M. Adam Davis email (remove spam text)
This is something I've been meaning to make. But it will still be a month or
two before I get to it, so...
You have 1 analog input, and run the chip at 20MHz. Use a fast fourier
transform to get the level in 10 different frequency bands, and drive a 10x10
matrix of LEDs. One could do an 8x8 or 16x16 or just about any size spectrum
analyzer out of such a setup. A 16f876 would have the right number of I/O to do
10x10 with one audio input and an extra i/o pin. It may not be too much to ask
for to have it drive two 8x8 displays with two audio inputs.
At any rate, there have been several threads on FFT on a PIC in the past, look
at http://www.piclist.com/ for the archive and search for FFT.
You should probably start out doing a reguler VU meter first, then do a
peak-holding VU meter, then decide whether a spectrum analyzer is worth it or
feasable. By then the 18Fxxx chips will be common with their 8x8 multiply to
speed your fft up quite a bit.
Josh Koffman wrote:
See also: www.piclist.com/techref/microchip/ios.htm?key=audio
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