@article {60, title = {Time-Aware Instrumentation of Embedded Software}, journal = {IEEE Transactions on Industrial Informatics}, volume = {6}, year = {2010}, month = {August}, pages = {652{\textendash}663}, abstract = {

Software instrumentation is a key technique in many stages of the development process. It is particularly important for debugging embedded systems. Instrumented programs produce data traces which enable the developer to locate the origins of misbehaviours in the system under test. However, producing data traces incurs runtime overhead in the form of additional computation resources for capturing and copying the data. The instrumentation may therefore interfere with the system\’s timing and perturb its behavior. In this work, we propose an instrumentation technique for applications with temporal constraints, specifically targetting background/foreground or cyclic executive systems. Our framework permits reasoning about space and time and enables the composition of software instrumentations. In particular, we propose a definition for trace reliability, which enables us to instrument real-time applications which aggressively push their time budgets. Using the framework, we present a method with low perturbation by optimizing the number of insertion points and trace buffer size with respect to code size and time budgets. Finally, we apply the theory to two concrete case studies: we instrument the OpenEC firmware for the keyboard controller of the One Laptop Per Child project, as well as an implementation of a flash filesystem.

}, keywords = {debugging, Instrumentation, real-time, tracing}, issn = {1551-3203}, doi = {10.1109/TII.2010.2068304}, url = {http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5559440}, author = {Fischmeister, Sebastian and Lam, Patrick} } @article {53, title = {Hardware Acceleration for Conditional State-Based Communication Scheduling on Real-Time Ethernet}, journal = {IEEE Transactions on Industrial Informatics}, volume = {5}, year = {2009}, pages = {325{\textendash}337}, abstract = {

Distributed real-time applications implement distributed applications with timeliness requirements. Such systems require a deterministic communication medium with bounded communication delays. Ethernet is a widely used commodity network with many appliances and network components and represents a natural fit for real-time application; unfortunately, standard Ethernet provides no bounded communication delays. Conditional state-based communication schedules provide expressive means for specifying and executing with choice points while staying verifiable. Such schedules implement an arbitration scheme and provide the developer with means to fit the arbitration scheme to the application demands instead of requiring the developer to tweak the application to fit a predefined scheme. An evaluation of this approach as software prototypes showed that jitter and execution overhead may diminish the gains. This work successfully addresses this problem with a synthesized soft processor. We present results around the development of the soft processor, the design choices, and the measurements on throughput and robustness.

}, keywords = {ASTM demo, NCM, real-time, state-based scheduling}, issn = {1551-3203}, doi = {10.1109/TII.2009.2026642}, url = {http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5196857}, author = {Fischmeister, Sebastian and Trausmuth, Robert and Lee, Insup} } @article {52, title = {Plug-and-Play for Medical Devices: Experiences from a Case Study}, journal = {Biomedical Instrumentation \& Technology}, volume = {43}, year = {2009}, keywords = {ASTM demo, medical devices, NCM, real-time, state-based scheduling}, doi = {10.2345/0899-8205-43.4.313}, author = {Arney, David and Fischmeister, Sebastian and Julian M. Goldman and Lee, Insup and Trausmuth, Robert} } @inproceedings {51, title = {Resource Scopes: Toward Language Support for Compositional Determinism}, booktitle = {Proc. of the 12th IEEE International Symposium on Object/component/service-oriented Real-time Distributed Computing (ISORC)}, year = {2009}, month = {March}, pages = {295{\textendash}304}, address = {Tokyo, Japan}, abstract = {

Complex real-time embedded systems should be compositional and deterministic in the resource, time, and value domains. Determinism eases the engineering of correct systems and compositionality simplifies the assembly of complex systems out of smaller modules. This paper describes the PEACOD framework that is developed to support deterministic behavior for resource consumption, value passing, and timing. The paper introduces the notions of determinism in the context of the resource, value, and temporal domains, and present the resource-scope language construct that can be used to program such deterministic behaviors. Furthermore, the paper also provides semantics for the resource scope construct and uses these semantics to show that the program behavior is preserved under composition. The paper briefly describes the current implementation of PEACOD.

