Use of an ADAU1761's input to control VCDelay

Hello,

BrettG recently posted a FAQ on this, see https://ez.analog.com/docs/DOC-2964

The easiest way to implement this in a signal flow is to multiply the aux ADC value by an integer constant from a DC source, as shown here:

Best regards,

Bob

Thanks for your answer !

So here in your schematic the GPIO is used as an ADC (just to be sure) ?

With the ADAU176 I think I cannot use GPIOs as Auxiliary ADC, so can I use an audio input instead ? (given that it's still an ADC)

Hi Arthur68,

The ADAU1761 doesn't have an auxiliary ADC and the GPIOs are digital, so you need to use one of the audio inputs to implement this. That unfortunately cuts your analog audio input channel count down to 1.

If you were using another SigmaDSP that has an auxiliary ADC, you would then use the aux ADC input cell, as shown here: https://wiki.analog.com/resources/tools-software/sigmastudio/toolbox/io/auxadcinput

Ok, thanks for your answer !

Oops! I forgot that not all SigmaDSPs have analog GPIO.

Bob

I have another question,

What will be the format of the ADC value ? Will it be a decimal (5.23 if I'm not wrong) value of the input voltage ? So if there is +0.5V in input of the ADC will the value in the software be 0.5 as well ?

The audio ADC values map from -1 to 1 in 5.23 format.

GND = -1

AVDD = 1

Common mode (AVDD/2) = 0