{
while (1)
{switch(P3)
{
case 0xfe:stepa();break;//0xfe = 1111 1110,
case 0xfd:stepb();break;
case 0xfb:stepa();break;
case 0xf7:stepb();break;
case 0xef:stepa();break;
case 0xdf:stepb();break;
case 0xbf:stepa();break;
case 0x7f:stepb();break;
default:break;
}