Abstract: An electronic circuit having a boundary scan test circuit receives, though one pin, an embedded clock encoded test signal having an encoded bit stream having occurrences of a first header followed by at least one encoded boundary scan mode bit and an encoded second header followed by at least one boundary scan test input bit. The bit stream and the clock are extracted and occurrences of the first header and second header are detected. Based on the detected occurrences the boundary scan mode bits and boundary scan input bits are identified and distributed to the electronic circuit, along with the extracted clock, and boundary scan test is performed.

Abstract: An optimized JTAG interface is used to access JTAG Tap Domains within an integrated circuit. The interface requires fewer pins than the conventional JTAG interface and is thus more applicable than conventional JTAG interfaces on an integrated circuit where the availability of pins is limited. The interface may be used for a variety of serial communication operations such as, but not limited to, serial communication related integrated circuit test, emulation, debug, and/or trace operations.

Abstract: A device test architecture and interface is provided to enable efficient testing embedded cores within devices. The test architecture interfaces to standard IEEE 1500 core test wrappers and provides high test data bandwidth to the wrappers from an external tester. The test architecture includes compare circuits that allow for comparison of test response data to be performed within the device. The test architecture further includes a memory for storing the results of the test response comparisons. The test architecture includes a programmable test controller to allow for various test control operations by simply inputting an instruction to the programmable test controller from the external tester. The test architecture includes a selector circuit for selecting a core for testing. Additional features and embodiments of the device test architectures are also disclosed.

Abstract: A system comprises a plurality of components, scan chain selection logic coupled to the components, and override selection logic coupled to the scan chain selection logic. The scan chain selection logic selects various of the components to be members of a scan chain under the direction of a host computer. The override selection logic detects a change in the scan chain and, as a result, blocks the entire scan chain from progressing.

Abstract: The disclosure describes a novel method and apparatus for providing expected data, mask data, and control signals to scan test architectures within a device using the falling edge of a test/scan clock. The signals are provided on device leads that are also used to provide signals to scan test architectures using the rising edge of the test/scan clock. According to the disclosure, device test leads serve to input different test signals on the rising and falling edge of the test/scan clock which reduces the number of interconnects between a tester and the device under test.

Abstract: Topology discovery of a target system having a plurality of components coupled with a scan topology may be performed by driving a low logic value on the data input signal and a data output signal of the scan topology. An input data value and an output data value for each of the plurality of components is sampled and recorded. A low logic value is then scanned through the scan path and recorded at each component. The scan topology may be determined based on the recorded data values and the recorded scan values.

Abstract: The disclosure provides a novel method and apparatus for inputting addresses to devices to select the device TAP for access. Further, the disclosure provides a novel method and apparatus for inputting addresses for selecting device TAPs and for inputting commands for commanding circuitry within the device. The inputting of addresses or the inputting of addresses and commands is initiated by a control bit input on TDI that is recognized during the Run Test/Idle, Pause-DR or Pause-IR TAP states.

Abstract: Embodiments related to identifying a reference scan cell locationally related to a fault condition exhibited by a scan chain in which the reference scan cell is included are provided. In one example, a method for identifying a reference scan cell is provided, the method comprising, in a capture mode, outputting combinational logic values to scan cells in the scan chain so that scan cell values for the scan cells are based on respective combinational logic values, the combinational logic values electrically connected with the scan chain. The example method further comprises, in a shift mode, sequentially determining the scan cell value for each scan cell, and identifying as the reference scan cell a scan cell last determined to be at an expected logical state for that scan cell.

Abstract: Reconstruction methods and devices are disclosed for scan chains in physical design that is based on two-way priority selection. The structural reconstruction method in the scan chains, in the first place, establishes a first preference sequence for a certain number of scanning elements in each of these scan chains as well as a secondary preference sequence for these scan chains in each of these scanning elements respectively. Then, two-way selection is executed between the scan chains and scanning elements based on the corresponding first preference sequence and secondary preference sequence, so that these scanning elements can be redistributed to these scan chains. The structural reconstruction method and device in the invention conduct an integrated optimization for a global scan chain, where the global wiring length is shortened dramatically and the wiring efficiency is improved.

