| 摘要 |
PURPOSE:To diagnose a diagnostic controller itself without being effected by a device to be diagnosed by controlling running/stop/advance of a clock of the diagnostic controller and shift-in/out of a scan path and making the interface ineffective with the device to be diagnosed at diagnosis. CONSTITUTION:In making a diagnostic control circuit 25 active by the separate command from that diagnosing the normal device to be diagnosed from a diagnostic processor 1, the circuit 25 makes the operation of diagnostic interface circuits 22-24 ineffective, and the diagnostic control circuit 25 stops the clock supply to a diagnostic control circuit 21' by the command of the diagnostic processor 1. When the shift-out of the scan path is commanded next, the diagnostic control circuit 25 shifts the diagnostic control circuit 21' to apply a shift clock. The shift data subject to shift-out is transmitted to the diagnostic processor 1 via the diagnostic control circuit 25 and a diagnostic interface 101 and at the shift-in command, a data is inputted to a scan path of the diagnostic control circuit 21' via the diagnostic control circuit 25 conversely. |
