On Aug 6, 2010, at 6:42 PM, Andrew Poelstra wrote: > On Sat, Aug 07, 2010 at 12:51:34AM +0200, Stefan Salewski wrote: >> >> The current status of my mind: >> >> Having net classes in gschem would make all much easier.
Nothing new needs to be added to gschem: you can attach arbitrary attributes to net segments already. The place where you need a new capability is gnetlist: a gnetlist back end cannot currently query a net segment for its attributes. >> We can start drawing schematics as now. Then we define a set (or load >> existing) of net classes, each class can define parameters like trace >> width, clearance, maximum length, maybe impedance... >> > > Sounds good so far. > >> First we select all nets and assign a default class. >> Then we select a other class and click on all nets which should be a >> member of this class (power3.3V, power5.0V, gnd, fast signals, slow >> signals, sensitive analog signals, traces with maximum total >> length, ...). The classes of nets can be marked by colors, we go on >> until all nets have the correct class. >> > > Do we want each net to have one class? Or would it be useful for nets > to be "tagged" with multiple classes? Probably not, but it's something > to think about. Classification is opposed to modular, orthogonal design. Don't classify, describe. Impedance, current handling capability, maximum length, etc. are independent properties. gEDA's attribute-oriented design makes this quite natural. Do not start from GUI and torque the design around according to that. Find a well-factored, orthogonal description of the problem space and then worry about capturing it graphically if necessary. Be hard-nosed about the "if necessary". John Doty Noqsi Aerospace, Ltd. http://www.noqsi.com/ [email protected] _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
