( ESNUG 356 Item 1 ) --------------------------------------------- [8/03/00]

Subject: ( ESNUG 355 #13 )  2nd Plea For Help On Opposite-Input Tri-states

> In the "early" days of ESNUG there was a thread talking about a Synopsys
> bug concerning the usage of tri-state buffers that have 2 enable inputs
> that require opposite logic levels.  I just ran into the same problem
> and am trying to find a solution.  Was there a solution posted (that I
> didn't find)?
>
> I tried to use the 'pin_opposite' attribute in the library but Design
> Compiler failed to map the tri-state buffers.  I tried the 'x_function'
> with the same result.  I tried the 'contention_condition' with the result
> that Design Compiler mapped the tri-state buffers but tied one input to
> VCC (as it did without any special attribute).
>
> I think there must be someone who has solved this problem.
>
>     - Volker Rzehak
>       Texas Instruments Deutschland              Germany


From: Volker Rzehak <v-rzehak@ti.com>

John,

Unfortunately I didn't receive any feedback from my post on ESNUG and I'm
not able to solve the problem up to now.  I am quite stuck.  The only
solution I can think of at the moment is either to do it manually or use
tristate buffers with one input (and bigger area requirements).  Help!

    - Volker Rzehak
      Texas Instruments Deutschland              Germany

   !!!     "It's not a BUG,
  /o o\  /  it's a FEATURE!"
 (  >  )
  \ - / 
  _] [_     (jcooley 1991)