Abstract: In a test data access system, a shift register is coupled the test data in pin. A first multiplexer is in data communication with the TDI pin and is configured to receive data from the TDI pin and to transmit data to each of the instruments. The first multiplexer is also configured to receive data from a data recirculation bit and to transmit data from the TDI pin to a plurality of instruments when the recirculation bit has a first value and to transmit data to the plurality of instruments from a recirculation line when the recirculation bit has a second value, different from the first value. A second multiplexer is configured to receive data from each of the plurality of instruments and is configured to transmit data from a selected one of the plurality of instruments, selected based on a value of data in the shift register. A first AND gate is configured to generate a gates clock to the shift register. A second AND gate is responsive to the first AND gate, configured to lock the shift register.

Abstract: An integrated circuit can have plural core circuits, each having a test access port that is defined in IEEE standard 1149.1. Access to and control of these ports is though a test linking module. The test access ports on an integrated circuit can be arranged in a hierarchy with one test linking module controlling access to plural secondary test linking modules and test access ports. Each secondary test linking module in turn can also control access to tertiary test linking modules and test access ports. The test linking modules can also be used for emulation.

Abstract: This disclosure describes a reduced pin bus that can be used on integrated circuits or embedded cores within integrated circuits. The bus may be used for serial access to circuits where the availability of pins on ICs or terminals on cores is limited. The bus may be used for a variety of serial communication operations such as, but not limited to, serial communication related test, emulation, debug, and/or trace operations of an IC or core design. Other aspects of the disclosure include the use of reduced pin buses for emulation, debug, and trace operations and for functional operations. In a fifth aspect of the present disclosure, an interface select circuit, FIGS. 41-49, provides for selectively using either the 5 signal interface of FIG. 41 or the 3 signal interface of FIG. 8.

Abstract: IEEE 1149.1 Test Access Ports (TAPs) may be utilized at both IC and intellectual property core design levels. TAPs serve as serial communication ports for accessing a variety of embedded circuitry within ICs and cores including; IEEE 1149.1 boundary scan circuitry, built in test circuitry, internal scan circuitry, IEEE 1149.4 mixed signal test circuitry, IEEE P5001 in-circuit emulation circuitry, and IEEE P1532 in-system programming circuitry. Selectable access to TAPs within ICs is desirable since in many instances being able to access only the desired TAP(s) leads to improvements in the way testing, emulation, and programming may be performed within an IC. A TAP linking module is described that allows TAPs embedded within an IC to be selectively accessed using 1149.1 instruction scan operations.

Abstract: A scan circuit (JTAG 1149 extension) for a microprocessor utilizes transport logic and scan chains which operate at a faster clock speed than the external JTAG clock. The transport logic converts the input serial data stream (TDI) into input data packets which are sent to scan chains, and converts output data packets into an output data stream (TDO). The transport logic includes a deserializer having a sliced input buffer, and a serializer having a sliced output buffer. The scan circuit can be used for testing with boundary scan latches, or to control internal functions of the microprocessor. Local clock buffers can be used to distribute the clock signals, controlled by thold signals generated from oversampling of the external clock. The result is a JTAG scanning system which is not limited by the external JTAG clock speed, allowing multiple internal scan operations to complete within a single external JTAG cycle.

Abstract: It is a purpose of the invention to provide a fault detection system, etc., having improved fault coverage with a reduced number of test patterns to be input to a logic circuit. The fault detection system detects a fault in a logic circuit based on multiple output logic values of the logic circuit after a test input pattern is input. The output logic values are input to the logic circuit as an updated test input pattern. The system comprises: a first acquisition unit which acquires a part of or all of the output logic values; a comparison unit which compares the logic values acquired by the first acquisition unit with those predicted for when there are no faults, or for when there is a specific fault; and a fault judgment unit which judges whether or not there is a fault based on the comparison result obtained by the comparison unit.

Abstract: A system and method for scan partitioning for testing an embedded logic circuit in an integrated circuit (IC) device is provided. One or more scan partitions in the embedded logic circuit are identified. Each scan partition includes one or more scan chains of scan registers. One or more interacting registers connecting scan registers of a first scan partition and scan registers of a second scan partition are identified and combined to form an interacting scan chain. The embedded logic circuit is tested by selectively activating the scan chains of the first and second scan partitions and the interacting scan chain.

