关键点:
先给PC口的低4为为输出高4位为输入,来判断是那一列,后交叉来赋值来判断是那一行
源代码:
#include <avr/io.h>
#include<util/delay.h>
#define F_CPU 8000000UL
const unsigned char table[]=
{
0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,
0x7F,0x6F,0x77,0x7C,0x39,0x5E,0x79,0x71
};
char key_num;
unsigned char check();
void key_scan();
void beep();
int main(void)
{
DDRE=0xff;
while(1)
{
if(check())
key_scan();
else
continue;
if (key_num<16)
{
PORTE=table[key_num];
beep();
}
}
}
void beep()
{
int i;
for (i=0;i<10;i++)
{
PORTF=0x04;
_delay_ms(1);
PORTF=0x00;
}
}
void key_scan()
{
switch(PINC)
{
case 0x0e: key_num=0;break;
case 0x0d: key_num=1;break;
case 0x0b: key_num=2;break;
case 0x07: key_num=3;break;
default:key_num=0xff;
}
DDRC=0x0f;PORTC=0xf0;_delay_ms(4);
switch(PINC)
{
case 0xe0: key_num+=0;break;
case 0xd0: key_num+=4;break;
case 0xb0: key_num+=8;break;
case 0x70: key_num+=12;break;
default:key_num=0xff;
}
}
unsigned char check()
{
DDRC=0xf0;PORTC=0x0f;_delay_ms(4);
return PINC!=0x0f ? 1:0;
}
截图: