Some questions about SigmaDSP

Hello Andrew,

Thanks for the inquiry and I will try my best to provide some answers.

First I am rather certain that the ADAU1401A will not have enough processing power to perform that she is asking about. But, I will keep it I'm mind as I learn more about the application.

1. she wants pitch control, Is it possible to vary the pitch control to an exponential or logarithmic function instead of a linear one?

I am assuming she wants to vary the pitch of incoming audio and not the pitch of an oscillator? An oscillator that is generated in the DSP is easy to control. We have a VCO that would work quite well for this. But I am assuming she wants to shift the pitch of voice or audio coming into the part from outside the DSP. The pitch shift algorithms are somewhat limited in how far you can go before the audio has too many artifacts from the pitch shifting. You do not want to go too much more than a few semi-tones or perhaps a third or so, but an octave might not sound good enough but, again, I do not know the exact application so they will have to experiment with it.

Regarding a log function, I think this could be done, it is a DSP that has many ways to adapt a signal. So this should be possible.

2. If the MCU sends 5 sound sources, does it have the ability to mix 5 sound sources after individually controlling the pitch?

Yes, you can mix up to 48 channels of inputs and then once inside the DSP you can split them off into how ever many channels you need and be able to mix all of them as long as you do not run out of MIPS. So there is no limitation inside the DSP core, the only limitation is with the input serial ports.

The ADAU1401A can only take in 10 inputs, 8 into the serial port and the two ADC inputs. Again, once in the core you can mix as many as you have instructions to spare.

3. Is it possible to raise or lower the sound pressure level at a certain frequency (eg 200Hz, 500Hz, 1kHz) through FFT conversion?

It can certainly be done using filters that are in the library. Doing it with an FFT is more difficult. We are adding in more functions for block processing of FFTs but I would have to research what is coming soon to the library. I suspect that this might have to be custom code. This is another discussion. For the ADAU1401A it would not be possible.

4. Is it possible to import sound sources directly from the external Flash Memory (sound source storage) to the SPI and tune them on the ADAU1401A?

Not with the ADAU1401A but the ADAU1452 can import audio from a flash. There is a cell for doing that.

Dave T