DESC: A Harware-Software Codesign Methodology for Distributed Embedded Systems

Trong-Yen Lee
Pao-Ann Hsiung
Sao-Jie Chen
Department of Electrical Engineering
Department of Computer Science and Information Engineering
Department of Electrical Engineering
National Taiwan University, Taipei, Taiwan.
National Chung Cheng University, Chiayi, Taiwan.
National Taiwan University, Taipei, Taiwan.
( IEICE Transactions on Information and Systems,
IEICE Publishers, Japan, accepted in October 2000.)


The hardware-software codesign of distributed embedded systems is a more challenging task, because each phase of codesign, such as copartitioning, cosynthesis, cosimulation, and coverification must consider the physical restrictions imposed by the distributed characteristics of such systems. Although the codesign of distributed systems is more complex than that of centralized ones, yet distributed systems often contain several similar parts, for which design reuse techniques can be applied. Therefore, an object-oriented (OO) codesign approach, which allows physical restriction and object design reuse, is adopted in our Distributed Embedded System Codesign (DESC) methodology. This newly proposed DESC methodology uses three types of models: Object Modeling Technique (OMT) models for system description and input, Linear Hybrid Automata (LHA) models for internal modeling and verification, and SES/workbench simulation models for performance evaluation. A two-level partitioning algorithm is proposed specifically for distributed systems. Software is synthesized by task scheduling and hardware is synthesized by system-level and object-oriented techniques. Design alternatives for synthesized hardware-software systems are then checked for design feasibility through rapid prototyping using hardware-software emulators. Through a case study on a Vehicle Parking Management System (VPMS), we depict each design phase of the DESC methodology to show benefits of OO codesign, necessity of a two-level partitioning algorithm, and formal timing coverification.

Keywords: distributed embedded systems, emulation, two-level partitioning, object-oriented codesign, software scheduling.