S3C2440-按键

哈尔滨理工大学软件工程专业08-7李万鹏原创作品，转载请标明出处

http://blog.csdn.net/woshixingaaa/archive/2010/12/14/6075129.aspx

使用按键控制跑马灯。扫描哪个按键被按下有两种方式。一个是查询扫描，一个是中断扫描。查询扫描就是不断轮询哪个引脚变成低电平了。中断扫描主要通过中断方式实现。

查询扫描程序：

#define rGPFCON (*(volatile unsigned *)0x56000050) 
#define rGPFDAT (*(volatile unsigned *)0x56000054) 
#define rGPFUP (*(volatile unsigned *)0x56000058)
#define rGPBCON (*(volatile unsigned *)0x56000010) 
#define rGPBDAT (*(volatile unsigned *)0x56000014) 
#define rGPBUP (*(volatile unsigned *)0x56000018)  
int KeyMain(){
	void Delay(unsigned int x);
	unsigned char ledtab[]={0xf7,0xef,0xdf,0xbf};
	unsigned int t;
	rGPBCON = 0xffc3fc;             //0,2 为输入，3，4，5，6为输出
	rGPBDAT = 0x7fe;                
	rGPFCON = 0xd54c;               //5，6为输入 
	rGPFDAT = 0xff;                  
	rGPBUP &= 0xf9f;
	rGPFUP &= 0x82;
	
	while(1){
		while(((rGPBDAT & 0x7ff) == 0x7fe) && ((rGPFDAT & 0xff) == 0xff));    //不断轮询，如果找到往下执行，看是那个被按下
		if((rGPBDAT & (0x1<<5)) == 0){                
			rGPFDAT = ledtab[0];         
			Delay(70);
		}
		if((rGPBDAT & (0x1<<6)) == 0){                          //取出rGPBDAT的第6位，看是不是0
			rGPFDAT = ledtab[1];
			Delay(70);
		}
		if((rGPFDAT & (0x1<<0)) == 0){
			rGPFDAT = ledtab[2];
			Delay(70);
		}
		if((rGPFDAT & (0x1<<2)) == 0){
			rGPFDAT = ledtab[3];
			Delay(70);
		}
		rGPFDAT = 0xff;                                       //恢复，以便重新响应按键
	}
}
void Delay(unsigned int x){
	unsigned int i, j, k;
	for(i =0; i <= x; i++)
		for(j = 0; j <= 0xff; j++)
			for(k = 0; k <= 0xff; k++)
				;
}

中断扫描程序：

#define rGPFCON (*(volatile unsigned *)0x56000050)   
#define rGPFDAT (*(volatile unsigned *)0x56000054)   
#define rGPFUP (*(volatile unsigned *)0x56000058)  
#define SRCPND (*(volatile unsigned *)0x4a000000)
#define INTPND (*(volatile unsigned *)0x4a000010)
#define INTMSK (*(volatile unsigned *)0x4a000008) 
#define _ISR_STARTADDRESS 0x33ffff00
#define pISR_EINT0 (*(unsigned *)(_ISR_STARTADDRESS+0x20))
#define pISR_EINT2 (*(unsigned *)(_ISR_STARTADDRESS+0x28))
#define U32 unsigned int 

void delay(U32 x){
	int i,j,k;
	for(i = 0; i < x; i++)
		for(j = 0; j < 0xff; j++)
			for(k = 0; k < 0xff; k++)
				;
}

void __irq EINT0_ISR(void){
	SRCPND |= 1;                 //SRCPND 通过写入数据清零，如果不清零，会反复进行请求
	INTPND |= 1;                 //INDPND 通过置1清零
	rGPFDAT = 0xf7;
	delay(1000);
	rGPFDAT = 0xff;
	delay(1000);
}

void __irq EINT2_ISR(void){     //使用__irq这个关键字定义终端服务例程，这样系统会自动为我们保留一些变量，并能在中断处理完后正确的返回
	SRCPND |= 1<<2;
	INTPND |= 1<<2;
	rGPFDAT = 0xef;
	delay(1000);
	rGPFDAT = 0xff;
	delay(1000);
}

int Main(){    
	rGPFCON &= 0xfc0c;    //0 2 3 4
	rGPFCON |= (1<<1)|(1<<5)|(1<<6)|(1<<8);
	rGPFUP = 0xe2;
	SRCPND |= (1<<0)|(1<<2); 
	INTPND |= (1<<0)|(1<<2);
	INTMSK &= (~(0x1<<0)) & (~(0x1<<2));     //开中断
	pISR_EINT0 = (U32)EINT0_ISR;             //给中断服务例程入口地址
	pISR_EINT2 = (U32)EINT2_ISR;
	while(1);
	return 0;
}