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- An HDL Approach to Board-Level BISTPublication . Alves, Gustavo R.; Gericota, Manuel G.; Ramalho, José L.; Ferreira, José M.Boundary scan is now the most promising technology for testing high-complexity printed circuit boards. The number of BST components available to board-level designers is however still restricted, limiting the achievable fault coverage. The requirements to improve board-level testability are analysed, and a corresponding set of testability building blocks are proposed. A low-cost and maximum-flexibility solution is described, which implements these blocks on medium-complexity PLDs, using a simple and powerful HDL.
- IEEE 1149.1 compliance-enable pin(s): a solution for embedded microprocessor-based systems debug and testPublication . Alves, Gustavo R.; Ferreira, José M.Microprocessor-based systems are usually debugged with the help of in-circuit emulators and logic analysers. However, these traditional debug tools cannot be used when the microprocessor is an embedded core. To overcome this problem we propose the use of an embedded debug and test infrastructure and the IEEE 1149.1 compliance-enable mode to implement the basic functionality provided by an In-circuit emulator and a logic analyser.
- Resolução do Problema das Torres de Hanói através de um Conjunto de Regras SimplesPublication . Alves, Gustavo R.Este artigo descreve um método de resolução do problema das Torres de Hanoi, não baseado na recursividade. O objectivo principal consiste em mostrar que, qualquer que seja a situação colocada a um jogador (no início do problema ou a meio), desde que este saiba qual foi a jogada anterior, poderá sempre acabar o jogo, seguindo um princípio de efectuar a única jogada que não viola um conjunto de regras a enunciar em seguida.
- Remote experimentation network - yielding an inter-university peer-to-peer e-servicePublication . Alves, Gustavo R.; Ferreira, José M.; Muller, Dieter; Erbe, Heinz-H; Hine, Nick; Alves, J. B. M.; Pereira, Carlos E.; Chiang, Luciano; Herrera, Oriel; Sucar, EnriqueThe goal of this paper is to discuss the benefits and challenges of yielding an inter-continental network of remote laboratories supported and used by both European and Latin American Institutions of Higher Education. Since remote experimentation, understood as the ability to carry out real-world experiments through a simple Web browser, is already a proven solution for the educational community as a supplement to on-site practical lab work (and in some cases, namely for distance learning courses, a replacement to that work), the purpose is not to discuss its technical, pedagogical, or economical strengths, but rather to raise and try to answer some questions about the underlying benefits and challenges of establishing a peer-to-peer network of remote labs. Ultimately, we regard such a network as a constructive mechanism to help students gain the working and social skills often valued by multinational/global companies, while also providing awareness of local cultural aspects.
- Integrity checking of 1149.4 extensions to 1149.1Publication . Felgueiras, Carlos; Alves, Gustavo R.; Ferreira, José M.The IEEE 1149.4 Standard for a Mixed-Signal (MS) Test Bus proposes an extension to the well-accepted IEEE 1149.1 boundary-scan test architecture, with the objective of facilitating interconnect, parametric and internal testing of MS circuits. An Analog Test Access Port (ATAP) comprising two pins called AT1 and AT2, and an internal analog bus (AB) comprising two lines (AB1, AB2), enable analog test stimulae and responses to be routed to any pin possessing an Analog Boundary Module (ABMs replace the IEEE 1149.1 test cells in the case of analog pins). A Test Bus Interface Circuit (TBIC) comprising ten analog switches defines how the ATAP and the internal analog bus are (dis)connected, and the six analog switches in each ABM define what connections should be established between the pin, the core circuitry, and the internal analog bus. The large number of analog switches in the 1149.4 test architecture may raise concerns about their integrity, particularly when they are used frequently, as would be the case in an 1149.4-based MS debug strategy. This paper proposes a set of integrity check procedures that address only the 1149.4 extensions: ATAP, TBIC, AB lines, ABMs.
