| 摘要 |
A micro computer is to be prevented from operating in a state that it cannot be monitored appropriately. By a reset signal RS outputted from a watchdog circuit (34), the micro computer is started and an output signal Q of a discriminating circuit (36) is reset. After that, when a clock signal ck is inputted from the started micro computer, the discriminating circuit outputs a clock signal CK to the watchdog circuit and sets an output signal. However, if the discriminating circuit detects a standby signal st when the micro computer is started, it stops outputting of the clock signal CK and setting of the output signal Q. Thus, a standby signal ST is not outputted from an AND circuit (38) to the watchdog circuit, and transmission of the reset signal from the watchdog circuit is repeated, thus preventing the micro computer from operating. |
