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MMCM instantiation

zanabonir

Dear Forum

 

how could be possiblee..if possible... to create and connect  and configure a MMCM via VHDL or other code/file, without use the IP CLK WIZARD to add in Block Deisgn ?

Thanks

 

Roberto

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  • 0

    Hi there,

    Any example I provide will be generated with a wizard.  As I mentioned, there are just too many things that you need to account for in order to make this work.  It really is not worth the time to try to hand code one.

    To generate a register, you will need to understand the interface.  A register is just a piece of memory.  You can instantiate a piece of BRAM and just interface to that.

    I'm also not sure you want to try to force the use of a specific cell.  You can do this, but Vivado will do a place and route best fit and utilize resources much better than you will be able to - especially if your design changes.  If you have a timing critical thing, you can typically use this mechanism, but again, we are talking a RARE case.  Vivado will do a much better job auto-placing.

    The only reason I would think you would need to hand place and hand code the MMCM is if you were doing Hyper-routing, however I do not think this is the case.  I suppose if your design is too large that could be another case, however proper constraints will take care of these kinds of issues as well.

    If you want to hand route things, you can of course use constraints to lock pieces around, but again, Vivado will perform this job quite well for you and you needn't worry about it.  If you are trying to hand place to try to "fix" a timing issue, your constraints need work, not the end design.  Proper constraints will take care of all but the very fewest of cases (hyper routing, which is certainly not a typical thing to be doing).

    --Dan

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  • 0

    Hi there,

    Any example I provide will be generated with a wizard.  As I mentioned, there are just too many things that you need to account for in order to make this work.  It really is not worth the time to try to hand code one.

    To generate a register, you will need to understand the interface.  A register is just a piece of memory.  You can instantiate a piece of BRAM and just interface to that.

    I'm also not sure you want to try to force the use of a specific cell.  You can do this, but Vivado will do a place and route best fit and utilize resources much better than you will be able to - especially if your design changes.  If you have a timing critical thing, you can typically use this mechanism, but again, we are talking a RARE case.  Vivado will do a much better job auto-placing.

    The only reason I would think you would need to hand place and hand code the MMCM is if you were doing Hyper-routing, however I do not think this is the case.  I suppose if your design is too large that could be another case, however proper constraints will take care of these kinds of issues as well.

    If you want to hand route things, you can of course use constraints to lock pieces around, but again, Vivado will perform this job quite well for you and you needn't worry about it.  If you are trying to hand place to try to "fix" a timing issue, your constraints need work, not the end design.  Proper constraints will take care of all but the very fewest of cases (hyper routing, which is certainly not a typical thing to be doing).

    --Dan

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