[sdiy] Digital VCO update

[Eric Brombaugh]

On Apr 29, 2006, at 8:43 PM, Michael Bacich wrote:

>  I wonder if you might have one additional i/o pin left to include a 
> hard sync input?  I'm not even sure hard sync is possible with your 
> wave generation technique, but if it is, it would be hella useful.

Hard sync is certainly feasible. That's a fine application for that 
last pin.

> I would also love to see you try to make a low-frequency 
> implementation of this for voltage-controlled digital LFO use.  What 
> do you think?  How smooth would these waves look/sound at LFO rates?

An LFO should be a fairly straight forward conversion. The output is 
pretty smooth at 20Hz, but I can hear some 'zzzzz' from the discrete 
steps. A longer wavetable would probably solve this thought, and an LFO 
could use a lower sample rate, so there would be more time to mitigate 
this. Someone suggested dithering, and I've had good luck with the PRN 
generator so this might work nicely.

Eric