1、功能说明
    1、TIM3 CH2捕获引脚通过CH1下降沿和CH2上升沿计算占空比和频率
2、使用环境
    软件开发环境：  KEIL MDK-ARM V5.34.0.0
                  IAR EWARM 8.50.1
    硬件环境：        N32G003F5S7-STB V1.0
3、使用说明
    系统配置；
        1、时钟源：
                    AHB=48M,APB=48M,TIM3 CLK=48M
        2、中断：
                    TIM3 CC2比较中断打开，优先级1
        3、端口配置：
                    PA2选择为TIM3的CH2输入
                    PA3选择为IO输出
        4、TIM：
                    TIM3 CH1捕获CH2信号的下降沿。TIM3 CH2捕获CH2信号的上升沿
    使用方法：
        1、编译后打开调试模式，连接PA3和PA2，将Frequency、DutyCycle、gOnePulsEn添加到watch窗口
        2、程序运行后，默认gOnePulsEn=0，每次手动给gOnePulsEn=1，此时可以看到被捕获到的占空比和频率的值分别存储在DutyCycle和Frequency变量
4、注意事项
    开发板默认PA2,PA3跳帽接到NSLINK的虚拟串口，若工程中PA2，PA3不作串口，用作其他用途，须拔掉串口跳帽。

1. Function description
    1. TIM3 CH2 capture pin calculates the duty cycle and frequency through the falling edge of CH1 and the rising edge of CH2
2. Use environment
    Software development environment: 	KEIL MDK-ARM V5.34.0.0
    Hardware environment:    	             	N32G003F5S7-STB V1.0
3. Instructions for use
     System Configuration;
         1. Clock source:
                    AHB=48M,APB=48M,TIM3 CLK=48M
         2. Interrupt:
                    TIM3 CC2 compare interrupt is turned on, priority level 1
         3. Port configuration:
                    PA2 is selected as the CH2 input of TIM3
                    PA3 is selected as IO output
         4. TIM:
                    TIM3 CH1 captures the falling edge of CH2 signals.TIM3 CH2 captures the rising edge of CH2. 
     Instructions:
         1. Open the debug mode after compiling, connect PA3 and PA2, and add the variables TIM3Freq and gOnePulsEn to the watch window
         2. The default gOnePulsEn=0, manually give gOnePulsEn=1 each time, then you can see that the values of the duty cycle and frequency captured are stored in the DutyCycle and Frequency variables.
4. Matters needing attention
  By default, the PA2 and PA3 jumper caps of the development board are connected to the virtual serial port of NSLINK. If PA2 and PA3 are not used as serial ports in the project, and are used for other purposes, the serial port jumper caps must be unplugged.
