Subject: RE: [IBIS-Users] Pin name assignment
From: Ingraham, Andrew (Andrew.Ingraham@hp.com)
Date: Fri Jan 31 2003 - 11:44:36 PST
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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