Caller Line Identification

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DEPARTMENT OF ELECTRONICS AND COMMUNICATIONS

MAR ATHANASIUS COLLEGE OF

ENGINEERING

KOTHAMANGALAM

MINI PROJECT REPORT-2010

CALLER LINE IDENTIFICATION

GUIDED BY SUBMITTED BY

Mr. AJI JOY (LECTURER IN ECE) ANGELO KURIAN

DEPT OF REG NO: 50363

ELECTRONICS & COMMUNICATION



MAR ATHANASIUS COLLEGE OF

ENGINEERING

KOTHAMANGALAM

CALLER LINE IDENTIFICATION

Bonafide Record of Mini Project done by

ANGELO KURIAN

Reg No: 50363

Dissertation submitted in partial fulfillment of the

Requirements for the degree of

BACHELOR OF TECHNOLOGY

Branch: ELECTRONICS AND COMMUNICATION

Of M.G. University

April-May 2010

Date:…………….

EXTERNAL EXAMINER FACULTY GUIDE



ACKNOWLEDGEMENT

First and foremost, I would like to express my sincere gratitude to my

project guide, Mr.Aji Joy. I was privileged to experience a sustained

enthusiastic and involved interest from his side.

I would also like to thank my seniors who were ready with a positive

comment all the time, whether it was an off-hand comment to encourage

us or a constructive piece of criticism and a special thank to Mr.Jiss Paul

who helped us to clear our various doubts regarding the project.

I thank our HOD Prof.Thomas George providing all the facilities which

helped us to successfully complete the project.

I also thank Ms.Surekha M ,HOD of the CS Department and also Ms.Jiso

George of the CS Dept for providing their lab for the demonstration of

our project

Last but not least, I would like to thank the Electronics and

communication department and the institute, in general, for extending a

helping hand at every juncture of need.



CONTENTS

1. Introduction 5

2. Working Principle 6

3. Block Diagram 8

4. Circuit Diagram 9

5. Circuit Explanation 10

6. Program Section 13

7. PCB Layout 21

8. Components Used 23

9. Softwares Used 24

10. Conclusion 25

11. Reference 26

12. Datasheets 27



INTRODUCTION

Caller ID (caller identification, CID), also called calling line

identification (CLID) or calling number identification (CNID), is a

telephone service, available in analog and digital phone systems and most

Voice over Internet Protocol (VoIP) applications, that transmits a caller's

number to the called party's telephone equipment during the ringing

signal, or when the call is being set up but before the call is answered.

This feature can be useful for example for storing numbers of the people

who have tried to call you when you were not home. This feature is

nowadays activated so that the caller number is transferred always to the

telephone central near called person. If the called person wants to get that

information, he/she must order this service from Telephone Company.

Where available, caller ID can also provide a name associated with the

calling telephone number. The information made available to the called

party may be displayed on a telephone's display or on a separately

attached device.

Caller ID may be used to track down or limit the impact of telemarketers,

prank calls, and other intrusions. However, it can also impede

communication by enabling users to become evasive. The concept behind

caller ID is the value of informed consent

It has enhanced the sense of privacy enjoyed by persons in their homes,

and has also greatly reduced the number of prank calls, as well as calls

made with threatening or criminal intent.

http://en.wikipedia.org/wiki/Telephone

http://en.wikipedia.org/wiki/Vertical_service_code

http://en.wikipedia.org/wiki/Voice_over_Internet_Protocol

http://en.wikipedia.org/wiki/Caller_(telecommunications)

http://en.wikipedia.org/wiki/Called_party


http://en.wikipedia.org/wiki/Ringing_signal


http://en.wikipedia.org/wiki/Telemarketer

http://en.wikipedia.org/wiki/Prank_call

http://en.wikipedia.org/wiki/Informed_consent

http://en.wikipedia.org/wiki/Informed_consent

http://en.wikipedia.org/wiki/Prank_call

http://en.wikipedia.org/wiki/Telemarketer




http://en.wikipedia.org/wiki/Called_party

http://en.wikipedia.org/wiki/Caller_(telecommunications)

http://en.wikipedia.org/wiki/Voice_over_Internet_Protocol

http://en.wikipedia.org/wiki/Vertical_service_code




WORKING PRINCIPLE

When a call is received, the Telephone exchange will send the

caller’s number using DTMF signals just before the first ring is placed.

The exchange will send the number only if the caller id service is

activated with the respective telephone operators. In DTMF telephones

(and exchanges), the numbers are transmitted using different tone

frequency pairs. A normal telephone instrument has 12 buttons (keys)

arranged in three columns and four rows. Each row in the key-pad matrix

activates a specific frequency tone. Similarly, each column also controls a

specific frequency tone. So when a key is pressed, two different tones

corresponding to the row and column combination of the key are

generated. Table I shows the tone frequencies associated with each row

and column of the telephone key-pad. Thus pressing 8 will generate a

combination consisting of row and column frequencies of 852 Hz and

1336 Hz respectively. Similarly, pressing 4 will generate 770 Hz and

1209 Hz combination. The same tone frequency combinations are used

for transmitting calling party’s number from exchange to the called

party’s telephone instrument.



