MonkeyListen uses the FRDM-K20D50 board (which has a Cortex M4 core with DSP instructions) with the FRDM-OLED shield so you can make your very
own spectrum analyzer display The end result will be a functional DSP system that will analyze incoming audio content via an electret microphone on FRDM-OLED board and display the spectral content. The example code will also show you how to plot time domain data (a simple audio scope!), Frequency domain data (via an FFT) and a time-frequency plot (spectrogram). Extra I/O are provided to hack the code and create your own DMM or oscilloscope.