V. SENSOR NODE
Since LED is inherently a DC load, it can be controlled using a microcontroller. Lighting control require a sensor node
to control the LED lights. A single sensor node contains a microcontroller, sensors, power supply and a transceiver.
Fig.9 shows a single sensor node block. Sensor part may have an LDR or PIR sensors [11] to control the lighting and to save the energy usage [7]. It is a closed loop operation on light intensity, and light intensity is proportional to the current
flowing through the light. Sensor will sense a combined light output of daylight and LED lamp, and then according to the
reference set in the microcontroller, the intensity of the lamp is varied. Five lamps are placed in different zones and the
central controller will detect the light intensity in each zone and adjusts the intensity accordingly via the sensor nodes