yeh...
what Harry said!
I've been thinking about this too and i endorse Harry's position.
In the wild, there's just no 'right' way position every kind of
pulse... and satisfy every kind of application.
Passive RC,
Active one shot (ala 555),
or software,
are all 'best' for different circumstances and making a choice now
(kinda) limits the flexibility.
of course...
(you can always dremel off the offending components) and solder right
on to the exposed traces)
(but i don't wanna gross anybody out)
;'>
-doc
--- In
ComputerVoltageSources@yahoogroups.com, Harry Bissell Jr
<harrybissell@...> wrote:
>
> I'd say its a bad idea to rely on some minimum or maximum trigger
> length... I've seen sub-millisecond triggers... and some much longer.
>
> If you get into triggers more than a few milliseconds long, they
are likely to
> affect the sound of the modules they are controlling.
>
> If its a problem for a particular user, they could do the RC trick
> (which does NOT work if the trigger is already generated by an
unbuffered
> RC) ... or add an active one-shot for their particular issue.
>
> Can't make everyone happy :^P (except me)
>
> H^) harry
>
> djbrow54 <davebr@...> wrote: I probably started this and
I'm having second thoughts. The issue
> with stretching the pulse is that you want to detect a trigger only
> once. So, having detected it with a stretched pulse, you now need to
> ignore it until it goes away. My initial thought was that you could
> assign the AtomPro pins appropriately such that you could use one of
> the hardware level interrupts. I'm assuming these are edge and not
> level. However, if they are level, then you have the same issue. In
> thinking about this, I'm starting to come to the conclusion that you
> can detect triggers via timer interrupts.
>
> I general run my timer interrupt at 1 mS. Most of my triggers are at
> least this wide (Is this a true statement in general?). Assuming
> triggers are at least 2 mS, it should be pretty simple to sample the
> digital input and look for a state change in a timer interrupt
> routine. This state change could then set a global variable that a
> trigger had occurred. The software could poll the variable and
decide
> what to do with it whenever. If you need immediate action, you can
> always do this inside of the timer interrupt routine.
>
> I think I can code this up in a pretty minimal overhead mechanism. I
> should have thought of it earlier as I already have interrupt
routines
> for input averaging the analog inputs.
>
> This is probably a simpler solution that would work and maintain code
> compatibility and minimal hardware.
>
> Dave
>
> --- In ComputerVoltageSources@yahoogroups.com, "Grant Richter"
> <grichter@> wrote:
> >
> > It seems like we could just put a simple RC pulse strecher on the
> triger input.
> >
> > That should allow enough time for detection with a software scan.
> >
> > There is always goin to be some latency. 5-10 milliseconds is not a
> lot.
> >
> > Or do we really need to generate an interupt from the trigger input
> jack itself?
>
>
>
>
>
>
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