stm32笔记:按键输入(精简版)

//GPIOA8是   LED0
//GPIOA13是  KEY0            仅包含启动代码 STM32F10x.s

#define GPIOA_CRL    (*(volatile unsigned long *)(0x40000000+0x10000+0x0800+0x00))
#define GPIOA_CRH    (*(volatile unsigned long *)(0x40000000+0x10000+0x0800+0x04))
#define GPIOA_IDR    (*(volatile unsigned long *)(0x40000000+0x10000+0x0800+0x08))
#define GPIOA_ODR    (*(volatile unsigned long *)(0x40000000+0x10000+0x0800+0x0C))
#define RCC_APB2ENR  (*(volatile unsigned long *)(0x40000000+0x20000+0x1000+0x18))

void delay(unsigned long i)   //超级不精确的软延时
{
	int j;
	while(i--)
	{
		for(j=0;j<1500;j++)
		{}			
	}	
}
	
int main(void)
{	
	u8 keyflag=1;	//按键进入标志,防止一次按键多次判断的简易做法
	
	RCC_APB2ENR= 1<<2;		 //打开PA时钟,默认启用内部8M时钟
	GPIOA_CRH &= 0XFFFFFFF0; //准备配置PA8 ,PA8是LED0
	GPIOA_CRH |= 0X00000003; //PA8 推挽输出   	 
  	GPIOA_ODR |= 1<<8;       //PA8 输出高,即先关闭led

	GPIOA_CRH &= 0XFF0FFFFF;  //准备配置PA13	,PA13是KEY0  
	GPIOA_CRH |= 0X00800000;  //配置PA13为带上拉下拉输入
	
	
	while(1)
	{ 
		if(!checkBit(GPIOA_IDR,13))  //键被按下的话,执行led反转
		{
			if(keyflag)
			{
				keyflag=0;
				GPIOA_ODR = revBit(GPIOA_ODR,8); //第8位反转,revBit是宏
			}
		}
		else
		{
			keyflag=1;
		}
		
		delay(10); //简易消抖
	}	 
}


//checkBit 和revBit都是关于位的宏
//#define  BIT(n)            (1<<(n))
//#define  revBit(val,n)     ((val)^(BIT(n)))
//#define  checkBit(val,n)   (((val)&(BIT(n)))>>(n))