key.c

AVR的SPI的通信例子

#include "key.h"
unsigned char KeyFlag[KEY_NUM];
unsigned char ReadKey(void)
{
 	unsigned char temp,i;
	temp=PINB&0x0f;
	switch(temp)
		{
		 case 0x0e:
		 	  KeyFlag[0]++;break;
		 case 0x0d:
		 	  KeyFlag[1]++;break;
		 case 0x0b:
		 	  KeyFlag[2]++;break;
		 case 0x07:
		 	  KeyFlag[3]++;break;
		 }
		 for(i=0;i<KEY_NUM;i++)
		 {
		  if(KeyFlag[i]==4)
		  		{
				 KeyFlag[0]=0;
				 KeyFlag[1]=0;
				 KeyFlag[2]=0;
				 KeyFlag[3]=0;
				 return (i+1);
				 }
		 }
	return 0;

}