Accurate Power Consumption Evaluation forPeripherals in Ultra Low-Power embedded systems

International audienceWe propose a methodology to measure, model and simulate power consumption of peripheral devices of a lowpower embedded micro-controller, while keeping a reasonable development cost. This methodology is experimented against the low-power MSP-EXP430FR5739 platform that includes nonvolatile RAM for intermittent computing purposes and a handful of peripherals. The experimental measurements enable the characterization of the consumption of the peripherals, while many existing comparable studies do not provide power consumption for peripherals. These measurements are integrated into a simulator that targets low-power peripheral-intensive applications, as are most of IoT embedded programs. The accuracy of the power consumption estimation is within a 5% error on intermittent embedded computing using peripherals

MPU-based incremental checkpointing for transiently-powered systems

International audienc

Sytare: Persistence de l'état des périphériques pour les systèmes à alimentation intermittente

National audienceLes systèmes dits à alimentation intermittente sont de petits systèmes embarqués récupérant l'énergie dans leur environnement. À cause de contraintes de taille et de coût, ils subissent de fréquentes coupures de courant, mais sont néanmoins capables d'exécuter un programme logiciel, en sauvegardant les données nécessaires au calcul dans une mémoire non-volatile. Cet article présente une technique permettant à ces systèmes d'utiliser des périphériques non triviaux tels qu'un convertisseur analogique-numérique, une interface série ou une radio

Peripheral State Persistence For Transiently Powered Systems

Our society relies increasingly on digital technologies to communicate, seek medical information, travel, or have fun. These often-invisible technologies simplify our tasks and enrich our daily lives, while also developing the economy. Recently has emerged the concept of powered by harvesting and being able to retain information between power failures using non-volatile RAM. This report presents a software layer called that permits the use of non-trivial peripherals such as timers, serial interface or radio devices in transiently powered systems

Sytare: a Lightweight Kernel for NVRAM-Based Transiently-Powered Systems

International audienceIn a near future, energy harvesting is expected to replace batteries in ultra-low-power embedded systems. Research prototypes of such systems have recently been proposed. As the power harvested in the environment is very low, such systems need to cope with frequent power outages. They are referred to as transiently-powered systems (TPS). In order to execute non-trivial applications, TPS need to retain information between power losses. To achieve this goal, emerging non-volatile memory (NVM) technologies are a key enabler: they provide a lightweight solution to retain, between power outages, the state of an application and of its peripheral devices. These include sensors, serial interface or radio devices for instance. Existing works have described various checkpointing mechanisms to adapt embedded applications to TPS but the use of peripherals was not yet handled. in these works. This paper proposes a solution for embedded applications using any peripheral device to run despite transient power. We follow a kernel-oriented approach resulting in minimal impact on the programming model of the application. We implement the new concepts in our lightweight kernel called Sytare, running on an MSP430FR5739 micro-controller and we analyze the cost of the proposed solution

Peripheral State Persistence and Interrupt Management For Transiently Powered Systems

International audienceRecently has emerged the concept of transiently powered systems powered by harvesting power and being able to retain information between power failures using non-volatile RAM. While existing solutions focus on purely computing systems, this article presents Sytare, a software layer designed to allow the use of non-trivial peripherals such as timers, serial interface or radio devices in transiently powered systems

Disruptive viability selection on a black plumage trait associated with dominance.

