| 摘要 |
PURPOSE:To prevent the repetitive resetting actions due to an everlasting fault by producing automatically an internal reset signal in case the CPU runaway of a bus master is detected by a watchdog timer to start a resetting action of the bus master and also to perform the self-diagnosis of the hardware for detection of the fault. CONSTITUTION:A watchdog timer 17 is periodically triggered by the output pulse of a CPU 11 and produces an abnormality detecting signal in case the triggering is not applied from the CPU 11 for a fixed time to inform the occurrence of the abnormality to a reset signal generator 18 and the CPU 11. The generator 18 detects the abnormality detecting signal received from the timer 17 or a system bus and produces the internal reset signal of a bus master unit to supply this signal to a system bus interface circuit 15, a CPU 11 and a peripheral circuit respectively. Thus the repetitive resetting actions due to the hardware troubles can be prevented. |
