>
> Yep,
>
> Ok - I think you are both correct - connecting up my DMM I get the
> expected results ... (although not quite as visually as i would
like)
> - derivatives huh, interesting and I understand what you are saying
> but for now I'll put it down to silly me and my interpretations of
> visual data translated into text, like you said you really have to
be
> here...
>
> I think I need to go to scope school
>
> ... I am using a Phillips PM3050 here and have never had the manual
or
> any instruction, just sort of picking up bits of enlightened 'oh! ok
> thats what that does' here and there ...
>
> Its has two probes which was helpful as I could look at the input to
> the TX XBee and the output of the RX XBee and see what was happening
> to the pulse (a slight phase shift in case you're interested which
can
> be easily accounted for in the mechanical side of the wotsit I'm
> building) ...
>
> So when the ground potentials of both trace's are equal I get good
> scopin results - TX or RX gnd - by using the RX ground I could then
> confirm what the DMM had done already anyhoo...
>
> When using the two separate ground potentials for both traces the TX
> trace that was using a benchtop power supply gave an ok scope (same
> gnd as the AC for the scope hmmm) yet the battery powered one went
> screwy ... Yet using the battery ground on both traces gave ok
> results on both traces (likewise both on the TX/benchtop as already
> discussed).
>
> There is likely some sort of lesson to be learned from this ?
>
Yeah, first off, I'm not sure what you just said. Secondly, whenever
you connect a scope probe to anything you also MUST connect the gnd
wire of the probe. Otherwise it's just an antenna.
Where you indicated above "input to the TX XBee and the output of the
RX XBee", I assume you were comparing signals on the 2 different
modules at the same time. This will only work properly with the probe
gnds connected to the individual boards, which will electrically
connect the gnds of the 2 boards together.
> I often jump into things a little fast and then get caught up on
> relatively simple 'problems' that in reality is just the gear doing
as
> it should ...
>
> Thanks as always for being my online tutors ! I hope I'm not
taking advantage
>
> in case anyone is interested:
>
> http://www.maxstream.net/blog/2007/07/03/filming-dog-races/
>
> Really need to get them going with serial transmission proper and
not
> this line-passing business - still got to learn to crawl
beforehand...
>
> cheers!
> nick
>
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/oopic/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/oopic/join
(Yahoo! ID required)
<*> To change settings via email:
mailto:oopic-digest@yahoogroups.com
mailto:oopic-fullfeatured@yahoogroups.com
<*> To unsubscribe from this group, send an email to:
oopic-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
No comments:
Post a Comment