| 摘要 |
<p>PURPOSE:To detect intermediate electric potential when it is inputted to an external signal input terminal and to prevent and erroneous action by adding flip lops of which threshold level is different mutually to the external signal input terminal and taking the exclusive logical sum of the output of it. CONSTITUTION:Flip flops 3, 6 and 7, of which threshold level is different mutually, connected to input stages 1 and 2 from an external part and a comparing arithmetic circuit 14 to compare-operate the output of the flip flops 6 and 7 and to take exclusive logical sum are possessed. Then, when intermediate level input comes, the one part of the flip flops becomes a high state, the other flip flops becomes an intermediate state or low state and when the comparing arithmetic circuit 14 compare-operates the output of the flip flops 6 and 7 and takes the exclusive logical sum of them, an object different from a case that the intermediate level input does not come is obtained from the output of it. Thus, it can be detected that input of intermediate level 5 comes to an internal circuit and the erroneous action of a microprocessor 4 can be prevented.</p> |
