keyboard.c

4*5矩阵键盘驱动

#include <Keyboard.h>

void key_delay(void)
{
	unsigned char  i,j;
	for(i=50;i>0;i--)
	for(j=200;j>0;j--);
}

//键盘扫描，没有键按下返回0
unsigned char KBScan(void)
{
	unsigned char key;
	unsigned char ScanCode;
	unsigned char temp;
	
	P2 = 0x0f;
	col1 = 1;
	
	if((P2&0x0f) != 0x0f && col1 != 1);    //判断是否有键按下，如有，则逐一判断是哪个键按下了
		{
			ScanCode = 0xef;
			
			while(ScanCode != 0xff)     //  循环4次结束标志
			{
				P2 = ScanCode;
				col1 = 1;
				temp = P2;
				temp = (temp << 1) | col1;				
				temp = temp & 0x1f;   //取低5位
				
				if(temp != 0x1f)
					{
						key_delay();    //防抖
						
						temp = P2;						
						temp = (temp << 1) | col1;
						temp = temp & 0x1f;
						
						if(temp != 0x1f)
							{
								temp = P2;
								temp = (temp << 1) | col1;
								temp = temp & 0x1f;
						
						    switch(temp)
						    {
							    case 0x1e:
								    key = ~ScanCode | 0x01;
								    while(col1 == 0);          //松开按键
								    return key;
								
							    case 0x1d:
								    key = ~ScanCode | 0x02;
								    while(col2 == 0);
								    return key;
								
							    case 0x1b:
								    key = ~ScanCode | 0x03;
								    while(col3 == 0);
								    return key;
								
							    case 0x17:
								    key = ~ScanCode | 0x04;
								    while(col4 == 0);
								    return key;
								
							    case 0x0f:
								    key = ~ScanCode | 0x05;
								    while(col5 == 0);
								    return key;
								
							    default: break;
						    }
					    }
			    }
			    ScanCode = (ScanCode << 1) | 0x01;		//扫描下一行
			}
		}
		return 0;
}