- Real Time Fault Injection Using On Chip Debug Infrastructures – A Case StudyPublication . Fidalgo, André Vaz; Gericota, Manuel G.; Alves, Gustavo R.; Ferreira, JoséAs electronic devices get smaller and more complex, dependability assurance is becoming fundamental for many mission critical computer based systems. This paper presents a case study on the possibility of using the on-chip debug infrastructures present in most current microprocessors to execute real time fault injection campaigns. The proposed methodology is based on a debugger customized for fault injection and consists of injecting bit-flip type faults on memory elements without modifying or halting the target application. Three different configurations are compared in terms of performance, area overhead and communication bus width. The basic debugger design is easily portable and applicable to different architectures, providing a flexible and efficient mechanism for verifying and validating fault tolerant components.
- Debugging mixed-signal circuits via the IEEE1149.4 Std. – analysis of limitations and requirementsPublication . Felgueiras, Carlos; Alves, Gustavo R.; Ferreira, J. M. MartinsDebugging mixed-signal circuits is traditionally seen as a complex task due to the presence of an analog part and the necessary interaction with a digital part. The use of debug tools that require physical access suffers from the same restrictions that led to the use of debug tools based on electronic access to digital circuits. While the IEEE1149.4 test infrastructure enables the structural and parametric test of mixed-signal boards, through electronic access, its use for debug purposes is still far from reaching a wide acceptance, namely due to the lack of a debug methodology. This work analyses several access mechanisms for Controllability, Observability and Verification operations via the IEEE1149.4 infrastructure, with an emphasis on the analysis of its limitations and requirements.
- REXIB: Remote Experiments Interface BuilderPublication . Alves, Jorge R.; Alves, Gustavo R.; Ferreira, Paulo; Ferreira, José M.Remote Experimentation is an educational resource that allows teachers to strengthen the practical contents of science & engineering courses. However, building up the interfaces to remote experiments is not a trivial task. Although teachers normally master the practical contents addressed by a particular remote experiment they usually lack the programming skills required to quickly build up the corresponding web interface. This paper describes the automatic generation of experiment interfaces through a web-accessible Java application. The application displays a list of existent modules and once the requested modules have been selected, it generates the code that enables the browser to display the experiment interface. The tools? main advantage is enabling non-tech teachers to create their own remote experiments.
- Experimenting through the web a linear variable differential transformerPublication . Costa, Ricardo J.; Alves, Gustavo R.Aiming for teaching/learning support in sciences and engineering areas, the Remote Experimentation concept (an E-learning subset) has grown in last years with the development of several infrastructures that enable doing practical experiments from anywhere and anytime, using a simple PC connected to the Internet. Nevertheless, given its valuable contribution to the teaching/learning process, the development of more infrastructures should continue, in order to make available more solutions able to improve courseware contents and motivate students for learning. The work presented in this paper contributes for that purpose, in the specific area of industrial automation. After a brief introduction to the Remote Experimentation concept, we describe a remote accessible lab infrastructure that enables users to conduct real experiments with an important and widely used transducer in industrial automation, named Linear Variable Differential Transformer.
- Interactive Exercises on Analysis Methods for DC Linear Electrical CircuitsPublication . Sousa, Pedro A.; Gericota, Manuel G.; Alves, Gustavo R.Electrical Engineering students must learn the fundamentals of electricity in a very short time, due to the increasing number and size of areas addressed on EE courses. While some students have been exposed to those fundamentals during secondary level education, others have not. These circumstances increase the complexity of devising a good approach to motivate all students for learning. One example occurs when teaching the analysis methods for DC Linear Electrical Circuits, where the number of all possible arbitrary choices grows exponentially with the number of circuit branches. While first-time-exposed students are required to learn first how to apply the different analysis methods, the remaining students are required to calculate the total number of possible set of equations that solve the circuit. To serve both student groups, we developed an application that helps understanding the way arbitrary choices affect the set of equations generated for solving a customizable circuit.