| 摘要 |
PURPOSE: To provide a watchdog timer which can monitor the runaway of a multitask system. CONSTITUTION: An MPU 3 on which plural tasks operate accesses the watchdog timer 1 at a specific frequency determined, task by task. The watchdog timer 1 monitors the frequency of the access at specific intervals of time, and judges as a runaway and outputs a runaway detection signal 4 when the frequency of access decreases below a specific value. Further, the tasks writes specific values determined by the tasks in registers in the watchdog timer 1 at specific frequencies. The watchdog timer 1 monitors the total of the values written in the registers at specific intervals of time, and judges as a runaway and outputs a runaway detection signal 4 when the total of the values written in the registers decreases below a specific value.
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