Many thanks to all Picsters for help with the dong sound generation.

Stuart
----- Original Message -----
From: "Peter L. Peres" <plp@ACTCOM.CO.IL>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: 11 February 2002 19:47
Subject: [pic] Sound generation on a pic "Dong"


> > 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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>

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