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Publications

Publications by João Canas Ferreira

2012

Run-time generation of partial FPGA configurations

Authors
Silva, ML; Ferreira, JC;

Publication
JOURNAL OF SYSTEMS ARCHITECTURE

Abstract
This paper presents and evaluates a method of generating partial bitstreams at run-time for dynamic reconfiguration of sections of an FPGA. The method is intended for use in adaptive embedded systems that employ run-time reconfiguration to achieve high flexibility and performance. The proposed approach combines partial bitstreams of coarse-grained components to produce a new partial bitstream implementing a given circuit netlist. Topological sorting of the netlist is used to determine the initial positions of individual components, whose placement is then improved by simulated annealing. Connection routing is done by a breadth-first search of the reconfigurable area based on a simplified resource model of the reconfigurable fabric. The desired partial bitstream is constructed by merging together the default bitstream of the reconfigurable area, the relocated partial bitstreams of the components, and the configurations of the switch matrices used for routing. The approach is embodied in a code library that applications can use to create new bitstreams at run-time. For the members of a set of 29 benchmarks (both synthetic and application-derived) having between five and 41 components, the complete process of bitstream generation takes between 8 s and 35 s when running on an embedded PowerPC 405 microprocessor clocked at 300 MHz.

2012

Run-time generation of partial FPGA configurations for subword operations

Authors
Silva, ML; Ferreira, JC;

Publication
MICROPROCESSORS AND MICROSYSTEMS

Abstract
Instructions for concurrent processing of smaller data units than whole CPU words are useful in areas like multimedia processing and cryptography. Since the processors used in FPGA-based embedded systems lack support for such applications, this paper proposes mapping sequences of subword operations to a set of hardware components and generating the corresponding FPGA partial configurations at run-time. The technique is aimed at adaptive embedded systems that employ run-time reconfiguration to achieve high flexibility and performance. New partial configurations for circuits implementing sets of subword operations are created by merging together the relocated partial configurations of the hardware components (from a predefined library), and the configurations of the switch matrices used for the connections between the components. The paper presents and discusses results obtained for a 300 MHz PowerPC CPU in a Virtex-II Pro platform FPGA. For the set of benchmarks analyzed, the complete configuration creation process takes between 1 s and 24 s. The run-time generated hardware versions achieve speed-ups between 11 and 73 over the software versions.

1993

Control and Observation of Analog Nodes in Mixed-Signal Boards

Authors
Matos, JS; Leão, AC; Ferreira, JC;

Publication
Proceedings IEEE International Test Conference 1993, Designing, Testing, and Diagnostics - Join Them, Baltimore, Maryland, USA, October 17-21, 1993

Abstract

1994

Architecture of test support ICs for mixed-signal testing

Authors
Matos, JS; Ferreira, JC; Leão, AC; Silva, JM;

Publication
12th IEEE VLSI Test Symposium (VTS'94), April 25-28, 1994, Cherry Hill, New Jersey, USA

Abstract

1994

An Approach to Testability Improvement of Mixed-Signal Boards

Authors
Matos, JS; Ferreira, JC; Leão, AC; da Silva, JM;

Publication
1994 IEEE International Symposium on Circuits and Systems, ISCAS 1994, London, England, UK, May 30 - June 2, 1994

Abstract

2005

Using a tightly-coupled pipeline in dynamically reconfigurable platform FPGAs

Authors
Silva, ML; Ferreira, JC;

Publication
DSD 2005: 8th Euromicro Conference on Digital System Design, Proceedings

Abstract
The paper describes the organization and use of a pipeline that is tightly-coupled to the CPU inside a platform FPGA with support for dynamic partial reconfiguration. It describes the overall hardware system organization and the pipeline structure, and presents the associated development environment and run-time support system, including the support for dynamically changing pipeline implementations and altering the operations of a pipeline stage.

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