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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Etude de la fiabilité des mémoires non-volatiles à grille flottante / Study of floating gate non-volatile memories reliability

Rebuffat, Benjamin 15 December 2015 (has links)
De nombreuses applications industrielles spécifiques dans les secteurs tels que l’automobile, le médical et le spatial, requièrent un très haut niveau de fiabilité. Dans ce contexte, cette thèse traite de l’étude de la fiabilité des mémoires non-volatiles à grille flottante de type NOR Flash. Après une introduction mêlant l’état de l’art des mémoires non volatiles et la caractérisation électrique des mémoires Flash, une étude sur l’effet des signaux de polarisation a été menée. Un modèle a été développé afin de modéliser la cinétique de la tension de seuil durant un effacement. L’effet de la rampe d’effacement a été montré sur les cinétiques mais aussi sur l’endurance. Une étude sur la durée de vie de l’oxyde tunnel a ensuite montré l’importance de l’utilisation d’un stress dynamique. Nous avons caractérisé cette dépendance en fonction du rapport cyclique et du champ électrique appliqué. Enfin l’endurance de la cellule mémoire Flash a été étudiée et les effets de la relaxation durant le cyclage ont été analysés. / Many specific applications used in automotive, medical and spatial activity domains, require a high reliability level. In this context, this thesis focuses on the study of floating gate non-volatiles memories reliability more precisely in NOR Flash architecture. After an introduction mixing the state of art of non-volatiles memories and the electrical characterization of Flash memories, a study on the polarization signals effect has been led. A model has been developed in order to model the threshold voltage kinetic during an erase operation. The erasing ramp effect has been shown on kinetics and also on cycling. Then, a study on the tunnel oxide lifetime has shown the importance of relaxation during stress. This dependence has been characterized as a function of duty cycle and the electric field applied. Finally, Flash memory cell endurance has been explored and the relaxation effects during the cycling has been analyzed.
2

Porting Linux on ARM-Based Micro-controllers

Tsai, Ju-Chin 30 July 2006 (has links)
More and more embedded systems choose ARM-based micro-controllers as CPU. If no embedded OS built with the system, the application scope will be restricted. Therefore, the need of embedded OS is vital. There are many embedded OS¡¦s in the market, but the embedded Linux has many advantages and is widely accepted. Commercial embedded Linux takes less refund than other embedded OS¡¦s. The kernel and most applications are distributed in GPL open source copyright, and is highly portable to many machine platforms. Presently, the hardware key-technology is highly skilled. The margin of 3C industrial has gone down rapidly. Therefore, people focus on adapting integrated technology to practicality and innovation to make cost down. Developers choose appropriate ARM micro-controllers according to demanding functionality of their products. The microcontroller is not necessary running with Linux distribution. Two approaches can be used to resolve the embedded OS issue. The first approach is porting Linux to the platform without any refund. The second approach is to pay for commercial Linux. Embedded system peripheral devices aim at powerful functionalities and economy. For instance, UART interface is cheap and low data transfer rate. The target board communicates with host via RS-232. RS-232 acts as serial console to play dumb terminal under Linux. Industrial applications often make use of RS-xxx for UART physical transmission layer. For instance, RS-485 applies modbus protocol to build cheap monitor systems. Network transmission is a necessary function, and it generally achieves high data transfer rate application through Ethernet. The UNIX-like network socket has served network application very well. Embedded systems are usually diskless systems. In order to keep permanent data, using flash memory as block disk system is a widely adapted strategy and which operates flash memory through MTD subsystems¡][28]¡^. An MTD subsystem contains two different modules, ¡§user¡¨and ¡§driver¡¨. In the driver module, CFI¡][40]¡^ is applied to probe flash chip, partition it and provide operating function. Flash translation layer and file-system are applied in the user module. MTD BLOCK is used to emulate the flash partitions as block devices which are then mounted into Linux virtual file system¡]VFS¡^with JFFS2 type, designed according to the feature of flash devices. In this thesis, we will describe in detail the procedure of porting Linux to ARM micro-controllers. The motivation of the work is introduced in chapter 1. In chapter 2, we introduce development tools and the main flow of the porting procedure. In chapter 3, we describe the LH79525 platform and the main perepherals on the target board, then introduce the ARM programmer model. In chapter 4, we examine the required knowledge and the important issues for porting ARM Linux. In chapter 5, we describe the details of porting Linux to run with Sharp LH79525, including modifying the key source codes and adjusting kernel configuration for embedding the UART, ethernet MAC, and MTD subsystem. In chapter 6, we do step-by-step validation and apply an integrated application with the LF-314CP temperature controller¡][46]¡^ by law-chain technology for the LH79525 target board running with the ported ARM Linux. In chapter 7, we present some issues for future work and improvement, then make a conclusion for the thesis.
3

