Peter Clifton wrote: > On Mon, 2009-01-12 at 18:53 -0800, Joerg wrote: >> Peter Clifton wrote: > >>> Actually, your idea has got me thinking more about how we handle >>> attributes on slotted parts, and the possibility that they could in some >>> way be treated as an aggregate component for the purposes of attributes >>> other than "slot=". >>> >> Not 100% sure if I understand correctly but yes, treating all slots as >> one component would be feasible. Even if you don't use all you must >> usually place all slots anyhow and, for example, connect inputs to GND. >> Exception being transistor arrays but even they should also be grounded >> and be on the schematic so folks can see what's available for cut/jumper >> style rework purposes. > > Sorry for typing before thinking that through fully. Treating all slots > as one component (for adding attributes) isn't actually possible with > gEDA's architecture. Attributes can only be added to symbols. > > I can imagine the GUI glossing over that fact, and perhaps offering to > help keep attributes in sync when renaming a single slot, it would be > difficult (perhaps impossible) to cater for the case where you have some > slots on one schematic page, and others elsewhere. >
Most of the time engineers could live with the restriction that all slots must be on the same page. Not perfect, but should be quite acceptable. >> That would be a serious one. I can't recall a single company I dealt >> with not using A, B, and so on (upper case). Most CAD programs >> auto-assign those when you place until you run out of slots. So if you >> place eight slots of a six-slot 74HC14 it bumps the refdes number for >> the last two you place. They don't all do it perfectly. OrCad usually >> does but I've had Eagle "forget" when I began placing some more slots >> later. gschem just places all as first slots with U? right now. > > Tricky to figure out how to do this flexibly. gEDA's flexibility means > special casing behaviours like this is hard (and often undesired). Some > kind of script or plugin hook might be a possible way to do this, but > again.. I'm just thinking "aloud". > > (I'm not suggesting users would have to write these scripts, more that > they shouldn't form part of gschem's hard-coded behaviour.) > > As an example I wrote for someone (and I ended up using it myself), I > have a script hook here which renames any component I copy back to > "U?" (removes the numbering), so that I don't end up accidentally naming > two components the same due to a copy-paste in my schematics. > Most CAD systems use such routines and they can be called from within the application. Eagle calls them user language programs (ULP). > > Joerg: I think I have some understanding now of the kind of visual > appearance of schematics you're thinking of, but I'm curious to see (if > you have any examples you could share - perhaps by private email), just > what the kind of schematic you're talking about looks like. (Either > slotted logic gates, or slotted op-amps). > > I'd like to put the discussion in context by seeing how a real schematic > looks using the styles we discussed, rather than just my mental pictures > so far, which just cover a symbol and its visible pins. > A bit problematic because most of my stuff is client designs. But I'll find something suitable. On the web I found your pcjc2 email address at Cambridge, let me know in case that isn't correct anymore. I am reading this group through gmane which hides people's web identities. -- Regards, Joerg http://www.analogconsultants.com/ _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
