| 摘要 |
PURPOSE:To easily detect a scan path error and also to shorten the error detecting time. CONSTITUTION:A scan address selection circuit 10 drives the AND circuits 12 and 13 based on the contents instructed by the scan address selection signal received from a diagnostic processor 2. Thus, the scan clocks are supplied to the F/Fs of both scan paths 14 and 15. A selection circuit 11 selects the optional shift-in data or the fixed value given from the processor 2 in accordance with a selection signal and uses the selected date as the final shift-in data. An error detecting circuit 18 detects an abnormal operation of the scan path to be controlled and a malfunction of the scan path not to be controlled based on the fixed value given from the processor 2, the selection signal, the driving result of the circuit 10, end the output data obtained from the shift operations of both paths 14 and 15. |
