Testing of integrated circuits
First Claim
1. An integrated circuit comprising:
- a core circuit;
terminals for coupling the core circuit to circuitry external to the integrated circuit,a test data input and a test data output;
a boundary scan chain comprising cells coupled between the test data input and output in a shift register structure, each cell also coupled between a respective one of the terminals and the core circuit,a test control circuit arranged to switch the boundary scan chain between a functional mode, in which the cells permit signal flow between the terminals and the core circuit, and a test mode, in which test data is shifted serially through the cells along the boundary scan chain and in which the cells intercept signal flow between the respective ones of the terminals and the core circuit,wherein the test control circuit is arranged to execute an instruction to switch the boundary scan chain to a further mode, in which further mode selectable first ones of the cells transport data serially along the boundary scan chain while selectable second ones of the cells write or read data that has been or will be transported through the first ones of the cells in the further mode to or from the terminals from or to the scan chain.
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Accused Products
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.
63 Citations
23 Claims
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1. An integrated circuit comprising:
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a core circuit; terminals for coupling the core circuit to circuitry external to the integrated circuit, a test data input and a test data output; a boundary scan chain comprising cells coupled between the test data input and output in a shift register structure, each cell also coupled between a respective one of the terminals and the core circuit, a test control circuit arranged to switch the boundary scan chain between a functional mode, in which the cells permit signal flow between the terminals and the core circuit, and a test mode, in which test data is shifted serially through the cells along the boundary scan chain and in which the cells intercept signal flow between the respective ones of the terminals and the core circuit, wherein the test control circuit is arranged to execute an instruction to switch the boundary scan chain to a further mode, in which further mode selectable first ones of the cells transport data serially along the boundary scan chain while selectable second ones of the cells write or read data that has been or will be transported through the first ones of the cells in the further mode to or from the terminals from or to the scan chain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of operating an electronic circuit that comprises an integrated circuit and a further circuit coupled to each other, the integrated circuit comprising a boundary scan chain with cells coupled between a test data input and output of the integrated circuit in a shift register structure, each cell being also coupled between a respective one of terminals of the integrated circuit and a core circuit of the integrated circuit, the integrated circuit being switchable
to a functional mode, in which the cells permit signal flow between the terminals and the core circuit, to a test mode, in which test data is shifted serially through the cells along the boundary scan chain and in which the cells intercept signal flow between the respective ones of the terminals and the core circuit, and upon an instruction, to a further mode in which selectable first ones of the cells transport data serially along the boundary scan chain while selectable second ones of the cells write or read data that has been or will be transported through the first ones of the cells in the further mode to or from the terminals from or to the scan chain, wherein the method comprises a step of: switching the integrated circuit to the further mode and supplying and/or extracting successive signals to and/or from selected ones of the terminals through the boundary scan chain, while not transporting signals through the scan chain for or from other ones of the terminals intervening between the successive signals. - View Dependent Claims (20, 21, 22, 23)
Specification