ADAU1452 to generate a DC control voltage for VCA
Thread Summary
The user seeks to generate a DC control voltage for a VCA using the ADAU1452. The final answer recommends the ADAU1701 instead, as it has built-in ADCs and DACs capable of DC output, with a digital input range of -1.0 to +1.0 resulting in an analog output range of +3 V to +0.2 V. The ADAU1701 is easier to integrate into a final design, though the ADAU1452 eval board offers more processing capabilities.AI Generated Content
Hi people,
I'm an analog engineer with close to zero digital experience. Nevertheless I'm curious about the possibility of using the ADAU1452 to generate a DC control voltage to drive a VCA, and I wanted to see if you all think I'm barking up the right tree here...
I am looking for a way to:
1) Convert an analog audio signal to digital
2) Rectify the audio in the digital domain, creating an absolute-value DC signal
3) Apply some time constants to the DC signal, slowing the rise and fall times to user-definable time constants
4) Convert the resulting signal to an analog DC output.
After scratching the surface, it seems like the ADAU1452 product, in conjunction with SigmaStudio, is a solid way to go. The chip has extensive capabilities, way beyond my requirements, which would leave me plenty of room to drastically overcomplicate the original simple idea into a long-term, never-ending development idea, which is exactly my idea of a good time!
Before I get the eval board and start committing time to this, I thought I'd check in here and see if you more experienced folk don't steer me in some other direction first.
Pardon the vague question! Just a sanity check, really. Thanks!
Audio Signal Processors
adau1452
SigmaDSP Audio Processors
Hi Rob:
I suggest you use a 1701 for your project. It has built in ADCs and DACs although I don't think the DACs can output DC voltage since they are meant for audio outputs.
Buy the 1701 mini board, it's the most affordable evaluation Board and use SigmaStudio for programming your algorithm. It should take you no time.
Regards
Miguel
Hi mmmike,
Thanks for your reply. Would you be willing to expand a little as to why you think the 1701 is a better fit? My two concerns are:
1) If the 1701 can't output a DC voltage, it won't work for my application
2) The 1701 evaluation board is the same price as the ADAU1452 evaluation board, so there's no advantage, price-wise.
Thanks!
Hi,
Yes Miguel is right in recommending the ADAU1701 -- it has built-in converters and can certainly handle the function you describe. Unless you have lots of additional processing in mind, the -1452 is overkill.
Good news -- the -1701's DACs do work down to DC, as shown here:
https://ez.analog.com/message/85908#85908
Each DAC output is centered at approx. 1.6 V. A digital input of -1.0 drives it to about +3 V while a digital input of +1.0 results in a +0.2 V output (the DAC inverts). Exact offset varies some, so I recommend implementing a self-calibrating routine at startup.
The -1452 eval board can do more processing for the same price, but if you're looking forward to building a prototype and then a final product, the -1701 is easier to integrate into your design.
Best regards,
Bob
Fantastic!! Thanks very much Miguel and Bob!
You're welcome of course. Your avatar does get warm, but your screen name is cool! I remember from my youth a construction project for a one-tube radio with no plate supply -- just light up the filament, and the space charge moved the electrons!
Bob
Hi Bob:
Tubes, really!
Anyway I think the correct answer should go to Bob, He was more thorough.
FYI SigmaDSP and SigmaStudio was originally meant for analog designers getting into the digital world without suffering.
Regards
Miguel
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