| 摘要 |
PURPOSE:To make it possible to measure the rotational speeds of several high speed rotating elements by storing precise periods of (n) pulses in a register with the use of a second counter for determining a measuring period and a control circuit, by calculating a rotational speed with interruption at every substantial set measuring period. CONSTITUTION:Each time when a detection pulse from a rotary element rises up, an increment of the content of, for example, a first counter 508 in a rotational speed measuring register is carried out. Meanwhile, a second counter 500A continuously counts clock pulses, and when it overflows, data on a measuring period setting register 504 is set. Simultaneously, a control circuit 510 holes the contents of both counters 508, 500A on registers 509, 502, respectively, with the timing of an input pulse from the next rotating element and a MPU 502 calculates a rotational speed per unit time from a pulse number (n) on the register 509 and a pulse period on the register 502 in association with an interruption demand signal. Thus it is possible to measure a rotational speed with a high degree of accuracy, and further, it is possible to shorten the process time of a microprocessor, thereby it is possible to measure several high speed rotating elements. |
