lect.10 - EEL 5722C Field-Programmable Gate Array Design...

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1 EEL 5722C Field-Programmable Gate Array Design Lecture 10: CAD 3: FPGA Routing (Advanced)* www.eecs.ucf.edu/~mingjie/EEL5722 Prof. Mingjie Lin * Some slides adopted from UMN EE5301 by Kia Bazargan & NWU EECS357 lectures
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2 Overview Recap + Feedbacks for the 2nd lab FPGA Routing – FPGA Routing Problem Formulation Difference from conventional VLSI routing problem – Steiner Tree and MST Algorithms – Practical FPGA Routing Algorithms
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3 FPGA Routing Problem Formulation
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4 4 FPGA Routing Problem • Routing represent the final step in that CAD system • The router tool allocates the FPGA’s routing resources to interconnect the placed logic cells • The router must ensure that all interconnections are formed • Other constraints might be applied, such as maximizing the speed performance of timing- critical connections
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5 5 INTRODUCTION A classic approach in solving the routing problem for FPGAs was to adopt a “Divide- and-Conquer” strategy: 1. Partition routing resources to routing areas 2. Perform Global Routing 3. Perform Detailed Routing Another approach is to perform one-step Detailed Routing
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6 FPGA Routing Resources Prefabricated wire segments – Routing constraints : Sharing of a wire segments by different nets is not possible Limited Routability – High RC delays – large area of switches
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7 FPGA Routing
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8 Routing Graph G r ( V r , E r ) V r : I/O pins of logic modules, wire segments E r : feasible connections between the nodes Routing problem: Find vertex disjoint trees T ={ T 1 ,… T n }
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9 Maze Routing Will find shortest path for a single wire, if such a path exists. Two phases: – Label nodes with distance, radiating from source – Use distances to trace from sink to source, choosing a path that always decreases distance to source Use different cost functions to achieve routing objective Timing-driven Routibility-driven
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10 Steiner Tree & Basic Algorithms
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11 Spanning Tree
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Building Minimal Spanning Trees Prim’s algorithm: simple variation of Dijkstra’s SSSP algorithm – Change Dijkstra’s algorithm so the priority of bridge (f n) is length(f,n) rather than minDistance(f) + length(f,n) – Intuition: Starts with any node. Keep adding smallest border edge to expand this component. Algorithm produces minimal spanning tree!
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This note was uploaded on 11/23/2011 for the course EEL 5722c taught by Professor Lin during the Spring '11 term at University of Central Florida.

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lect.10 - EEL 5722C Field-Programmable Gate Array Design...

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