频率测量，对于周期波频率的测量方法很多，但大多是通过测量间接计算频率。本文介绍了用目前应用比较广泛的MCS-51系列单片机对周期波频率进行测量，并通过LED以数字形式直观地示出频率，实现测量的智能化，省去间接对频率计算的麻烦与错误。文章对其测量原理、设计和实现作了说明，并进行了误差分析-Frequency measurement, the cycle frequency of the measurement method, but are calculated indirectly by measuring the frequency. In this paper, compared with the current application of a wide range of MCS-51 series single-chip frequency of the periodic wave measurements, and in digital form through the LED to visually indicate the frequency, the realization of the intelligent measurement, indirectly saved the trouble of calculating the frequency and错误. Article of its measuring principle, design and realization of an explanation, and the error analysis