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Using "add net constraints" command in Conformal

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Hi

I have tried using "add net constraints" command to place one-cold constraints on a tristate enable bus. In the command line we need to specify the "net pathname" on which the constraints are to be enforced.

The bus here is 20-bit. How should the net pathname be specified to make this 20-bit bus signals one_hot or one_cold.

The bus was declared as follows:
ten_bus [19:0]

The command I used was

add net constraints one_hot /ren_bus[19]

What would the above command mean?
Should we not specify all the nets' pathnames on the bus?
Is it sufficient to specify the pathname of one net on the bus?
I could not get much info regarding the functionality of this command. I would be obliged if anyone can throw some light.

Thanks
Prasad.


Originally posted in cdnusers.org by anssprasad
Parents

  • Hi Prasad,
    Add the net contraint only one side of the design, -revised preferably
    And as said do all in one line . .
    SETUP> add net constaint one_hot ZN[zero] ZN[one] ZN[two] . . . -revised

    Constraints are essentially assumptions that the Equivalence Checker can use to "ignore" Non-equivalences.
    For eg.

    if you apply a one-hot on revised
    Golden: net1, net2, net3
    Revised: net1, net2, net3

    Then only conditions where revised is 001, 010, 100 will be honored.
    A condition such as (G)110 and (R)011 will be ignored even if it is
    non-equivalent because of the constraint.

    -- Masood

    PS: You better simulate the one_hot in a simulator. Also if you have
    conformal - ASIC license, you may be able to actually verify that
    your one-hot bus is truly a one-hot formally without vectors. You
    can invoke that tool by
    unix> lec -verify
    From there it is pretty intuitive with a check called bus contention.

    PPS: There are experts in the support channel who can guide you with
    this. You may want to file an SR.


    Originally posted in cdnusers.org by makkarm
Reply

  • Hi Prasad,
    Add the net contraint only one side of the design, -revised preferably
    And as said do all in one line . .
    SETUP> add net constaint one_hot ZN[zero] ZN[one] ZN[two] . . . -revised

    Constraints are essentially assumptions that the Equivalence Checker can use to "ignore" Non-equivalences.
    For eg.

    if you apply a one-hot on revised
    Golden: net1, net2, net3
    Revised: net1, net2, net3

    Then only conditions where revised is 001, 010, 100 will be honored.
    A condition such as (G)110 and (R)011 will be ignored even if it is
    non-equivalent because of the constraint.

    -- Masood

    PS: You better simulate the one_hot in a simulator. Also if you have
    conformal - ASIC license, you may be able to actually verify that
    your one-hot bus is truly a one-hot formally without vectors. You
    can invoke that tool by
    unix> lec -verify
    From there it is pretty intuitive with a check called bus contention.

    PPS: There are experts in the support channel who can guide you with
    this. You may want to file an SR.


    Originally posted in cdnusers.org by makkarm
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