Abstract: The present disclosure describes using the JTAG Tap's TMS and/or TCK terminals as general purpose serial Input/Output (I/O) Manchester coded communication terminals. The Tap's TMS and/or TCK terminal can be used as a serial I/O communication channel between; (1) an IC and an external controller, (2) between a first and second IC, or (3) between a first and second core circuit within an IC. The use of the TMS and/or TCK terminal as serial I/O channels, as described, does not effect the standardized operation of the JTAG Tap, since the TMS and/or TCK I/O operations occur while the Tap is placed in a non-active steady state.

Abstract: At least one external pin of an integrated circuit (IC) is coupled to receive a first configuration signal used in configuring an internal circuit block for a test designed to uncover faults in the circuit block, and to receive a first test signal during the test. Configuration logic in the IC is designed to generate control data by decoding configuration signals that include the first configuration signal. A test configuration register stores the control data and applies the control data during the test, but is decoupled from the configuration logic prior to commencement of the test. A sequence detector in the IC is designed to detect a reset sequence signifying an end of the test and in response to re-couple the test configuration register to the configuration logic. The number of external pins needed for testing the IC is reduced.

Abstract: Stacked integrated circuits (ICs) having a base component and secondary component are tested. The base component has a scan input pad, a scan output pad, a base scan chain, and a base chain access block including a base chain select multiplexor and a base bypass multiplexor. The secondary component has a secondary scan chain and a secondary chain access block including a secondary chain select multiplexor and a secondary bypass multiplexor. The secondary chain select multiplexor is configured to receive input directly from the base component and another component. The base and secondary chain access blocks are configured to selectively access the base scan chain and/or the secondary scan chain.

Abstract: A system and method for sharing a communications link between multiple protocols is described. A system includes a communications interface configured to exchange information with other systems using at least one of a plurality of protocols; a protocol select register that stores a value that selects a protocol from among the plurality of protocols to become an active protocol; and a state machine accessible to the communications interface, the state machine used to control the exchange of information through the communications interface according to the active protocol. The active protocol is used by the communications interface to exchange information while the remaining protocols of the plurality of protocols remain inactive. The state machine sequences through a series of states that cause the communications interface to operate according to the active protocol, and that are designated as inert sequences under the remaining protocols.

Abstract: The present disclosure describes novel methods and apparatuses for directly accessing JTAG Tap domains that exist in a scan path of many serially connected JTAG Tap domains. Direct scan access to a selected Tap domain by a JTAG controller is achieved using auxiliary digital or analog terminals associated with the Tap domain and connected to the JTAG controller. During direct scan access, the auxiliary digital or analog terminals serve as serial data input and serial data output paths between the selected Tap domain and the JTAG controller.

Abstract: A boundary scan node of a boundary scan chain for testing an associated node of core logic core logic includes a first boundary scan cell having an input that is coupled to a first data output of the core logic. A second boundary scan cell having an output is coupled to a first data input of the core logic. A programmable series connection is arranged to selectively couple an output of the first boundary scan cell to an input of the second boundary scan cell when the boundary scan node is arranged in an internal test mode for the core logic. Test stimulus can be written to the boundary scan node using a data register clock and test results can be read from the boundary scan node using the data register clock.

Abstract: A circuit arrangement for controlling the masking of test and diagnosis data with X values of an electronic circuit with N scan paths, wherein the test data are provided on insertion into the N scan paths by a decompressor with m inputs and N outputs (m<N) and wherein the masked test data are compacted by a compactor with N data inputs and n data outputs and m<N applies is provided.

Abstract: An apparatus for protecting against external attacks for a processor based on an ARM core and a method using the same are provided. A method for protecting against external attacks for a processor based on an ARM core in accordance with an embodiment of the present invention includes: setting up a register using a reset handler, which is executed first within a boot image; generating a control signal for protecting against external attacks using any one of an external debug request signal and an output signal of the register; and blocking a JTAG interface used for JTAG communication with the processor based on the ARM core according to the control signal for protecting against external attacks.

Abstract: A contactless smartcard type integrated circuit needing only two pins for performing a standard ATPG test is disclosed. A scan test may be performed using one pin for the clock and the other pin for the input and input of the scan test data. Additionally, security is enhanced by using an embedded signature generator to avoid observation of the data shifted out.

