M. Sashikanth

Bio: M. Sashikanth is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Field-programmable gate array & Lookup table. The author has an hindex of 3, co-authored 7 publications receiving 58 citations.

Detecting SEU-caused routing errors in SRAM-based FPGAs

Abstract: This paper proposes a new CLB architecture for FPGAs and an associated testing technique that detects routing errors caused by SEUs in the SRAM configuration memory of the FPGA. The proposed testing technique detects all possible routing errors including bridging faults, and requires a single configuration of only the LUTs of the FPGA. Any routing error that affects the logic of the circuit is detected by the proposed technique in a maximum of 8 clock cycles. It is noteworthy that the time required for error detection is independent of both the number of switch matrices and the number of logic blocks in the FPGA.

A novel CLB architecture to detect and correct SEU in LUTs of SRAM-based FPGAs

Abstract: This work proposes a new CLB architecture for FPGAs that can detect and correct single event upset (SEU) faults in the LUTs. A methodology for mapping logical functions onto the LUTs is presented that exploits the features of the proposed CLB architecture to detect and correct the SEU faults in the LUTs. Experimental results obtained by mapping standard benchmark circuits on the proposed architecture indicate that on an average, 96% of the SEU in the LUTs can be detected without employing any redundancy. Further, by using duplication with comparison (DWC) techniques it is shown that 100% of the SEU in the LUTs can be detected for any circuit that is mapped on the proposed architecture; and for the benchmark circuits, on an average, 96% of the SEU in the LUTs can be automatically (without any user intervention or reconfiguration) corrected.

A novel CLB architecture and circuit packing algorithm for logic-area reduction in SRAM-based FPGAs

Abstract: The main objective of the technique presented in this paper is to exploit the relations between a set of Boolean functions so as to generate one function from another. The paper defines a relation termed as split-equivalence between logical functions. Using this relation, a single look-up table (LUT) storing the truth table of a function F may be used to generate other functions that are split-equivalent to F resulting in an overall reduction in the logic area used to map the circuit on the FPGA. This paper proposes a new configurable logic block (CLB) architecture containing a single LUT that stores the truth table of a Boolean function F and is capable of generating three split-equivalent functions of F. Given a set of Boolean functions to be mapped onto LUTs, the technique proposed identifies sets of four functions such that any three of them are split-equivalent to the fourth. These sets are mapped on to the proposed CLB architecture. The proposed CLB architecture was compared with the standard CLBs available on Xilinx Virtex architecture and it was found that the former occupies 26% lesser area than the latter with a small increase in the SRAM configuration bits required to configure a CLB.

Cluster-based detection of SEU-caused errors in LUTs of SRAM-based FPGAs

Abstract: This paper proposes a cluster-based parity-checking technique that can detect 100% of all Single Event Upset (SEU) faults in the LUTs of SRAM-based FPGAs. The paper describes two different Configurable Logic Block (CLB) architectures that could be used to implement the proposed SEU detection technique. Of the two, the first architecture can perform at-speed testing of the LUTs without interrupting the normal functioning of the FPGA. The second one works by switching the CLBs from normal-mode to testing-mode and vice-versa. The LUTs are tested in the testing-mode. The switching frequency can be externally programmed and hence varied depending on the rate of SEU occurrences. Both the proposed architectures were compared with the Xilinx Virtex and Virtex Pro architecture. The proposed architectures require only 2 (when compared with Virtex) and 4 (when compared with Virtex Pro) additional SRAM configuration bits per LUT. This is extremely low when compared to the 16 additional SRAM configuration bits required by CLB architectures used to implement standard DWC techniques for detecting SEUs in LUTs. The area requirements of both the proposed architectures are also significantly less than the area requirements of DWC techniques. The proposed detection technique requires only 3 clock cycles of the Xilinx Virtex internal clock to detect the effect of an SEU in any LUT of the FPGA.

