User manual

First of all, sensor 1 will detect any presence of object. If there are object

detected, the microcontroller will proceed to detect sensor 2, and in 0.5 second range,

there are object detected, the counter will counting up and relay will turned on. This

counting is represent a visitor is entering the laboratory. Henceforth, it is similar for

visitor that leaving the room. If sensor 2 detect the object first and a sensor 1 trace

0.5 second after sensor 1, the counter will counting down indicates a visitor is

leaving the laboratory. As there are nobody left inside the room, which counter will

hit zero, microcontroller will send data to control relay and turn off the lighting in the

room.

There also an additional function inside microcontroller to calculate the

height of the visitor that is entering and leaving the laboratory. It involve sensor 3 at

the top of the door to calculate the difference between the door and the detected

object that will equal to the height of the person.

3.2.3 Writing the control program

A programming language will be use depends on things such as desired

execution speed, program length and convenience. For this project, the most suitable

language is C++ language. The main advantages of C++ language are that there is

not much vocabulary to learn, and that the programmer can arrange the program very

fast. The high language C++ is very easy to learn and still a practical compact

language. It comprises a good semantic. The syntax of C is also clear [27]. This

language is a systems language suitable for low-level programming especially for

student. Finally, C language is easy to understand, has facilities for structured

programming and allows lexical variable scope and recursion, while a static type

system prevents many unintended operations [7].