05-04-2012, 12:59 PM
AUTOMATIC CALL BELL SYSTEM
ABSTRACT
This project takes over the task of ringing of the bell. It replaces the manual switching of the bell. The circuit comprises of a transmitter unit and a receiver unit, which are mounted face to face such that the IR beam gets interrupted when someone passing through it. The Transmitter circuit is built around LM555timer IC. The infrared (IR) beam is transmitted through IR LED1. The receiver circuit comprises of IR sensor TSOP1738, AT89C51 microcontroller, Buzzer and some resistors and capacitors .The power supply for the receiver is done by using a 5V adapter. The transmitter and receiver circuits are aligned in such a way that the IR beam fall directly on the IR sensor. When anyone interrupts the IR beam falling on the sensor the Bell Rings automatically. The bell keeps ringing as long as one stands between transmitter and receiver.
BLOCK DIAGRAM OF TRANSMITTER AND RECEIVER CIRCUITS
CONCLUSION
This project is successfully designed and tested. Detailed study of all the components used in the circuit has been performed. The design of the circuit includes the study of 8051 microcontroller which was also done. This circuit is designed to make the bell ring automatically when anyone interrupts the IR beam. The main aim of the circuit is to replace the manual switching of the bell.
Automatic Cell Bell System consists of following main components:
LM555 timer: It is high stable devices for generating accurate time delays and oscillations. Additional Terminals are provided for triggering or reset if desired. In the time delay mode of Operations, the time is precisely controlled by one external resistor or capacitor. AT89C51: The AT89C51 is a low –power, high –performance CMOS 8-bit microcomputer with 4k bytes of Flash Programmable and Erasable Read Only Memory (PEROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard MCS-51TM instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.
DEVELOPING THE ABOVE AUTOMATIC CALL BELL SYSTEM INVOLVES THE FOLLOWING STEPS:
Study of 8051 microcontroller.
Study of LM555 timer IC.
Study of Tsop17…series sensors.
Study of light emitting Diodes (LED’S).
Designing the circuit of the above system with selected components.
To test whether the selected components follow standards.
Final step is implementation.
INTRODUTION:
This project takes over the task of ringing of the bell. It replaces the manual switching of the bell. It has an inbuilt LM555 timer which provides the time delay. The Microcontroller AT89C51 is used to control all the functions. The AT89C51 is a low power, high performance CMOS 8-bit microcomputer with 4k bytes of Flash programmable and Erasable Read Only Memory (PEROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard MCS-51tm instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in system or by a conventional nonvolatile memory programmer. By combing a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly flexible cost effective solution to many embedded control applications.
The circuit comprises of Transmitter and receiver units, which are mounted face to face such that the IR beam gets interrupted when someone passing through it. The Transmitter circuit is built around LM555 timer. The transmitter circuit also consists of IR LED1 through which the IR beam is transmitted. This IR LED is connected in series with a 100 ohms resister to the output pin. Two potentiometers 22k ohms and 10k ohms are connected to the VCC. The capacitors 1uf and 0.01uf are connected to the 6th and 5th pin respectively and are grounded.
INTRODUCTION TO 8051 MICRO CONTROLLER
The whole story begin in the far 80s when Intel launched its series of the microcontrollers labeled with MCS051. Although, several circuits belonging to its series had quite modest features in comparison to the new ones, they took over the world very fast and became a standard for what nowadays is ment by a word microcontroller.
The reason for success and such a big popularity is a skillfully chosen configuration which satisfies needs of a great number of the users allowing at the same time stable expanding (refers to the new types of the microcontrollers). Besides, since a great deal of software has been developed in the meantime, It simply was not profitable to change anything in the microcontrollers basic core.
That is the reason for having a great number of various microcontrollers which actually are solely upgraded versions of the 8051 family. What is it what manufacturer it today under different name?
As shown on the previous picture, the 8051 microcontroller has nothing impressive at fast sight
4 Kb program memory is not much at all.
128Kb RAM satisfies basic needs, but it is not imposing amount.
4 ports having in total of 32 input/output lines are mostly enough to make connection to peripheral environment and are not luxury at all.
As it is shown on the previous picture, the 8051 microcontroller have nothing impressive at first sight:
The whole configuration is obviously envisaged as such to satisfy the needs of most programmers who work on development of automation devices. One of advantages of this microcontroller is that nothing is missing and nothing is too much. In other advantages is the way RAM is organized, the way Central Processor Unit (CPU) operates and ports which maximally use all recourses and enable further upgrading.
THE FOLLOWING IS THE CONNECTION DIAGRAM OF LM55TIMER.
1) GND 2) TRIGER 3) OUTPUT 4) RESET 5) CONROL VOLTAGE
6) THRESHOLD 7) DIS CHARGE 8)+VCC
The receiver unit comprises of IR sensor Tsop1738. This is used to receive the Ir beam From the IR LED1. This unit also consists of AT89C51 microcontroller. The out put pin of the Tsop1738 is connected to the 10th pin of the microcontroller. The following is The AT89C51 microcontroller,
PIN DIAGRAM OF AT89C51
The 10th pin of the microcontroller is receiver pin. And then the 11th pin is connected to the Buzzer from which the sound is produced. Here the 11th pin of the microcontroller is the transmitter pin. When anyone interrupts the IR beam falling on the sensor the bell rings. The bell keeps ringing as long as one stands between transmitter and receiver. The one end of the buzzer is connected to the VCC and the other end is connected to the ground
This concept is better understood by observing the circuit diagram shown in the figure1. the IR beam from IR LED1 are received by the IR sensor and this connected to 10th pin of the microcontroller. And the 11th pin is connected to the buzzer. When anyone interrupts the Ir beam falling on the sensor the bell rings automatically. The bell keeps ringing as long as one stands between transmitter and receiver.