| 摘要 |
PURPOSE:To eliminate an illegal operation in an external interface or internal logic by independently controlling a scan mode flip-flop (F/F), by providing a command decode part. CONSTITUTION:When a command to be issued from a diagnosis processor 1 is a scan operation execution request, a command decode part 3 turns a scan data set signal SET to '1' and sets '1' to a scan mode F/F 4. When the command is a scan mode reset request, a scan mode reset signal RESET is turned to '1' and the F/F 4 is reset to '0'. According to a scan mode signal SFM as the output of the F/F 4, the F/F in a processing part 5 is formed as one bus and further, the suppression of signal transmission to the external interface of the processing part 5 or the stop of the internal operation, etc., is executed. Thus, the diagnostic operation is enabled without disturbance to the external interface or the malfunction of the internal circuit, etc. |
