2 Replies Latest reply on Feb 14, 2011 1:54 PM by shreyas.rao

    How to create GND ,positive and negative supplies?


      I am new to mentor graphics and we need to design a board on Design capture and do Layout on Expedition PCB.

      The GND and supply pins have been assigned symbols but there are no cells associated with it and hence it gives errors trying to import and fwd annotate into layout .


      The Partpkg is giving out this error for all the GND and supplies assigned .


      " ERROR: Block Design1, Page 1, Symbol NegV:

            No part data.

            No Part Number, Part Name, nor Part Label has been entered.

            Please enter some data to enable packaging. "


      How to get around this problem . Is there any menthod to place the global signals directly ?

      Please help.

        • 1. Re: How to create GND ,positive and negative supplies?

          There are a couple of things you need to do for using global signals in DC. Firstly there are special symbols of type 'Positive Tap', 'Negative Tap' or 'Ground Tap' which you place in your schematic, there should be some examples in the libraries shipped with DC. Basically the symbol represents a power rail of some kind, to define it the symbol should have a single pin with two properties, Pin Name (it doesn't matter what you call this) and Net Name, this one is important, the Net Name must equal the global signal you wish to use. For example, if you want a global GND signal then the Net Name should be GND on the symbol. Symbol Type in this case would be Ground Tap.

          The other part of the 'global' equation is a file called the Global Signals file (see help pages 'install tree'/7.9EE/docs/htmldocs/wwhelp/wwhimpl/js/html/wwhelp.htm?href=dc_olh_ref/dcolh_6th1.html&tab=search&ihub=mgc_ih available from Help, do a search on Global Signal).

          This file lists all of the global signals available to the system and has a syntax of:


          !Netname    Allowed tap rotations     Supply Attribute 

          !-------         ---------------------                   ----------------

          AGND          FF FF FF FF               SUPPLY=GND

          CGND          FF FF FF FF               SUPPLY=GND

          GND            FF FF FF FF               SUPPLY=GND

          VBB           FF FF FF FF                SUPPLY=NEGATIVE

          VCC           FF FF FF FF                SUPPLY=POSITIVE



          You will find it in the SDD_HOME\standard\config\vbdc folder, the file is called global. There must be a corresponding entry for every 'tap' symbol you have in your library. Personally I created a number of symbols for various supplies such as +5v, +12V, -12V, GND, AGND etc. each symbol had a corresponidng entry in the global file. The allowed tap rotations section may be left as FF FF FF FF, it has no relevance in Design Capture/DesignView and is a carry over from ACE and ACEPlus (now I'm showing my age :-) ).


          • 2. Re: How to create GND ,positive and negative supplies?

            Thanks Robert for the suggestion !

            I will try to implement it .