Power symbol

[Anonymous]

Hello,

In my circuit design, i use much power voltage.

I try to use Vcc symbol for every power voltage, changing the value, but, as default, every NET that i connect to this device became Vcc.

Is it possible to defin a Vcc symbol as like 12V, an other 5V and when i connet them, the NET became the same that i choose as Value.

Thank you

Silvio

[one-of-the-robs]

I'm not entirely sure what you mean but...

If two nets have the same name then they are the same net. This is a fundamental rule.

The "symbol" of a supply symbol declares a name; that is the name of its net. The "value" is irrelevant.

You can override the net to which a power pin of a component is connected, simply by drawing it explicitly. There will be an ERC warning but you can ignore (or approve) that.

What you should do is create your own library of supply symbols with all the names you need. Alternatively, it's probably possible to create things that look like supply symbols but don't impose net names, and then explicitly name the net connected to them... but that feels like a flaky and error-prone workaround. I'm sure someone will come along with a better alternative...

[rachaelATWH4]

---

@one-of-the-robs wrote:

What you should do is create your own library of supply symbols with all the names you need. 

---

This is exactly what I have. I have a library which contains all my various different voltage power rails. If I need to add a new rail voltage which I haven't got already I quickly add another to the library. I was also toying with the idea of adding a menu for quick access to these rather than having to open up the libraries but I haven't set that up yet.

I do think that there could be a better system put in place to provide easy/configurable global power rail symbols. Something that gave a dialog for configuring all the power rails required for a particular design and added them to a menu for quick access. I can probably do something in ULP to assist in this, I might have a look and see what I can do when I get a little spare time.

Best Regards,

Rachael

[jorge_garcia · Accepted solution]

Hi @Anonymous,

In addition to what Rob and Rachael have said, look through the supply1 and supply2 libraries since these contain the default set of supply symbols that come with EAGLE. The attached ULP written by @Anonymous really simplifies creating your own supply symbols in a library.

Let me know if there's anything I can do for you.

Best Regards,

[Anonymous · Accepted solution]

Hello jorg,

if there are not other way, i'll do as you suggest.

I'thing that a simply way for user will be to put a generic Vcc, change the neme and the next nets that i'll connect will have the same name of the power

name.

If i change name after to have connected a net, a window coul'd say "Attention, net name will be changed." If you choose yes the net name change, if you select No the name of power don't change.

This would be only a sugget of a possible way.

Thank you for your answerrs and work.

Silvio

[Anonymous]

Hello,

i do what you suggest to solve my problem and it works good but i think that is really restricting.

If tomorrow i need a power that i like to name Pippo or Pluto " Disney ceklebrity" i must to create it in library.

I see that in library the name that i assign to the power is for example B1 and all net connected to it will name B1.

I see, as you said that value is not important, but for power point, the value coul'd be the value of power, for example 12V and the net could have the same name as like value.

In this way, every time i want, i can create simply a power point, without modifing the library.

Thank you

Silvio

[rachaelATWH4]

---

@Anonymous wrote:

Hello,

i do what you suggest to solve my problem and it works good but i think that is really restricting.

If tomorrow i need a power that i like to name Pippo or Pluto " Disney ceklebrity" i must to create it in library.

I see that in library the name that i assign to the power is for example B1 and all net connected to it will name B1.

I see, as you said that value is not important, but for power point, the value coul'd be the value of power, for example 12V and the net could have the same name as like value.

In this way, every time i want, i can create simply a power point, without modifing the library.

Thank you

Silvio

---

Hi Silvio,

I do think you have a valid point here. There have been plenty of times I have needed a very circuit specific global net which has lead me to have a few oddball globals in my library so I do think something needs to be done to make it easier for defining globals without library sprawl. I'm not sure your suggested method is the right way though, I suspect it could lead people into having incorrectly named and mismatching global nets which they did not realise until it was too late.

I wonder if a better way would be as follows:

1. Enable a base set of global symbols to be defined by the user in their own libraries.
2. Have a feature in EAGLE to import the base global symbols and create variants of these which are stored within a design but referencing the library so if you update the symbol to change how it looks it will update in the schematic.
3. Also allow a common set of defaults to be defined and stored in the .eaglerc file so that commonly used rails are always available by default in a new schematic.

This would change the schematic file format slightly as there would need to be a section for holding the detail about the used global symbol variants, but changing the file format isn't something new, it's been changing quite a bit over the course of v8. The only thing that would have to be ensured is that if it were exported to an earlier version it would be possible to export all of the global symbols to a library in the previous format using say the exp-lbrs.ulp such that global rail symbols could be correctly generated for backwards compatibility.

Does this make sense?

Best Regards,

Rachael

[Anonymous]

Ciao Rachael,

I can read only today your message.

I'have some difficult to follow your proposal, but about one thing you are right. to change automatically the name of a net could be dangerous.

In the time that i used Eagle, i see that, if you try to connect two different net, of you try to connect a pin previously connected with a net, you have got a warning.  In my proposal, i thought this: you put a power symbol and you re-name this or assign a value as like the name you wont for the nate to it connected; for example you put a power simpol and name it or put value Vcc-A. Now you try to connect it to a net called N$xx. You could have a warning as like the same when you want to change the name of a net and you can choose change "this segment", "all segment..." and OK CANCEL buttons. The "name" must be visualized near the symbol.

Other ways could be this:

1 You put a power symbol and when you connect it to a net it bring and visualize the name of the net connected, if you wont to change the name you must to change the net's name. This coul'd be simplyer.

2 In the drop down menu with right mouse button, after "voltage probe", you coul have a selection "power point" or similar.

3 In the same menu, you could have in alternative to solution 2 after the "name" selection, power point selection.

I think that 2 and 3 are very very simply way to solve the problem to attach a power poin to a net.

Thank you and good work.

Silvio

[Anonymous]

I forgot,

it coul'd be good if some one said what he thinks about.

[Anonymous]

Jut wanted to add my two cents, I have run into this same problem as I think many have and I wish Eagle would be updated to include a clean fix.

What I had done was create my own symbols - dedicated for some common voltages, as well as a "Custom_VCC" one which I intended to be renamed when used by just renaming the net after placement. What I found however, was that if I needed two or more unique custom voltage sources in some project I could NOT use the generic source symbol in a circuit and give it two different names. Actually I could at first but then later with ERC / DRC Eagle would throw a fit that I have Custom_VCC connected to two different nets. I'm not sure if eagle still have this complaint I don't test it with each version I found a solution that works enough for me and moved one long ago.

So for now, what I have in my library are a set of dedicated common voltage sources, and then a series of generic ones like Custom_Vcc1, Custom_Vcc2, Custom_Vcc3 etc. If I am working on a project that needs a voltage source which is not in my list of common voltages (like 12V, 5V, 3.3V) then I will use a custom one and rename it - but if I need a second or third unique source I just use one of the remaining custom ones and rename it. The only difficult part is making sure to use the same custom part for the same voltage source everywhere in the schematic. So if I need something like 2.5V then I will make sure I always use Custom_Vcc1 for 2.5V everywhere in the project, and then if I also happen to need 4.25V I will make sure to always use Custom_Vcc2 everywhere for 4.25V. It's not ideal but it gets around errors and warnings without having to manually approve them and then not knowing if you accidentally approved one that was legitimately warning you about a bad connection you had overlooked.

It seems like all that would be needed is a way to name a symbol pin with a variable instead of a name that causes a popup at schematic placement time to rename the voltage source. But for now, my solution works for me.