CPAL: High-Level Abstractions for Safe Embedded Systems

Innovation in the field of embedded systems, and more broadly in cyber-physical systems, increasingly relies on software. The productivity gain in software development can hardly keep up with the demand for software despite the increasing adoption of Model-Driven Development (MDD). In this context, we believe that major productivity and quality improvements are still ahead of us through better programming languages and environments. CPAL, the Cyber-Physical Action Language, is a contribution in that direction with the objective to speed-up the development of embedded systems with dependability constraints. The objective of this paper is to present and illustrate the use-cases of the high-level abstractions offered to the developer in CPAL with respect to real-time scheduling, introspection mechanisms, native support of Finite State Machines (FSMs), abstracting the hardware and decoupling functional concerns from non-functional concerns

A Model-Driven Co-Design Framework for Fusing Control and Scheduling Viewpoints

Model-Driven Engineering (MDE) is widely applied in the industry to develop new software functions and integrate them into the existing run-time environment of a Cyber-Physical System (CPS). The design of a software component involves designers from various viewpoints such as control theory, software engineering, safety, etc. In practice, while a designer from one discipline focuses on the core aspects of his field (for instance, a control engineer concentrates on designing a stable controller), he neglects or considers less importantly the other engineering aspects (for instance, real-time software engineering or energy efficiency). This may cause some of the functional and non-functional requirements not to be met satisfactorily. In this work, we present a co-design framework based on timing tolerance contract to address such design gaps between control and real-time software engineering. The framework consists of three steps: controller design, verified by jitter margin analysis along with co-simulation, software design verified by a novel schedulability analysis, and the run-time verification by monitoring the execution of the models on target. This framework builds on CPAL (Cyber-Physical Action Language), an MDE design environment based on model-interpretation, which enforces a timing-realistic behavior in simulation through timing and scheduling annotations. The application of our framework is exemplified in the design of an automotive cruise control system

Battery Aware Dynamic Scheduling for Periodic Task Graphs, Rapport de contrat

Battery lifetime, a primary design constraint for mobile embedded systems, has been shown to depend heavily on the load current profile. This paper explores how scheduling guidelines from battery models can help in extending battery capacity. It then presents a ’Battery-Aware Scheduling’ methodology for periodically arriving taskgraphs with real time deadlines and precedence constraints. Scheduling of even a single taskgraph while minimizing the weighted sum of a cost function has been shown to be NP-Hard [6]. The presented methodology divides the problem in to two steps. First, a good DVS algorithms dynamically determines the minimum frequency of execution. Then, a greedy algorithm allows a near optimal priority function [4] to choose the task which would maximize slack recovery. The methodology also ensures adherence of real time deadlines independent of the choice of the DVS algorithm and priority function used, while following battery guidelines to maximize battery lifetime. Battery simulations carried out on the profile generated by our methodology for a large set of taskgraphs show that battery life time is extended up to 23.3 % as compared to existing dynamic scheduling schemes. 1

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