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 Hard macros power routing issues 

Last post Mon, Sep 28 2009 11:54 PM by verysmart. 19 replies.
Started by dbekiaris 03 Aug 2009 10:48 AM. Topic has 19 replies and 7675 views
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  • Mon, Aug 3 2009 10:48 AM

    • dbekiaris
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    Hard macros power routing issues Reply

    Hello everybody,

     I import a design in SoC Encounter 7.1, where three hard macros (SRAMs) exist. The problem is that when I am trying to create the power stripes and connect them with the core rings to synthesize the power grid, the SRAM p/g pins cannot connect with the remaining power/ground network, although I have selected the proper metal layer from the .lef files of the macros. Is there anything possible to do for this? I tried also to align pins of the specified macros with the power/ground stripes, but it failed again. If it is possible, please help. Thank you very much in advance.

     

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  • Mon, Aug 3 2009 8:20 PM

    • magicflute
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    Re: Hard macros power routing issues Reply

      try to set Sroute-> Advanced->Connect Corners of ring pins   validation

    Keep Moving............
    • Post Points: 5
  • Mon, Aug 3 2009 9:18 PM

    Re: Hard macros power routing issues Reply

    Hi dbekiaris,

    whether the problem is for few RAMS or is it for all RAMS. If it is for few RAMS the problem could be orientation of RAM pins. For example ram pins are in MET4 and conventional direction for MET4 is say vertical and RAM is placed in such a way that MET4 pins on RAM are horizontal and when you try to draw stripes over RAM in say MET5. They may not get connected.

    Anyway there is a command to form vias . we can use this command even after the powerplan is completed.

    Before this command select rams on which connection is required. 

    editPowerVia -add_vias 1 -selected_blocks 1 -top_layer MET6 -bottom_layer MET4 -orthogonal_only 1 .

    This is what i understood from problem you described. correct me if i misunderstand the problem and give bit more clarification. 

     

     

     

    • Post Points: 5
  • Mon, Aug 3 2009 9:26 PM

    Re: Hard macros power routing issues Reply

    Hi  dbekiaris,

    Use this command for connecting stripes to Ram pins and let me know whether it solved your problem or provide more details about problem.

    editPowerVia -add_vias 1 -selected_blocks 1 -top_layer top_layer_name -bottom_layer  bottom_layer_name -orthogonal_only 1

    Thanks

    suraj

     

     

    • Post Points: 20
  • Tue, Aug 4 2009 5:26 AM

    • dbekiaris
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    Re: Hard macros power routing issues Reply
    Hi surajece01 Thank you very much for your helpful and immediate response!However, the problem is that I propable do not need any power vias to be added, as far as the stripes I selected have been put at the metal layer where the VDD/VSS of SRAMS are also placed. So, I suppose there is no need for vias. The problem is that the power grid creation takes a lot of time and the messages during the execution are not that emcouraging (e.g. CPU time for FollowPin 0 seconds). Does this message means problems with the follopin connections ? Thank you very much again in advance. Kind Regards dbekiaris
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  • Wed, Aug 5 2009 9:11 AM

    • dbekiaris
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    Re: Hard macros power routing issues Reply

    Hello everybody again

     The aforementioned problem continues to occur. In perspective, what I am doing is to create the power ring around the core at first and after that, I am creating custom power rings around the perimeter of the hard macros at the design boundary, so that each of them is connected to the core ring. However, the result is always a failure. I don't know whether the hard macro lefs are responsible for this. I would be grateful if someone could help me with this, because I don't know where is the wrong step that leads to opens. Thank you very much in advance.

     Kind Regards

    dbekiaris

     

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  • Wed, Aug 5 2009 11:30 AM

    • Kari
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    Re: Hard macros power routing issues Reply

     dbekiaris,

    Can you attach a picture or drawing of what you are trying to do? And maybe the commands you are using? 

    - Kari

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  • Thu, Aug 6 2009 6:20 AM

    • dbekiaris
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    Re: Hard macros power routing issues Reply
    Hi Kari and thanks for answering! Here is the picture of the open violations, demonstrating the hard macros (floorplan view). I also followed the advise of rotating some of the macros so that the pins are aligned, but nothing changed. What I have done is to create first of all the core ring (M6/M5 metal layers). I have choosen these because the metal layer for VDD/VSS of macros is M5. Also, the stripe metal layer is M5, while the standard cell special pins are of M1. After the core ring, I created 4 block rings, each for one macro. The rings I created are custom and they seem to be attached to the core ring. However, I can't see why these opens occur. I would be grateful if you could help/advise me on this problem. Thank you very much in advance. The picture follows. Kind Regards dbekiaris
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  • Thu, Aug 6 2009 7:28 AM

    • Kari
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    Re: Hard macros power routing issues Reply

    Thanks for the picture - I hate to ask again, but could you post a picture that is zoomed in to one particular problem area, so I can really see what your issue is? Also, another thing you can try is to draw the connection yourself, with the wire editor, and see what happens. This is a method we use a lot to figure out why sroute sometimes can't make a connection. Make sure DRC is turned on, so you can see any violations that may be preventing sroute from completing the connections.

