kbscan.c

用ICC写的ATMega8的4X4键盘驱动程序

/**************************************************************************
Description:线翻转法键盘扫描程序，只检测和处理单键

4*4键盘排列：
   0   1   2   3
 -----------------
|  0   1   2   3  | 0
|  4   5   6   7  | 1
|  8   9   A   B  | 2
|  C   D   E   F  | 3
 -----------------

Time:2007-1-5
***************************************************************************/
#include <iom8v.h>
#include <macros.h>

#define key_port PORTB         //定义键盘接口
#define port_DDR DDRB
#define port_PIN PINB
typedef unsigned int UINT;
typedef unsigned char UCHAR;

const UCHAR digital[16] = 
{
 0x3f, 0x6, 0x5b, 0x4f,  //0,1,2,3
 0x66, 0x6d, 0x7d, 0x7,  //4,5,6,7
 0x7f, 0x6f, 0x77, 0x7c,  //8,9,A,B
 0x39, 0x5e, 0x79, 0x71   //C,D,E,F
};

/*延时程序*/
void delay_1ms(void)
{//1ms延时函数
	UINT i;
	for(i=0; i<141; i++)
	{}
}

void delay(UINT n)
{//延时n毫秒
	UINT i;
	for(i=0; i<n; i++)	//执行n次1毫秒延时
		delay_1ms();
}

/*键盘扫描*/
void scan_init(void)
{//初始化键盘扫描端口
 	key_port = 0xff;
	port_DDR = 0x0f; //高四位输入，开上拉电阻
	key_port = 0xf0; //低四位输出0
}

void scan_turn(void)
{//端口输出翻转
	key_port |= 0x0f;
	port_DDR = 0xf0;  //低四位输入，开上拉电阻
	key_port &= 0x0f; //高四位输出0
}

UCHAR kbscan(void)
{
	UCHAR row, col; //行、列坐标
	row = 4;
	col = 4;
	scan_init();
	if((port_PIN&0xf0)!=0xf0) { //有键按下
		delay(5);   //防抖
		if((port_PIN&0xf0)!=0xf0) {
			row = (port_PIN&0xf0); //行值
			
			scan_turn();   //翻转
			
			if((port_PIN&0x0f)!=0x0f)
				col = (port_PIN&0x0f); //列值
			
			/*行坐标*/
			switch(row)
			{
			case 0xe0: row = 0;
				break;
			case 0xd0: row = 1;
				break;
			case 0xb0: row = 2;
				break;
			case 0x70: row = 3;
				break;
			default: row=4; //未知数值
			}
			/*列坐标*/
			switch(col)
			{
			case 0x0e: col = 0;
				break;
			case 0x0d: col = 1;
				break;
			case 0x0b: col = 2;
				break;
			case 0x07: col = 3;
				break;
			default: col=4; //未知数值
			}
		}
	}
	if((row!=4)&(col!=4))
		return row*4+col;
	else return 16; //错误返回
}

/*MAIN*/
void main(void)
{
 	UCHAR key;
	DDRD = 0xff;
 	while(1){
		key = kbscan();
		if(key!=16)
			PORTD = ~digital[key];	//数码管输出相应数字
	}
}