}, keywords = {determinism, distributed computing, real-time}, isbn = {978-0-7695-3573-9}, doi = {10.1109/ISORC.2009.42}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5232027}, author = {Anand, Madhukar and Fischmeister, Sebastian and Lee, Insup} } @inproceedings {50, title = {Specification and Analysis of Network Resource Requirements of Control Systems}, booktitle = {Proc. of the 12th International Conference on Hybrid Systems: Computation and Control (HSCC)}, year = {2009}, month = {April}, pages = {381{\textendash}395}, address = {Los Angeles, USA CA}, abstract = {

We focus on spatially distributed control systems in which measurement and actuation data is sent via a bus shared with other applications. An approach is proposed for specifying and implementing dynamic scheduling policies for the bus with performance guarantees. Specifically, we propose an automata-based scheduler which we automatically generate from a model of the controlled plant and the controller. We show that, in addition to ensuring performance, our approach allows adjustments to dynamic conditions such as varying disturbances and network load. We present a full development path from performance specifications (exponential stability) to a control design and its implementation using Controller Area Network (CAN).

}, keywords = {NCM, real-time, state-based scheduling}, isbn = {978-3-642-00601-2}, doi = {10.1007/978-3-642-00602-9_27}, url = {http://dl.acm.org/citation.cfm?id=1538216}, author = {Gera Weiss and Fischmeister, Sebastian and Anand, Madhukar and Rajeev Alur} } @inproceedings {49, title = {On Time-Aware Instrumentation of Programs}, booktitle = {Proc. of the IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS)}, year = {2009}, month = {April}, pages = {305{\textendash}314}, address = {San Francisco, USA}, abstract = {

Software instrumentation is a key technique in many stages of the development process. It is of particular importance for debugging embedded systems. Instrumented programs produce data traces which enable the developer to locate the origins of misbehaviours in the system under test. However, producing data traces incurs runtime overhead in the form of additional computation resources for capturing and copying the data. The instrumentation may therefore interfere with the system\&$\#$39;s timing and perturb its behavior. In the worst case, this perturbation leads to new system behaviours that prevent the developer from locating the original misbehaviours. In this work, we propose an instrumentation technique for applications with temporal constraints, specifically targetting background/foreground systems. Our framework permits reasoning about space and time for software instrumentations. In particular, we propose a definition for trace reliability, which enables us to instrument real-time applications which aggressively push their time budgets. Using the framework, we present a method with low perturbation by optimizing the number of insertion points and trace buffer size for code size and time budgets. Finally, we apply the theory to a concrete case study and instrument the OpenEC firmware for the keyboard controller of the One Laptop Per Child project. This publication has been superseeded by an article in the IEEE Transactions on Industrial Informatics to be published soon.

}, keywords = {debugging, real-time, tracing}, isbn = {9780769536361}, doi = {10.1109/RTAS.2009.26}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=04840591}, author = {Fischmeister, Sebastian and Lam, Patrick} } @inproceedings {54, title = {Tracing Interrupts in Embedded Software}, booktitle = {Proc. of the ACM SIGPLAN/SIGBED Conference on Languages, Compilers, and Tools for Embedded Systems (LCTES)}, year = {2009}, note = {

(best in research forum award)

}, month = {June}, pages = {137{\textendash}146}, address = {Dublin, Ireland}, abstract = {

During the system development, developers often must correct wrong behavior in the software\–-an activity colloquially called program debugging. Debugging is a complex activity, especially in real-time embedded systems because such systems interact with the physical world and make heavy use of interrupts for timing and driving I/O devices. Debugging interrupts is difficult, because they cause non-linear control flow in programs which is hard to reproduce in software. Record/replay mechanisms have proven their use to debugging embedded systems, because they provide means to recreate control flows offline where they can be debugged. In this work, we present the data tracing part of the record/replay mechanism that is specifically targeted to record interrupt behavior. To tune our tracing mechanism, we use the observed principle of return address clustering and a formal model for quantitative reasoning about the tracing mechanism. The presented heuristic and mechanisms show surprisingly good results\–-up to an 800 percent speedup on the selector function and a 300 percent reduction on duplicates for non-optimal selector functions\–-considering the leanness of the approach.