Traits used in communication, such as colour signals, are expected to have positive consequences for reproductive success, but their associations with survival are little understood. Previous studies have mainly investigated linear relationships between signals and survival, but both hump-shaped and U-shaped relationships can also be predicted, depending on the main costs involved in trait expression. Furthermore, few studies have taken the plasticity of signals into account in viability selection analyses. The relationship between signal expression and survival is of particular interest in melanin-based traits, because their main costs are still debated. Here, we first determined the main factors explaining variability in a melanin-based trait linked to dominance: the bib size of a colonial bird, the sociable weaver Philetairus socius. We then used these analyses to obtain a measure representative of the individual mean expression of bib size. Finally, we used capture-recapture models to study how survival varied in relation to bib size. Variation in bib size was strongly affected by year and moderately affected by age, body condition and colony size. In addition, individuals bearing small and large bibs had higher survival than those with intermediate bibs, and this U-shaped relationship between survival and bib size appeared to be more pronounced in some years than others. These results constitute a rare example of disruptive viability selection, and point towards the potential importance of social costs incurred by the dominance signalling function of badges of status.Our research was funded by the DST-NRF Centre of Excellence at the Percy FitzPatrick Institute (University of Cape Town), the Portuguese Foundation for Science and Technology (FCT, PTDC/BIA-BEC/103818/2008) to RC, the region Languedoc Roussillon, the programme "Chercheur(se)s d’avenir" 2013 and ANR JC 09-JCJC-0050-01JCJC to CD, the Natural Environment Research Council (NERC, UK: NE/G018588/1 and NE/K015257/1) to BJH, and the University of Cape Town and St John’s College, Cambridge (UK) to CNS. This research was also supported by a Marie Curie-IRSES grant (FP7-PEOPLE-2012-IRSES; ‘Cooperation’ 318994) to all and was conducted within the CNRS-CIBIO International Associate Laboratory (LIA) ‘Biodiversity and Evolution’. RC was funded by a ‘Ciência 2008’ fellowship (FCT, Portugal) with further support from FEDER (Operational Programme for Competitiveness Factors – COMPETE, Project “Biodiversity, Ecology and Global Change” co-financed by North Portugal Regional Operational Programme 2007/2013 (ON.2), under the NSRF, ERDF.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1111/jeb.1271

Système d'exploitation dédié aux systèmes embarqués basse consommation basés sur NVRAM

Some electronic devices cannot embed any battery because of space- or cost-related concerns. Notably, small devices harvest energy from their environment to gap the absence of battery. Medical sensors and crop probes are examples of such devices. These devices are likely to consume energy faster than they can harvest, when considering non-solar energy or small harvesters for instance. They are thus exposed to frequent power outages and must cope with an intermittent supply and are referred to as transiently-powered systems. Instead of restarting the application from the very beginning on every boot, it is possible to resume the application where it stopped. Non-volatile memories keep their data across power outages and their usage enable persistent data storage. Non-volatile RAM (NVRAM) and traditional volatile RAM have similar access latencies, which makes NVRAM technologies good candidates for persistent storage of energy-constrained devices. This work highlights the benefits of using NVRAM for the purpose of enabling the execution of long-running application despite power outages. This study proposes to solve issues related to intermittent supply at operating system level, which role is to manage application progress persistence and maintain consistency between memories and peripherals. This work also proposes a model for transiently-powered systems to lay the ground for energy consumption estimation of code involving peripherals. A new checkpointing mechanism, based on a hardware MPU, is proposed as a checkpointing optimization. Finally, this work proposes an introduction to proof of correctness at operating system level for transiently-powered systems.Certains objets électroniques ne peuvent embarquer de pile ou de batterie, pour des raisons de place ou de coût. C'est le cas de petits objets, récoltant de l'énergie depuis leur environnement, afin de pallier l'absence de batterie. Capteurs médicaux et sondes agronomiques en sont des exemples. En général, ces objets consomment de l'énergie plus rapidement qu'ils n'en récoltent, notamment pour les appareils non équipés de cellules photovoltaïques. En résultent de fréquentes coupures de courant lors de l'exécution de l'application, on parle alors d'alimentation intermittente. Plutôt que de recommencer l'application du début à chaque redémarrage, il est possible de développer des mécanismes afin de reprendre l'exécution à l'endroit où elle s'était arrêtée. L'utilisation de mémoires non-volatiles, qui ne perdent pas leurs données lorsque la plate-forme est éteinte, permet le stockage de données en dépit des coupures de courant. En particulier, les RAM non-volatiles (NVRAM) ont des temps d'accès voisins des RAM volatiles, ce qui permet de les utiliser comme des mémoires courantes, à l'opposé des mémoires type Flash dont le temps et l'énergie d'écriture sont trop élevés. Ce travail met en exergue l'utilisation de NVRAM afin d'exécuter une application longue en dépit des coupures de courant. Il s'articule autour du développement d'un système d'exploitation visant ce type d'objet, assurant une cohérence entre les mémoires et l'état des périphériques à chaque instant. En outre, il propose un modèle de systèmes à alimentation intermittente, servant de base pour l'évaluation des coûts énergétiques de portions de code impliquant des opérations sur les péripheriques. Un nouveau mécanisme de sauvegarde basé sur une MPU matérielle est proposé pour optimiser la sauvegarde de données. Enfin, ce travail propose une introduction à la preuve formelle d’exécution correcte pour systèmes à alimentation intermittente

