ard at p850ug1.demon.co.uk
Thu Mar 30 12:29:27 CST 2006
> Tony wrote...
> > If the input signal is noisy, or something like that you might get
> > spurious results.
> It looked noisy to me!
> > What have you connected the ground lead of your 'scope probe to?
> When measuring BUS LTC L at CD1, I used CC2 as my ground reference. Just
> before that I put the scope between CC2 and CA2 and got a nice non-ripply
Fine. I was just making sure you'd connected it to a logic ground.
> +5v trace. I should point out that the ground clip on my probe is a bit
> large for clipping to a backplane pin, so I used an alligator to microclip
> extension that is about 8 inches long. Surely that wouldn't mess up the
> signal that badly.
Not a 60Hz signal, no :-) And as you saw it's not even got a fast rise time.
[Where LTC L goes on the DL11-W card]
> Good idea. The 7414 is at E45, CD1 goes in pin 9 (4a) and out pin 8 (4y).
> I'll ground the scope at pin 7 and see how the signal looks. If the issue is
Yes, I'll agree with that.
> bit 7 in the RTC is not setting (according to the diag), and I get a good
> clock out of the schmitt trigger, I assume the next thing to check is the
> pin 8 output of the flipflop the trigger drives? That seems to be where bit
> 7 comes from.
> > The interurpt logic does not require LTC L to work.
> Ok gotcha. I still suspect something with trap/interrupts being broke. But
> more on that later :)
Good luck if you haev to dive into the arbiter in the processor board
set. It's not exactly simple :-).
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