介绍了以AT89C2051单片机为核心的智能频率计的设计，利用单片机内部的定时(计数)器完成待测信号周期(频率)的测量。对系统的信号预处理电路、控制电路和显示电路三大部分进行了研究，采用RS232接口电路，利用VB6编程语言实现了PC机串口接收控制程序。-Introduced a single chip AT89C2051 frequency as the core of intelligent design, the use of single-chip internal timer (count) device under test signals completed cycle (frequency) measurements. The system signal pre-processing circuit, control circuit and display circuit three most studied, using RS232 interface circuit, the use of VB6 programming language to achieve a PC serial port to receive machine control procedures.