A function generator-based reconfigurable system

Abstract: This paper proposes a new reconfigurable system which has a function generator-based CLB architecture. This is different from the standard look-up table (LUT) based CLB architectures available in commercial FPGAs. The new function generation architecture is based on the fact that a small set of k-input Boolean functions can generate all the 2/sup 2k/, k-input Boolean functions using a simple mapping technique. The area required by the new function generation architecture is 58.6% lesser than the area required by a standard 16/spl times/1 LUT used in commercial FPGAs. In addition, the proposed architecture consumes 40.8% lesser power than the standard 16/spl times/1 LUT. The routing architecture for the proposed reconfigurable system is the same as those present in current-day FPGAs. Hence, the algorithms presently used for technology mapping, packing, placement and routing on FPGAs can be used for the proposed reconfigurable system without much modification. The new architecture requires a 10% increase in the SRAM configuration memory. This is an insignificant penalty in comparison to the reduction in the area of the FPGA and power consumption, achieved by the proposed CLB architecture.

BIST-based test and diagnosis of FPGA logic blocks : Reconfigurable and Adaptive VLSI Systems

Abstract: We present a built-in self-test (BIST) approach able to detect and accurately diagnose all single and practically all multiple faulty programmable logic blocks (PLBs) in field programmable gate arrays (FPGAs) with maximum diagnostic resolution. Unlike conventional BIST, FPGA BIST does not involve any area overhead or performance degradation. We also identify and solve the problem of testing configuration multiplexers that was either ignored or incorrectly solved in most previous work. We introduce the first diagnosis method for multiple faulty PLBs; for any faulty PLB, we also identify its internal faulty modules or modes of operation. Our accurate diagnosis provides the basis for both failure analysis used for yield improvement and for any repair strategy used for fault-tolerance in reconfigurable systems. We present experimental results showing detection and identification of faulty PLBs in actual defective FPGAs. Our BIST architecture is easily scalable.

Field Programmable Gate Array Applications—A Scientometric Review

Abstract: Field Programmable Gate Array (FPGA) is a general purpose programmable logic device that can be configured by a customer after manufacturing to perform from a simple logic gate operations to complex systems on chip or even artificial intelligence systems. Scientific publications related to FPGA started in 1992 and, up to now, we found more than 70,000 documents in the two leading scientific databases (Scopus and Clarivative Web of Science). These publications show the vast range of applications based on FPGAs, from the new mechanism that enables the magnetic suspension system for the kilogram redefinition, to the Mars rovers’ navigation systems. This paper reviews the top FPGAs’ applications by a scientometric analysis in ScientoPy, covering publications related to FPGAs from 1992 to 2018. Here we found the top 150 applications that we divided into the following categories: digital control, communication interfaces, networking, computer security, cryptography techniques, machine learning, digital signal processing, image and video processing, big data, computer algorithms and other applications. Also, we present an evolution and trend analysis of the related applications.

Area-oriented technology mapping for LUT-based logic blocks

Abstract: Abstract One of the main aspects of logic synthesis dedicated to FPGA is the problem of technology mapping, which is directly associated with the logic decomposition technique. This paper focuses on using configurable properties of CLBs in the process of logic decomposition and technology mapping. A novel theory and a set of efficient techniques for logic decomposition based on a BDD are proposed. The paper shows that logic optimization can be efficiently carried out by using multiple decomposition. The essence of the proposed synthesis method is multiple cutting of a BDD. A new diagram form called an SMTBDD is proposed. Moreover, techniques that allow finding the best technology mapping oriented to configurability of CLBs are presented. In the experimental section, the presented method (MultiDec) is compared with academic and commercial tools. The experimental results show that the proposed technology mapping strategy leads to good results in terms of the number of CLBs.

Single-event-upset (SEU) awareness in FPGA routing

Abstract: The majority of configuration bits affecting a design are devoted to FPGA routing configuration. We present a SEU-aware routing algorithm that provides significant reduction in bridging faults caused by SEUs. Depending on the routing architecture switches, for MCNC benchmarks, the number of care bits can be reduced between 13% and 19% on average with comparable delay, hi addition, in asymmetric SRAM FPGA using our router average FIT (failure-in-time) rate is reduced by 36%.