Abstract: Aspects of the invention relate to techniques for determining scan chains that could be diagnosed with high resolution. A circuit design and the information of scan cells for the circuit design are analyzed to determine information of potential logic relationship between the scan cells. The information of potential logic relationship between the scan cells may comprise information of fan-in cones for the scan cells. Based at least in part on the information of potential logic relationship between the scan cells, scan chains may be formed. The formation of scan chains may be further based on layout information of the circuit design. The formation of scan chains may be further based on compactor information of the circuit design.

Abstract: An integrated circuit includes a first signal processing circuit in which first combination circuits and scan FFs are connected in an order of a scan FF, a first combination circuit, and a scan FF; a second signal processing circuit including a second combination circuit different from the first combination circuit; a first selection circuit configured to select data from a scan FF on an input side of one first combination circuit or data from an input terminal of the second signal processing circuit, and to output the data to the second combination circuit; and a second selection circuit configured to select data from another first combination circuit different from the one first combination circuit or data from the second combination circuit, and to output the data to the scan FF on an output side of the another first combination circuit.

Abstract: A device test architecture and a reduced device test interface are provided to enable efficient testing of embedded cores and other circuits within devices. The reduced device test interface is achieved using a double data rate (DDR) signaling technique between the tester and the device. The DDR test interface allows the tester to interface to test circuits within the device, such as IEEE 1500 and/or IEEE 1149.1 test circuits, to provide high test data bandwidth to the test circuits using a minimum of test interface signals. The test architecture includes compare circuits that allow for comparison of test response data to be performed within the device. The test architecture further includes a memory for storing the results of the test response comparisons. The test architecture includes a programmable test controller to allow for various test control operations by simply inputting an instruction to the programmable test controller from the external tester.

Abstract: A boundary scan circuit containing a freeze circuit and a transparency circuit that provides a capability to selectively place portions of a system logic in a sleep mode and thereby conserving power. There are two transparency circuit configurations, one that connects to an input pad cell and one that connects to an output pad cell. The circuitry in the transparency circuit is controlled in such a manner as to establish at the output of transparency circuit a known logic state to control leakage current resulting from the circuitry of the various pad cell configurations, which further conserves power during sleep mode.

Abstract: A process and apparatus provide a JTAG TAP controller (302) to access a JTAG TAP domain (106) of a device using a reduced pin count, high speed DDR interface (202). The access is accomplished by combining the separate TDI and TMS signals from the TAP controller into a single signal and communicating the TDI and TMS signals of the single signal on the rising and falling edges of the TCK driving the DDR interface. The TAP domain may be coupled to the TAP controller in a point to point fashion or in an addressable bus fashion. The access to the TAP domain may be used for JTAG based device testing, debugging, programming, or other type of JTAG based operation.

Abstract: Scan architectures are commonly used to test digital circuitry in integrated circuits. The present disclosure describes a method of adapting conventional scan architectures into a low power scan architecture. The low power scan architecture maintains the test time of conventional scan architectures, while requiring significantly less operational power than conventional scan architectures. The low power scan architecture is advantageous to IC/die manufacturers since it allows a larger number of circuits (such as DSP or CPU core circuits) embedded in an IC/die to be tested in parallel without consuming too much power within the IC/die. Since the low power scan architecture reduces test power consumption, it is possible to simultaneously test more die on a wafer than previously possible using conventional scan architectures. This allows wafer test times to be reduced which reduces the manufacturing cost of each die on the wafer.

Abstract: This invention permits selectively bypasses serial scan chains. Constant or low toggle data is directed to the bypassed serial scan chain, thus reducing power consumption. The number and identity of serial scan chains bypassed during a particular test can be changed dynamically dependent upon the semiconductor process variations of a particular integrated circuit. This enables an optimal test to be preformed for integrated circuits having differing semiconductor process variations.

Abstract: In a method for creating a clock domain in a layout of an integrated circuit, a test circuit of the integrated circuit includes a plurality of first scan cells and a plurality of second scan cells, the first scan cells are arranged to be on a first scan chain, and the second scan cells are arranged to be on a second scan chain. The method includes: for a first region in the layout, determining whether the first region needs a test clock domain adjustment according to densities of first scan cells and second scan cells within the first region; and when it is determined that the first region needs the test clock domain adjustment, arranging at least one first scan cell within the first region to be on the second scan chain.

