利用89C-51单片机作为主控器组成一个转速表。由转动电机提供计数脉冲。设置定时器/计数器T0和T1，内部定时器T0设置为定时方式，且定时时间为50ms，即每50ms定时器T0中断一次，中断20次达到1秒；计数器T1设置为外部脉冲计数工作方式，并将初值置为0FFFFH，转动电机每转一周产生一个脉冲使得计数器加1溢出产生中断，设在1s内测量的脉冲个数为n即为测到的转动电机的转速。-The use of 89C-51 microcontroller as master composed of a tachometer. Counting pulses provided by a rotating motor. Set timer/counter T0 and T1, the internal timer T0 is set to regular mode, and the regular time of 50ms, or 50ms Timer T0 interrupt every time, interrupted 20 times to 1 second　counter T1 is set to an external pulse counting methods of work, and the initial value set to 0FFFFH, rotating motor to generate a pulse per revolution makes the counter a week plus an overflow interrupt, located in the 1s to measure the pulse number n shall be measured for the motor rotation speed.