Continuing on from my Ambient Noise Level Indicator, I wanted to create an enclosure and make it stand-alone – not requiring a computer to do the processing. I ended up with a little device that converts noise amplitude to the light spectrum: Noise Crayon.
The Ambient Noise Level Indicator used the MCU serial host Processing to perform a FFT and various averaging routines to create an indicator for ambient noise. The idea being that it would change colour when background levels rise above a threshold. Moving to an ATMEGA328, performing this processing – especially the FFT – is asking a little too much of it. There are libraries but I’ve heard of limited successes.