Abstract: A method and system for reducing switching activity of a spreader network during a scan-load operation is disclosed. According to one embodiment, a spreader network receives a plurality of scan input signals from a tester. A linear feedback shift register of the spread network is updated using the plurality of scan input signals. Each bit of the linear feedback shift register is shifted at each shift cycle for a plurality of shift cycles. The linear feedback shift register outputs a nonlinear gating signal using a first set of outputs and a data value feeding one or more scan chains of the spreader network using a second set of outputs. The pipeline clock of a pipeline element of the scan chains is gated using the nonlinear gating signal, and the data value is fed to the scan chains based on the pipeline clock. The scan chains are fed with updated values at the pipeline stage.

Abstract: A test circuit includes a plurality of TAP controllers conforming to a standard specification defined in IEEE 1149 and includes a master TAP controller which receives a control code and a test control signal and performs a test on a circuit to be tested and which outputs a shift mode signal, a first slave TAP controller which receives the control code and the test control signal and performs a test on a circuit to be tested, and a first TAP pin control circuit provided to correspond to the first slave TAP controller and which switches between inputting the control code to the first slave TAP controller from the outside and inputting the control code through the master TAP controller, on the basis of the shift mode signal.

Abstract: In a first embodiment a Test Access Port (TAP) of IEEE standard 1149.1 is allowed to commandeer control from a Wrapper Serial Port (WSP) of IEEE standard P1500 such that the P1500 architecture, normally controlled by the WSP, is rendered controllable by the TAP. In a second embodiment (1) the TAP and WSP based architectures are merged together such that the sharing of the previously described architectural elements are possible, and (2) the TAP and WSP test interfaces are merged into a single optimized test interface that is operable to perform all operations of each separate test interface. One approach provides for the TAP to maintain access and control of the TAP instruction register, but provides for a selected data register to be accessed and controlled by either the TAP+ATC (Auxiliary Test Control bus) or by the discrete CaptureDR, UpdateDR, TransferDR, ShiftDR, and ClockDR WSP data register control signals.

Abstract: An integrated circuit carries an intellectual property core. The intellectual property core includes a test access port 39 with test data input leads 15, test data output leads 13, control leads 17 and an external register present, ERP lead 37. A scan register 25 encompasses the intellectual property core and ERP lead 37 carries a signal indicating the presence of the scan register.

Abstract: An IC includes an IEEE 1149.1 standard test access port (TAP) interface and an additional Off-Chip TAP interface. The Off-Chip TAP interface connects to the TAP of another IC. The Off Chip TAP interface can be selected by a TAP Linking Module on the IC.

Abstract: A system comprises a plurality of components, scan chain selection logic coupled to the components, and override selection logic coupled to the scan chain selection logic. The scan chain selection logic selects various of the components to be members of a scan chain under the direction of a host computer. The override selection logic detects a change in the scan chain and, as a result, blocks the entire scan chain from progressing.

Abstract: The disclosure describes a novel method and apparatus for allowing response data output from the scan outputs of a circuit under test to be formatted and applied as stimulus data input to the scan inputs of the circuit under test. Also the disclosure described a novel method and apparatus for allowing the response data output from the scan outputs of a circuit under test to be formatted and used as expected data to compare against the response data output from the circuit under test. Additional embodiments are also provided and described in the disclosure.

Abstract: Scan distributor, collector, and controller circuitry connect to the functional inputs and outputs of core circuitry on integrated circuits to provide testing through those functional inputs and outputs. Multiplexer and demultiplexer circuits select between the scan circuitry and the functional inputs and outputs. The core circuitry can also be provided with built-in scan distributor, collector, and controller circuitry to avoid having to add it external of the core circuitry. With appropriately placed built-in scan distributor and collector circuits, connecting together the functional inputs and outputs of the core circuitry also connects together the scan distributor and collector circuitry in each core. This can provide a hierarchy of scan circuitry and reduce the need for separate test interconnects and multiplexers.

Abstract: A TAP linking module (21, 51) permits plural TAPs (TAPs 1-4) to be controlled and accessed from a test bus (13) via a single TAP interface (20).