}, keywords = {debugging, real-time, tracing}, isbn = {978-1-60558-356-3}, doi = {10.1145/1542452.1542471}, url = {http://dl.acm.org/citation.cfm?doid=1542452.1542471}, author = {Giovani Gracioli and Fischmeister, Sebastian} } @inproceedings {47, title = {Compositional Feasibility Analysis of Conditional Real-Time Task Models}, booktitle = {Proc. of the IEEE International Symposium on Object/Component/Service-oriented Real-Time Computing (ISORC)}, year = {2008}, month = {May}, pages = {391{\textendash}398}, address = {Orlando, USA}, abstract = {

Conditional real-time task models, which are generalizations of periodic, sporadic, and multi-frame tasks, represent real world applications more accurately. These models can be classified based on a tradeoff in two dimensions expressivity and hardness of schedulability analysis. In this work, we introduce a class of conditional task models and derive efficient schedulability analysis techniques for them. These models are more expressive than existing models for which efficient analysis techniques are known. In this work, we also lay the groundwork for schedulability analysis of hierarchical scheduling frameworks with conditional task models. We propose techniques that abstract timing requirements of conditional task models, and support compositional analysis using these abstractions.

}, keywords = {real-time, state-based scheduling}, isbn = {978-0-7695-3132-8}, doi = {10.1109/ISORC.2008.47}, url = {http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4519608}, author = {Anand, Madhukar and Arvind Easwaran and Fischmeister, Sebastian and Lee, Insup} } @inproceedings {46, title = {Generating Sound and Resource-Aware Code from Hybrid System Models}, booktitle = {Model-Driven Development of Reliable Automotive Services}, year = {2008}, month = {August}, pages = {48{\textendash}66}, address = {San Diego, USA}, abstract = {

Modern real-time embedded systems are complex, distributed, feature-rich applications. Model-based development of real-time embedded systems promises to simplify and accelerate the implementation process. Although there are appropriate models to design such systems and some tools that support automatic code generation from such models, several issues related to ensuring correctness of the implementation with respect to the model remain to be addressed. In this work, we investigate how we can derive sampling rates for distributed real-time systems generated from a hybrid systems model such that there are no switching discrepancies and the resources spent in achieving this are a minimum. Of particular interest are the resulting mode switching semantics and we propose an approach to handle faulty transitions and compute execution rates for minimizing missed transitions. As a guiding example for our approach, we describe a hybrid systems model for vehicle coordination in which one vehicle acts as a leader and a second follows the leader

}, keywords = {charon, hybrid systems, real-time}, isbn = {ISBN: 978-3-540-70929-9}, doi = {10.1007/978-3-540-70930-5_4}, url = {http://dl.acm.org/citation.cfm?id=1422807}, author = {Anand, Madhukar and Kim, Jesung and Fischmeister, Sebastian and Lee, Insup} } @inproceedings {45, title = {Hardware Acceleration for Verifiable, Adaptive Real-Time Communication}, booktitle = {Proc. of the 13th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)}, year = {2008}, month = {September}, pages = {1425{\textendash}1432}, address = {Hamburg, Germany}, abstract = {

Distributed real-time applications implement distributed applications with timeliness requirements. Such systems require a deterministic communication medium with bounded communication delays. Ethernet is a widely used commodity network with a large number of appliances and network components and represents a natural fit for real-time application. Unfortunately, standard Ethernet provides no bounded communication delays. Network Code Processor is a soft processor implementation for real-time communication on Ethernet. The system provides a smart network-card functionality and can be seen as a co-processor for time-triggered communication. Its most distinguishing feature, the programmability of the processor via the Network Code language, allows developers to write adaptive but verifiable communication schedules tailored to the application needs. In this work we present results around the development of the soft processor, discuss the specific challenges of how to build a reliable and fast communication system, the tradeoffs involved when moving from a generic software prototype to a programmable hardware implementation.

}, keywords = {NCM, real-time, state-based scheduling}, isbn = {978-1-4244-1505-2}, doi = {10.1109/ETFA.2008.4638584}, url = {http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4638584}, author = {Fischmeister, Sebastian and Lee, Insup and Trausmuth, Robert} } @inproceedings {48, title = {A Programmable Arbitration Layer For Adaptive Real-Time Systems}, booktitle = {Proc. of the Intl. Workshop on Adaptive and Reconfigurable Embedded Systems (APRES)}, year = {2008}, month = {April}, pages = {27{\textendash}31}, address = {St. Luis, USA}, abstract = {

Adaptive real-time systems can respond to changes in the environment and thus allow for an extended range of operations and for improved efficiency in the use of system resources. Building such adaptive real-time systems requires flexibility at each layer in the system stack. In this paper, we introduce and discuss our on-going effort to build a programmable arbitration layer. It builds on the Network Code language and enables the developer to program application-specific arbitration mechanisms which optimize bandwidth or encodes specific properties such as data redundancy, collision-free communication, and temporal isolation.

