| 摘要 |
PROBLEM TO BE SOLVED: To detect abnormality while suppressing power consumption even if the operation state of the abnormal state detecting circuit changes owing to an external factor and a clock stops by storing the change of a register which controls the operation stop of oscillation when the register become abnormal and no write signal is inputted. SOLUTION: If the value of the oscillation control register 51 varies although a write enable signal 52 is '0', that means that the value of the oscillation control register 51 varies owing to a factor such as external noise. For the purpose, this is detected by D type flip-flop circuits 55 and 56 and an abnormal state detection signal is outputted through an OR circuit 58. When the write enable signal is '1', there is the possibility that the value of the oscillation control register 51 varies and an AND circuit 54 cuts off it so as to prevent its detection. The D type flip-flop circuits 55 and 56 detect the oscillation control register changing from '0' to '1' and from '1' to '0' respectively.
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