Indian Institute of TechnologyHyderabad

AUTOMATIC ROOM LIGHTCONTROLLER

byV Swetha

B Deepthi Priyaas

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 projectWe used AT89S52 microcontrollerIt receives the signal from the sensorsThis signal is operated under the control of

software which is stored in ROMMicrocontroller At89S52 continuously monitor

the IR receiversWhen 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 OscillatorIt 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

IRTX

IRRX

89S52

RELAY

pP2.0

P2.1

Advantages and future developmentIt 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 conservationIn future , we can send this data to remote

areas using mobile or internetVoice alarm system can be used to indicate

that room is full & person can’t enter inside