The DTMF decoder decodes each set of frequency pairs representing the

number and the number is available as binary at the output pins of the

decoder when the TOE pin is made high. After decoding each pair of DTMF frequencies the StD pin of the decoder goes high and interrupts

the microcontroller. The output pins of the DTMF decoder are connected

to the port A of the microcontroller. After each interrupt the decoded

number is stored in a register in the microcontroller, once all the numbers

are received, the number is displayed on the LCD. After displaying the

caller’s number on the LCD the number is stored in the internal

EEPROM of the Microcontroller, so that the received number can be

reviewed later. By Pressing RB4 display mode can accessed, By pressing

RB5 you can cycle through the received calls, Pressing RB4 again exits

the display mode.By Pressing RB6 Previous entries can be cleared.When

the memory is full newly received number automatically replaces the

oldest entry in the memory.



BLOCK DIAGRAM

TELEPHONE

DTMF DECODER

MICROCONTROLLER KEYPAD

LCD DISPLAY

INCOMING LINE



CIRCUIT DIAGRAM



CIRCUIT EXPLANATION

POWER SUPPLY

The power is supplied using a 5V DC adapter

DTMF DECODER SECTION

It consists of the CM8870 DTMF Decoder.DTMF decoder CM8870 is

AC coupled to telephone lines and keeps on sensing tone frequencies.

The circuit is configured in balanced line mode. To reject common-mode

noise signals, a balanced differential amplifier input is used. The circuit

also provides an excellent bridging interface across a properly terminated

telephone line. Transient protection may be achieved by splitting the

input resistors and inserting zener diodes (ZD1 and ZD2) to achieve

voltage clamping. This allows the transient energy to be dissipated in the

resistors and diodes, and limits the maximum voltage that may appear at

the inputs. As soon as a valid DTMF digit is detected, it sets StD pin (Pin

15) high and interrupts the micro-controller. DTMF decoder also requires

a Micro-controller which then reads the digital number on four data lines

(D4-D7).The output of the DTMF Decoder can be viewed on the LED’s

Connected to the output pins.



MICROCONTROLLER SECTION

It Consists of the PIC 16F873A Microcontroller. The First pin of the

Microcontroller is connected to the Vcc through a resistor and to the

ground through a switch. The switch acts a reset switch which resets the

microcontroller. The Microcontroller has three ports, Port A is connected

to the output pins of the DTMF decoder (RA0 to RA3). Three switches

are connected to PORT B , the switches are for reviewing the numbers of

the previously received calls. The control pins of the LCD are also

connected to PORT B (RS, R/W, and EN). The output of the pins

connected to the switches S1 to S3 are pulled high using pull-up resistors.

The StD pin of the DTMF decoder which is used to interrupt the

microcontroller is connected to RB0/INT pin (pin 21). The Port C is

connected to the data lines of the LCD.

DISPLAY SECTION

The Display Section Uses a 16 X 2 LCD Display Unit to display and

review the received numbers

LCD display unit: LCD display is a Double-line, 16-character unit.Interface with microcontroller is accomplished via eight data lines D7-D0

and two control lines RS and E. Using these six lines, micro-controller

displays all messages and telephone numbers.

LCD controller is a flexible controller and can be used with 8-bit or 4-bit

micro-controller. In 4-bit mode, only D4-D7 is used, leaving D0-D3

open. In our circuit, we have connected R/W pin to ground as we areusing it for write operation only. Reading back of the module’s status,



which is required to see if LCD module is busy, is not possible. To avoid

problems, extra delays in software are provided after every write

command so that before writing another command/data, LCD module

should be ready (not busy). Here the LCD is used in 8 bit mode.



PROGRAM SECTION

/* PROGRAM FOR CALLER LINE IDENTIFICATION

( USING MPLAB & HITECH C COMPILER ) *

#include<pic.h>

unsigned char i,ad=0,m=0,count=0,dat[10],chk=0,tadd;

unsigned char init[]="caller id";

unsigned char disp[]="display:";

unsigned char clr[]="clearing";

void command(unsigned char c);

void command2(unsigned char c);

void display(unsigned char w);

void display2(unsigned char w);

void delay();

void delay2();

void dispreview(unsigned char c);

void initdisplay();

void interrupt isr(void) // interrupt service routine for pic

{

if (INTE==1&&INTF==1) // to store and display valid dtmf signals

{unsigned char val;

dat[m]=PORTA;



m++;

if(m==11) // to check whether full number is received

{command(0x01);

delay();

for(i=0;i<m;i++) // displaying number on lcd

{val=dat[i]&0x0F;

if(val==0x0A)

