Lucent Technologies Inc.

Agere Systems Inc.

Dafca, Inc.

The University of North Carolina at Charlotte

Other

University of Kentucky Research Foundation

Lattice Semiconductor Corporation

Miron Abramovici

Charles Eugene Stroud

John M Emmert

Xiaoming Yu

Jose T De Sousa

Daniel G Saab

Krishna B Rajan

Mahesh A Iyer

Barry Britton

Harold Scholz

Kwang-Ting Cheng

Alfred E Dunlop

Vishwani D Agrawal

Yuzheng Ding

Gerard Memmi

Sajitha S Wijesuriya

Eric Seng-Kar Lee

Premachandran Rama Menon

Signals sent from one system-on-chip core become switched to a reconfigurable logic core (RLC) for observation and, perhaps, replacement with another signal. A first signal line couples together a plurality of cores. A switch, disposed between the first signal line and an input signal line of the RLC, selectively controls whether the signal gets sent to the RLC. A multiplexer, having the first signal line and an output signal line of the RLC as inputs, selectively controls whether the signal or a replacement signal becomes conveyed to another core of the system-on-chip. Observation and control configuration memory bits act as inputs in the selective control of the switch and the multiplexer. Other embodiments teach shared RLC input signal lines amongst multiple cores. The RLC may contain an inverter, a test circuit, a logic analyzer or other. Methods of observing and replacing signals are also taught.

Programmable interconnect for reconfigurable system-on-chip

A method that enables testing any point (target point) within a core, including a point within a combinatorial circuit of a core, permits testing of points that are not otherwise unobservable in normal debugging processes. Such a target point is tested by identifying a fanout cone from that point to observable outputs, and by performing one or more tests, where each test sensitizes one or more paths that extend the signal of the target point, or its complement, to one or more of the observable outputs, and ascertains the values at those observable outputs. By having more than one observable output at which the signal of target point (or its complement) is tested significantly increases the level of confidence in the test when the observable points concur in the signal value of the target point.

Determining the value of internal signals in a malfunctioning integrated circuit

Systems and methods for delay-fault testing field programmable gate arrays (FPGA's), applicable both for off-line manufacturing and system-level testing, as well as for on-line testing within the framework of the roving self-test area (STARs) approach are described. In one described method, two or more paths under test receive a test pattern approximately simultaneously. The two paths are substantially identical and thus should propagate the signal in approximately the same amount of time. An output response analyzer receives the signal from each of the paths and determines the interval between them, and then determines whether a delay fault has occurred based at least in part on the interval. The output response analyzer may include an oscillator and a counter. The oscillator generates an oscillating signal during the interval between when the test signal propagates through the first path and the last path under test.

Methods for delay-fault testing in field-programmable gate arrays

Serial assertion checking is realized in a System On a Chip (SoC) device by connecting scan chain output to a bit extractor configured within a functionally reconfigurable module that is part of the SoC, which extracts the bits necessary for the assertion checking. The extracted bits are applied to a finite state machine that implements the assertion checking.

Serial implementation of assertion checking logic circuit

When, in the course of an integrated circuit's functional test an assertion fires at clock k, the operational clock is stopped, the sequence is reapplied to capture inputs to the assertion circuit that fired, signals within the assertion circuit are computed, and the error is backtraced. Once one or more inputs of the assertion circuit are identified as potentially the source of the error, the process of backtracing is performed for each such input. When the input that is potentially the source of the error emanates from a memory circuit, the fanin cone of the memory circuit is identified and the process of backtracing through the last-identified fanin cone is undertaken for clock k&#x2212;1. This is repeated iteratively until either a module of the integrated circuit is found to be the source of the error, or the error is extended to inputs of the SoC.

Method to locate logic errors and defects in digital circuits

An arrangement that includes a core with a flaw is effectively made error free with an auxiliary circuit that interacts with input and output leads of the core, which detected occurrence of an input that causes an erroneous output at the core, and modified that output either essentially directly, or through changes in accessible core inputs.

Fixing functional errors in integrated circuits

An SoCs with functionally reconfigurable modules employing the modules to configure circuitry for performing assertion checking. Both at-speed assertion checking as well as continuous single step (CSS) assertion checking is disclosed. Advantageously, the checking of the various cores within the SoC is carried out concurrently, in subsets of the entire set of assertions that need to be checked out. Advantageously, bit extraction and injection is used in CSS assertion checking to permit use of relatively small registers for the assertion checking of each subset of assertions.

Assertion checking using two or more cores

An exceptionally effective SoC design is achieved by the user of wrappers that comprise a functionally reconfigurable module (FRM) that is capable of affecting the operational functionality of the wrapper and that, consequently, is capable of affecting the operational functionality of a designed SoC. One embodiment of a core+wrapper combination comprises distinct input and output cells within the wrapper, and a separate FRM. Another embodiment may embed the input and output cells within the FRM. The FRM may be implemented with, for example, a field programmable logic array (FPLA). An additional advance is realized by providing a number of spare leads in the signal paths network that interconnects the various SoC elements.

Reconfigurable fabric for SoCs using functional I/O leads

Techniques for testing a sequential circuit comprising a plurality of flip-flops or other types of registers. The circuit is first configured such that substantially all feedback loops associated with the registers, other than one or more self-loops each associated with a corresponding one of the registers, are broken. Test patterns are then generated for application to the circuit. The test patterns are applied to the circuit in conjunction with partitioned clock signals each of which is associated with a corresponding level of the circuit containing at least one of the self-loops.

