| 摘要 |
PURPOSE:To accurately calculate and display information on the rotation of vehicle members by calculating the number of revolution such as the revolutions of the engine at an interval of a fixed time from an integral number of pulses and a total time for each cycle. CONSTITUTION:A rotary pulse train 6 is taken into a computer 8 as input signal and a pulse edge detection circuit 11 detects eacn rising edge 12a of the rotary pulse train 12 to execute an interrupt routine in the course of the processing of a main program executed in a computer 8. Then, in the interrupt routine, a processing is performed with a pulse edge time measuring section 15 to get the current time (t) stored into a memory tp(n)16a for pulse edge time generating a timer 14. On the other hand, the pulse edge time tp(n)29b the closest prior to the rear end time ts(n)28b among the pulses 6 in a pulse edge updating section 22 is stored into a memory tp(n-1)16d to be utilized as pulse edge time tp(n-1)42 the closest prior to the front end time of the subsequent fixed time Tc27b. The number of pulses gamma per unit time averaged from a total time tp(n) -tp(n-1) for cycles of rotary pulses in an integral number of rotary pulse trains as difference between the tp(n-1) and the tp(n) thus stored and the number of pulses NP in the rotary pulse train is calculated at an interval of the fixed time Tc to determine the veicle speed accurately. |