{

val=0x30;

}

else

{

val=val|0x30;

}

display(val);

delay();

}

ad=eeprom_read(EEPROM_SIZE-1); /* current memory location in eeprom is

stored in last location of eeprrom */

for(i=0;i<m;i++) // storing number in eeprom

{ val=dat[i]&0x0F;

if(val==0x0A)

{

val=0x30;

}

else



{

val=val|0x30;

}

eeprom_write(ad,val);

ad++;

if(i==(m-1))

eeprom_write((EEPROM_SIZE-1),ad); // updating stored memory location

}

if(ad>=0x6F)

eeprom_write((EEPROM_SIZE-1),0x00); // for resetting on overflow

m=0;

}

INTF=0;

}

if( RBIF==1&&RBIE==1 ) // PORTB interrupt used for displaying previous no.s

{

if( RB4==0 )

{ chk++;

if( chk>1 )

{chk=0;

initdisplay();

}

tadd=(eeprom_read(EEPROM_SIZE-1));

if( chk==1 )



{

command(0x01);

delay();

for(i=0;i<8;i++)

{ display(disp[i]);

delay(); /* press RB4 once for initiating display;

then press RB5 for displaying numbers

stored in eeprom; press RB4 again to

exit display mode */

}

}

}

if(chk==1)

{

if(RB5==0)

{ tadd=tadd-11;

dispreview(tadd);

if(tadd==0)

tadd=(eeprom_read(EEPROM_SIZE-1));

}

}

if (RB6==0) // for manually resetting eeprom

{ command(0x01);

delay();

for(i=0;i<8;i++)

{ display(clr[i]);



delay();

}

eeprom_write((EEPROM_SIZE-1),0x00);

}

RBIF=0;

}

}

void main()

{

unsigned char com[]={0X38,0X07,0X0E,0X80,0X06};

TRISA=0XFF; // decoder o/p given to PORTA

TRISB=0XF3;

/* controls for lcd and display

RB0 : ext int. given to 'std' pin of mt8870

RB2 : data i/p or command i/p

RB3 : enable pin for lcd

RB4-RB6: as interrupt for displaying */

TRISC=0X00; // data o/p for lcd

INTCON=0XD8; // to enable ext interrupt & PORTB interrupt

INTEDG=1; // to set ext int to falling edge

ADCON1=0X06; // for setting PORTA as Digital input

for(i=0;i<5;i++) //initializing lcd



{command2(com[i]);

delay2();

}

command2(0x01);

delay2();

for(i=0;i<9;i++)

{display2(init[i]);

delay2();

}

while(1) // infinite loop

{

delay2();

}

}

void command(unsigned char a) // for giving commands to lcd

{

RB2=0;

PORTC=a;

RB3=1;

RB3=0;

}

void command2(unsigned char a) // for giving commands to lcd

{

RB2=0;

PORTC=a;

RB3=1;



RB3=0;

}

void delay() // delay reqiured for writing into lcd

{

unsigned char b,c;

for(b=0;b<255;b++)

for(c=0;c<255;c++);

}

void delay2() // delay reqiured for writing into lcd

{

unsigned char b,c;

for(b=0;b<255;b++)

for(c=0;c<255;c++);

}

void display(unsigned char a) // to display the argument in lcd

{

RB2=1;

PORTC=a;

RB3=1;

RB3=0;

}

void display2(unsigned char a) // to display the argument in lcd

{

RB2=1;

PORTC=a;



RB3=1;

RB3=0;

}

void dispreview(unsigned char c) // to display numbers from eeprom

{ unsigned char y;

command(0x01);

delay();

for(y=0;y<11;y++)

{display(eeprom_read(c+y));

delay();

}

}

void initdisplay() // to display "caller id" on lcd

{unsigned char e;

command(0x01);

delay();

for(e=0;e<9;e++)

{display(init[e]);

delay();

}

}



PCB LAYOUT

BOTTOM LAYER



TOP LAYER



COMPONENTS USED

1.PIC 16F873A Microcontroller

2.CM8870 DTMF Decoder

3.16 X 2 LCD Module

4.Crystal

5.Zener Diodes

6.LED’s

7.Resistors

8.Capacitors

9.Push Switches



SOFTWARES USED

1. Microchip MPLAB

2. Orcad Capture

3. Orcad Layout Plus

4. Pic Simulator



CONCLUSION

The project entitled “CALLER LINE IDENTIFICATION” has been

designed and developed successfully. The PCB layout is also

created. The project was completed successfully within the

stipulated time, tested and verified.



REFERENCES

1. www.microchip.com

2. www.calmicro.com

3. www.picbasic.nl

4. www.epanorama.net

5. www.efy.com

Caller Line Identification

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