Re: Help: Programmable Outputs

-- [ From: Ron Christopher * EMC.Ver #2.5.1 ] --

It seems like the proposed BIRD will have the user manually edit the
IBIS model for each different condition. The IBIS model is in the
category of rules data when processing at the higher level package.
Would you require each user to have their own copy of the IBIS model in
an MCM or board design shop? Can this proposal support a user who needs
the IBIS model set one way for one net and a different way for a
different net in the same higher level package being processed?

Would a standardized filter identifier associated with the pin in the
design data base improve the proposal? The filter identifier would
identify to the programs which subset of the IBIS model to use for each
instance of a pin. The standardized identifier can then be used by
other functions such as system level delay or tristate rules checking
etc. One could perhaps write a checker that checked that the
standardized identifier was correct for the conditions which might
require tracing a couple of levels of logic through the network.

Ron Christopher

==================

Text item:

Scott,

BIRD30.2 addresses the problem you have. Hopefully it will be
implemented in IBIS3.0 soon. Untill then, in our models we use
comments. Spceifically, I put everything that is legal in BIRD30.2
into the IBIS file with comment characters in front of each line. This
and an explanation gives enough information to the user to know how to
edit the IBIS file for the various conditions. When IBIS3.0 arrives,
all they need to do is to rmove the comment characters.

Arpad
========================================================================
=======

Ibis folks,

I guess this question is mainly aimed at the simulation vendor folks,
but feedback is welcome from everyone:
(Our products are programmable logic devices, for those who are not
familiar with Actel)

For a component that has a programable behavior for the I/O pins, what
might be the preferred way of presenting the data for the different
possible configurations? Specifically, let's say that a pin can be
programmed to be either:
     1) Tristateable I/O with a fast slew rate
     2) " " " " slow slew rate
     3) Open Drain output (data input to the output buffer is
             programmed to be tied to the enable of the buffer)

Would it be better to actually make a main IBIS file that contains all
of the I/Os in condition (1), with 2 extra IBIS files that contain only
one pin in them each for conditions (2) and (3)? Or, perhaps only make
one IBIS file with all of the pins configured in condition (1) and
commented out sections for conditions (2) and (3). Or, even another
possibility of dividing the I/Os into 3 equal sections, one for each
configuration? All comments/suggestions welcome, and please forgive me
if this has been discussed already. Thanks,
-Scott Schlachter
 scotts@actel.com
 Actel Corporation
 Sunnyvale, CA.

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Subject: Help: Programable outputs
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From: scotts@actel.com (Scott Schlachter)
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Received on Sat Dec 7 05:55:08 1996