Abstract: A module (100) has test controller (140) for evaluating a functional block (120). The test controller (140) includes a first register (142) coupled between an input pin (162) and an output pin (164) from a plurality of pins (160) and a second register (144) coupled to the first register (142) for capturing an update of the content of the first register (142) responsive to an update signal from a decoder (170). The second register (144) is further arranged to generate evaluation control signals (145). The test controller further includes dedicated control circuitry including a plurality of logic gates (180) and a first logic gate (182). The plurality of logic gates is arranged to decode the content of the first register (142) and provide the first logic gate (182) with a resulting gating signal for blocking the update of the second register (144). Consequently, the dedicated control circuitry is able to prevent undesired changes in the module (100) during an evaluation mode of for instance another module.

Abstract: An integrated circuit with a test interface contains a boundary scan chain with cells (14) coupled between a test data input (TDI) and output (TDO) in a shift register structure. Each cell (14) is also coupled between a respective one of the terminals (16) and the core circuit (10). A test control circuit (TAP_C) supports an instruction to switch the boundary scan chain to a mode in which mode selectable first ones of the cells (14) transport data serially along the boundary scan chain while selectable second ones of the cells (14) write or read data that has been or will be transported through the first ones of the cells (14) in the further mode to or from the terminals (16) from or to the scan chain.

Abstract: In a method for testing a testable electronic device having a first and a second plurality of test a arrangements a first shift register (110) is used in parallel with a second shift register (130) to time-multiplex a first test vector (102) and a second test vector (104) into a number of smaller test vectors (102a–c; 104a–c) for provision to the first and second plurality of test arrangements. By varying the size of the first shift register (110) and the second shift register (130) a trade-off between the number of pins of the electronic device to be contacted and the required test time can be made. The first shift register (110) may be coupled to a first buffer register (120) and second shift register (130) may be coupled to a second buffer register (140) for enhanced test data stability. First shift register (110) and second shift register (130) can be partitions of a larger shift register.

Abstract: An electronic device has a plurality of subdevices with each subdevice coupled to a test interface. The test interfaces are arranged in a chain of test interfaces by coupling the TDO contact of a predecessor test interface to the TDI contact of a successor test interface in the chain. In addition, at its beginning, the chain is extended with a boundary scan compliant test interface for testing other parts of electronic device. Both the TDO contact of the last test interface in the chain as well as the TDO contact of test interface are coupled to a bypass multiplexer, thus yielding two possible routes from test data input to test data output: through the full chain or through test interface only. Consequently, electronic device can be tested or debugged as a macro device or as a collection of subdevices.

Abstract: Boundary scan test circuits are controlled by a test state machine capable of assuming respective test states successively in successive test clock cycles. A single input of the test signal is normally used to control selection of successive states assumed by the test state machine. The test state machine has a standard state diagram of possible states. Further the test circuit contains a shift register to transport test data. A co-processor state machine is provided, capable of assuming respective co-processor states successively in successive cycles of the test clock. The co-processor state machine, when enabled, starts making transitions from a start state in response to assumption of a predetermined one of the test states by the test state machine.

Abstract: An electronic device (100) has a plurality of subdevices (120a, 120b) with each subdevice (120a; 120b) coupled to a test interface (140a; 140b). The test interfaces (140a, 140b) are arranged in a chain of test interfaces (140) by coupling the TDO contact (142b) of a predecessor test interface (140a) to the TDI contact (141b) of a successor test interface (140b) in the chain (140). In addition, at its beginning, the chain (140) is extended with a boundary scan compliant test interface (160) for testing other parts of electronic device (100). Both the TDO contact (142b) of the last test interface (140b) in the chain (140) as well as the TDO contact (162) of test interface (160) are coupled to a bypass multiplexer (102), thus yielding two possible routes from test data input (110) to test data output (112): through the full chain (140, 160) or through test interface (160) only. Consequently, electronic device (100) can be tested or debugged as a macro device or as a collection of subdevices (120a, 120b).

Abstract: A method for testing a testable electronic device having a first and a second plurality of test arrangements, e.g. scan chains, is disclosed. A first shift register (110) is used in parallel with a second shift register (130) to time-multiplex a first test vector (102) and a second test vector (104) into a number of smaller test vectors (102a-c; 104a-c) for provision to the first and second plurality of test arrangements. By varying the size of the first shift register (110) and the second shift register (130) a trade-off between the number of pins of the electronic device to be contacted and the required test time can be made. Preferably, first shift register (110) is coupled to a first buffer register (120) and second shift register (130) is coupled to a second buffer register (140) for enhanced test data stability. First shift register (110) and second shift register (130) can be partitions of a larger shift register, e.g. a boundary scan chain.