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This article proposes an efficient and accurate embedded motor imagery-based brain–computer interface (MI-BCI) that meets the requirements for wearable and real-time applications. To achieve a suitable accuracy considering hardware constraints, we explore BCI transducer algorithms, among which Infinite impulse response (IIR) filter, common spatial pattern, and support vector machine are used to preprocess, extract features, and classify data, respectively. With our hardware implementation of these tasks, we have achieved an accuracy of 77%. Our system is designed at register transfer level (RTL) targeting an ASIC implementation, which significantly decreases power consumption, latency, and area compared to the state-of-the-art (SoA) architectures for embedded BCI systems. To this end, we fold IIR filters using time-shared and RAM-based techniques and use hardware-friendly algorithms for the implementation of other tasks. The RTL design is realized on 45 nm CMOS technology consuming 4 mW power and 0.25 mm2 area, which outperforms the SoA platforms for embedded BCI systems. To further illustrate the outperformance of our design, the proposed architecture is implemented on Virtex-7 field program gate array as a prototyping platform consuming 6 μJ energy with 1.52% area utilization. [ABSTRACT FROM AUTHOR]

This article proposes a methodology for critical path selection and delay sensor insertion for aging monitoring in field-programmable gate arrays (FPGAs). The aging information can be used to reconfigure FPGAs to achieve better performance or wear leveling. To filter out the paths aging less aggressively, our methodology decides based on both physical-level parameters [e.g., path delay, process variation, temperature, static stress (duty cycle), and dynamic stress (switching activity) as well as aging-relevant parameters (e.g., fan-out, and endpoint physical location)]. After selection of an optimal set of paths, age sensors, introduced in our earlier work, are placed in a distributed fashion throughout the FPGA area to provide aging information of its various parts as they are being used. Accurate aging models for FPGAs are required to determine the contribution of the above-mentioned parameters in aging. In this article, ASICs’ aging models are adapted for FPGAs through measurement-based fitting approach. The experimental results using various benchmarks reveal that our algorithm selects paths with a minimum error. [ABSTRACT FROM AUTHOR]

In this article, we propose a fine-grained FPGA aging mitigation method. Our method focuses on Look Up Tables (LUTs) on which Boolean functions are mapped. Based on our observations, for any configuration, even if it is carefully selected, a number of LUT transistors experience severe stress rates. Therefore, an algorithm is presented to select several alternative configurations for each LUT. Alternative configurations are obtained by LUT input reordering. These alternative configurations are rotationally loaded into the FPGA. Experimental results shows that our method achieves 263 and 14.1 percent Mean Time To Failure (MTTF) improvement for Hot Carrier Injection (HCI) and Bias Temperature Instability (BTI), respectively. Additionally, due to changing only local routings, our method imposes up to 1 percent performance overhead to the systems. [ABSTRACT FROM AUTHOR]

Having an automatic tool capable of completing all steps of debugging including correction specially for complex designs such as modern processors is ideal for every debugging engineer. Although in theory, quantified Boolean formulas (QBFs) can be used to formulate this class of problems effectively, current solvers are still too immature for accomplishing this goal. In this paper, we propose a scalable symbolic simulation-based method utilizing QBF to correct the candidate bug locations in abstract formal models. We assume that candidate bug locations are determined already, the bug is located in bit-level logic, and the input arguments are known. We define correcting functions and adjust their parameters by formulating the problem as QBF and solving it using symbolic simulation-based method. To further improve scalability, we propose dynamic pruning which breaks the main problem into several smaller subproblems. The efficiency of the proposed method is proved by solving problems for which existing methods are not capable of providing results. [ABSTRACT FROM AUTHOR]

The increasing demand for lower power forces designers to use sophisticated power management strategies such as multivoltage and power gating which are often accompanied with many design bugs. Correcting such bugs can be a timeconsuming process that requires considerable manual efforts. In this paper, we propose a scalable automated method for correcting dynamic power management architectures by an incremental SAT-based mechanism. First, an initial counterexample (CEX) is generated by checking the equivalency between the specification model of the processor and its buggy implementation model. Then, we find two candidate solutions instead of one to satisfy this CEX. If two solutions are not equivalent, we generate new CEX in an iterative process which effectively converges into the final solution. The proposed method enables designers to correct multiple bugs such as missing isolation cells between two power domains, disordering in the sequence of control signals, error in the data restoring or saving, and powering off in always-on domains which are not addressed by existing methods. We have shown the effectiveness of our method on modern processors supporting complex power management mechanisms. The results confirm that our proposed method, respectively, reduces symbolic simulation steps and runtime by 2.33× and 47.93× compared to the state-of-the-art methods. [ABSTRACT FROM AUTHOR]

Although using presilicon information in postsilicon debugging phase seems interesting, space and time limitations of existing formal verification tools restrict the possibility of this idea. In this paper, the effective usage of presilicon information to enhance postsilicon trace signal selection in modern processors is discussed. Furthermore, a novel architecture for dynamic per-cycle selection of signals based on the present instruction is implemented and synthesized. In presilicon phase, first, a set of controlling signals and their corresponding rules are extracted manually. Based on these rules, a set of data from model is extracted using an automatic formal method, which determines which signals should be traced at postsilicon according to the values of controlling signals. This mechanism alone results in an average of 79% and 54% bits to be pruned from the traceable signals for Leon3 and multithreaded DLX processors and 86% and 75% improvement when used in conjunction with traditional methods, respectively. [ABSTRACT FROM AUTHOR]

