[ibis-interconn] EMD BIRD Draft 23

From: Walter Katz <wkatz@xxxxxxxxxx>
To: "IBIS-Interconnect" <ibis-interconn@xxxxxxxxxxxxx>
Date: Tue, 29 Oct 2019 16:36:02 -0400 (EDT)

All,

I have enclosed the EMD BIRD draft 23.

I added the following sentence to the EMD Pin interface and Designator Pin
Interface for rail terminals:

Note that if the terminal is associated with a bus_label, and the bus_label
name is the same as the signal name then the list of EMD pins shall consist
of those pins with this signal name that either have no bus_label, or a
bus_label that is explicitly set to the signal_name.

I believe that this is the intent, however I could not see this stated or
implied in IBIS 7.0 (for BIRD 189 package models or BIRD 182)

I sent this BIRD to Bob for his review, and his response (which I included
on page 16 and 17:

First, there are valid rules on pages 8 and 12  in the EMD section and ahead
of the EMS section:

"If the bus_label column is not specified for signal_type POWER or GND, then
the bus_label shall be assumed to be the signal_name."

Also, we allow that an explicit bus_label name can be identical to a
signal_name entry. (No restriction is stated.)

---

The whole bullet on page 15 needs to be re-examined:

o   At the EMD pin interface, a terminal whose Terminal_type is Pin_Rail can
be identified by a pin_name, signal_name, or bus_label.  A pin_name maps
directly into a Pin_Rail pin_name.

*  Note that a terminal whose Terminal_type is Pin_Rail may be associated
with one EMD pin_name or a list of EMD pin_names on a rail that is
associated with a signal_name or bus_label.  If the terminal is associated
with more than one pin_name then these pin_names are shorted together. Note
that if the terminal is associated with a bus_label, and the bus_label name
is the same as the signal name then the list of EMD pins shall consist of
those pins with this signal name that either have no bus_label, or a
bus_label that is explicitly set to the signal_name.

I would eliminate the indirect listing of pin_names as a rule.  Randy
questioned this at a meeting you skipped because the application of the rule
was error-prone and not readable.  Also, it is not necessary because other
rules cover the same functionality in a more concise manner.  The [EMD Pin
Listing] and [Designator Pin List] entries already provide the cross-check.

Instead, I would break this down as:

o   At the EMD pin interface, a terminal whose Terminal_type is Pin_Rail can
be identified by a pin_name, signal_name, or bus_label

*  A pin_name maps directly into a Pin_Rail pin_name entry

*  A bus_label maps directly into a Pin_Rail bus_label entry  If undeclared
and/or identical, the bus_label name can be the signal_name entry.

*  A signal_name maps directly into a Pin_Rail signal_name entry whether or
not there are different bus_label entries.

The same rule applies for the designator pin interface.

---

Regarding BIRDs182 and 189,  if a bus_label is not explicitly defined under
[Pin Mapping], [Die Supply Pads], or [Bus Label], then a default signal_name
entry could be used in either [Pin Mapping] or in a *_Rail bus_label  line.
The reason for this deduction is that [Bus Label] and [Die Supply Pads]
require a signal_name entry that matches a name under [Pin].  If bus_labels
are not defined, the default single_name entry is available as a bus_label
entry.

Walter

Walter Katz

<mailto:wkatz@xxxxxxxxxx> wkatz@xxxxxxxxxx

Office 978.461-0449 x 133

Mobile  720.417-3762

Attachment: BIRD_EMD_draft_23.docx
Description: application/vnd.openxmlformats-officedocument.wordprocessingml.document

[ibis-interconn] EMD BIRD Draft 23

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