Indian Institute of Technology Hyderabad AUTOMATIC ROOM LIGHT CONTROLLER by V Swetha B Deepthi Priya as

Functions of the controller  This controller performs the task of controlling the room lights as well as counting the number of persons in the room accurately  The total number of persons in the room is displayed on the seven segment display  When a person enters into the room, the counter is increased by 1 and the light glows  In the absence of person in the room, the light automatically goes off

Circuit Diagram

IR Sensor  A pair of LEDs can be used as IR sensors.  The first IR LED is used to emit signals  The second one receives the input and transmits the signals.  When an object comes within the range of the emitted IR, it reflects the IR back to the receiving LED  Then a signal is produced from the IR.

Microcontroller  This is the CPU of our project  We used AT89S52 microcontroller  It receives the signal from the sensors  This signal is operated under the control of software which is stored in ROM  Microcontroller At89S52 continuously monitor the IR receivers  When any object passes through the IR receivers, then the IR rays falling on the receivers are obstructed

 This obstruction is sensed by the microcontroller and count is displayed on seven segment display. Crystal Oscillator  It is an electronic circuit that uses the mechanical resonance of vibrating crystal of piezoelectric material  The material creates an electrical signal with a very precise frequency

Block Diagram IRTXIRTX IRRXIRRX 89S52 RELA Y pP2.0 P2.1

Advantages and future development  It can be used in various rooms like seminar halls, where the capacity of the room is limited and should not be exceeded  It can be used in our homes because we often forget to switch off our room lights  It helps in energy conservation  In future, we can send this data to remote areas using mobile or internet  Voice alarm system can be used to indicate that room is full & person can’t enter inside