Nice to hear the post has been useful.
I'm making good progress attaching a mic, sampling it and displaying the FFT on a simple 128x64 glcd.
this requires use of the ADC, use of the DMA (pdc), the dsp library and U8glib. and a lot of large arrays.
but it still fits.
I created my own constants to refer to the registers, just to be sure to understand the datasheet
the DMA is freerunning, the sampling rate controlled by the prescaler value.
when needed I ask the PDC to get an array worth of ADC data, then busy-wait for the array to be filled.
after that FFT and display.
I am confused by the large amount of clocks in the system. it is correct to assume MCK is 4 Mhz in the DUE ?
does anybody know for sure ?
I do see FFT output, but relating it to frequencies is out of my league and currently done by running
the baudline (great piece of software !) tone generator at a known frequency in my PC.
current code (as an example, quite possibly of "how not to program"..) : see attachment
ownDMA_ADC_GLCD_fft_v3.ino (63.6 KB)