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How do I remove default VDD and GND connections?

Former Member

I have designed some symbols in a custom library. It seems like pins named VDD and GND are connected in my board, even though this is not the case in the schematic. This might not be problem in this case, but what if I need different supply voltage for different ICs? I need a way to remove these connections so I can connect them myself the way I want. The screenshots below shows the problem.

 

Thanks in advance :-)

image

 

image

  • 0

    Peter Haagerup schrieb:

     

    I have designed some symbols in a custom library. It seems like pins

    named VDD and GND are connected in my board, even though this is not the

    case in the schematic. This might not be problem in this case, but what

    if I need different supply voltage for different ICs? I need a way to

    remove these connections so I can connect them myself the way I want.

     

    Simply INVOKE the related power gates and connect them as you like.

     

    You will get ERC warnings claiming that they are connected to

    differently named nets. Acknowledge and ignore them.

     

    The screenshots below shows the problem.

     

    Note: Thanks to the crappy element14 web interface, there are no

    screenshots below.

     

    Tilmann

     

  • 0 in reply to autodeskguest

    Thanks for your reply. The problem is not about symbols with gates - so the INVOKE command does not solve this problem. The problem is that all pins named "GND" are connected together between different symbols in the board even though they are not connected in the schematic. The same problem applies to pins named "VSS". I want to turn this feature off, so I can connect them myself. I think that I need to do something for the symbol or device in my library, but I do not know what to do.

     

    I am sorry about the missing screenshots. I have uploaded them on a web server and the links are:

    http://rc700.dk/peter/eagle/schematic.png

    http://rc700.dk/peter/eagle/board.png

     

    As you can see in board.png, some pins with the same labels are connected between ICs, but I have not connected them in the schematic. That is the problem. I hope there is a solution for this :-)

     

    Thanks in advance :-)

  • 0 in reply to Former Member

    Peter Haagerup schrieb:

     

    Thanks for your reply. The problem is not about symbols with gates - so

    the INVOKE command does not solve this problem. The problem is that all

    pins named "GND" are connected together between different symbols in the

    board even though they are not connected in the schematic. The same

    problem applies to pins named "VSS". I want to turn this feature off, so

    I can connect them myself. I think that I need to do something for the

    symbol or device in my library, but I do not know what to do.

     

    Simply connect them as you desire - the problem is basically the same.

     

    I was thinking that you didn't even /see/ the pins that are

    automatically connected to nets, this is a rather FAQ...

     

    If you don't want pins to be automatically connected to equally named

    nets, you need to correct that in the libraries. Change the pins

    "direction" to (i.e.) "passive" instead of "power". Implicit naming only

    happens for "supply" (sources) and "power" (loads) - see the manual and

    the HELP for PIN.

     

    Tilmann