Arduino base parking system - Simple Arduino Based Automated Parking Lot System - page 42

timing() function
In the Arduino programming to make different times, millis() instruction can be used.
This instruction holds the elapsed time from Arduino starts and give back time in milli-
second format. In the timing function by this instruction, the following times are set:
1. Blinking red LED.
2. The time duration that entrance arm gate stays open.
3. The time duration time that exit arm gate stays open.
4. The time for one beep to notify that the card is valid.
5. The time for three beeps to notify that the card is invalid.