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