int knob_start(void)
{
int light_reading, course_side;
while(!stop_button())
{
light_reading=knob();
if (light_reading<128)
{
printf("Black %d\n",light_reading);
course_side=1;
}
if (light_reading>128)
{
printf("White %d\n",light_reading);
course_side=-1;
}
sleep(.5);
}
return course_side;
}