Somebody mentioned on the PICLIST:

   http://www.dontronics.com/see.html#sound

However, I don't think they produces the correct pitch on the
musical scale.

So you might like to try my formula for musical tone
generation....

Theory of Operation
===================

i.   The note "A" below "middle-C" is defined as 220 Hz.

ii.  An octave higher/lower corresponds to frequency
     doubling/halving, i.e.,

     "DO", "RE", "MI", "FA", "SO", "LA", "TI", "DO"
      ^                                         ^
      |                                         |
      +-----------------------------------------+
              one octave / 2x frequency

iii. You have 12 semitones (including flats and sharps) in an
     octave.

iv.  The pitch(freq) increases exponentially going up the scale.

Formula
=======
Therefore,
             ___
     k = 12 /           (twelth root of 2)
          \/  2

where k = multiplier to the next semitone.

if you natural log the above formula, it would be clearer,

    ln k = ln 2 / 12

Calculation
===========
So, you have,
                                   ___
             "DO" / middle-C = 12 /    * 220 * 3
                                \/  2
                             = 261.63 Hz
             "DO" is 3 semitones above the reference note A.

    and,
                                   ___
             "RE" / D        = 12 /    * 220 * 5
                                \/  2
                             = 277.18 Hz
             "RE" is 5 semitones above the reference note A.

    etc.

So use a spreadsheet to calculate the frequency for the notes
in the octave that you want to cover and the corresponding periods
and reload values for your timers.

I'm sorry that I do not have the PIC codes (haven't done one).

I do have the assembly codes for Hitachi's 4-bit, C codes for
8-bit and 16-bit uC.

And by the way, although the PIC I/O ports can drive relatively
high current, it would be safer to use the circuit below (which
I think is relatively simple and cheap).

Regards,


Peter Tiang
Design & Applications Lab
Hitachi Semiconductor(M) Sdn Bhd

====================================================================

>>> Mark Devin Newland <ape@eskimo.com> 30/May/1998 11:49am >>>
I just build up my proto board for a similar project but used a 2N7000
instead.  However, I do not have the tone formulas and graciously ask
for a copy.  Thanks in advance

Peter (Chee Foon Tiang) wrote:

> Drive the buzzer thru a pnp transistor as thus:
>
>                               +5V
> I/O    10k          100k      |
>  ---/\/\/\/\---+---/\/\/\/\---+
>                |        E_____|
>                |     B |/
>                +-------|\__
>                         C  |
>                            |
>                            /
>                           /
>                          +-----+
>                          |     | BUZ
>                          +-----+
>                             |
>                            GND
>
> Use a "frequency-controlled" type of
> buzzer (which works like conventional
> speakers), and you can generate
> various frequency to your liking.
>
> If you like I can mail you the formula
> for generating melodies, like
> "DO, RE, MI", etc.
>
> Regards,
> Peter Tiang
> ======================================
>
> >>> NCS Products <ncs@WORLDNET.ATT.NET> 29/May/1998 09:04am >>>
> I want to add sounds to a product--beeps and boops and the like.
>
> Can I just hook a piezo speaker to a PIC output pin?
> Or should I use a resistor and/or capacitor in series?