If you don't have a scope - do you have a soundcard in your PC? If so
there are a multitude of programs available that will turn your PC
into an audio frequency scope.

RP

On 12/03/2008, John Coppens <john@jcoppens.com> wrote:
> On Tue, 11 Mar 2008 17:48:18 +0100
> "Rikard Bosnjakovic" <rikard.bosnjakovic@gmail.com> wrote:
>
> > Since I never had the opportunity to play around with ADC and DAC's, I
> > got these MAX549-chips (dual 8-bit DAC) to be able to increase my
> > experience. Using a PIC, I wrote a quick code that outputs 0 up to 255
> > (and then back to 0) to the DAC, getting a 5Hz "sinewave".
>
> If you send values from 0 to 255 and back, in a linear way, you will have
> a triangle wave. If you look up the theory, that is a sine wave plus
> (weaker) harmonics (multiples of the basic sine).
>
> If you really want a sine, you'll have to send values from a table, which
> contains the amplitudes of the sine. At 256 levels it will give you a
> quite good approximation of the sine (very little distorsion). To
> eliminate most of the noise, you can put a simple lowpass filter (a
> resistor + capacitor) calculated at twice or three times the wanted sine
> frequency.
>
> John
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