RE: Stupid question

Syed,

I think his question is a little different. It seems to that
he wants to know what he should do with the I/O cells which
are used as input, or output.

Bob,

This is what you should do. Generate four I-V curves from the
ASIC cells. (pulddown, pullup, GND relative 3-state, and Vcc relative
3-state). When you have an I/O make an I/O IBIS model from these,
that is do the usual subtraction method to generate the [Pulldown]
and [Pullup] tables. The 3-state curves go into the clamp curves
as usual, cut at the appropriate points to avoid double counting.

When you need an input only model, keep these clamp curves, but
discard the [Pullup], [Pulldown] curves and the V-t curves (and ramps).

When you need an output only model, discard the clamp curves, and
use the unsubtracted [Pulldown] and [Pullup] curves (keeping the V-t
and ramp also).

Arpad Muranyi
Intel Corporation
======================================================================

-----Original Message-----
From: Syed Huq [mailto:shuq@cisco.com]
Sent: Monday, May 01, 2000 10:33 AM
To: ibis@eda.org; rhaller@cereva.com
Subject: Re: Stupid question

Since this is an FPGA, the user needs to generate his/her own [Pin] list
table
based on your configuration. This [Pin] list would point to the appropriate
buffer models. Then attach the buffer models to the modified [Pin] list to
create the full component model.

You can even use the [Model selector] scheme from v3.2 but that depends if
your simulator supports it.

Regards,
Syed
Cisco Systems, Inc

>
> Dear IBIS users,
> I am trying to ascertain the optimal way to configure a FPGA IBIS
model.
> I have input only, output only and Bi-directional I/O's while the
supplier's
> model provides
> a generic I/O model. If someone could email me an optimized example I
would
> be most grateful.
>
> Regards,
> Bob Haller
Received on Mon May 1 10:51:04 2000