4x4_fanzhuan.c

51单片机的4x4键盘扫描程序

#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int

#define no_key 255
#define K1_1 1
#define K1_2 2
#define K1_3 3
#define K1_4 4
#define K2_1 5
#define K2_2 6
#define K2_3 7
#define K2_4 8
#define K3_1 9
#define K3_2 10
#define K3_3 11
#define K3_4 12
#define K4_1 13
#define K4_2 14
#define K4_3 15
#define K4_4 16
#define key_mask_x 0xF0
#define key_mask_y 0x0F

#define key_port P2
#define led_cport P0

bit key_stime_ok;
sbit leden=P0^7;

//线反转法读键盘
uchar read_keyboard(void)
{
 static uchar key_state = 0;
 static uchar key_x,key_y;
 uchar key_return = no_key;

 switch (key_state)
 {
 	case 0 :
		key_port |= key_mask_x;
		key_port &= ~key_mask_y;
		key_x = key_port & key_mask_x;
		if(key_x == key_mask_x) break;
		key_port |= key_mask_y;
		key_port &= ~key_mask_x;
		key_y = key_port & key_mask_y;
		key_state++;
		break;
	case 1 :
		if(key_y != key_port & key_mask_y)
		{
			key_state = 0;
			break;
		}
		key_port |= key_mask_x;
		key_port &= ~key_mask_y;
		if(key_x != key_port & key_mask_x)
		{
			key_state = 0;
			break;
		}
		switch (key_x & key_y)
		{
			case 0x77 :
				key_return = K1_1;
				break;
			case 0x7b :
				key_return = K1_2;
				break;
			case 0x7d :
				key_return = K1_3;
				break;
			case 0x7e :
				key_return = K1_4;
				break;
			case 0xb7 :
				key_return = K2_1;
				break;
			case 0xbb :
				key_return = K2_2;
				break;
			case 0xbd :
				key_return = K2_3;
				break;
			case 0xbe :
				key_return = K2_4;
				break;
			case 0xd7 :
				key_return = K3_1;
				break;
			case 0xdb :
				key_return = K3_2;
				break;
			case 0xdd :
				key_return = K3_3;
				break;
			case 0xde :
				key_return = K3_4;
				break;
			case 0xe7 :
				key_return = K4_1;
				break;
			case 0xeb :
				key_return = K4_2;
				break;
			case 0xed :
				key_return = K4_3;
				break;
			case 0xee :
				key_return = K4_4;
				break;
		}
		key_state++;
		break;
	case 2 :
		if((key_port & key_mask_x) == key_mask_x)
			key_state = 0;
		break;				
 }
 return key_return;
}

void initTimer(void)
{
 TMOD=0x1;
 TH0=0xd8;
 TL0=0xf0;
}

//定时器0产生10ms定时
void timer0(void) interrupt 1
{
 TH0=0xd8;
 TL0=0xf0;
 key_stime_ok=1;
}

void main(void)
{
 uchar key_value; 

 initTimer();
 TR0=1;
 ET0=1;
 EA=1;
 
 while(1){
 	if(key_stime_ok){
		key_stime_ok = 0;
		key_value = read_keyboard();
		if(key_value != no_key){
			led_cport = (key_value & 0x0f);
			leden=1;
		}
	}
 }
}