i maintain and have said so before and am well aware that it sucks, BUT:
the best 'library' (at this time and for pcbs) is a working and recent
production board.
failing that, it takes a good memory and some drilling around to find a
footprint and it is sometimes a close call whether or not to just make
another (incomprehensibly named) new one
i can't suggest what the best solution to this conundrum is, but i would
say that i don't either want to be locked into some ISO you must use
this (possibly wrong but it's not wrong because it's approved) footprint
as i and many others have said for YEARS, just a simple comment field
would go a long long way
please protel don't lock us into some bureaucratic system unless it is
elective
Dennis Saputelli
Abd ul-Rahman Lomax wrote:
>
> At 10:24 AM 6/29/01 +1000, Michael Beavis wrote:
> > >... If update footprints is selected, it will
> > > also detect if any footprints have been changed. It will not necessarily
> > > give an *error* if the schematic is different; rather it will create a
> > > macro to implement the change. If there are no macros the schematic and
> > > board match.
> > >
> >
> >I would assume the libraries used by the original designer are still in
> >play.
> >Checking created macros for footprint updates shouldn't be a prob but if any
> >changes to the pcb are required how do you tell if you're still linked to
> >the correct library ? More of a problem if the designs span several Protel
> >format versions.
>
> Remember, the objective here is to test to see if the schematic and PCB are
> synchronized. Fixing any differences is a different task, and the
> synchronizer or netlist load processes are not up to it unless you know
> that the errors are on the PCB and that the available and enabled libraries
> are also correct. In the case before us, not only is that not known, it is
> unlikely.
>
> That there is a deviation between the schematic and PCB in *footprint* is a
> class of error or incompleteness that one might wish to set aside in the
> subject case, or to consider as a detail. *Many* designers don't bother to
> back-update the footprints. It could be argued that we should, but in the
> absence of good library control, there is not a great motive; the process
> could still go awry.
>
> If one has an approved company library and all parts must come from it,
> then discovering deviations will be relatively easy, though, with current
> Protel, if the names match there is no easy way to proceed beyond that. One
> could play tricks to do it: rename all the parts in a library as FNAME_x
> (add a _x to the name). Hopefully none of them are long enough to run into
> the string length restriction on footprint names. Then likewise globally
> edit all the footprints in the schematic to add that extension. Then update
> a copy of the board from the schematic, allowing footprint corrections. If
> everything was done properly, all the footprints will be replaced but no
> errors will be created. But there are lots of ways for this to go wrong.
>
> For example, sometimes a designer will alter pad specifications once the
> footprint is on the PCB. One reason for this would be to reduce the count
> of differing hole sizes. (A more sophisticated footprint library, instead
> of having a simple hole size, would be like a design rule: minimum size,
> maximum size, preferred size. This could be used with a utility to automate
> hole count reduction once the board is finished.)
>
> Bottom line: if boards have been designed in an undisciplined environment,
> and have been fabbed and work properly, don't monkey with the assigned
> footprints unless you want to review the whole design. And using the
> present update tools would be too crude.
>
> Instead, a partial check could be done by making a PCB project library,
> back-updating the footprint names to the schematic, and then using that
> library and the schematic to check assignments. This would detect, for
> example, that the schematic usage of, say, 0805 and 1206 packages was
> consistent with the PCB.
>
> To be careful, I would suggest first examining the files without changing
> anything (or, as others noted, making backups, but remember not to make any
> changes you want to keep on copies that you are going to abandon!). Then
> any differences which turn up would be examined to determine where to go.
>
> [EMAIL PROTECTED]
> Abdulrahman Lomax
> P.O. Box 690
> El Verano, CA 95433
--
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