DJ Delorie wrote: >> -- putting out a new version of the >> gnetlist-pcb netlist with circuit values for the trace capacitances >> and distances. > > The LF netlister is all new anyway, I could add more attributes if > needed.
[jg] I read here: http://www.linuxfund.org/projects/pcb/proposal/ that the LF netlister means forward annotation. The thing is, PCB doesn't do anything with them at the > moment. How would gschem know about trace capacitances anyway? The > netlister is only sch->pcb at the moment. [jg]I wasn't thinking of the gschem representation of the design getting back annotated, just a separate simulation version of the design schematic. A subset that is the zone of interest for simulation purposes. Hmmm... back annotation -- I guess a good way would be similar to the way PCB handles an imported netlist -- it shows rat-nest lines and notes how many missing nets there are. That kind of functionality in gschem would be handy for adding trace capacitance lumped parameter components to a simulation schematic. You would not want all of the netlist usually, just the part you are simulating, so having a way to export only some from pcb would be a good way. Drawing a polygon on a layer so it contains the traces you want exported for back annotation is what I think of first for selecting a zone of interest for simulating. Then the back annotation file could be a difference file -- a to do list of changes to make just like the .pfa forward annotation file in the LF proposal. I guess my idea doesn't fit in the LF proposal after all -- it would mostly be an addition to gschem rather. To add gschem functions that let you load a netlist, then add components to match it as in pcb layout. Instead of that, you could just handle little cases like trace capacitance as a special feature of wires, but that would be specific and a fair amount of work. To import new netlist elements would be general and more power/flexibility. So the short answer is: gschem would know about trace capacitances by getting a "match the netlist" mode as well as the "extract the netlist from the current state of the schematic" mode it has now. John Griessen -- Ecosensory Austin TX _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
