| 摘要 |
A test cell (12) provides boundary scan testing in an integrated circuit (10). The test cell (12) comprises two memories, a flip-flop (24) and a latch (26), for storing test data. A first multiplexer (22) selectively connects one of a plurality of inputs to the flip-flop (24). The input of the latch (26) is connected to output of the flip-flop (24). The output of the latch (26) is connected to one input of a multiplexer (28), the second input to the multiplexer (28) being a data input (DIN) signal. A control bus (17) is provided for controlling the multiplexers (22,28), flip-flop (24) and latch (26). The test cell allows input data to be observed and output data to be controlled simultaneously. A bidirectional cell (30) uses the test cell (12) and additional circuitry to provide bidirectional operation. <IMAGE> |
