> Stuart Brorson wrote: > > > FWIW, I wrote a blurb about this question for the wiki a couple of > > weeks ago. Here it is: > > > > http://geda.seul.org/dokuwiki/doku.php?id=geda:faq-gschem#what_should_i_do_about_power_pins_on_my_symbolsmake_them_visible_explicit_or_invisible_implicit > > Well, I agree only half way with you. > It is true, that power pins in analog circuits should be visible on the > schematic. But having them on attached to the triangular shape is not > correct either. Imagine a quad opamp: If you use symbols with visible > power pins, you get eight visible power pins. > > My preferred solution would be a special slot just for the power > connections. This is how we dealt with this issue in Protel99 and it has > its advantages for circuits that contain lots of opamps. The power > connections plus the necessary caps don't clutter the feedback loops. So > the circuit is easier to read. Still the power pins are explicitly drawn > and can be tied to some exotic net. I usually draw all the power symbols > with their caps in some quite corner of the paper. > The only drawback is that the supply caps are not in the neighborhood of > the corresponding triangular shape. But with quadamps the triangular > shapes that belong to one component are scattered over the schematic anyway. > > Nevertheless, I don't see how I could implement this technique with > gschem. There seems to be no way to let a gschem symbol contain slots > with different pinout. The same problem arises if a component has slots > that perform different functions. This is the case for some analog > multipliers that contain an additional opamp with no internal connection > to the multiplier. Did I miss something obvious?
No, you are right. Gschem's slotted parts must all use the same symbols, I am pretty sure. For slotted opamps, I just wire up the power pins on slot 1, and leave the power pins on slots 2 ... N unconnected. Gschem & gnetlist like this just fine. (FWIW, Orcad *insists* that you wire the power pins on *all* slots to *exactly* the same net. It's a real PITA. I like gschem better.) As for having a separate "power" slot on slotted parts: sounds like a nice idea. I don't know how much work it would take to implement in gschem, but the work/payback ratio might be rather high . . . . Stuart
