I'm designing a circuit, and there's a couple of points in the circuit where I can't leave unused pins floating, so I either connect them to Vcc or to ground. What I would prefer though is being able to mark them as "don't care", meaning that they can be connected to _either_ of Vcc or ground, depending on which route is shortest on the circuit board.
Do you know of any applications that have this feature? I'm using Protel 99 SE at the moment, and I don't know whether it can.
-- Tomás Ó hÉilidhe
r_=20
This phantastic idea is not supported in Protel99SE. You should forward it to the Altium designer forum, as the current version is not supporting it either.
Rene
--=20 Ing.Buero R.Tschaggelar -
On Fri, 23 Nov 2007 09:34:12 GMT, I said, "Pick a card, any card" and Tomás Ó hÉilidhe instead replied:
Put in a triple row of pins that can be jumpered to either VCC or Ground.
-- Ray
Just leave them unconnected, route it, and when you've finished routing, look at the result and decide which to connect them to. The only danger is in forgetting to do it in the inevitable rush to finish, so a big yellow memo sticker on your monitor should help, if you've got room next to the dentist appointment, car tax reminder and reminder to buy flowers and a bottle of wine for the cat.
Yoiu could add them to a net thgat you deliberately don't route, or tell the autorouter to leave alone, so that there's always an unrouted net nag.
PB
If you're doing a multi-layer board with VCC or ground as a middle layer, routing a pin to either is just a short route and a via. This gets complicated only when traces are dense enough to preclude vias at your convenience. Even on 2-layer boards, I usually flood the bottom layer with copper attached to ground, so ground connections with a via are my most common solution.
Sometimes you can decide the level by simply examining the proximity of other ground or Vcc pins. But I do like the idea of having the autorouter make the decision. AFAIK, it doesn't work that way in PADS 2007, so I still have to make the decisions myself.
Mark Borgerson
If the application design tools were that smart, you'd be out of a job!
Sometimes, designers do have to think, just a little :)
Look at the package, and take an educated guess. Most common default is to GND connect them, but some designers use the rule that they route them to be 'cut-able' post assembly, just in case it turns out they are needed later....
[Then, the Automated setting you are seeking , would be called: "don't care now, but we might care later!" ]-jg
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