[ibis-interconn] Re: NC or not to NC...

From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
To: "ibis-macro@xxxxxxxxxxxxx" <ibis-macro@xxxxxxxxxxxxx>, IBIS-Interconnect <ibis-interconn@xxxxxxxxxxxxx>
Date: Thu, 13 Jan 2022 04:31:34 +0000

Hello Everyone,

As they say, never a dull moment…

I started reading the description of the 3rd column (signal_type) under the
[Designator Pin List] keyword (pg. 368) to see what we would have to do
to make the ‘NC’ possible.  However, I found something in the description
of the 2nd column (see highlighted text below) which would also need to
be changed to make ‘NC’ work in the 3rd column, because we will need
‘NC’ for I/O pins also, not just for power pins.

[cid:image003.png@01D80803.732E2E00]

How should we do this?  Allow the 3rd column of I/O pins if and only if it
contains ‘NC’?
Any other ideas/suggestions?

Thanks,

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

From: ibis-macro-bounce@xxxxxxxxxxxxx <ibis-macro-bounce@xxxxxxxxxxxxx> On
Behalf Of Muranyi, Arpad
Sent: Wednesday, January 12, 2022 9:00 PM
To: ibis-macro@xxxxxxxxxxxxx; IBIS-Interconnect <ibis-interconn@xxxxxxxxxxxxx>
Subject: [ibis-macro] Re: NC or not to NC...

Bob,

Thanks for your comments.  Looks like the three of us (you, Walter, and me)
agree that going with the ‘NA” idea in the 2nd column is not a good idea.  But
I think if we add ‘NC’ back as a reserved word for the 3rd column, we should
still add the rule for it that if it is present in the 3rd column (for
signal_type),
the signal_name in the 2nd column should be ignored/ineffective/meaningless
as far as connectivity is concerned.  I understand your point that in this case
there will be most likely no [EMD Model] terminal lines referencing these
designator pins, but I want to make it absolutely sure that there would be
no chance of EDA tools to inadvertently doing something that the model maker
didn’t intend to do…  And I also want to make sure that the model maker wouldn’t
feel obligated to come up with unique signal_names, being afraid of possible
connections made by the EDA tool.  But we can discuss this further…

Thanks,

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

From: Bob Ross <bob@xxxxxxxxxxxxxxxxx<mailto:bob@xxxxxxxxxxxxxxxxx>>
Sent: Wednesday, January 12, 2022 6:04 PM
To: wkatz@xxxxxxxxxxxxx<mailto:wkatz@xxxxxxxxxxxxx>; Muranyi, Arpad
<Arpad_Muranyi@xxxxxxxxxx<mailto:Arpad_Muranyi@xxxxxxxxxx>>;
ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: RE: [ibis-macro] Re: NC or not to NC...

Arpad,

I would vote No for the “NA” usage (already a reserved word) and the proposed
restrictive rule.  We would already have the equivalent restriction.

There is no requirement that all [EMD Pin List} and any [Designator Pin List]
pins are connected in any [EMD Model].
So if the intention is to not connect an NC pin, then its electrical connection
will not be documented.

The EMD board designer might have had a valid reason (reserved for future
expansion) for adding additional routing to NC pins.  Such “connections’ can be
designated by unique signal_names (NC1, NC2, …)

So the “NA” functionality already exists if we support NC in [Designator Pin
List].

Bob

From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Walter Katz
Sent: Wednesday, January 12, 2022 11:52 AM
To: Arpad_Muranyi@xxxxxxxxxx<mailto:Arpad_Muranyi@xxxxxxxxxx>;
ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: [ibis-macro] Re: NC or not to NC...

Yes

Walter Katz
Work  508.647-7633
Cell      720.417-3762
[Description: Description: Visit MathWorks.com]

From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
<ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>> On
Behalf Of Muranyi, Arpad
Sent: Wednesday, January 12, 2022 1:22 PM
To: ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: [ibis-macro] Re: NC or not to NC...

Walter, (and Everyone),

Another option, instead of adding a reserved signal name ‘NA’ for the 2nd column
would be to write a rule that would state that if the 3rd column has ‘NC’, then
the
2nd column becomes meaningless, i.e. the usual associations between signal names
in [EMD Pin List] and [Designator Pin List]  would not be made when the 3rd
column
has ‘NC’.

Would that be a better way to do this?

Thanks,

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

References:
- [ibis-interconn] Re: NC or not to NC...
  - From: Muranyi, Arpad

[ibis-interconn] Re: NC or not to NC...

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