8 Replies Latest reply on Jul 13, 2010 8:38 AM by randall_myers

    Cannot swap pins across fractured symbols - This is not a good thing!


      This is more of a statement of concern/frustration. But, at the end of this I would like to know if there are other companies having the same issues and if so what have they come up with as a work around.


      I have been developing our PDB's to include pin swapping in Library Manager. So, when we get to the PCB level, the PCB Designer can swap all the defined pins and then back annotate into DxD thus allowing us to keep the schematic flow intact. Also, this will give the PCB designer much more flexibility on his end rather than force feeding those swaps via the schematic, which adds more time and well you, know the rest.


      I have seen a lot of companies create PDB’s with very little parametric data and pin swap capability, either because they have not taken or had the time to develop their libraries appropriately or maybe they just didn’t know how. Now, I am not saying that it is right or wrong, just that some initial planning and preparation can really stream line your process and make life easier on your designer and the team when being task to complete a rather dense design that may also be layer strapped and schedule crunched.


      Anyway, we have a semi-high pin count BGA - 780 pins and within that part there are 12 fractures which will allow us to have a cleaner much more functional schematic. Unfortunately the way the tools work we cannot swap pins across the fractures only pin to pin within the same fracture. NOT GOOD!


      I know some will say use I/O designer and this will take care of your issues. I disagree, what if I/O designer is not an option and in our case it is the latter. What would be the work around? Sounds to me that creating a very basic or generic library with very little structure or dynamics is the way to go, which means staying away from fractures and creating one massive symbol which we all know is not a good approach.


      There should be a process or an avenue that will allow the same type of functionality on a general level that I/O designer offers. At least to the level in the PDB structure via Library Manager which will allow fracture to fracture swap capability?


      I submitted and SR and talked with some of the AE’s at Mentor about this issue and there response was..."this is a limitation in the tools”. Now, I am not sure if they are planning to develop an alternative to I/O designer (within Library Manager) or if they’re going to push I/O designer. I am going to lean towards the latter on this one.


      Any thoughts or comments?

        • 1. Re: Cannot swap pins across fractured symbols - This is not a good thing!



            I do not understand your situation... so if you could explain a little more: Why is I/O Designer NOT an option?




          • 2. Re: Cannot swap pins across fractured symbols - This is not a good thing!

            I would think that the stopper to the swap any pin in a fractured symbol set are the programmable parts like the FPGAs, etc.  Swap all the you want with in a bank but no pin swapping between banks.  One bank gets a power supply fracture, dedicated pins go into their fracture and the rest of the pins go into another fracture.  Big connectors that are placed in the schematic in multiple symbols are would be handled as single pin symbol - gates.  They are just stacked next to each other and given the same RefDes to build the connector symbol.  Micro-controllers have GPIO pins and multiple function pins but they are not endlessly swappable and I would think not always a good candidate to have pins swappable between fractures.


            Outside of IO Designer, if I can't setup gates to swap or pins swappable with in a gate, then I would have to say that having unlimited pin swapping between fractures is not something that I would vote for.


            Have fun


            • 3. Re: Cannot swap pins across fractured symbols - This is not a good thing!

              I guess I should have stated swappability on defined pins (I/O) not powers, grounds, clocks etc (pins that are deemed fixed or not swappable within the device). I did not mean to imply EVERY pin of the BGA.


              That I assumed went without saying.


              We are dealing with standard I/O pins that can be swapped normally. But, if they are not a part of the same fracture they cannot be swapped within Expedition.


              I have come across a situation currently with a board house who is doing work for us and they want to swap pins in a specific area of the BGA (Physically) but they are NOT a part of the same fracture. This is preventing them from truly utilizing the swap capability within Expedition.


              So, the current configuration within Library Managers PDB will not support or allow it.

              • 4. Re: Cannot swap pins across fractured symbols - This is not a good thing!



                The reason I/O designer is not an option is 2 fold:


                1. The design is already in layout (via service bureau), so it is too late to utilize it.


                2. We currently do not own a seat of I/O designer.

                • 5. Re: Cannot swap pins across fractured symbols - This is not a good thing!

                  I totally understand what your frustrations are.  Altium is 1/6th the price than what we've paid for between DX Designer and Expedtion.  Altium seems to be able to handle pin swapping.  Even without Being forced to purchase I/O Designer for another 25K.  Watch the video from Altium.  Specifically 2. Setting up for Pin Swapping.  Altium will move Net Names around not change Symbols or Parts, if done correctly.  I have too complained about the lack of functionality.  BUYING MORE OPTIONS IS A POOR ANSWER.






                  Variants is another gem the users are asked to purchase, but is included in both the other tools we use.

                  • 6. Re: Cannot swap pins across fractured symbols - This is not a good thing!

                    25K for IO Designer is a bargain.

                    The price for each perpetual license that I have seen is twice of that one.

                    • 7. Re: Cannot swap pins across fractured symbols - This is not a good thing!



                      Even using IO designer this is a limitation.


                      Major unravelling is better done in IOD but lower level swaps are often easier in the layout.

                      I set up swap groups in IOD then let the layout engineer use these pin swaps in Expedition.

                      This doesn't work correctly if the swap groups span fractured symbols (which they often do).


                      A change as suggested would actually enhance IOD



                      • 8. Re: Cannot swap pins across fractured symbols - This is not a good thing!

                        So, IO Designer is one option then:  It can swap across fractured PCB symbols and manage all the many issues that effect swap in an FPGA.  It can provide automated symbol generation and automatic & optimizing unraveling.


                        IO Designer is not mandatory.  You can keep track of all the design and FPGA rules that constrain swapping yourself and make swap groups yourself and still swap across fractured PCB symbols.  What you cannot do is swap across functional symbols.  Hopefully this is good news in that you can go back to making your PCB symbols the correct size for good schematic design with your style.  The limitation here is to get the most power from swapping, put all your FPGA PCB symbols under the one functional symbol.