Systems and methods for non-intrusive testing of signals between circuits
AssigneeLSI Logic Corporation
InventorsKeith W. Holt, Jeremy D. Stover, Andrew A Cottrell
Life of this patent
Estimating the term…
Abstract
Structures and methods for non-intrusive testing of communication signals exchanged between two circuit boards via an intermediate interconnect board. In one aspect hereof, the functional signal normally exchanged between the circuits is latched during the exchange of test signals and the latched functional signal is utilized within the circuit that normally receives the functional signal to continue normal operations. In another aspect hereof, the test signals are exchanged over a dedicated test signal path between the two circuits. In another aspect hereof, the test signals are exchanged over the functional signal paths as out of band signals.
Claims20
A system for testing communication between a first circuit board and a second circuit board, the system comprising:
- a functional signal path coupled between the first circuit board and the second circuit board for transmitting a functional signal from the first circuit board to the second circuit board;
- a test signal path coupled between the first circuit board and the second circuit board for exchanging test signals between the first circuit board and the second circuit board;
- a first test control circuit in the first circuit board coupled to the test signal path and adapted to apply a test request signal to the test signal path;
- and
- a second test control circuit in the second circuit board coupled to the functional signal path and coupled to the test signal path and adapted to latch the present state of the functional signal on the functional signal path for use within the second circuit board in response to receipt of the test request signal from the first circuit board.
A system for testing a cross-coupled signal pair coupled between a first circuit board and a second circuit board, the system comprising:
- a first functional signal path of the cross-coupled signal pair for applying a first functional signal from the first circuit board to the second circuit board;
- a second functional signal path of the cross-coupled signal pair for applying a second functional signal from the second circuit board to the first circuit board;
- test signal means for exchanging test signals between the first and second circuit boards associated with testing the first functional signal path and associated with testing the second functional signal path;
- first test control logic in the first circuit board coupled to the test signal means and coupled to the second functional signal path for latching the present state of the second functional signal within the first circuit board during testing of the second functional signal path;
- and
- second test control logic in the second circuit board coupled to the test signal means and coupled to the first functional signal path for latching the present state of the first functional signal within the second circuit board during testing of the first functional signal path,
- wherein the first test control logic is operable to latch the present state of the second functional signal in response to a test request signal received from the second test control logic through the test signal means, and
- wherein the second test control logic is operable to latch the present state of the first functional signal in response to a test request signal received from the first test control logic through the test signal means.
A method for testing a cross-coupled signal pair coupled between a first and second circuit board, the method comprising the steps of:
- applying a test request signal from the first circuit board to the second circuit board wherein the test request signal is out of band with respect to the cross-coupled signal pair;
- latching within the second circuit board the present state of a functional signal of the cross-coupled signal pair in response to detection of the test request signal;
- exchanging test signals between the first circuit board and the second circuit board to test the signal path for the functional signal;
- and
- using the latched present state of the functional signal within the second circuit board during the exchange of test signals.
Dependencies are inferred from the claim text.