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Power port connection

Greatrebel

Hi all,

 I have some problem with power/ground port connection. The problem is that when I did special routing, the power and ground were not connected. I got some clue from Encounter log to check my netlist. So I instantiated power and ground cells under the top module which is a dummy module and includes all IO cells and the core design module.

I added two pins in the pin list of the top module as well, called VDD_PIN and VSS_PIN. In my design, the global power/ground net are called VDD/VSS. The power pad cell has two inout ports, I connected one of them to the VDD_PIN. For the other one, according to the specification, it should be connected to core. But I do not know where I should connect it to. If I connect it to the power net VDD, I will get a warning saying "This can create a short circuit if the output is 0.  Check the connectivity in the netlist." So I just leave it floating.

 When I tried to connect power/ground port to global net VDD/VSS by using 

GlobalNetConnection: VDD -pin VDD_PIN -inst * -type pgpin -module {}
GlobalNetConnection: VSS -pin VSS_PIN -inst * -type pgpin -module {}

I got errors below:

A global net connection rule for connecting P/G pins of the pattern 'VDD_PIN' was specified.  But the connections cannot be made because there is no such pin in any cell.  Check the pin name pattern and make sure it is correct.

A global net connection rule for connecting P/G pins of the pattern 'VSS_PIN' was specified.  But the connections cannot be made because there is no such pin in any cell.  Check the pin name pattern and make sure it is correct.

Any help for how to connect power/ground ports will be greatly appreciated.

 

Thanks in advanced

Wei

Parents

  •  Hi Wei,

    What are the names of the pwr/gnd pins of your std cells? (Usually something like VDD and VSS.) This is what you need in the globalNetConnect statement.

    globalNetConnect VDD   -type pgpin -pin VDD  -inst * -all -override

    I don't think you needed to create those VDD_PIN and VSS_PIN pins. You should have several pwr/gnd IO cells in your design and that is where the pwr/gnd nets originate from. The core-facing pin of these IO cells (usually much larger than a signal pin) will connect to the power grid that you create. 

    Get the globalNetConnect statments going, then try again to route your pwr/gnd.

    - Kari

Reply

  •  Hi Wei,

    What are the names of the pwr/gnd pins of your std cells? (Usually something like VDD and VSS.) This is what you need in the globalNetConnect statement.

    globalNetConnect VDD   -type pgpin -pin VDD  -inst * -all -override

    I don't think you needed to create those VDD_PIN and VSS_PIN pins. You should have several pwr/gnd IO cells in your design and that is where the pwr/gnd nets originate from. The core-facing pin of these IO cells (usually much larger than a signal pin) will connect to the power grid that you create. 

    Get the globalNetConnect statments going, then try again to route your pwr/gnd.

    - Kari

Children
  • in reply to Kari

    Hey Kari,

    I have been searching all over, but can't seem to find an answer to my issue, but this seems close.  I have no issue connecting my VDD18 and VSS to my macros and std cells, but in this current iteration of my design, I have a SRAM and 45 std cells that I need to connect to a different power source.  The issue is that the power source, called VBATT is an input from one of the I/O pads.  Every time I use globalNetConnect VBATT -pin VDD -type pigpen -inst "instance path/*" -override, but when I run sroute with just the area I fenced these cells into after placing rings and stripes, the VDD pin in the SRAM still only wants to connect to VDD18, my global VDD and not the signal power source VBATT I am trying to attach it to.  Any help would be appreciated.

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