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
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 89S52 IRTX IRRX pP2.0 RELAY 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