Abstract: A non-fighting fully clocked scan latch is described that is dynamically configurable to support both logic data latching and scan data latching. The described scan latch circuit design reduces a load placed on a logic data latch portion of the described circuit by a scan latch portion of the described circuit, and thereby increases the speed of the described scan latch to that of an output latch without scan capability. Power required to drive the described scan latch is reduced by clocking the circuit to avoid fighting and by reducing the number of transistors included in transistor stacks internal to the scan latch. By reducing drive power requirements, eliminating internal latch fighting, and increasing latch response, a versatile scan latch is achieved that may be successfully implemented in a wide range of circuits despite the use of different supply drive voltage, threshold voltage, source-to-drain voltage, and transistor technology combinations.

Abstract: A test architecture accesses IP core test wrappers within an IC using a Link Instruction Register (LIR). An IEEE P1500 standard is in development for providing test access to these individual cores via a test structure called a wrapper. The wrapper resides at the boundary of the core and provides a way to test the core and the interconnections between cores. The test architecture enables each of the plural wrappers in the IC, including wrappers in cores embedded within other cores, with separate enable signals.

Abstract: An integrated circuit or circuit board includes functional circuitry and a scan path. The scan path includes a test data input lead, a test data output lead, a multiplexer, and scan cells. A dedicated scan cell has a functional data output separate from a test data output. Shared scan cells each have a combined output for functional data and test data. The shared scan cells are coupled in series. The test data input of the first shared scan cell is connected to the test data output of the dedicated scan cell. The combined output of one shared scan cell is coupled to the test data input lead of another shared scan cell. The multiplexer has an input coupled to the test data output, an input connected to the combined output lead of the last shared scan cell in the series, and an output connected in the scan path.

Abstract: In some embodiments, a computer-implemented method includes receiving, in a processor, a device description code identifying components of a device and connections between the components, wherein some of the components and connections form boundary cells used for testing the device. The method can include processing, in the processor, the device description code to determine that the components and the connections meet a standard governing components and connections necessary for the boundary cells. The method can also include traversing the connections between the components to determine that the connections meet the standard, and reporting, via one or more output devices, that the device complies with the standard.

Abstract: Embodiments of integrated circuits include a first input interconnect, a second input interconnect, an output interconnect, a shift register, a select register, a test access port (TAP) controller, and select register decode circuitry. The TAP controller is coupled to the first input interconnect and the select register, and the TAP controller is configured to shift a select value provided on the first input interconnect into the select register. The select register decode circuitry is configured to control, based on the select value, which of a plurality of test data output signals are provided to the output interconnect, where the plurality of test data output signals includes a first test data output signal and a second test data output signal. The first test data output signal is provided by the shift register, and the second test data output signal is received from a second integrated circuit on the second input interconnect.

Abstract: A debug system scans a scan memory element group having a plurality of scan memory elements which are connected in series in a semiconductor integrated circuit device and collects data in the scan memory element group. The semiconductor integrated circuit device has an end code register which is provided between an input terminal and an input side of the scan memory element group and holds an end code, a start code register which is provided between an output terminal and an output side of the scan memory element group and holds a start code, and a scan control circuit which controls shift operations of the scan memory element group, the end code register and the start code register, and outputs scan data to the output terminal.

Abstract: An architecture for testing a plurality of circuits on an integrated circuit is described. The architecture includes a TAP Linking Module located between test pins on the integrated circuit and 1149.1 Test Access Ports (TAP) of the plurality of circuits to be tested. The TAP Linking Module operates in response to 1149.1 scan operations from a tester connected to the test pins to selectively switch between 1149.1 TAPs to enable test access between the tester and plurality of circuits. The TAP Linking Module's 1149.1 TAP switching operation is based upon augmenting 1149.1 instruction patterns to affix an additional bit or bits of information which is used by the TAP Linking Module for performing the TAP switching operation.

Abstract: Apparatus and techniques for performing JTAG testing on production devices and systems through industry standard interfaces. The devices employ processors configured to receive packetized test input data from a tester over a standard communication interface such as a USB or Ethernet port and perform associated testing operations defined by the test input data, such as JTAG-compliant testing. This is facilitated, in part, via use of a bridge and one or more DFx handlers, with the bridge operating as an interface between the DFx handlers and a bus and/or interconnect over which test input and result data is transferred via the standard communication interface. The techniques enable testing such as JTAG testing to be performed on fully-assembled devices and systems without requiring the use of dedicated test or debug ports.