1、功能说明

	/* 简单描述工程功能 */
        这个例程配置并演示使用EXIT外部中断及TIM定时器中断


2、使用环境

	/* 硬件环境：工程对应的开发硬件平台 */
        开发板：N32G43XRL-STBV1.0


3、使用说明
	
	/* 描述相关模块配置方法；例如:时钟，I/O等 */
        SystemClock：108MHz

        USART：TX - PB4，波特率115200
	EXIT：PA0为浮空输入模式，外部中断线 - EXIT_LINE0，开启外部中断
	TIM：预分频系数 - （SystemClock/1200-1），周期 - （1200-1），开启定时器中断

	/* 描述Demo的测试步骤和现象 */
        1.编译后下载程序复位运行；
        2.查看串口打印信息，定时器中断信息每1S打印一次，按下按键打印停止，再次按下则继续打印，表明程序运行正常；


4、注意事项


1. Function description
	/* A brief description of the engineering function */
	This routine configures and demonstrates the use of EXIT external interrupts and TIM timer interrupts

2. Use environment
	/* Hardware environment: the corresponding development hardware platform */
	Development board: N32G43XRL-STBV1.0
        
3. Instructions for use    
	/* Describe the related module configuration method; For example: clock, I/O, etc. */
	SystemClock: 108 MHZ
	USART: TX-PB4, baud rate 115200
	EXIT: PA0 is in floating input mode, and external interrupt line -EXIT_LINE0 is used to enable external interrupt
	TIM: Pre-dividing frequency coefficient - (SystemClock/1200-1), period - (1200-1), start timer interrupt

	/* Describes the test steps and symptoms of Demo */
	1. Reset and run the downloaded program after compilation;
	2. Check the serial port printing information. The timer interrupt information is printed every 1S. Press the button to stop printing, and press it again to continue printing, indicating that the program is running normally.

4. Matters needing attention