基于XILINX平台设计的数字频率计，在FPGA内部设计信号源，产生100KHz方波，板上数码管用于显示被测信号频率，并显示6位有效数字，实现对TTL电平的测试，测量精度为10Hz。-: The digital frequency meter based on XILINX development terrace generates 100 KHz square waves by a supply oscillator within FPGA. The nixietubes of the board, which is available of 6 significant figures, are used to display the frequency of the test signal. The meter can realize the function of testing TTL level and gain 10 Hz accuracy.