming into the DSP needs to be from the same source as the serial port clocks. 

Try this experiment. 

Set up an oscillator in the DSP core to go out of the DACs. Do not forget to go through a volume control so it is not at 0dBFS. Then do not turn on the clocks to the serial port. You should have output from the DSP. Then just turn on the clocks to the serial port and I expect the DACs to mute. 

I have also seen it where the frequencies are close so it works for a few cycles of audio then mutes for a short time then unmutes for a short time etc. You end up with lots of distortion. If the clocks are way off you get a steady mute. 

Dave T

HI Dave,

Will try what you have suggested. Currently I am getting some output but its full of noise and distortion. This is why I asked earlier, is it possible to use a different value close than 12.188 so I can match these values with a same value clock and with PLL0 & 1. 

Thanks
-Mayuresh

Hello Maturesh,

Draw out a diagram showing where the clocks are coming from? Where is the master clock, the bit clock, the LRCLK coking from and going to and what is the direction of the clocks? 

Then the actual frequencies will also help. 

Dave T

Hello Maturesh,

Draw out a diagram showing where the clocks are coming from? Where is the master clock, the bit clock, the LRCLK coking from and going to and what is the direction of the clocks? 

Then the actual frequencies will also help. 

Dave T

Hi Dave,

For now, I am dropping the idea of using ESP32 for multiple reasons. Instead, I am now trying to make use of AD1938 DAC and I am having similar question. I will raise it in a new thread.

Thanks for your help so far.

Regards
-Mayuresh