single_key.i

一个关于AVR单片机的例程

#line 1 "C:\DOCUME~1\administrator\桌面\教程\single_key\single_key.c"




char read_key(void)
{
static char key_state = 0;
char key_press, key_return = 0;
key_press = PIND.7;
switch (key_state)
{
case 0 :
if (!key_press) key_state = 1;
break;
case 1 :
if (!key_press)
{
key_return = 1;
key_state = 2;
}
else
key_state = 0;
break;
case 2 :
if (key_press) key_state = 0;
break;
}
return key_return;
}