| 摘要 |
PROBLEM TO BE SOLVED: To immediately detect the occurrence of an abnormal state of an electric apparatus by comparing the voltage level of an output port with the level of an output data register and outputting a control signal when a state in which they do not coincide continues for a fixed time. SOLUTION: When an output port is destroyed, the value of an output data register 11 is different from the level of an output port 13 through an output buffer 12, all of outputs of plural comparator circuits 14 which are sampled in different timings become a high level, and an output of an AND gate also become a high level, by which a control signal S is generated. An interrupt control circuit 16 receives an interrupt to an interrupt processing program of a CPU 17, the interrupt processing program is carried out in the CPU 17, and declaration or the like, due to, e.g. the off of a heater protective switch, a buzzer and panel display is performed. An interrupt does not occur when it is decided that comparison results do not agree because of the effect of noise of the output port. |
