硬件电路主要分为信号转换电路、分频电路、数据选择电路、单片机系统和显示电路五部分。

电平转换电路：

　　电平转换电路的必要性：因为在单片机计数中只能对脉冲波进行计数，而实际中需要测量的频率的信号是多种多样的，有脉冲波，还有可能有正弦波、三角波等，所以需要一个电路把待测信号可以进行计数的脉冲波。

　　通过电平转化电路将正弦输入信号fx整形成同频率方波fo,要将正弦信号转换成方波信号可以用过零比较电路实现。正弦信号通过LM833N与零电平比较，电压大于零的时候输出LM833N的正电源+5V，电压小于零的时候输出负电源0V。

-Hardware circuit can be divided into signal conversion circuit, frequency divider circuit, the data selection circuit, single-chip systems, and display circuit of five parts.

　Level-shifting circuit:

The need for level-shifting circuit: as in the MCU can only count on the pulse count, but the actual need to measure the frequency of the signal is varied, a pulse wave, there may be sine, triangle, etc. so they need a circuit to test the signal pulse can be counted.

By the level conversion circuit to form a sinusoidal input signal with frequency fx entire square wave fo, convert square wave to sine wave signal can be used to achieve zero comparator circuit. Sinusoidal signal with the zero level by LM833N comparison, the voltage output of LM833N greater than zero when the positive power supply 5V, output voltage is less than zero, the negative power supply 0V.