Rough 'n Ready Audio Frequency extraction with a PIC

[HankMcSpank]

Hi Paul,

I was aware that the PIC simply threw the decimal portion away, but I'm no mathmetician & just wanted to clarify that I wasn't approaching this incorrectly!

Thank you for your suggestion...but my goal here is simply to detect the frequency remaining the same for a set length of time (ie the guitar player is 'holding' a note for more than x seconds)....so I don't actually even need to convert to hertz - for simplicity, I can just work in counts.

It might be handy one day to detect the actual 'Note Played'. when I think my approach would be along the lines of a monster lookup table (with a 'window' either side of the centre frequency for each note)...

                  Hertz     Clock Count

	 (from ) 	78	6410  
Open	E	82.41	6067
	 (to) 	84.85	5893  
			
	 	84.86	5892
Fret 1	F	87.31	5727
	 	89.90	5562
			
	 	89.91	5561
Fret 2	F#	92.50	5405
		95.24	5250
			
	 	95.25	5249
Fret 3	G	98.00	5102
		100.91	4955
			
	 	100.92	4954
Fret 4	G#	103.83	4816
		106.91	4677
			
	 	106.92	4676
Fret 5	A	110.00	4545
	 	113.26	4415
			
	 	113.27	4414
Fret 6	A#	116.54	4290
	 	120.00	4167

& so on (I guess Hertz could be derived to decimal points using an even bigger lookup table?!)


PS Once you get to the highest note on the fretboard (E on the 24th fret - 1318.5Hz) , the compartor clock count between interrupts comes down to something around 379....so it might be worth messing with the prescaler to give a bit more granularity)