the flowchart shown that is explains about light sensor and buzzer.When press the button to start the light sensor system on peripheral to meter when a passenger using the service. When a passenger bring your baggage to put on the car ,then light sensor will detecting a baggage .If it's have a baggage , laser light is sent to the light sensor will cut through the baggage of the passenger. Make the light can not be shining on the light sensor. Thus,it's show the results as the pressure higher than 2V system and know that there is a baggage on the car, but will not display until the passenger will pay each carrier to hold the meter. When a passenger press the button for stop meter and to check a baggage in the baggage compartment that has on the car or not ,by checking out the pressure sensor light shows come out. If have a baggage ,the pressure must be higher than 2V but if not it must be lower than 2V.