More pronounced aging effects, more frequent early-life failures, and incomplete testing and verification processes due to time-to-market pressure in new fabrication technologies impose reliability challenges on forthcoming systems. A promising solution to these reliability challenges is self-test and self-reconfiguration with no or limited external control. In this work a scalable self-test mechanism for periodic online testing of many-core processor has been proposed. This test mechanism facilitates autonomous detection and omission of faulty cores and makes graceful degradation of the many-core architecture possible. Several test components are incorporated in the many-core architecture that distribute test stimuli, suspend normal operation of individual processing cores, apply test, and detect faulty cores. Test is performed concurrently with the system normal operation without any noticeable downtime at the application level. Experimental results show that the proposed test architecture is extensively scalable in terms of hardware overhead and performance overhead that makes it applicable to many-cores with more than a thousand processing cores. [ABSTRACT FROM AUTHOR]

This paper concentrates on high-level data-flow optimization and synthesis techniques for datapath intensive designs such as those in Digital Signal Processing (DSP), computer graphics and embedded systems applications, which are modeled as polynomial computations over Z2^{n_1 } \times Z2^{n_2 } \times \cdots \times Z2^{n_d } to Z2^m . Our main contribution in this paper is proposing an optimization method based on functional decomposition of multivariate polynomial in the form of f(x) = g(x) \;o \;h(x) + f0 = g(h(x)) + f0 to obtain good building blocks, and vanishing polynomials over Z2^m to add/delete redundancy to/from given polynomial functions to extract further common sub-expressions. Experimental results for combinational implementation of the designs have shown an average saving of 38.85 and 18.85 percent in the number of gates and critical path delay, respectively, compared with the state-of-the-art techniques. Regarding the comparison with our previous works, the area and delay are improved by 10.87 and 11.22 percent, respectively. Furthermore, experimental results of sequential implementations have shown an average saving of 39.26 and 34.70 percent in the area and the latency, respectively, compared with the state-of-the-art techniques. [ABSTRACT FROM PUBLISHER]

As design of digital systems become more complex and more transistors are incorporated into a single chip, design and verification methodologies moves into higher levels. Now that design at the register transfer level (RTL) has reached its maturity, the focus is shifting to electronic system level (ESL) design tools, languages and methodologies. At the centre of this and perhaps the most challenging are verification methods and tools to use for verifying designs at the ESL. This study presents a new concept of system‐level assertions for ESL verification. It also demonstrates an environment for functionally verifying system‐level designs using these system‐level assertions. The proposed environment adapts existing EDA simulation tools, which are mainly used for RTL design and verification, and utilises them for system‐level verification. In this environment, designs are modelled in SystemC‐transaction level modelling 2.0, and assertions are written in SystemVerilog. Design and verification parts are connected together using SystemVerilog Direct Programming Interface mechanism, and designs that are described in SystemC are verified against system‐level assertions in the course of SystemVerilog simulation. [ABSTRACT FROM AUTHOR]

This paper proposes a technique for dynamic power reduction of pipelined processors. It is based on eliminating unnecessary transitions that are generated during the execution of NOP instructions. The approach includes the elimination of unnecessary changes in pipe register contents and the limitation of boundary movement of transitions caused by inevitable changes in pipe register contents due to insertion of a NOP into a pipelined processor. To assess its efficiency, the proposed technique is applied to MIPS, DLX, and PAYEH processors considering a number of benchmarks. The experimental results show that the techniques can lead to up to 10% reduction in the dynamic power consumption at a cost of negligible (almost zero) speed and (about 0.2%) area overheads. [ABSTRACT FROM AUTHOR]

This paper presents programs and models for interfacing VLSI design tools and the VHDL hardware description language. The programs convert CIF files to VHDL component instantiation lists, and extract timing parameters from Spice transistor specifications. The models are simulatable VHDL descriptions for the instantiated components. We will describe various linking alternatives and the details of a switch level linkage. This technique will be useful in an academic setting for integrating VHDL into Magic tool-set. [ABSTRACT FROM PUBLISHER]

Digital hardware can be described at various levels of abstraction. Functional descriptions merely capture the behavior of the circuit without revealing the details of the architec ture. On the other hand, the gate or switch level models are more robust and include great amounts of detail about the circuit (timing and architecture). Functional models are attractive because they simulate faster than low level models. However, the tradeoff is that the simulation results are not as accurate (primarily from the timing standpoint) as those obtained from low level models. Clearly, having a model that simulates as fast as the functional model and produces accuracies comparable to those of gate level models is desirable.This paper is an investigation of achieving such models. Two levels of abstractions, dataflow and gate level, are considered and the VHDL language (an industry standard) is used for describing Finite State Machine circuits at both levels. Feasibility of timing back-annotation of dataflow models with the information obtained from gate level is analyzed. [ABSTRACT FROM PUBLISHER]