ADAU1467 using aux adc for volume

Good afternoon. I made volume control on ADAU1467 in Sigma Studio.

I used:

- 5000 ohm potentiometer.

- AUXADC pin 7 to connect to the potentiometer.

-ADAU1467's pin 9 to get 3.3 volts (also i tried supply power 3.3V)

I have the following problem - the numbers are constantly changing, running around. There are no stable numbers. I used different potentiometers, but the result is the same.How to fix that problem?

 v07-tonecomp.rar

Thanks

Parents
  • Hi, I'm Viktor, we are building stuff together with Nynasty.

    We had no luck with DaveThib's suggested debouncer block, so we rolled our own like this:


    custom-debouncer.zip

    It works by storing the last seen value of the input, comparing it with the new one, and updating if the difference is big enough.

    We have tried cleaning up the signal in hardware. It does help, but doesn't eliminate the noise completely (that isn't surprising). A software debouncer is a must anyway, as any adc will sometimes jump between adjacent readouts even with very clean signal. I'm really surprised that we couldn't find a built-in debouncer in register configuration like in adau1701 for example.

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    •  Analog Employees 
    on Jul 29, 2021 8:52 PM in reply to Invendelirium

    Hello Victor,

    This means there are still some significant hardware issues that need to be solved. Many customers have used these AUXADCs in many products successfully without have to resort to even software debouncing. So without all the details it is difficult to know where the problems are. So I am glad you have come up with a solution that works for you. 

    Dave T

  • to be honest, we did not yet notice any audible problems without the debouncer. Though unlikely to be a problem in practice, i can imagine an artificial test that might reveal this noise in the audio - feeding a full-scale very low frequency tone for example.

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  • 0
    •  Analog Employees 
    on Jul 30, 2021 4:07 PM in reply to Invendelirium

    Yes, that would be a good test. This would show if it is changing volume up and down over and over again but it switches so fast that it never gets very far so it is not easily heard but you may pick it up with a THD analyzer but looking at a very low frequency tone is great. It also can sometimes make things like this audible. I have done that to find flaky switches in audio consoles. 

    Dave T