Hardware Choices & Implementation - FFT

[jsalerno]

Hi all.
First post here and a newbie to hardware at this level.
I am a C/++/Java developer and looking to find the most direct solution for my FFT project

I want to live stream fft frames back to an Android OTG consumer (I already fft on-droid the analog TRS input, but wish to offload this work to a dedicated unit and consume only frequency domain data for presentation/storage ... so that's the motivation).

Signal source will be an op-amped piezo audio signal.
That op-amp will be approximately this design/pcb : https://sagittronics.wordpress.com/2019/07/04/simple-phantom-power-preamp-alex-rice-piezo-amplifier/

• Currently I use a high impedance DI box (a phantom powered StageBug SB-4 by Radial, but wish to use my own components instead)

So, my basic hardware questions are:
How to

• physically mount/connect and power such an op-amp on an Arduino,
• stream the transformations back to the droid

I have looked at

• https://github.com/pschatzmann/arduino-audio-tools/wiki/FFT
• https://github.com/pschatzmann/arduino-audio-tools/blob/main/examples/examples-audiokit/streams-audiokit-fft/streams-audiokit-fft.ino
• https://github.com/pschatzmann/arduino-audio-tools/wiki/Pipelines

I assume some hardware solutions are more optimal than others, and I am trying to piece the hardware puzzle together without really having any decent understanding of the domain.

The software aspect I expect to not be a problem.

Many thanks in advance

[pschatzmann]

Audio processing on microcontrollers is challenging because of their limited RAM and processing speed. Specially floating point operations are much slower then what you get on Android and the data transmission speeds are limited.

Some microcontrollers have a built-in ADC but the quality is usually quite poor, in in general I recommend to use an Audio ADC or an Audio Board that has provides audio input.

I suggest you do some prototyping with an ESP32 because you can try to exchange the data via BLE, Bluetooth, IP or UDP to get a better feeling about the limits.