| 摘要 |
PURPOSE:To keep a program in the middle of initial processing from becoming complicated and to surely detect its abnormal action such as out of control by permitting an initial timer to issue the alarm if the preset value of the initial timer excludes an access to a watch dog timer. CONSTITUTION:A resetting signal MPU to reset a microprocessor 1 is also transmitted to the initial timer 4 and an RS type flip flop 6. Receiving the resetting signal MPU, the initial timer 4 starts its counting. When the microprocessor 1 completes initial processing, enters normal processing and accesses to a register 2, an access signal being the output of the register 2 is also transmitted to the RS type flip flop 6, and due to the action of an AND gate 8 an initial timer output signal from the initial timer 4 is inhibited and not outputted. If the microprocessor 1 does not access to the register 2, the AND gate 8 remains opened. When the initial timer output signal is generated after the initial timer 4 passes the prescribed time, a run-away detection signal is transmitted.
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