ADAU1701 Readback Register on a Microcontroller

Hello Rk4321,

I can see why you are having difficulty. The using a readback cell will not be the correct way to do this. The readback will give you one sample at the instant you initiated the readback. It could be a positive or negative number and the next time you read it you will miss thousands of samples. So you need to integrate the sample values over a period of time then read that value. The meters already do this so it is a matter of reading the correct meter parameter and using that value. 

There are many posts about this but I will point you to a couple here. 

This first one has a PDF in it that is more about the compressors but it also discusses the meters a little. 

(+) Compressor input level appears to be displayed/calculated incorrectly - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone (analog.com)

This next one has some code with it but it is also for the ADAU1452 so you have to adapt to the 1701. 

(+) Reading meters with a controller on the ADAU1452 - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone (analog.com)

This is a good one for the 1701:

(+) ADAU1701 VuMeter Missing parameter address, how can i read that? - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone (analog.com)

This should get you started in the right direction. 

Dave T

Hello Rk4321,

I can see why you are having difficulty. The using a readback cell will not be the correct way to do this. The readback will give you one sample at the instant you initiated the readback. It could be a positive or negative number and the next time you read it you will miss thousands of samples. So you need to integrate the sample values over a period of time then read that value. The meters already do this so it is a matter of reading the correct meter parameter and using that value. 

There are many posts about this but I will point you to a couple here. 

This first one has a PDF in it that is more about the compressors but it also discusses the meters a little. 

(+) Compressor input level appears to be displayed/calculated incorrectly - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone (analog.com)

This next one has some code with it but it is also for the ADAU1452 so you have to adapt to the 1701. 

(+) Reading meters with a controller on the ADAU1452 - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone (analog.com)

This is a good one for the 1701:

(+) ADAU1701 VuMeter Missing parameter address, how can i read that? - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone (analog.com)

This should get you started in the right direction. 

Dave T

Hey David,

This was very helpful, I'm new to the DSP/SigmaStudio side of things so I didn't know you could pull values directly from the components. My new design will flow input -> filters -> Level Meter, and my firmware will then pull the reading from a parameter in the Level Meter and convert. Is this more in line with what you'd think is the correct way of approaching this?

FYI, I've gotten more comfortable with the firmware conversion of fixed-point values, so I should be set there.

RK

Hello RK,

Yes, this is how you would do it. You would read the parameter every ten milliseconds. The meter will get the absolute value and integrate the level of the audio so then all you need to do is convert it and setup some ballistics for peak or VU. 

This is the document where I went into the meter data a little. This is mostly about the compressor.

PDF

Dave T