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In this chapter, the following content will be discussed: Introduction, component technology in embedded systems, case study – ABB’s field devices, prerequisites for effective development of component-based embedded systems.
Chapter 16 Component based embedded systems Building Reliable Componentbased Overview Introduction Component technology in embedded systems Case study – ABB’s Field Devices Prerequisites for effective development of Componentbased embedded systems Summary Building Reliable Componentbased Where is the problem? Huge market arises for embedded devices, and thus for software for them Similar basic functionalities are repeated New functionalities are added constantly Shorter development time is required Building Reliable Componentbased Introduction Building Reliable Componentbased Embedded vs Component-based Monolithic approach requires re-implementing the functionalities Embedded devices are too small for component offthe shelf technologies Component based SE provides a mean to reuse the functionalities Component based SE can provide a framework instead of technology Building Reliable Componentbased Component technology in embedded world Contractually specified interfaces Component as a unit of composition and independent deployment Explicit context dependencies Component granularity Reuse Location transparency Component wiring Portability, platform independence Building Reliable Componentbased Contractually specified interfaces State-of-the-art technologies approach: Interfaces as pure collection of methods • Embedded environment constraint: Nonfunctional specifications are equally important part of the contract Building Reliable Componentbased Interfaces II Component interfaces support: Late binding, Polymorphism, Semantic specification Pre conditions, Post conditions, Invariants Building Reliable Componentbased Unit of composition and independent deployment Run-time composition Component model, Run-time environment, Dynamic communication, Design-time composition Capable of generating monolithic firmware from component-based design, Optimization Building Reliable Componentbased Explicit context dependencies What is a context in embedded world? Other components and interfaces Run-time environment CPU, RTOS, Component implementation language, Resource constraints Building Reliable Componentbased Portability, Platform independence Source level portability suffices, Design-time composition, Run-time environment restrictions Source level portability requires: Agreement on implementation language, Agreement on available libraries, Providing proper abstractions (i.e RTOS API) Building Reliable Componentbased Other issues Location transparency For embedded devices there is a single location, Component wiring Needed for flexible composition of software, Optimizes component interaction, Component ”glue code” should be in implementation language Building Reliable Componentbased Case study – ABB’s Field devices Synchronous approach Architecture of the field devices Dynamic behavior Inter-component communication Building Reliable Componentbased Synchronous approach Synchronous languages have been developed to simplify the programming of reactive systems Provide the mean to handle concurrency, determinism, response time control Based on synchrony hypothesis Building Reliable Componentbased Architecture of the field device Block Container Scheduler AO Function Block SP AO Algorithm Transducer Block OUT MODE OUT_CHAN READBACK IN_CHAN POS_VALUE CTRL_PAR I/O HW FEEDBACK Profibus PA Mapper Pos Control Pos Measure AccessManager Profibus PA Stack Display, Buttons Local Operation Persistent Storage PC/Handheld-Interface Building Reliable Componentbased Dynamic behavior manipulated variable (3) a) setpoint Controlled System Controller (2) actual value (1) b) Sensors (1) PID (2) Building Reliable Componentbased out out error Setpoint Tv,Tv,kp speed speed Signalbus Actuator (3) Inter-component communication Based on Signal Bus Signal Bus communication is maintained by Object Manager Communication itself is based on signals One source per signal Building Reliable Componentbased Types of Interfaces User Interface (1) (4) Communication Link (2) Realtime System (3) Mass storage Interface Building Reliable Componentbased Process Interface Prerequisites for effective development Component model Additionally must address non functional properties, Allow for code generation, Allow for efficient functional interfaces, Allow for specification of architectural styles that describe component connections and containment relations, Building Reliable Componentbased Framework Component Model Component-based Architecture for field devices Component Repository Composition environment Building Reliable Componentbased Run-time environment Prerequisites II Component-based architecture for field devices Framework, Compile time optimizations, Field-bus architecture, Repository Storage and retrieval of components, Storage of non-functional properties, implementation, support and test scripts, Versioning Building Reliable Componentbased Prerequisites III Composition environment Constraint verification, Component adaptation and code generation, Composition techniques, Definition of composition rules Building Reliable Componentbased Prerequisites IV Run-time environment Provide efficient implementation model, Address embedded systems constraints, Allow for compilation to optimized firmware thus allowing for no extra run-time environment that RTOS Allow for hardware and RTOS independent implementation of components Building Reliable Componentbased Case study summary Architecture of the field device Prerequisites for effective development Framework Building Reliable Componentbased Presentation summary Introduction Component technology in embedded systems Case study – ABB’s Field Devices Prerequisites for effective development of Componentbased embedded systems Summary Building Reliable Componentbased ... Building Reliable Componentbased Introduction Building Reliable Componentbased Embedded vs Component-based Monolithic approach requires re-implementing the functionalities Embedded devices are too small for ... Component technology in embedded systems Case study – ABB’s Field Devices Prerequisites for effective development of Componentbased embedded systems Summary Building Reliable Componentbased ... platform independence Building Reliable Componentbased Contractually specified interfaces State-of-the-art technologies approach: Interfaces as pure collection of methods • Embedded environment constraint: