| 摘要 |
PROBLEM TO BE SOLVED: To surely detect the runaway of a program by utilizing a watchdog timer(WDT) or the like. SOLUTION: A CPU 11 is operated according to a program stored in a ROM 12 or the like. The program contains an instruction for clearing a WDT 14 within fixed time. When the program runs away, the WDT 14 can not be cleared within the fixed time and the CPU 11 is reset by the WDT 14. In order to prevent the WDT 14 from being cleared in spite of the runaway of the program, the program is divided into plural loops and a gate is provided inside each of loops. Then, passing of the gate is confirmed, the WDT 14 is cleared and while defining the end of the preceding loop as a condition, the WDT 14 is cleared in the following loop.
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