设计一个频率测量仪,要求可测被测信号的频率并将转速值在四个LED上现实出来，用8253采样点电动机产生的转速脉冲测频率。

为微机接口课程设计，成绩中等。-Design a frequency meter, required frequency of the signal can be measured and the value of speed out of the four LED on the reality, with 8253 sample points generated by the motor speed pulse measurement frequency. Courses for the computer interface design, performance medium.