Abstract:
This paper describes the development of a microprocessor based room
illumination control system that offers advantage of improved efficiency in the use
of electrical energy and reduced cost of electricity over manually controlled
lighting systems. This system is developed to regulate the intensity of light from
direct current (DC) bulbs when the presence of a person(s) is detected in the room
so that ambient light is always maintained between 135 lux and 300 lux. Lights are
however completely turned OFF if the ambient light level is beyond this range. At
the heart of this system is an Intel 8085 microprocessor which controls all
operations of the system. The infrared and the passive infrared (PIR) sensors are
used to detect the occupancy status of the room while the visible light sensor is
used to detect the ambient light level in the room. The PIR sensor is mounted at a
height of about 2 m which prevents the system from detecting the presence of
animals like cats and dogs in the room and therefore avoids turning the lights ON
falsely. Analog signals are produced as outputs from the three sensors and are fed
to the microprocessor unit (MPU) for processing through the analog-to-digital
converter (ADC). The MPU is then capable of controlling all operations and
automating the system. The entire hardware functioning is coordinated by a
software program written in low level 8085 assembly language and stored in the
erasable programmable read only memory (EPROM). Implementing this system
improves efficiency in the use of electrical energy and reduces the cost of
electricity.
