I think Bob has hit the nail on the head. I'll just add that Anything that
you send out thru a Win PC port will be way beyond jitter at times and the
timing will change. You could work at your triggering level mannually and
perhaps see a little more, but even that will change from time to time.
Unless you can master the windows API, there just won't be much
repeatability to the output. Do you know what else the OS is trying to do
while you are trying to output a nice clean toggle? I didn't think so...I
don't either...

Too bad you didn't get a DSO or something like a BitScope instead...then you
could capture the equivalent of one scan clearly.

If I had neither, I would certainly have gotten a scope first too,
though....


C
>
> Finally, the same hardware that slows down access to the port
> introduces an
> amazing amount of jitter to the signal. So instead of getting a clean
> 1MHzish signal you'll get what almost looks like random edges.
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads