目前广泛使用的不含微机的数字式转速表,其硬件电路复杂,测量范围与精度不能兼顾,而且采样时间长,难以测得瞬时转速,更不能扩展仪表的功能:如任意设置报警值、转速值的永久存贮、按需要进行打印控制等等。单片微型计算机的出现为自动检测仪表打开了广阔的前景。特别是MCS-51型单片微机的性能价格比、 Currently widely used computer-free digital tachometer, the hardware circuit complexity, measurement range and accuracy can not take into account, and the sampling time is long, it is difficult to measure the instantaneous speed, but can not extend the function of the instrument: such as arbitrarily set the alarm value, speed Permanent storage of values, print control as needed, and more. The advent of single-chip microcomputers opens up a huge future for automatic instrumentation. In particular, MCS-51-type single-chip computer’s cost performance,