A circuit comprises scan gating devices inserted between outputs of scan chains and inputs of a test response compactor. The scan gating devices divides the scan chains into groups of scan chains. Each of the scan gating devices operates in either an enabled mode or a disenabled mode based on a first signal. A scan gating device operating in the enabled mode blocks, blocks only at some clock cycles, or does not block a portion of a test response of a test pattern captured by and outputted from a scan chain in the associated scan chain group based on a second signal. Scan gating devices operating in the disenabled mode do not block, or based on a third signal, either block or do not block, a portion of the test response captured by and outputted from all scan chains in each of the associated scan chain groups.

Systems and methods for latches are presented. In one embodiment a system includes scan in propagation component, data propagation component, and control component. The scan in propagation component is operable to select between a scan in value and a recirculation value. The data propagation component is operable to select between a data value and results forwarded from the scan in propagation component, wherein results of the data propagation component are forwarded as the recirculation value to the scan in propagation component. The control component is operable to control an indication of a selection by the scan in propagation component and the data propagation component.

Physical or off-chip interfaces may be selectively bypassed in a boundary scan chain. A bypass control signal may be produced that indicates whether to bypass a selected one of the interfaces. In response to a first state of a bypass control signal, a multiplexer may couple the scan chain output of an interface boundary scan cell to the scan chain input of a successor boundary scan cell of the interface boundary scan cell. In response to a second state of the bypass control signal, the multiplexer may couple the scan chain output of a predecessor boundary scan cell of the interface boundary scan cell to the scan chain input of the successor boundary scan cell, bypassing the interface boundary scan cell.

An apparatus comprises a first semiconductor chip comprising a first communication controller to receive first debug data from a second semiconductor chip; a memory to store the first debug data from the second semiconductor chip and second debug data of the first semiconductor chip; and a second communication controller to transmit the first debug data from the second semiconductor chip and the second debug data of the first semiconductor chip to an output port of the first semiconductor chip.

An example integrated circuit (IC) die in a multi-die IC package, the multi-die IC package having a test access port (TAP) comprising a test data input (TDI), test data output (TDO), test clock (TCK), and test mode select (TMS), is described. The IC die includes a Joint Test Action Group (JTAG) controller having a JTAG interface that includes a TDI, a TDO, a TCK, and a TMS, a first output coupled to first routing in the multi-die IC package, a first input coupled to the first routing or to second routing in the multi-die IC package, a master return path coupled to the first input, and a wrapper circuit configured to couple the TDI of the TAP to the TDI of the JTAG controller, and selectively couple, in response to a first control signal, the TDO of the TAP to either the master return path or the TDO of the JTAG controller.

A failure diagnostic apparatus includes a path calculation unit which calculates, for each input pattern to a diagnosis target cell, a path affecting an output value of the diagnosis target cell when a failure is assumed as an activation path, a path classification unit which classifies the activation path associated with the input pattern for which the diagnosis target cell has passed a test and the activation path associated with the input pattern for which the diagnosis target cell has failed the test, a path narrowing unit which calculates a first failure candidate path, a second failure candidate path and a normal path of the diagnosis target cell based on classified activation paths, and a result output unit which outputs information on the first failure candidate path, the second failure candidate path and the normal path.

Disclosed are methods, systems and devices for implementing built-in self-test (BIST) to be performed by an untrusted party and/or in an unsecure testing environment. In an embodiment, a test access port (TAP) on a device may enable a party to initiate execution of one or more BIST procedures on the device. Additionally, such a TAP may enable loading of encrypted instructions to be executed by one or more processors formed on a device under test.

An example integrated circuit (IC) die in a multi-die IC package, the multi-die IC package having a test access port (TAP) comprising a test data input (TDI), test data output (TDO), test clock (TCK), and test mode select (TMS), is described. The IC die includes a Joint Test Action Group (JTAG) controller having a JTAG interface that includes a TDI, a TDO, a TCK, and a TMS, a first output coupled to first routing in the multi-die IC package, a first input coupled to the first routing or to second routing in the multi-die IC package, a master return path coupled to the first input, and a wrapper circuit configured to couple the TDI of the TAP to the TDI of the JTAG controller, and selectively couple, in response to a first control signal, the TDO of the TAP to either the master return path or the TDO.

The disclosure describes a novel method and apparatus for improving interposers to include embedded monitoring instruments for real time monitoring digital signals, analog signals, voltage signals and temperature sensors located in the interposer. An embedded monitor trigger unit controls the starting and stopping of the real time monitoring operations. The embedded monitoring instruments are accessible via an 1149.1 TAP interface on the interposer.

A method includes injecting scan patterns into an input of a decompressor that distributes the scan patterns to a plurality of scan chains whose outputs are coupled to inputs of a compressor, which provides a compressed scan test result representing the plurality of scan chains. The method also includes, in response to the compressed scan test result being indicative of failure, identifying a particular scan chain of the plurality of scan chains that is responsible for the failure by a debug circuit that is coupled to the input of the decompressor and to a compressor output. The debug circuit enables an output of any single scan chain of the plurality of scan chains to be available at the compressor output while suppressing outputs of all other scan chains of the plurality of scan chains.