    • Post Points: 20
  • Thu, Aug 6 2009 8:08 AM

    • dbekiaris
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    Re: Hard macros power routing issues Reply
    Hi Kari, Thanks again for answering!Here is the detailed view of one of the macros (in a larger design now, but based on the same technology library). It seems that the pins are not very well located, because the opens are put inside the area of the macro. Therefore, the ring for the specific block should be redrawn. But how can somebody find out the location of pins for a hard macro, apart from creating a specific partition? Thank you very much in advance again! Kind Regards dbekiaris
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  • Thu, Aug 6 2009 10:06 AM

    • Kari
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    Re: Hard macros power routing issues Reply

    I still can't really tell what the issue is. Could you make sure the pwr/gnd pins of the macro are displayed, along with the ring you want to connect to? It may help to annotate the picture with some comments - I recommend Jing for this - it's free and very easy to use. You can easily take a picture from your screen, then draw arrows, circles, add text, etc.

    http://jingproject.com/
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  • Thu, Aug 6 2009 11:03 AM

    • dbekiaris
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    Re: Hard macros power routing issues Reply

    Hi Kari,

    Thanks for answering and for the support. However, the problem is much more serious that I could imagine, except if I make wrong steps. The opens are shown at the left side of the macro boxes. So, as far as the rings cannot connect to the pins at these areas, the VDD/VSS pins stay unconnected. Therefore, I suppose the pin assignment of the macro blocks should change. Is this possible in SoC Encounter ? Can I create a partition and reassign the pins to the left top or to the bottom of the macro? Or the problem is not that ? Anyway, if you have any answer of idea on these questions, please help. Thank you very very much again in advance.

     Kind Regards

     

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  • Thu, Aug 6 2009 11:31 AM

    • Kari
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    Re: Hard macros power routing issues Reply

     You still haven't said how you're trying to connect the macro pins to the ring. Are you using the GUI? An sroute command? Just creating a ring around the macro isn't going to automatically connect the macro pins to the ring. I'm worried that some steps are being left out here. Have you reviewed the "Power Planning and Routing" chapter in the User Guide?

    • Post Points: 5
  • Thu, Aug 6 2009 10:37 PM

    Re: Hard macros power routing issues Reply

    few clarifications needed...

    The core ring is not visible. could u provide zoomed view of pins on macro. what is the top metal layer of your design and in which layer do u have pins on macros.

    If i were to do powerplan for this and there is no specific requirements given.....

    1) i would make a core ring in M5/M6 bypassing all the macros.

    2) Make separate rings for each macro M5/M6 ( block rings not attached to core ring).

    3) make io wire connections from io pads to core ring and to block rings.

    4) make connection of macro pins to the block ring. ( depending on how the pins are on the macro).

    5) now adding stripes limiting them only to core ring. 

    6) here iam providing power to block ring directly from ios.and providing connections to macro only from block ring and iam completely excluding core ring and M5 stripes to Macros.

    try this if u like and let me know any issues in doing so........

     

    Thanks

    suraj 

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  • Fri, Aug 7 2009 4:23 AM

    • dbekiaris
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    Re: Hard macros power routing issues Reply
    Hello everybody and thanks again for answering Actually, everything I have done up until now is through the GUI. So, I create the core ring (following the .lef dimensions) on M6/M5 and then, I create block rings of M6/M5 for each of the macros, and then I try to do the special route only for the macro blocks. The result shows always unconnected pins, even if I try the "Connect corners of pin rings" option in the 'Sroute' window. I suppose the block rings are not on the corners, but on the left and the right side of the macro blocks, that's why they seem to be unconnected. The question is that if happens so, how can I connect them ? It would be difficult to do all this manually, as there are about 15 macros on the design. Thank you very much.
    • Post Points: 20
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Started by dbekiaris at 03 Aug 2009 10:48 AM. Topic has 19 replies.