}, keywords = {NCM, real-time, state-based scheduling}, url = {http://www.artist-embedded.org/artist/IMG/pdf/ProceedAPRES08dinA4-final.pdf}, author = {Fischmeister, Sebastian and Trausmuth, Robert} } @inproceedings {43, title = {Composition Techniques for Tree Communication Schedules}, booktitle = {Proc. of the 19th Euromicro Conference on Real-Time Systems (ECRTS)}, year = {2007}, month = {July}, pages = {235{\textendash}246}, address = {Pisa, Italy}, abstract = {

A critical resource in a distributed real-time system is its shared communication medium. Unrestrained concurrent access to the network can lead to collisions that reduce the system\’s reliability. Therefore in this area, one goal is to develop effective models for coordinating and controlling access to the shared medium and its channels. Network Code is a verifiable, executable model for coordinating and controlling access to a shared communication medium in a distributed real-time system. In this paper, we investigate the problem of building an application by composing multiple Network Code programs. To reason about the composition, we model Network Code programs as Tree Schedules (TS) and then consider the composition of schedules that describe how the network is accessed by different applications. Specifically, we first define the notions of compatibility and composability of tree schedules, and then provide algorithms for their composition and reason about overhead of composition. We illustrate the techniques by considering the composition of two control applications.

}, keywords = {NCM, real-time, state-based scheduling}, doi = {10.1109/ECRTS.2007.88}, author = {Anand, Madhukar and Fischmeister, Sebastian and Lee, Insup} } @inproceedings {42, title = {A Dynamic Scheduling Approach to Designing Flexible Safety-Critical Systems}, booktitle = {Proc. of the 7th Annual ACM Conference on Embedded Software (EMSOFT)}, year = {2007}, month = {October}, pages = {67--74}, address = {Salzburg, Austria}, abstract = {

The design of safety-critical systems has typically adopted static techniques to simplify error detection and fault tolerance. However, economic pressure to reduce costs is exposing the limitations of those techniques in terms of efficiency in the use of system resources. In some industrial domains, such as the automotive, this pressure is too high, and other approaches to safety must be found, e.g., capable of providing some kind of fault tolerance but with graceful degradation to lower costs, or also capable of adapting to instantaneous requirements to better use the computational/communication resources. This paper analyses the development of systems that exhibit such level of flexibility, allowing the system configuration to evolve within a well-defined space. Two options are possible, one starting from the typical static approach but introducing choice points that are evaluated only at runtime, and another one starting from an open systems approach but delimiting the space of possible adaptations. The paper follows the latter and presents a specific contribution, namely, the concept of local utilization bound, which supports a fast and efficient schedulability analysis for on-line resource management that assures continued safe operation. Such local bound is derived off-line for the specific set of possible configurations, and can be significantly higher than any generic non-necessary utilization bound such as the well known Liu and Layland\’s bound for Rate-Monotonic scheduling.

}, keywords = {aptivity, real-time}, isbn = {978-1-59593-825-1}, doi = {10.1145/1289927.1289942}, url = {http://dl.acm.org/citation.cfm?id=1289942}, author = {Luis Almeida and Anand, Madhukar and Fischmeister, Sebastian and Lee, Insup} } @inbook {44, title = {Temporal Control in Real-Time Systems: Languages and Systems}, booktitle = {Handbook of Real-Time and Embedded Systems}, year = {2007}, pages = {10-1 to 10-18}, publisher = {CRC Press}, organization = {CRC Press}, chapter = {10}, abstract = {

Temporal control is an important concept for real-time systems, and several systems and languages provide means for setting temporal constrains on the program. However, the way temporal constraints are placed on the program, the granularity, and the supported kinds of temporal constraints differ from system to system. This chapter provides an introduction to temporal control in real-time systems on the basis of temporal constraints. First, it introduces the notion and nature of a temporal constraint and presents a generic model of the task life cycle. Second, it discusses six different systems and languages with temporal control by adapting the generic model to the individual system and by presenting a short example of a stopwatch task. Finally and third, a summary and discussion of the differences among these systems conclude the chapter.

