> After a spell on other things, I am back to a PIC project, and need to
> generate a 'Dong' sound (as in "ding-dong", without the ding..)
>
> On cost grounds I can't go the ISD route, so I want to store and output
> a waveform from a 12C PIC. Question is, how can I easily create the
> table of tones/durations required? As I am tone deaf, trial and error
> could take a lifetime...

You don't need to record a dong, just get the frequencies for a good one.
You can do that with almost any musical instrument. Sneak up to a piano or
organ and try pressing down 2 or 3 keys together at the same time &
release.

You also don't need to record the instrument, the dong is a sine wave with
some distortion (i.e. 2nd 3rd 4th etc harmonics are present). So you need
to store the table for 1/4 wave of this in a pic and read it out and send
it to a D/A (R2R probably). You make the decreasing sound by reducing the
output all the time. A natural dong decreases in amplitude with a law that
depends on A = A * e^(1/((t+1)*q)) where e is Euler's number t is the time
from the strike and q a number proportional to the quality factor of the
gong. You can easily calculate a table for this function in a spreadsheet
and use it to amlitude modulate your gong tone.

Similar thinking applies to any repetitive tones (bird chirp, miaow, mooh,
you get it).

hope it helps,

Peter

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