Design and Development of a CubeSat Hardware Architecture with COTS MPSoC using Radiation Mitigation Techniques

Vasudevan, Siddarth January 2020 (has links)
CubeSat missions needs components that are tolerant against the radiation in space. The hardware components must be reliable, and it must not compromise the functionality on-board during the mission. At the same time, the cost of hardware and its development should not be high. Hence, this thesis discusses the design and development of a CubeSat architecture using a Commercial Off-The- Shelf (COTS) Multi-Processor System on Chip (MPSoC). The architecture employs an affordable Rad-Hard Micro-Controller Unit as a Supervisor for the MPSoC. Also, it uses several radiation mitigation techniques such as the Latch-up protection circuit to protect it against Single-Event Latch-ups (SELs), Readback scrubbing for Non- Volatile Memories (NVMs) such as NOR Flash and Configuration scrubbing for the FPGA present in the MPSoC to protect it against Single-Event Upset (SEU)s, reliable communication using Cyclic Redundancy Check (CRC) and Space packet protocol. Apart from such functionalities, the Supervisor executes tasks such as Watchdog that monitors the liveliness of the applications running in the MPSoC, data logging, performing Over-The-Air Software/Firmware update. The thesis work implements functionalities such as Communication, Readback memory scrubbing, Configuration scrubbing using SEM-IP, Watchdog, and Software/Firmware update. The execution times of the functionalities are presented for the application done in the Supervisor. As for the Configuration scrubbing that was implemented in Programmable Logic (PL)/FPGA, results of area and latency are reported. / CubeSat-uppdrag behöver komponenter som är toleranta mot strålningen i rymden. Maskinvarukomponenterna måste vara pålitliga och funktionaliteten ombord får inte äventyras under uppdraget. Samtidigt bör kostnaden för hårdvara och dess utveckling inte vara hög. Därför diskuterar denna avhandling design och utveckling av en CubeSatarkitektur med hjälp av COTS (eng. Custom-off-The-Shelf) MPSoC (eng. Multi Processor System-on-Chip). Arkitekturen använder en prisvärd strålningshärdad (eng. Rad-Hard) Micro-Controller Unit(MCU) som Övervakare för MPSoC:en och använder också flera tekniker för att begränsa strålningens effekter såsom kretser för att skydda kretsen från s.k. Single Event Latch-Ups (SELs), återläsningsskrubbning för icke-volatila minnen (eng. Non-Volatile Memories) NVMs som NOR Flash och skrubbning av konfigurationsminnet skrubbning för FPGA:er i MPSoC:en för att skydda dem mot Single-Event Upsets (SEUs), och tillhandahålla pålitlig kommunikation mha CRC och Space Packet Protocol. Bortsett från sådana funktioner utför Övervakaren uppgifter som Watchdog för att övervaka att applikationerna som körs i MPSoC:en fortfarande är vid liv, dataloggning, och Over- the-Air-uppdateringar av programvaran/Firmware. Examensarbetet implementerar funktioner såsom kommunikation, återläsningsskrubbning av minnet, konfigurationsminnesskrubbning mha SEM- IP, Watchdog och uppdatering av programvara/firmware. Exekveringstiderna för utförandet av funktionerna presenteras för den applikationen som körs i Övervakaren. När det gäller konfigurationsminnesskrubbningen som implementerats i den programmerbara logiken i FPGA:n, rapporteras area och latens.

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