KEIL中的键盘扫面程序这么跳不出循环 新人求解答

Question

uchar jianpan()
{
uchar temp,tem;
uchar sm12[]={'d',0,'g',1,2,3,4,5,6,7,8,9 };
do
{
uint r=0;
for(r;r<3;r++)
{
P0=sm[r];
tem=P0;
temp=tem&0xf0;
if(temp!=0xf0)
{
delay(50);
if(temp!=0xf0)
{
switch(temp)
{
case 0xe0:num=sm12[r]; break;
case 0xd0:num=sm12[r+3];break;
case 0xb0:num=sm12[r+7]; break;
case 0x70:num=sm12[r+10]; break;
}
}
}

} //for

}while(num!=0xf0);

if(temp!=0xf0)
{
temp=P0&0xf0;
}

return num;
}

Answer 1

http://tieba.baidu.com/p/3045901325