| 摘要 |
PURPOSE:To enable the removal of effect from chattering without use of any complicated filter by inhibiting the subsequent interrupt processing when a pulse receiving processing is done in the interrupt processing. CONSTITUTION:Inhibition is done by masking the interrupt on a program in the interrupt processing. Then, after the masking of interrupt, as the level of a pulse signal will not be ''1'' continuously upto halfway in a pulse P<2>, no interrupt is triggered with the falling of the noise P<5> and the falling time t<4> is overridden. Then, after the masking of interrupt is released halfway in the pulse P<2>, the falling of the subsequent pulse P<4> is applied again while the masking of interrupt is done by a program. The masking continues halfway in the pulse P30 and interrupt is triggered at the falling of the pulse P30. Then, the interrupt processing starts at the falling of the subsequent pulse P31. In the end, the time t<1>, t<5> and t<3> is memorized as pulse receiving time respectively and thus, the detection of the vehicle speed can be performed accurately. |
