| 摘要 |
PURPOSE:To correctly detect whether both a corresponding central processing unit 1 and a watchdog timer operate always normally or not through simple circuit configuration. CONSTITUTION:In a circuit constituted of the watchdog timer 2 connected to the central processing unit 1 and a capacitor voltage detecting means 4 which compares the voltage of a capacitor 3 connected to the watchdog timer 2 with the prescribed voltage and informs the central processing circuit of this result, the pulse P of a prescribed period is generated from the central processing unit 1 to the watchdog timer 2, and simultaneously, the watchdog timer 2 is provided with a means to generate a reset pulse RP to the central processing unit l when the pulse from the central processing unit 1 does not come, and further, the capacitor voltage detecting means 4 includes the means to inform the central processing unit 1 of information based on relation between the voltage of the capacitor and the prescribed reference voltage and informing whether the watchdog timer 2 operates normally or not. |
