Arduino base parking system - Simple Arduino Based Automated Parking Lot System - page 50

set_key(), up_pb(), down-pb() functions
These three functions are for tuning time and date. With the set_key, we can choose
any appropriate value of time or date. Up_pb and down_pb are considered external inter-
rupts and when they are active, we can increase the value of time or date that is selected by
set_key . You can see the related programs in attendant CD.