>... David's guitar tuner project .....

how about amplifying,low-pass filtering ( 3rd order), and clipping
the guitar signal with a cheapo 324 quad-opa. Generate the desired
reference freq. with the RTCC. Make a software-PLL style frequency-
comparator ( edge-triggered RS-flip-flop )which is set by ref.-timing
and reset by input signal . Connect a 'sharp' LED to the Fin>Fref port and
a 'flat' LED to the Fref>Fin port. As the input freq. comes up/
down towards the ref.freq. the flat/sharp LED will dim.
Just a quick idea; don't know if it makes sense.
Another idea, not mine , saw it on Frankfurt Musik fair about 10yrs ago:
A guy fed a bright LED with a microcontroller generated reference
frequency  and used the stroboscobe effect to visually tune the strings
without making noise - nice !

>It would be interesting to also pursue the generation of MIDI from a
>guitar signal ....

and from other real world events.  In my free-time ( not much) I currently
work on such a project : a microphone is placed at each end of a 1m plastic
tube. If you hit the tube with e.g. a drum-stick the mikes generate pulses
with a runtime delay. A 16C54 along with a 324 opamp digitizes these pulses
( MIDI key velocity ) and calculates a MIDI-note-# from the trigger delays.

I 'll put schematics, layouts + code related to MIDI, musicelectronics, PICs
and other controllers on my ftp site as soon as possible ( late summer ?)
Will be announced here and on MIDI.boards

P.S.
I too have some code that sends MIDI. MIDI IN is tough.
a 20MHz PIC with HW-interrupt could do it. Somebody tried it ?
Anybody else doing MIDI with PICs ?
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