ComputerVoltageSources

It wouldn't be that hard to do.  It's been 2.5 years since I wrote my 
trig-gate-cv delay but the basic concept is I have three 128 event 
buffers.  The first is used to timestamp an event (trigger high, 
trigger low, etc.). The second buffer is to record a trigger or gate 
transition (high or low). The third buffer is to record a CV value.  
When I detect a trigger, I timestamp it with a 'delay' factor and put 
the timestamp, trigger, gate, and CV in the buffer.  The buffer is 
circular and at 128 events long it never fills up.

Timer interrupts advance the timebase. When the timebase matches the 
next timestamp in the buffer, I output the event.  It would be pretty 
easy to modify the concept to continue to record until some other 
event (e.g. stop) and then simply playback the buffer. At the end of 
the buffer you'd simply reset the timebase. 

Note that this only works for discrete events such as a keyboard. It 
won't record a continuously changing CV such as with a pitchbend.

Four channels would be tough since you'd need 12 outputs.  A CVS with 
an optional digial I2C expander could do it, though.

Maybe someday when I'm bored I'll give it a try.

Dave


--- In ComputerVoltageSources@yahoogroups.com, "Grant Richter" 
<grichter@...> wrote:
>
> I always thought it would be fun to have a 4 channel looper that 
could loop the VCO CV, 
> wave CV, filter CV and VCA CV. That way when you play a neat little 
lick, you could hit 
> "loop" and then have you hands free to twiddle the knobs.
> 
> For Tangerine Dream kind of days (they did a lot of knob twiddling 
over sequences that 
> sound real good).
> 
> The old ARP 1603 would do 4 bars of 4/4 (16) so only 16 to 32 actual 
notes need to be 
> stored. I saw pictures of them using 1603s and 2600s at some point.
> 
> Just a thought.
> 
> --- In ComputerVoltageSources@yahoogroups.com, "djbrow54" <davebr@> 
wrote:
> >
> > Not exactly sure what you mean by a looper.  It depends upon 
whether 
> > your CV is continuously variable or steps between discrete values.
> > 
> > I did an arpeggiator where I would monitor the CV for a change 
since 
> > it was hard to detect a trigger (I since use edge interrupts).  
With a 
> > real-time clock, you just timestamp the CV value change. Ram use 
is 
> > minimal since you just have a record of the changes.  Worked 
great.
> > 
> > I did something similar for a CV delay which can implement some 
really 
> > long delays.  Sample the CV transitions and clock them out at a 
> > variable delay later.
> > 
> > Dave
> > 
> > --- In ComputerVoltageSources@yahoogroups.com, "Grant Richter" 
> > <grichter@> wrote:
> > >
> > > Has anyone experimented with doing a 4 channel recorder looper?
> > > 
> > > I need one for an experiment.
> > > 
> > > Any comments before I try to program one?
> > >
> >
>