Sequential test pattern generation using clock-control design for testability structures

A method of fault tolerant operation of field programmable gate arrays (FPGAs), whether as an embedded portion of a system-on-chip or other application specific integrated circuit, utilizing incremental reconfiguration during normal on-line operation includes configuring an FPGA into a self-testing area and a working area. Within the self-testing area, programmable interconnect resources of the FPGA are tested for faults. Upon the detection of one or more faults within the interconnect resources, the faulty interconnect resources are identified and a determination is made whether utilization of the faulty interconnect resources is compatible with an intended operation of the FPGAs. If the faulty interconnect resources are compatible with the intended operation of the FPGA, utilization of the faulty interconnect resource is allowed to provide fault tolerant operation of the FPGA. If the faulty interconnect resources are not compatible with the intended operation of the FPGA, on the other hand, a multi-step reconfiguration process may be initiated which attempts to minimize the effects of each reconfiguration on the overall performance of the FPGA. In an alternate embodiment, the entire FPGA may be configured as one or more self-testing areas during off-line testing, such as manufacturing testing.

Fault tolerant operation of field programmable gate arrays

A method of identifying faulty programmable interconnect resources of a field programmable gate array (FPGA) may be carried out during manufacturing testing and/or during normal on-line operation. The FPGA resources are configured into a working area and a self-testing area. The working area maintains normal operation of the FPGA throughout on-line testing. Within the self-testing area, programmable interconnect resources of the FPGA are grouped and comparatively tested for faults. Upon the detection of one or more faults within a group of programmable interconnect resources, the group of resources is subdivided for further comparative testing in order to minimize a region of the group of resources including the fault for each fault. Once the region of the group of resources which includes the fault is minimized, the wires within the minimized region are comparatively tested in order to determine which wire includes the faulty resource or resources. Once the wire which includes the faulty resource is determined, a variety of testing configurations may be utilized to identify the faulty resource within the wire.

Identifying faulty programmable interconnect resources of field programmable gate arrays

A method of fault tolerant operation of an adaptive computing system includes identifying a faulty resource in a signal path of the adaptive computing system, reconfiguring the signal path to avoid the faulty resource, estimating a time delay created by reconfiguring the signal path, and adjusting a system clock period to accommodate the time delay. In a preferred embodiment, an FPGA is configured into an initial self-testing area and a working area. Resources located within the self-testing area are tested and faulty resources identified. The FPGA is then reconfigured to avoid the identified faulty resources. When the resources are reconfigured for fault tolerant operation, signal path delays may be introduced into the system. If the signal path delays are in a critical path, a period of a system clock may be adjusted in order to insure proper fault tolerant operation.

Fault tolerant operation of reconfigurable devices utilizing an adjustable system clock

Test pattern generation is performed for a sequential circuit by first separating the circuit into overlapping pipelines by controlling corresponding clocks for one or more registers of the circuit so as to break feedback loops of the circuit, and then processing each of the pipelines separately in order to determine if particular target faults are detectable in the pipelines. Independent clocks may be provided for each of a number of registers of the circuit in order to facilitate the breaking of the feedback loops. The processing of the pipelines may include a first processing operation which detects target faults in a single time frame, and a second processing operation which detects target faults in two or more time frames. The first processing operation generates as many combinational test vectors as possible for each of the pipelines, while the second processing operation generates sequences of two or more combinational test vectors for each of the pipelines. Advantageously, the invention allows efficient combinational test pattern generation techniques to be applied to a sequential circuit.

Sequential test pattern generation using combinational techniques

A method of testing field programmable gate array (FPGA) resources and identifying faulty FPGA resources during normal on-line operation includes configuring an FPGA into a working area and an initial self-testing area. The working area maintains normal operation of the FPGA throughout testing and identifying of the resources. Within the initial and subsequent self-testing areas, the FPGA resources are initially tested for faults. Upon detection of a fault in the FPGA resources, the initial self-testing area resources are reconfigured or subdivided and further tested in order to identify the faulty resource. Dependent upon the further test results, the FPGA resources may be further subdivided and tested until the faulty resource is identified. Once the faulty resource is identified, the FPGA is reconfigured to replace unusable faulty resources or to avoid faulty modes of operation of partially faulty resources diagnosed during further testing. In this manner, partially faulty resources are allowed to continue operation in a diminished capacity to enhance fault tolerance. After testing each of the FPGA resources located within the initial self-testing area for faults, identifying the faulty resources, and in some instances diagnosing faulty modes of operation of the faulty resource, the FPGA is reconfigured such that a portion of the working area becomes a subsequent self-testing area and the initial self-testing area replaces that portion of the working area. In other words, the self-testing area roves around the FPGA testing its resources in a continuous manner.

On-line testing of field programmable gate array resources

A method of self-testing the programmable routing network in a field programmable gate array (FPGA) during normal on-line operation includes configuring the FPGA into an initial self-testing area and a working area. The initial self-testing area is preferably configured to include an horizontal self-testing area primarily for testing horizontal wire segments and a vertical self-testing area primarily for testing vertical wire segments. Programmable logic blocks located within the self-testing areas are configured to function as a test pattern generator and an output response analyzer, and a portion of the programmable routing resources within the self-testing areas is configured as groups of wires under test. An exhaustive set of test patterns generated by the test pattern generator is applied to the groups of wires under test which are repeatedly reconfigured in order to completely test the programmable routing resources within the self-testing areas. The outputs of the groups of wires under test are compared by the output response analyzer and resultant fault status data for each group of wires under test is received by a controller in communication with a memory for storing the fault status data. After completely testing the programmable routing resources in one of the initial self-testing areas, the FPGA is reconfigured such that a portion of the working area becomes a subsequent self-testing area and at least a portion of one of the initial self-testing areas replaces that portion of the working area. In other words, the self-testing areas rove around the FPGA repeating the steps of testing and reconfiguring until the entire FPGA has undergone testing or continuously.

Growing community of inventors

Berkeley Heights, NJ, United States of America

Miron Abramovici