}, keywords = {real-time}, isbn = {9781584886785}, url = {http://www.crcpress.com/product/isbn/9781584886785}, author = {Fischmeister, Sebastian and Lee, Insup} } @inproceedings {37, title = {An Analysis Framework for Network-Code Programs}, booktitle = {Proc. of the ACM \& IEEE International Conference on Embedded Software (EMSOFT)}, year = {2006}, month = {October}, pages = {122{\textendash}131}, address = {Seoul, South Korea}, abstract = {

Distributed real-time systems require a predictable and verifiable mechanism to control the communication medium. Current real-time communication protocols are typically independent of the application and have intrinsic limitations that impede customizing or optimizing them for the application. Therefore, either the developer must adapt her application and work around these subtleties or she must limit the capabilities of the application being developed. Network Code, in contrast, is a more expressive and flexible model that specifies real-time communication schedules as programs. By providing a programmable media access layer on the basis of TDMA, Network Code permits creating application-specific protocols that suit the particular needs of the application. However, this gain in flexibility also incurrs additional costs such as increased communication and run-time overhead. Therefore, engineering an application with network code necessitates that these costs are analyzed, quantified, and weighted against the benefits. In this work, we propose a framework to analyze network-code programs for commonly used metrics such as overhead, schedulability, and average waiting time. We introduce Timed Tree Communication Schedules, based on timed automata to model such programs and define metrics in the context of deterministic and probabilistic communication schedules. To demonstrate the utility of our framework, we study an inverted pendulum system and show that we can decrease the cumulative numeric error in the model\’s implementation through analyzing and improving the schedule based on the presented metrics.

}, keywords = {NCM, real-time, state-based scheduling}, isbn = {1-59593-542-8}, doi = {10.1145/1176887.1176905}, url = {http://dl.acm.org/citation.cfm?id=1176905}, author = {Anand, Madhukar and Fischmeister, Sebastian and Lee, Insup} } @inproceedings {38, title = {Network-Code Machine: Programmable Real-Time Communication Schedules}, booktitle = {Proc. of the IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS)}, year = {2006}, month = {April}, pages = {311{\textendash}324}, address = {San Jose, USA}, abstract = {

Distributed hard real-time systems require guaranteed communication. One common approach is to restrict network access by enforcing a time-division multiple access (TDMA) schedule.The typical data representation of offline-generated TDMA schedules is table-like structures. This representation, however, does not permit applications with dynamic communication demands, because the table-like structure prevents on-the-fly changes during execution. A common approach for applications with dynamic communication behavior is dynamic TDMA schedules. However, such schedules are hard to verify, because they are usually implemented in a programming language, which does not support verification. Network code is a behavioral model for specifying real-time communication schedules. It allows modeling arbitrary time-triggered communication schedules with on-the-fly choices, and it is also apt for formal verification. In this work, we present network code and show how we can use a model checker to verify safety properties such as collision-free communication, schedulability, and guaranteed message reception. We also discuss its implementation in RTLinux and provide performance measurements.

}, keywords = {NCM, real-time, state-based scheduling}, isbn = {0769525164}, doi = {10.1109/RTAS.2006.31}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1613346}, author = {Fischmeister, Sebastian and Sokolsky, Oleg and Lee, Insup} } @inproceedings {36, title = {Distributed Code Generation from Hybrid Systems Models for Time-delayed Multirate Systems}, booktitle = {Proc. of the ACM Conference on Embedded Software (EMSOFT)}, year = {2005}, month = {September}, pages = {210{\textendash}213}, address = {New York, USA}, abstract = {

Hybrid systems are an appropriate formalism to model embedded systems as they capture the theme of continuous dynamics with discrete control. A simple extension, a network of communicating hybrid automata, allows for modeling distributed embedded systems. Although it is possible to generate code from such models, it is difficult to provide formal guarantees in the code with respect to the model. One of the reasons for this is that, the model is set in continuous time and concurrent execution with instantaneous communication, whereas the generated code is set in discrete time with delayed communication. This can introduce semantic differences between the model and the code such as missed transitions, faulty transitions, and altered continuous behavior. The goal of faithful code generation is to minimize these differences. In this paper, we propose a relaxed criteria of faithfulness, coined relative faithful implementation. Based on this criteria, and we propose dynamically adjusting the guard at runtime using estimates of errors for preventing faulty transitions. We also identify a sufficient condition to ensure no missed transitions in the code.

