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cicero
United Kingdom
26 Posts |
 Posted - 11 Aug 2015 : 12:35:52
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So I recently had a PCB come back, and whilst checking it I realised a few pins were floating - which were meant to be 5V.
I look on the schematic, it has a +5V bar symbol to those pins. When I checked the PCB, they're floating. I right clicked on the connections in the schematic, show net, and its a random N1004?! Is this normal? Do I need to always go through all my power nets and physically check the net is actually what I intended with the power bar?
Seems a little ridiculous.
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Iain Wilkie
United Kingdom
1010 Posts |
Posted - 11 Aug 2015 : 20:09:50
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Just don't use the power symbols ... if you forget to allocate the power net to it, its just like any other auto named net. This is what seems to have happened here.
This is the reason I never use them .... they can fool you. Better to simply make the actual net into a "T" shape, allocate the power net name to it and display the net name and stick it on top of the "T". That way you'll never go wrong.
You can also check by allocating a different colour to each of the power lines, that way you see where all the power connections are in your schematic.
Iain
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cicero
United Kingdom
26 Posts |
Posted - 12 Aug 2015 : 10:20:36
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Thanks Iain, but wow, you've gotta be kidding me!? That's an utterly ridiculous workaround for what should really be a core feature - net matching with bar symbols.
Really, there are loads of bells and whistle features in this program, auto route etc etc, but such a core requirement gets no attention.
Might use the colour method you propose though, but will continue to shake my head in dismay every time. |
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AndyB
United Kingdom
208 Posts |
Posted - 12 Aug 2015 : 11:23:16
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I've been caught out on this problem.
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Iain Wilkie
United Kingdom
1010 Posts |
Posted - 12 Aug 2015 : 12:49:20
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It's not a work-around I am describing, just another way of doing it. You have to remember the power symbol is just that ... a symbol .... just like any other component you need to tell it what net you want it connected to.
Iain |
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cicero
United Kingdom
26 Posts |
Posted - 12 Aug 2015 : 13:04:49
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quote:
Originally posted by Iain Wilkie
It's not a work-around I am describing, just another way of doing it. You have to remember the power symbol is just that ... a symbol .... just like any other component you need to tell it what net you want it connected to.
Iain
Hmm, this smells remarkably like the old "its not a bug, its a feature" argument, and it doesn't work here. If it is a 'dumb' symbol as you describe, then its just lazy programming because absolutely no one would use it this way.
Its not intuitive, take anyone who's come from a different PCB CAD suite and ask them if this seems right...
*Disclaimer: Seeing as I've just been burnt by this 'feature', obviously I'm slightly bitter. |
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Iain Wilkie
United Kingdom
1010 Posts |
Posted - 12 Aug 2015 : 13:44:03
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It's always been like that .... It's just another symbol that can be used to embelish your schematics.
I don't think it was ever described as being intelligent, and it's been like this since as long as I can remember.
As I say, I see no need to use it at all, it's easy and safer to simply use the display net name ...
Iain |
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cicero
United Kingdom
26 Posts |
Posted - 12 Aug 2015 : 14:09:29
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quote:
Originally posted by Iain Wilkie
It's always been like that .... It's just another symbol that can be used to embelish your schematics.
I don't think it was ever described as being intelligent, and it's been like this since as long as I can remember.
As I say, I see no need to use it at all, it's easy and safer to simply use the display net name ...
Iain
I'm not denying the way they are and have been working - thats a given. I'm saying how utterly stupid it is and how they should actually be implemented...and in fact, how it is everywhere else already.
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636steve
United Kingdom
14 Posts |
Posted - 12 Aug 2015 : 16:21:32
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I have also been caught out by this.
My solution was to still use the symbol but ensure that it always displays the net name on the net as well as above the bar. This way I know it is connected to the correct net.
Iain's solution to using different colours for the nets is another way round it that I have also used. |
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edrees
United Kingdom
766 Posts |
Posted - 14 Aug 2015 : 09:44:34
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You can create a (schematic only) "component" for these "T" shaped symbols and assign a Net Name (and Terminal Name) to it just like any component. So I have for example, +5V, +12V, +15V, +24V etc components. When the schematic only component is added to a net on a schematic, EPC will join an existing auto-named net to the "proper" name. Otherwise it will ask whether you want to join (a named) net to the net associated with the power rail T symbol.
There is still a possibility of accidentally getting the symbol net name mis-assigned, so I double check by assigning different colours to the power nets.
I think the "T" power symbol looks a bit more professional in the schematic but you have to understand it's limitations! |
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Power bar symbol, and net