Camilo Quintáns

A Method Based on Petri Nets and a Matrix Model to Implement Reconfigurable Logic Controllers

This paper presents a method to implement reconfigurable logic controllers (RLCs) using a new matrix model to describe Petri nets (PNs). The method obtains the general equations and directly translates them into a hardware description language (HDL) to configure a field-programmable gate array (FPGA). To achieve a generalized model in a comprehensible way, several PN examples including timers, counters, and hierarchical subnets are described in detail. The working principles and robustness of the method are validated by simulating each example and by their practical implementation in an RLC.

An Integrated System for Logic Controller Implementation Using FPGAs

At present, logic controllers use sequential programmable logic controllers (PLC) and industrial computers with scan strategies and special instructions for parallel events detection. Also, nowadays, reconfigurable devices improvement allows the implementation of parallel control strategies in a more natural way. This paper describes an integrated system for logic controller implementation using FPGA. It consists of a hardware card and a design automation environment which improves design performance. The hardware, as well as doing typical automation tasks, contributes to achieving additional characteristics such as simulation and monitoring. To show the integrated system applications, a real industrial project is undertaken

FPGA-based system for the education in data acquisition and signal generation

Signal generation, signal conditioning and data acquisition systems usually have fixed structures, whose functionality cannot be modified. In an educational context, students can only modify some of their functional parameters and check the effect of such changes on the generation and acquisition processes. This paper presents a reconfigurable signal generation, conditioning and acquisition system that, in addition to cover these basic educational tasks, allow students to test different structures and to choose the most suitable for a given application. It basically consists of a SCXI environment from national instruments and an FPGA development board, which adds reconfigurability capabilities to the system. An application example is discussed, in which functionality is reconfigured for reading an incremental encoder and generating a PWM signal.

Methodology to Implement Logic Controllers with both Reconfigurable and Programmable Hardware

The flexibility and benefits of field programmable gate arrays (FPGA) technology to carry out reconfigurable logic controllers (RLC) in order to implement parallel control strategies in a natural way has been recently proved. Moreover, programmable logic controllers (PLC) are widely introduced in the industrial market. Therefore the necessity of obtaining a global and complete solution to combine traditional design process and the hardware implementation with both technologies appears. This paper describes a hardware-software platform which enables the implementation of logic controllers with both PLC and RLC. The software aids the development of logic controllers using design methods based on Petri nets (PN) and translates them into instruction lists or into hardware description language (HDL) codes. The hardware utilized is formed by a commercial Simatic S7 and a specific reconfigurable hardware which consists of a main card, combining a cyclone FPGA and a USB controller, and on a set of digital and analog I/O cards. This hardware, as well as doing typical automation tasks, contributes to achieving additional characteristics such as simulation and monitoring.

E-Learning Tool for dc Choppers

This work presents a software tool in order to facilitate the learning of the dc choppers. This tool consists of an integrated web-access set of multimedia animation-clips which present, in an interactive way, how the different dc choppers topologies work. The different topologies are classified depending on their quadrant operation and then the user can realize the circuits performance from the simplest class-A to the four quadrant operation class-E converter. To do this, all circuit parameters including load values, duty ratio, and frequency may be selected by the user. Moreover, the load includes an electromotive force (EMF) that allows understanding the energy flow between the source and the load and then, the quadrant operation. Other useful characteristic of the tool is the way in which the circuits are drawn because they can be shown as a bridge or in their simplest form in the case of only the essentials devices being shown. The information about the currents and voltages paths is dynamically presented with sliding rules over the graphs during simulations indicating the state of semiconductor switches by means of changing colours. The multimedia system includes documentation on all the subjects, showing basic concepts and equations, in pdf format and links to industrial manufacturers.

Application of a Reconfigurable Platform for the Education of Electronic Control Loops

Data acquisition and signal generation systems are basic building blocks of electronic control loops. They usually have fixed structures, whose functionality cannot be modified. In an educational context, students can only modify some of their functional parameters and check the effect of such changes on the generation and acquisition processes. In a previous paper, a reconfigurable generation and acquisition system has been presented, which not only covers these basic educational tasks, but also allows students to test different structures and to choose the most suitable for a given application. In this paper, its practical application for the education of electronic control loops is presented.