}, keywords = {charon, hybrid systems, real-time}, isbn = {1-59593-091-4}, doi = {10.1145/1086228.1086267}, url = {http://dl.acm.org/citation.cfm?id=1086267}, author = {Anand, Madhukar and Fischmeister, Sebastian and Kim, Jesung and Lee, Insup} } @inproceedings {33, title = {Multi-Dimensional Schedules for Media-Access Control in Time-Triggered Communication}, booktitle = {Proc. of the IEEE Symposium on Computers and Communications (ISCC)}, year = {2005}, month = {June}, pages = {664--670}, address = {Murcia, Cartagena, Spain}, abstract = {

A shared communication medium is characterized by multiple entities that use this medium by reading and writing from and to it. Write operations on the shared communication medium must be coordinated and collision-avoidance schemes are one technique to achieve this - for example time-division multiple access (TDMA). Common solutions for TDMA include descriptive tables or algorithm-based client/server mechanisms. Yet, they are all limited in their expressiveness: at the beginning of the communication period at most one write operation can be scheduled for a specific time slot. In this work, we propose a system that allows for scheduling several write operations for the same time slot but guarantee that at most one will be performed though. It does not deal with scheduling algorithms per se, it deals with describing and implementing a computed schedule. The consequences of this added expressiveness allow for parallel and stateful communication schedules merged and serialized in an ad-hoc way. The contribution is the proposed more expressive yet still value and time-deterministic way of describing communication schedules for time-triggered communication plus a description of its implementation in an interpreter implemented as infrastructure in RTLinuxPro.

}, keywords = {NCM, real-time, state-based scheduling}, doi = {10.1109/ISCC.2005.48}, url = {http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1493796}, author = {Fischmeister, Sebastian} } @inproceedings {34, title = {Non-blocking Deterministic Replacement of Functionality, Timing, and Data-Flow for Hard Real-Time Systems at Runtime}, booktitle = {Proc. of the Euromicro Conference on Real-Time Systems (ECRTS)}, year = {2005}, month = {July}, pages = {106--114}, address = {Las Palmas, Spain}, abstract = {

Embedded systems are usually an integral component of a larger system and are used to control and/or directly monitor this system by using special hardware devices. The complexity of the whole system, which the embedded control system monitors, increases steadily. Consequently, the initial version of the control software that is used at the time of deployment may be inadequate and may need to be updated. Often this requires the whole system to be shut down to have the software replaced. This is not a desirable solution. In this work, we propose a non-blocking mechanism embedded into an infrastructure for RTLinuxPro for determin- istic replacement of system functionality, task timing, and data-flow for hard real-time systems. We explain the mechanism, discuss its implementation using RTLinuxPro, and present a case study of a stop watch in which we replace single functionality and timing behavior at runtime without compromising the timeliness of tasks or the correctness of the output values. The contribution is to show how such a mechanism can work, how it can be implemented, and what problems arise in multi-mode real-time applications.

}, keywords = {adaptivity, real-time}, isbn = {0-7695-2400-1}, doi = {10.1109/ECRTS.2005.20}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01508452}, author = {Fischmeister, Sebastian and Klemens Winkler} } @inproceedings {35, title = {Towards Efficient Use of Shared Communication Media in the Timed Model}, booktitle = {Proc. of the 11th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS)}, year = {2005}, month = {March}, pages = {342{\textendash}351}, address = {San Francisco, USA}, abstract = {

Embedded computers are increasingly tighter integrated with each other forming distributed embedded systems that interact through a shared communication medium. Often these embedded systems perform services for safety-critical operations that require deterministic computation and predictable communication. However, since these systems are embedded, they must cope with limited resources. One fundamental challenge is to make efficient use of the shared communication medium, especially in the timed model, in which communication tends to cumulate at the end of harmonic periods of tasks. In this article, we present an approach that uses Micro-tasks for splitting computation and communication into several sequentially executed steps to allow for better balanced load on the communication medium in the timed model. We discuss the approach and describe its implementation in OSEK/Works with TTCAN.

