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 setup/hold time constraint 

Last post Sat, Jan 9 2010 3:19 PM by seyyed morteza. 4 replies.
Started by seyyed morteza 29 Dec 2009 11:46 PM. Topic has 4 replies and 2735 views
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  • Tue, Dec 29 2009 11:46 PM

    setup/hold time constraint Reply

    hello,

    Is ther any mean that I can define setup/hold time constraint in constraint folder so that I can use it for similar nets?

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    • Post Points: 20
  • Tue, Jan 5 2010 7:03 AM

    • Dennis Nagle
    • Top 500 Contributor
    • Joined on Mon, Oct 13 2008
    • Chelmsford, MA
    • Posts 34
    • Points 485
    Re: setup/hold time constraint Reply

    Hi Seyyed,

    There may be many ways to accomplish what you are after. Please contact me offline if you want to discuss your particular situation.

    Regards,

    -Dennis

    • Post Points: 5
  • Wed, Jan 6 2010 10:11 AM

    Re: setup/hold time constraint Reply
    dear dennis,
     
    thanks a lot for your answer. what do you mean from offline? I am in iran and it is better to me to discuss about my problem via electronic means.any way in my board I have address and data bus. I want to place setup/hold time constraints on some devcices on databus (cpu and sdram only, because other devices are asynchronus). further I want to set diffrent constraint for pin pairs of "cpu-to-sdram" and "sdram-to-cpu".but setup/hold time exist only in net folder and not in constraint folder. thus I can not reuse the constraints of a bit of databus for other bits and I must explicitly define this for all bits one by one. I want to know if I can define this as a generic constraint and apply it for all bits of databus.
     
    regards,
    seyyed morteza havaedgi.
    • Post Points: 20
  • Wed, Jan 6 2010 8:10 PM

    • Dennis Nagle
    • Top 500 Contributor
    • Joined on Mon, Oct 13 2008
    • Chelmsford, MA
    • Posts 34
    • Points 485
    Re: setup/hold time constraint Reply

    Hi Seyyed,

     By offline, I meant that you could email me directly so that we wouldn't bore others with the details. You are correct that there is no corresponding ECSet entry for setup/hold values. If what you are concerned with is easing the process of setting the values, you have 2 options. One is to make use of the hierarchy in CM and put the bits in a bus or class (depending on the version you are using) and set the values at the bus or class level and have them propagate down to the bit level. The second option is to make use of the fact that setup/hold are both net and pin properties. You could use your netlist or the property editor to set the values. If you are concerned about specific pin pairs then the pin option might be best here.

    You should also be aware of the limitation that a specific pin pair can only have one value. In other words, you can not have different values for the same pin pair depending on which pin/device is driving.

     Regards,

    -Dennis

    • Post Points: 5
  • Sat, Jan 9 2010 3:19 PM

    Re: setup/hold time constraint Reply
    dear dennis,
     
    thanks a lot for your answer.
     
    regards,
    seyyed morteza havaedgi.
    • Post Points: 5
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Started by seyyed morteza at 29 Dec 2009 11:46 PM. Topic has 4 replies.