A Reconfigurable Communication Processor Compatible with Different Industrial Fieldbuses

Fieldbuses constitute the lower level of communication networks in a flexible manufacturing system. Nowadays there are a lot of proprietary protocols, thus the interconnection of equipment from different manufacturers has become very problematic. Changing equipment supposes the change of the fieldbus too with the consequent economic losses. This paper proposes the implementation of a communication processor based on a reconfigurable device that makes different fieldbuses compatible. In this way, using the appropriate level and impedance matching circuit, the same hardware can be connected to different fieldbuses. In order to verify this proposal a communication processor based on an FPGA supporting two very important fieldbus standards in the area of industrial control such as WorldFIP and Profibus, has been developed. Design constraints and performance of the implemented processor are analyzed in this paper.

A Practical Example to Understand Pipeline A/D Converters Performance Using Software Tools

Pipeline A/D converters (ADC) are widely used when a high frequency analog signal is sampled. Nevertheless the architecture and operation of this kind of ADC is limited to the domain of microelectronics experts due to their integration in complex mixed-signal IC. Therefore two main problems emerge when a deep study and analysis of the pipeline converters are carried out. The first is related to their internal structure and operating mode, for example the synchronization between the different concurrent stages is a topic of special importance. At the same time, pipeline ADC are difficult to simulate with the CAD tools commonly used by designers of electronic circuits. The second inconvenience is derived from the difficulty of obtaining a dynamic characterization of this architecture. This paper proposes a simple methodology facilitating the understanding of this kind of ADC through simulation and testing of a basic pipeline structure including a rule for clocking the parallel stages. As an example, a 5-bit pipeline ADC is designed and simulated using Oread Pspice and signal-to-noise ratio and distortion (SINAD), the total harmonic distortion (THD) and effective number of bits (ENOB) parameters are obtained from Matlab scripts

Aprendizaje Práctico de Sistemas Electrónicos Digitales a través de Proyectos Semiguiados

This article presents the application of Project- Based Learning to the course “Digital Electronic Systems”, taught in the fourth year of the Industrial Electronics and Automation Engineering Degree (B.Eng.) at Universidad de Vigo, Spain. The lab assignments and the working methodology are based on two semi-guided projects developed through an incremental process, in which the target systems are progressively provided with additional functionalities. To do that, students must combine predefined circuits with others designed by them, until a final prototype is obtained. To address timing and materials constraints, students are provided at the beginning of the course with all required hardware components, as well as with detailed information regarding the tasks to be performed before, during and after each of the laboratory sessions. Tasks evolve from fully guided to mostly autonomous ones. Assessment results are also presented and discussed.

A Methodology to Teach Advanced A/D Converters, Combining Digital Signal Processing and Microelectronics Perspectives

ADCs (analog-to-digital converters), especially Pipeline and Sigma-Delta (Σ-Δ) converters, are designed using complex architectures in order to increase their sampling rate and/or resolution. Consequently, the learning of ADC devices also encompasses complex concepts such as multistage synchronization, latency, oversampling, modulation, noise shaping, filtering, or decimation. This paper is focused on a new learning methodology, based on the simulation of the main circuit topologies used in commercial ADCs, in order to understand their working principles more thoroughly. At the same time, the ADC dynamic and static tests are obtained from the simulation results, and their characterization is obtained at an application level. In this way, the methodology combines the microelectronics perspective, at the design level, with the digital signal processing perspective. This methodology saves time in practical classes and encourages self-learning because it does not require special hardware. Moreover, it uses only software tools that are common in electronic engineering, like the OrCAD PSpice simulator, a C compiler, or a hardware description language (HDL) simulator. The methodology has been validated during two consecutive offerings of academic courses in the Telecommunication Engineering curriculum at Vigo University, Vigo, Spain, and the results obtained are discussed.