Re: gEDA-user: Power (and other non-graphical) pins

[Joerg <joergsch@xxxxxxxxxxxxxxxxxxxxx>]

John Doty wrote:
> On Jan 12, 2009, at 1:50 PM, Joerg wrote:
> 
>> John Doty wrote:
>>> On Jan 12, 2009, at 12:36 PM, Joerg wrote:
>>>
>>>> When you place the first instantation it'll be pins 1,2,3, the next
>>>> one
>>>> 5,6,7 and so on. But all are supplied via the common supply pins  
>>>> 4 and
>>>> 11. In gschem you only have two choices. Either you create a library
>>>> model that repeats those pins 4 and 11 visibly for all four
>>>> instantations or you create the library part with the power pins
>>>> detached where none of the instantations show power pins. This  
>>>> can be
>>>> practical for auto-connecting digital stuff to a VCC rail but it
>>>> doesn't
>>>> work well in the analog world. Now you could also have pins 11 and
>>>> 4 as
>>>> a separate "fifth" device. Anyhow, neither method looks  
>>>> professional,
>>>> neither is industry practice, and all make schematics more
>>>> difficult to
>>>> understand for others. Especially for non-analog guys.
>>> Joerg,
>>>
>>> What do you think of the approach in:
>>>
>>> http://archives.seul.org/geda/dev/Nov-2008/msg00069.html
>>>
>> Thanks, but it says "useless with gschem", whatever that means.
> 
> It means you're just supposed to netlist it, not look at it.
> 
>> In the
>> telephone.sch file I could only see a mike and a speaker with coil,  
>> but
>> no power pins.
> 
> Where did you expect to see the power pins? You don't want them on  
> the main symbol, but you also don't want them on a separate symbol.  
> This approach puts them in a text file, and gives you a way to merge  
> such files into the net list.
> 
> You've told us what you don't want. That doesn't tell us what you want.
> 

Ok, here's what I (and lots of other) would like:

Take a device with multiple parts in there such as the 74HC14 and handle 
it like Eagle and Orcad do: None of them has power symbols. Then if you 
must connect it to some special power net you can "invoke" the power 
symbols along with correct pin numbers on only the first instantation. 
So U1A then has power symbols but U1B, U1C and so forth don't. The power 
pins absolutely must show up in the schematic where you want them and 
not show up at the instantation where you don't want them. If they only 
show up in the netlist that doesn't work because the schematic will be 
hard to understand.


>> In the end it's important that a decent power pin handling is  
>> inside the
>> program itself,
> 
> Why?
> 

Because IMHO it's basic schematic capture functionality, used all the 
time. It's not something that is rarely used and where a patch file may 
work.


>> not something that must be handled by letting a command
>> line routine run over some files.
> 
> Monolithic programs are inflexible. gEDA's strength is radical  
> flexibility.
> 

Well, true, but having to remember which patch files must be run to 
massage a certain schematic and which don't is a serious source of error 
for the user. Radical flexibility can be achieved differently. For 
example, Eagle has tons of scripts that can be run from within the 
application, you never need to leave it to call up the command line. 
Every user is welcome to write their own scripts and if he or she feels 
compelled can share them with others via their corporate server.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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