DESIGN AND IMPLEMENTATION OF A MICROPROCESSOR BASED ROOM ILLUMINATION CONTROL SYSTEM

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.