| 摘要 |
PURPOSE:To get rid of effect from chattering and noises without use of any complicated filter by providing an interrupt mode for the rising and falling to calculate the vehicle speed from the time of receiving a pulse. CONSTITUTION:When interrupt is initiated at the rising time t1 of a pulse P1, it is switched over to the rising trigger mode. This allows the triggering of interrupt at the rising time t7 of a pulse P4 at the next time. Subsequently, interrupt is trigered at the rising time t8 of a pulse P2. At the next step 11, the interrupt mode is changed to the falling trigger mode. then, interrupt is triggered at the falling time t2 of the pulse P2 an done again at the falling of a pulse P5. The change of the interrupt mode is made. Then, interrupt is triggered at the rising time t9 of a pulse P30. Subsequently, interrupt is triggered at the rising time of a pulse P31 and then done at the falling thereof. It is changed to the rising trigger mode from the falling trigger mode. In the end, the time t1, t5 and t3 is memorized in the falling processing and time t8 and t10 done in the rising processing. Thus, the effect of chattering or the like can be reduced using either of the processings. |
