Subject: RE: [IBIS-Users] Pin name assignment
From: Dunbar, Tony (tony_dunbar@mentorg.com)
Date: Fri Jan 31 2003 - 12:32:04 PST
While we are now also debating the [Pin] column characters (and I know this
thread didn't start there), may I throw in a point of practicality (and
hopefully stay on topic)? This particulary concerns the use of the alpha
character range, [a-z] and [A-Z], for PGA/BGA alpha-numeric pinnames.
Please be aware that certain SI tools IBIS parsers differentiate between
upper- and lower-case characters, just as the IBIS spec is case-sensitive,
except for reserved words and keywords. The common convention for PGA/BGA
pinnames is to use upper-case alpha-numeric characters; e.g. AE4. If you
write an IBIS [Pin] list that contains pin name "ae4", this may not auto-map
to pinname "AE4" that exists in the CAD library for the part/package.
Regards,
Tony
-----Original Message-----
From: Ingraham, Andrew [mailto:Andrew.Ingraham@hp.com]
Sent: Friday, January 31, 2003 1:45 PM
To: ibis-users@server.eda.org
Subject: RE: [IBIS-Users] Pin name assignment
For the [Pin] name itself (first column), the IBIS spec is not clear that
you can even use A-Z characters. All of the examples in the IBIS spec have
purely numeric pin names. Most PGAs and BGAs use alpha-numeric pinnames,
and there have probably been discussions about this in the maillists, but
the spec itself is mum about it.
For the [Pin] signal_name, a trailing '#' ought to be OK for IBIS-aware
tools, because they use it in the examples in the IBIS specs.
To be as generic as possible, you probably can't go wrong with A-Z, 0-9, and
'_'.
Obviously, the IBIS comment character shouldn't be used anywhere in a name.
This seems like a good topic for a BIRD! This is not just a matter of
setting project naming conventions and sticking to them. IBIS model files
are meant to be transportable between different companies, so one needs
worldwide standards that one should adhere to.
In lieu of a standard written into the IBIS spec, ibischk* may be the best
we have to go on. Then deal with exceptions if/when they come up.
It's strange that the one place the IBIS standard is specific about
allowable characters, is in the filename; yet the filename is the one thing
most easily corrected by the end-user should there be a problem.
Other odd characters that I used to see in signal names (not in IBIS but
elsewhere), include the space character, and a trailing backslash. The
latter was once used to mean that a signal was low-true, kind of a shorthand
for drawing a bar over the whole signal name. Perhaps '#' evolved as a
better replacement.
SPICE2 could use almost any non-whitespace character in names, except for
parentheses, commas, or the equal sign. SPICE would treat any of these as
field delimiters or separators, equivalent to whitespace. The first
character in a name had some additional restrictions; for example, it
couldn't be a digit. I wouldn't assume even that all Berkeley SPICEs follow
the same conventions.
HSpice is similar but has some differences. I think it has the same problem
with parentheses, but brackets ... square, angle, or curly ... are OK. But
beware that HSpice, unlike SPICE2, converts curly brackets into square
brackets.
Regards,
Andy
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