What is the deffinition of a heavy symbol? And secondly why put a data base behind one? I have been pondering this from several levels.
One level is about how heavy large components have become and the tasks that are used in building a working programed printed circuit board. Take a large fpga that has a large number of io pins that can have many different functions. these are typically broken up into groups other wise called banks. On a bank by bank basis it is possible to sellect the following logic families 3.3-V LVTTL/LVCMOS 2.5-V LVTTL/LVCMOS 1.8-V LVTTL/LVCMOS 1.5-V LVCMOS 3.3-V PCI 3.3-V PCI-X mode 1 LVDS LVPECL Differential 1.5-V HSTL Class I and II Differential 1.8-V HSTL Class I and II Differential SSTL-18 Class I and II Differential SSTL-2 Class I and II Within a bank a pair of io pins can be used differentialy or as single ended inputs. At lay out time pin swapping to detangle the netlist becomes very attractive. Which pins can be swapped? On a second level, even a resistor has limitations. For a given manufacturor of a given product line there exists only a finite number of resistance values? To support manufacturing I would like to know what are the options for a particular package? Can I expect the package to survive the expected power levels? On a third level, I would like to tie models and/or code (verilog, vhdl, spice) to a symbol and have the ability to generate simulatable netlists. So packages, must have correct pin numbers and available land patterns, part numbers must be correct to generate boms and thus purchase orders. To support layout the netlist needs to tell the layout program what can be swapped with what and the layout program needs to tell the schematic program what was swapped so that the schematic can be corrected for reality. Idealy the layout needs to be back-integrated into the simulation models for looking for tdr effects, paracitic capacitance etc. The schematic output needs to be capable of generating pin to signal descriptions for importing into proprietary software to support fpga or asic development. Why do we need to have heavier symbols... well in my opinion because the world of elcetronics is getting more complicated not less and light symbols presume a simple world and heavy symbols support the real world. But best of all is a comprimise where a data base generates or at least supports the symbols and simulations needed. Steve Meier P.S. If you were looking for a deffinition, well so am I. Please write your ideas... If there is one truely beautifull idea behind open knowledge it is the idea of sharing ideas. Randall Nortman wrote: > On Tue, Dec 04, 2007 at 06:36:45PM -0800, Steve Meier wrote: > >> I am becomming more and more a proponent of heavy symbols or even a data >> base then can generate heavy symbols. One of the really nice things >> about geda is its tollerent or flexible and that heavy symbols could >> easily be implemented. So the question is... is there enough support in >> the geda community to create a heavy symbol library? >> > > > I've been noticing this whole heavy vs. light debate for a while, but > not really following it. A heavy symbol is something that is fully > specified, including footprint, right? Does that go all the way to > particular manufacturer part numbers? A light symbol would be what > the majority of the included library is right now -- generic symbols > with no footprint specified, using generic pin assignments (which > sometimes do not agree with reality for certain parts), right? > > Personally, when I need a "heavy" symbol, djboxsym does the job in a > jiffy. (Thanks, DJ!) I use resistor, capacitor, diode, etc. symbols > from the included library, and pretty much everything else comes from > djboxsym. > > _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
