International Journal of Smart Home
Vol. 7, No. 2, March, 2013
54
UART enables the communication between the sensor nodes and the GUI to be
established. UART is configured so that the functions developed on the GUI can be
corresponded to the stimulated signal triggered from sensor nodes. The analogue signal
is sent to UART. Then the “high” or “low” signal is delivered to the CPU and the GUI
will translate it into an ASCII code as programmed. Then the functionality is based on
the ASCII code will be returned by the GUI.
4.2.1 PIC Programming: The process is initiated by a power source switch as shown in
Figure 5. The triggering of each sensor node results in different sequential actions that
are aimed to chase the thieves away. The triggered signal will be sent to a
microcontroller to be interpreted. Then a responding signal is directed to output
components like light bulbs and buzzer. In the first level of MHSS, the laser sensing
sensor is in the standby mode where the sensor is actually waiting for the triggering of
external stimulant which refers to the thief’s breaking-in e.g. the gate is opened or the
wall is climbed over without switching off the main power source of the system. Once
the first level is triggered, the light bulbs will be turned on by the responding signal
which directed from the microcontroller unit after receiving the triggered signal. This
level is basically to alert the house owners that thief has entered the covered area
without any authorized mean.
The next flow of the process is followed by the second level of the MHSS where the
unauthorized presence of the thief will trigger the second level system which consists of
presence detecting sensor node. In the triggering stage of this level, the second set of
light bulbs and the camera are turned on. Then, the third level of MHSS makes the light
bulbs of the first and the second level to be turned on since the camera needs a higher
brightness level to capture the break-in evidence before it is automatically delivered to
the house’s owner and the law enforcement body. The buzzer will also make noise in
this stage.
The triggered signal is given approximately two minutes before the whole system is
reset. It simply means that the light bulbs will turn off automatically even without any
manual action. Then the whole system is restarted. The whole logic is mainly controlled
by the main control unit of MHSS which consists of an 18F4520 microchip. If one level
has not been stimulated, then the prompting will loop from the specific stage until the
specified period has past. Figure 5 summarizes the process flow of the security
monitoring of MHSS.
(32 pages)
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