Java for Real-Time Embedded Systems
Authors
Frost, Christian ; Jensen, Casper Svenning ; Luckow, Kasper Søe
Term
3. term
Education
Publication year
2011
Submitted on
2011-01-10
Pages
166
Abstract
Dette speciale undersøger, hvordan man kan udvikle indlejrede hårde realtidssystemer med Java—systemer indbygget i enheder, som altid skal reagere inden faste tidsfrister. Det sammenligner denne form for udvikling med almindelig software ved at beskrive typiske hardwarebegrænsninger, realtidsoperativsystemer og sprogrestriktioner. Centrale realtidsbegreber forklares i enkle termer: Worst-Case Execution Time (WCET), den maksimale tid en opgave kan tage, og planlægbarhedsanalyse, som vurderer, om alle opgaver kan overholde deres deadlines. Med dette som grundlag gennemgår specialet eksisterende Java-profiler målrettet realtids- og indlejrede miljøer og vurderer deres fordele og ulemper. For at gøre det konkret implementeres et klassisk eksempel: en minepumpe-controller. Én implementering kører på Java Optimized Processor (JOP) og demonstreres med en LEGO-opbygget pumpe. Tidskorrekthed undersøges med WCET Analyzer (WCA) og TIMES-værktøjerne. Til sidst udføres en planlægbarhedsanalyse med udnyttelsesbaserede metoder og Response Time Analysis (RTA) for at anvende teorien i praksis.
This thesis explores how to develop embedded hard real-time systems with Java—systems built into devices that must always respond within strict deadlines. It contrasts this kind of development with conventional software by outlining typical hardware constraints, real-time operating systems, and language restrictions. Key real-time concepts are explained in plain terms: Worst-Case Execution Time (WCET), the maximum time a task can take, and schedulability analysis, which checks whether all tasks can meet their deadlines. On this foundation, the thesis reviews existing Java profiles designed for real-time and embedded use and assesses their strengths and limitations. To ground the discussion, the work implements a classic case study: a mine-pump controller. One implementation runs on the Java Optimized Processor (JOP) and is demonstrated with a LEGO-built pump. Timing correctness is examined with the WCET Analyzer (WCA) and the TIMES tools. Finally, the system is analysed for schedulability using utilisation-based methods and Response Time Analysis (RTA) to apply the theory in practice.
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