Sv: [sdiy] Digital VCO update

[Eric Brombaugh]

Richard Wentk wrote:
> What's the acquisition time of the ADC? Could you add a MUX to give 
> yourself two (or more...) independent CV ins?
It's a Delta-Sigma converter, so it's not amenable to muxing. As I've 
got it set up right now it's doing conversions at about 250Hz, which 
seems fine for tracking note changes and slow modulation, but definitely 
isn't good enough for stuff like FM.

I tried an experiment to see if I could speed up the ADC. It's spec'd to 
run as fast as 7.5kHz, but it eats up almost the entire CPU bandwidth 
then so there's nothing left over for the NCO. I might be able to get it 
up to 500Hz, but that's probably about the max.

Eric