ADAU1452 eval' board - AUX ADC ReadBack Values

MDThommo81 Question

Aug 31, 2020 00:00

Hi there,

I've setup a simple SigmaStudio project to attempt to readback the values returned from the potentiometers on the EVAL-ADAU1452REVBZ, connected to AUX ADC 0 and 1. I want to understand the readback values they return so then I can use an interpolator for other functions in the future. I looked at some other Q&A on this EZ, for example: https://ez.analog.com/dsp/sigmadsp/f/q-a/65650/adau1701-aux-adc-numeric-range and the values I'm seeing there are very different to my readback values.

What range of readback values should I be getting from the AUX_ADC0 & 1 pot's on the eval' board? Below are the min and max values I am getting:

(potentiometer turned to minimum/0)

Then turning it to max I get:

Shouldn't I be getting ~1.0?

Many thanks for any assistance you can provide.

Kind regards,

Mark

Audio Signal Processors

adau1452

aux adc

SigmaDSP Audio Processors

readback

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DaveThib Reply

Sep 2, 2020 00:00

Hello Mark,

The two parts have a significant difference in how the AUXADCs were implemented. There are good things and bad things about both ways so you cannot say one is better than the other. The 1701 has the 10 bit data normalized to the left so that it goes almost to 1.0 in 5.23 format. In the ADAU1452 family of parts the data it right justified. So the 10 bit data does not go up very high when looking at it as a 5.24 number. If you change it to HEX you will see what I mean. So all you need to do it shift it left by 14 bits. Here is how you do it.

The good things about this default right justified format is when you want to drive an index selectable switch all you have to do is control its max limit. I know you did not ask about this but, You would do it like this:

Dave T

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MDThommo81 Reply

Sep 4, 2020 00:00

As always, an excellent response. Thanks, Dave!

Could you share the rest of your example showing how the 4 filters are used? Very interesting!