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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