I get the basic idea of a Fast Fourier Transform to take a waveform and turn it into a histogram of frequencies. I also get that an FFT algorithm is probably beyond what I want to run in software on a modest AVR platform.

However, I don’t understand how to do analog filtering into known bands at all. I’d like to do a basic display like a stereo’s equalizer, receiving voltages on analog inputs to represent the prevalence of signal in multiple frequency bands.

Anyone have some resources that help the analog helpless?