Sure Adau 1701 external Potentiometer


I got the Sure Adau1701 Board and want to do an external Volume control over an 10k Linear Potentiometer.

I use the litte dsp for my mobile Boomboxes. In my earlier versions i use the miniDSP. This works fine.

But now i have the problem, that the potentiometer have no functionality to the dsp. I have no idea why it don't work.

So i do an Sigmastudio DSP design as the one below:

So i want to use the Aux ADC 3 Input to the GPIO MP8 to regulate the volume over an potentiometer.

I try it with an 430Ohm resistor in front of the MP8 and without an resistor. But nothig is happend.

the only differnece is a loud plopping if the potentiometer reachs the end of its rotation without the resistor.

What i do wrong?

  • 0
    •  Analog Employees 
    on Aug 14, 2017 7:26 PM

    Hello mukboxx,

    I am not sure exectly what it going wrong. I suspect that your are not getting the DC level into the DSP.

    The first thing you should try is to place a readback cell right after the AUXADC so you can see what is coming into the DSP core. The number should go between 0 and just below "1" so 0.9999... or somewhere like that. All pots do not always go all the way to ground or all the way to the top.

    If you do not see anything changing then take an oscilloscope or multimeter and look at the signal coming from the pot. See what the pot is actually sending out.

    Start there and see where that leads you. Your project seems fine at first glance.

    Dave T

  • Hello Dave

    Thanks for your fast response.

    So i try the following things:

    I do messure the Pot with my Voltmeter, the Voltage reaches between 0.00V and 3.295V an the middle Pin from the Potentiometer. it seems ok . this voltage i put in to the dsp  -> to MP 8.

    I try another dsp board with the same dsp design. ( i have 5pieces of dsp Boards). nothig is happend.

    I try another Potentiometer the same issue.

    I simplify the design

    nothing happend.

  • So i try it with the readback

    you right, the number is always the same. nothing changes while i rotate the Potentiometer.

    but the potentiometer seems to work correctly. Mayby a problem with the frequency from the pot?

  • 0
    •  Analog Employees 
    on Aug 14, 2017 10:42 PM


    Sorry, I just now when I was doing something else I realized that this is really simple. Click the "Enable" on the Control ADC section right below the GPIO section.

    Sorry, it was too obvious and I missed it.

  • Hy Dave

    Now it works, you right, thanks.

    I have now another question

    Can i expand the range of the potentiometer?

    at the moment i think its about -12dB to 0dB i want to get a wide range for the volume regulation -72dB to 0 dB.

    And what do means the number (12) of the slew vol.?