[sdiy] DsPIC timer issue when used as DCO!

[karl dalen]

Colin f <colin at colinfraser.com>:

> You're not looking at the output of a rising ramp.

yes i do.

> The waveshaper on the 3396 (and presumably the 397) 'folds
> over' the top of  the wave once it reaches the upper limit.

No it does not, the folding takes action at +2.5V if +12v vcc,
then continues into saturation to create very narrow clipped
triangle, have look in the 3396 datasheet Colin if you dont
beleve me.

> If you want a ramp wave, you apply a timing control voltage
> that causes the
> wave to just reach the fold over point at the end of a
> timer period, so you
> only get a rising ramp.
> If you want a triangle wave, you apply double the timing
> voltage for the
> ramp.

Thats what im saying. i talk about the timing and shape voltage
as two separate issues that causes the final wave. As do the data sheet.

> ramp and tri, like on a Matrix 6.
> I don't think the behaviour of the wave shaper if it
> doesn't get reset after  returning to zero is documented, but my guess is - you end  up with a change
> to the positive direction, and a slow rise, like you see in
> the diagram.

No, guessing are not an option, once again, it saturates, practical
tests confirms this as do the 3396 data sheet!
http://www.synthtech.com/cem/c3396pdf.pdf

> Which brings us back to a timer error.

Sorry, no!


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