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Protel DXP question

  1. May 10, 2007 #1

    cepheid

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    Hi,

    maybe this is a dumb question, but I'm learning to use Protel DXP for PCB layout, and I'm just practising for the sake of getting the hang of it right now. I have two component footprints laid down next to each other, one for a 14-DIP IC, another for a 16-DIP IC. All I'm trying to do is connect together a pin on one of those ICs to a pin on the other one. When I try to connect the corresponding pads together with a track, I get a violation:

    Short Circuit Constraint Between Pad on Multilayer and Track on Top Layer.

    I don't know too much about PCB's yet. Am I doing something stupid (i.e. is it conceptually wrong to try to connect those pads with a track?), or is it just a question of the software not being configured properly.

    Also, why is it so hard to "get there" using the interactive routing tool? So I start with the crosshair in the centre of one pad, click to provide a starting anchor point, move to the centre of the other pad, try to click, fumble around several times, and then finally right click. If I'm "lucky", after having created several unwanted track segments along the path I want, I'll reach the centre of the second pad. If I'm unlucky, right clicking will make the track stop short of its target, even though my cursor is over the target.
     
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  3. May 10, 2007 #2

    chroot

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    Is this a 2-layer (i.e. top and bottom) board? DIP sockets are through-hole, which mean they necessarily exist on all layers at once. Normally, vias are plated with solder, so you can connect to your device with a trace on any layer.

    Make sure you don't somehow have it set up to use a four-layer board with power and ground planes in the middle. If you did that, and then dropped a plated via through the whole board, the tool might complain that you're trying to connect a trace on one layer to a power or ground plane on another.

    You probably need to tell us more about how your board and layers are configured.

    - Warren
     
  4. May 10, 2007 #3

    cepheid

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    It's just whatever the default is.

    It seems like it's a two-layer board. When I go to the Design menu and click Layer Stack Manager, it shows me a diagram of a board with arrows pointing to the top layer and the bottom layer, with no other layers in between. I know it's not a four-layer board, because that is one of the examples you can click on and the diagram changes when you do so (it becomes thicker and includes power and ground planes).

    Anyway, meanwhile, in the main window, there are six tabs at the bottom of the screen: top layer, bottom layer, mechanical 1, top overlay, keep-out layer, and multilayer. Based on the colour coding, the pads (grey) seem to exist on the multilayer (I guess this means that the round conductive pads exist through all layers as you described). The tracks (red) exist on the top layer.

    EDIT:

    Just talked to a co-worker. It's really dumb. I don't have any "nets" (list of connections in my circuit) yet, because I didn't import a schematic file in. I'm starting from scratch, because when I made the schematic using some other program, I didn't have PCB layout in mind (I didn't expect my supervisor to look at the circuit and say, "okay, looks good. We'll need to make a PCB now." Since I don't have any nets, as far as Protel is concerned, the pad in question is not supposed to be connected to anything (hence the violation). Anyway, sorry to bother you.
     
    Last edited: May 10, 2007
  5. May 10, 2007 #4

    chroot

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    It's been a while since I've used Protel, so I'm trying to remember a few things. I suspect that you don't want to use the Multilayer layer at all; I can't remember ever using it for anything. You just want to put the DIP footprints on the top layer. It should put a little red circle of copper for each pin, through which a hole will be drilled.

    Then you can connect the pads (which should now be red) with red tracks (on the the top layer).

    - Warren
     
  6. May 10, 2007 #5

    cepheid

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    Hmm, interesting. When I right click the footprint as a whole, and click "Properties...", it says that the DIP footprint is on the top layer (because that is the tab that was selected when I placed the footprint). Despite that, the individual pads on the footprint are grey, and are on the multilayer by default. I'd have to right click each one of them and change its properties separately to get it to turn red. Anyway, I realize that if you haven't used Protel in a while, you can't help me with all of these intricacies, but thanks for your responses so far nonetheless.
     
  7. May 10, 2007 #6

    chroot

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    What's the name of the library were you got the DIP footprints? Maybe somehow you grabbed the wrong one?

    I wish I had a copy of Protel installed here so I could duplicate your problem. I can probably install it at home later though.

    - Warren
     
  8. May 10, 2007 #7

    cepheid

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    I'll have to get back to you on this tomorrow.
     
  9. May 11, 2007 #8

    cepheid

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    Okay, the library is Miscellaneous Devices.IntLib, and the footprint is DIP-14 (or 16).

    By the way, I haven't been having any trouble routing since I started adding in the nets.
     
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