}, keywords = {distributed LET, modecs, real-time}, isbn = {0-7695-2302-1}, doi = {10.1109/RTAS.2005.57}, url = {http://dl.acm.org/citation.cfm?id=1049923}, author = {Guido Menkhaus and Fischmeister, Sebastian and Michael Holzmann and Claudiu Farcas} } @inbook {30, title = {EmBase: Strength, Weakness, Opportunities, and Threats Analysis}, booktitle = {Embedded Systems Knowledge Base {\textendash} Austria and Surrounding Regions}, volume = {182}, year = {2004}, pages = {61{\textendash}75}, publisher = {Austrian Computer Society}, organization = {Austrian Computer Society}, keywords = {embase, real-time}, author = {Barbara Birke and Klaus-Michael Koch and Fischmeister, Sebastian and Helmut Hafner and Daniel Karlsson}, editor = {Fischmeister, Sebastian} } @book {29, title = {Embedded Systems Knowledge Base --- Austria and Surrounding Regions}, series = {OCG-Schriftenreihe}, volume = {182}, year = {2004}, pages = {200}, publisher = {Austrian Computer Society}, organization = {Austrian Computer Society}, keywords = {embase, real-time}, author = {Fischmeister, Sebastian} } @inbook {28, title = {Research Directions in Embedded Systems}, booktitle = {EmBase News as Web Portal}, volume = {182}, year = {2004}, pages = {75{\textendash}93}, publisher = {Austrian Computer Society}, organization = {Austrian Computer Society}, keywords = {embase, real-time}, author = {Emilia Coste and Claudiu Farcas and Fischmeister, Sebastian and Wolfgang Pree} } @inproceedings {27, title = {Task Sequencing for Optimizing the Computation Cycle in a Timed Computation Model}, booktitle = {Proceedings of the International Digital Avionics Systems Conference (DASC)}, year = {2004}, month = {October}, publisher = {IEEE Press}, organization = {IEEE Press}, address = {Salt Lake City, UT, USA}, abstract = {

Recent developments in embedded control systems promote the timed computation model following the principles of logical execution time (LET). Resulting control applications are time deterministic, value deterministic, and their properties may be subject to formal verification against a mathematical model of the control design. However, the timed computation model introduces inefficiencies to computation cycles. As the LET of a real-time control task requires being greater than its worst-case execution time and computed values are always propagated at the end of the LET, actuator updates are unnecessarily delayed. This makes the control cycle less responsive. In this paper, we present an approach that allows the definition of task sequences for a timed computation model implemented by the timing definition language (TDL). Task sequences help minimizing timing delays between sensor readings and actuator updates (e.g., in estimator-based control systems), managing startup and shutdown phases of control systems, and providing mechanisms for error-detection in fault-tolerant systems.

}, keywords = {control systems, distributed LET, modecs, real-time, timed computation model}, isbn = {0-7803-8539-X}, doi = {10.1109/DASC.2004.1390783}, url = {http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1390783}, author = {Fischmeister, Sebastian and Guido Menkhaus} } @inproceedings {23, title = {Embedded Systems Knowledge Base}, booktitle = {Proc. of the 3rd International Conference on Knowledge Management}, year = {2003}, month = {September}, publisher = {J.UCS Journal of Universal Computer Science}, organization = {J.UCS Journal of Universal Computer Science}, address = {Graz, Austria}, abstract = {

Embedded systems play an increasingly important role in today\’s society. The spectrum of embedded systems ranges, for example, from mobile phones to X-by-wire control systems in cars and airplanes. The regional embedded systems knowledge base, called EmBase, is a comprehensive project which investigates and maps the knowledgebase in embedded systems with a focus on Austria and Central Europe. EmBase supports individuals, private and public institutions and companies that implement, develop, support, purchase or sell embedded systems so that they can successfully identify key market trends and directions and align themselves and their activities with these trends.

}, keywords = {embase, real-time}, url = {http://i-know.tugraz.at/blog/2003/11/embedded-systems-knowledge-base}, author = {Klaus-Michael Koch and Monja Loge and Wolfgang Pree and Fischmeister, Sebastian} } @article {25, title = {Middleware fuer eingebettete Systeme (Middleware for Embedded Systems)}, journal = {Noeo}, year = {2003}, keywords = {distributed LET, modecs, real-time}, author = {Wolfgang Pree and Fischmeister, Sebastian and Guido Menkhaus and Gerald Stieglbauer} }