用51单片机的定时计数器0脉冲进行计数，并用LCD1602显示，如果脉冲特性好，精度可以达到1Hz，带宽1Hz-50KHz（系统时钟12M）-With 51 SCM timing counter pulse count, and 0 LCD1602 shows that if the pulse, precision can reach 1Hz, 1Hz bandwidth 50KHz- 12M clock (system).

频率计 测量范围1-100MHz 测量阈值0.1s 计数部分为FPGA/CPLD 语言VHDL 显示部分为51 单片机加八位数码管 语言C-Frequency meter Measuring range 1-100 MHZ Measure threshold is 0.1 s Count part of FPGA/CPLD Language VHDL Display part of 51 MCU with eight digita