Hopefully my other post will show up here. I don't see it yet.
One more comment. If you do manage to get a decent picture of the
DAC voltage waveform, in test mode please, change the horizontal
timebase to see all of the waveform before it repeats. If you are too
zoomed in, you won't get a stable waveform. If the CPU is working,
you should see a number of voltage levels in a repeating pattern.
You should set the scope so that we can see the start of the pattern
at the left, then the whole pattern, then at the right edge of the scope
we should see it starting the next loop. This way we can see how many
voltage levels there are in a loop, and how long it takes the loop to complete.
You should use DC trigger mode, and set the trigger level to a level that
only occurs once in the loop, if you can. So either near the highest
part of the waveform, or near the lowest part. If you pick a voltage near
the middle of the waveform to trigger on, the waveform will cross this value
many times in the loop and it will be impossible to get a nice clean scope
image.
On a simple waveform like ALE, it's much easier to get a nice stable scope
image.
Oh. If you do get DAC voltage showing different
steps, we will want to see what T0 input is doing at the same time. Do you
have two channels on your scope? To show two signals, you would need to
change to 2V/div so that each signal has half of the screen.
Bob
--------------------------------------------
On Mon, 7/4/16, noddyspuncture@hotmail.com [PolySix] <PolySix@yahoogroups.com> wrote:
Subject: Re: [PolySix] Another P6 with all LED's lit....
To: PolySix@yahoogroups.com
Date: Monday, July 4, 2016, 7:33 AM
By the way Bob,
The trigger options I have on my
scope are AC/DC/HF/LF/Line
I
am trying them all each time I scope a pin and the only ones
I see of any use are the AC and the HF
ones...!
CheersTom