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This proposal suggests simplifying the ICM-IBIS interface by using a simple link through external circuits and node declarations, eliminating the need for complex pin mappings. It provides examples and outlines four cases for complete coverage.
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IBIS & ICM Interfacing:Simple Link Michael Mirmak September 21, 2005
Original ICM-IBIS Proposal Too Complex • Original ICM-IBIS proposals (“BIRD100”) • Permitted ICM with “classic” IBIS • Allowed complex package paths for IBIS 3.2/4.0 structures • Sketched out [External Circuit], [External Model] support • Need to simplify proposal • Tool vendor discomfort at [Pin] changes • [Pin Mapping] complicates classic IBIS support • Size of resulting BIRD would have been very large ICM and IBIS Interfacing: Simple Link
[External Circuit] Easy! Just change [Package Model] • Linking ICM to IBIS [E. Circuit] • Use [Node Declarations] to list internal ICM map pin names • |**************************************** [Node Declarations] |Die pads OR PIN NAMES A1, A2, A3, A4 buff1, buff2, buff3, buff4 [End Node Declarations] |**************************************** [ICM Pin Map] Example1_external Pin_order Row_ordered Num_of_columns = 4 Num_of_rows = 1 Pin_list |Pin Name A1 AD2 A2 AD5 A3 AD7 A4 GND Both sides of ICM interconnect are mapped Only downsides: Names must be matched; arbitrary packages not reusable IBIS • [ICM Pin Map] Example1_internal • Pin_order Row_ordered • Num_of_columns = 4 • Num_of_rows = 1 • Pin_list • |Pin Name • buff1 AD2 • buff2 AD5 • buff3 AD7 • buff4 GND ICM (IIRD8) ICM and IBIS Interfacing: Simple Link
Simplification Proposals • No update to [Pin] • No support of multiple paths under “classic IBIS” • Weak support of ICM with [Pin Mapping] • No “dot syntax” • ICM can only be used with… • [External Circuit] through [Node Declarations] • [Model]/[E. Model] through 1-to-1 package descriptions • Assumptions • No integrated parser • [Pin Mapping] connects packages to buffers ICM and IBIS Interfacing: Simple Link
BACKUP ICM and IBIS Interfacing: Simple Link
Four Cases • We must handle these four cases to be complete • Case 1 – ICM expresses coupling [External Model] ICM Digital Port Pin A1 [External Model] Digital Port Pin B1 [External Model] Digital Port Pin C1 ICM and IBIS Interfacing: Simple Link
Four Cases • Case 2 – Wired-or or “mux” connections • Multiple pins, single [Model] ICM Pin A1 [External Model] Digital Port Pin B1 Pin C1 ICM and IBIS Interfacing: Simple Link
Four Cases • Case 3 – Coupling & power distribution • Single model, single signal pin • No different than Case 2, from [Pin] perspective ICM POWER [External Model] Digital Port Pin A1 GND ICM and IBIS Interfacing: Simple Link
Four Cases • Case 4 – Wired-or or “mux” connection • Single pin, multiple [Model]s [External Model] ICM Digital Port [External Model] Digital Port Pin A1 [External Model] Digital Port ICM and IBIS Interfacing: Simple Link
Four Cases • Case 4a – Wired-or or “mux” connection • Single pin, multiple [Model]s • Variation: where are the package t-lines linked? [External Model] ICM Digital Port [External Model] Digital Port Pin A1 [External Model] Digital Port ICM and IBIS Interfacing: Simple Link