Vers des communications anonymes et efficaces

This theses focuses on information dissemination in computer networks. We study two aspects of this topic : anonymous communication on Internet in presence of rational nodes and uniform total order broadcast in a computer cluster. Concerning the first aspect, we observed that no anonymous communication protocol is capable of working in presence of rational nodes while scaling existed. Therefore, we proposed RAC, the first anonymous communication protocol functioning in presence of rational nodes and able of scaling. Concerning the second aspect, we observed that no existing uniform total order broadcast protocol is capable of ensuring both a good latency and an optimal throughput. In order to fill this lack we proposed FastCast, the first uniform total orderCette thèse porte sur la transmission d'informations dans les réseaux d'ordinateurs. Nous nous sommes plus particulièrement penchés sur deux aspects de ce problème : les communications anonymes sur Internet en présence de nœuds rationnels (aussi appelés “égoïstes") et la diffusion à ordre uniformément total dans le cadre d'une grappe de machines. Concernant le premier aspect, nous avons constaté qu'il n'existait pas de protocole de communications anonymes fonctionnant en présence de nœuds rationnels et capable de monter en charge (c'est à dire de fonctionner efficacement en présence d'un grand nombre de noeuds). Nous avons donc proposé RAC, le premier protocole de communications anonymes capable de monter en charge et fonctionnant en présence de nœuds rationnels. Concernant le deuxième aspect, nous avons constaté qu'il n'existait pas de protocole de diffusion à ordre uniformément total assurant à la fois un débit optimal et une latence faible. Nous avons donc proposé FastCast, le premier protocole de diffusion à ordre uniformément total garantissant un débit optimal tout en assurant une latence faible

Implementation of an object-detection algorithm on a CPU+GPU target

Systems like autonomous vehicles may require real time embedded image processing under hardware constraints. This paper provides directions to design time and resource efficient Haar cascade detection algorithms. It also reviews some software architecture and hardware aspects. The considered algorithms were meant to be run on platforms equipped with a CPU and a GPU under power consumption limitations. The main aim of the project was to design and develop real time underwater object detection algorithms. However the concepts that are presented in this paper are generic and can be applied to other domains where object detection is required, face detection for instance. The results show how the solutions outperform OpenCV cascade detector in terms of execution time while having the same accuracy.System så som autonoma vehiklar kan kräva inbyggd bildbehandling i realtid under hårdvarubegränsningar. Denna uppsats tillhandahåller anvisningar för att designa tidsoch resurseffektiva Haar-kasad detekterande algoritmer. Dessutom granskas en del mjukvaruarkitektur och hårdvaruaspekter. De avsedda algoritmerna är menade att användas på plattformar försedda med en CPU och en GPU under begränsad energitillgång. Det huvudsakliga målet med projektet var att designa och utveckla realtidsalgoritmer för detektering av objekt under vatten. Dock är koncepten som presenteras i arbetet generiska och kan appliceras på andra domäner där objektdetektering kan behövas, till exempel vid detektering av ansikten. Resultaten visar hur lösningarna överträffar OpenCVs kaskaddetektor beträffande exekutionstid och med samtidig lika stor träffsäkerhet