ComputerVoltageSources

Trigger success!

It turns out I read the AtomPro24 datasheet incorrectly the first 
time. IRQ1 is on P8 which is the AUX input/output. You have to program 
the PMR1 register (took a while to figure that out) to select this 
input as an interrupt. The interrupt detects negative edges. I can now 
generate an interrupt on a trigger edge. Great!

It seems to work reasonably well with a positive trigger. It just 
detects the trailing edge. However, you get one extraneous interrupt 
when you enable IRQ1 since the level is low.

Inverting the signal for a negative trigger works well and eliminates 
the extraneous interrupt when you enable IRQ1.

Just make sure that P8 is used as a digital input. The only way I see 
to eliminate the extra interrupt for a positive trigger would be to 
invert it on the PCB or via an external module as I have done to test 
this. I'll keep playing with it as I have time to see if I can figure 
out a way in software to reset this first interrupt. Off to read the 
hardware manual.

Dave


--- In ComputerVoltageSources@yahoogroups.com, "drmabuce" <drmabuce@.
..> wrote:
>
> 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) & solder right
> on to the exposed traces)
> (but i don't wanna gross anybody out)
> ;'>
> -doc