IVR SYSTEM

Tulika Aggarwal10103465

OVERVIEW OF PROPOSED APPROACH Interactive voice response refers to technology supporting the interaction of

customer with the service provider generally over the telephone lines. When a person wants to access any of the services of the Interactive Voice

Response System, he presses a number through his telephone keypad. The pressed number appears across the line and the ring detector circuit senses this

ring. After a specified number of rings the relay is activated through the

microcontroller, which in turn connects the line to DTMF decoder. The activation of relay causes the number pressed to appear across the DTMF

decoder. The decoder decodes the number pressed and then the decoder output is passed

through the microcontroller to the computer. Now, when the caller presses a number, the number pressed is decoded by the

DTMF decoder and passed to the computer through the microcontroller. The computer recognizes the number and accesses the particular file from the

database to output the voice message. The output voice is passed through the voice card where the digitized serial data is

converted into analog voice form and passed to the line. The caller gets the information through the line.

REQUIREMENTS

HARDWARE REQUIREMENTS

o Basic Microcontroller based Hardware • To interface Telephone line • To provide various control signals Give commands serially to PC o Telephone Line Interfacing Circuit • Ring Detection Circuit o DTMF Decoder Circuit • To detect DTMF Pulses on telephone line o USART Serial Port Driver • For serial communication between

microcontroller and laptop

SOFTWARE REQUIREMENTS

• Net Beans 6.9 • Arduino Interfacing software • Proteus V7.6

COMPONENT DESCRIPTION

DTMF DECODER 8870

The DTMF (Dual Tone Multi Frequency) decoder is a specific IC which performs the function of converting the DTMF frequency tones into BCD codes. These BCD codes are fed to the microcontroller to process the data and take necessary action. DTMF decoder 8870 IC has an external crystal oscillator to generate the clock signal, the pins to detect the presence of DTMF tone at its inputs and pins to transmit the BCD codes to the microcontroller. These frequencies are compared with the Vref at the IN+ pin. This comparator pin output is then filtered and fed to the digital detection algorithm within the IC. It then passes to the code converter where it is converted into 4 BCD codes. Its features are:- • Complete DTMF Receiver • Low power consumption • Internal gain setting amplifier • Adjustable guard time • Central office quality • Power-down mode

PIN DIAGRAM OF DTMF DECODER 8870

MICROCONTROLLER ATMEGA328

Following task are done by microcontroller in our hardware:

1. As power is switched on microcontroller is reset and sets the Mode and the baud rate required for serial communication with PC.

2. Monitors ring detector circuit. When ring detector circuit gives low signal to μC it picks up the phone by applying high signal to ON/OFF hook simulator. 3. Microcontroller now informs the PC that call has been made by sending character ‘1’ to the PC to activate IVRS software. Now μC checks the StD pin status of DTMF decoder.

4. When StD is at logic high level means that a number has been registered. So microcontroller reads it, and transmits that number hex to PC through TxD pin (serial communication).

5. Whenever the user press hash key (#) on telephone pad, then call is to be terminated or if user does not press any number for 70 sec then also call is to be terminated.

6. Microcontroller sends a low signal to ON/OFF hook switch simulator to terminate the call.

PIN DIAGRAM OF ATMEGA328

SERIAL COMMUNICATION INTERFACE

The main purpose of the RS 232 IC is

• To act as a serial interface between the microcontroller and the PC. • It provides the voltage compatibility between the TxD and RxD pins of the microcontroller and the serial port of the PC. • The voltage level of the TxD and RxD pins of the serial port of the PC are 12V. • The R S 232 IC therefore provides compatibility required to interface the computer and the microcontroller.

BLOCK DIAGRAM

IMPLEMENTATION

The circuit was first designed and tested on Proteus V7.6 as below.

• Thereafter using this PCB was made. • In order to communicate between system and microcontroller, a serial port driver board is

used.

• The code for detection of the BUTTON pressed is written in Arduino IDE and burnt. • Thereafter the DTMF Decoder is connected to the Microcontroller.

• Finally a battery is connected and complete system is made functional.

OVERALL CIRCUIT DIAGRAM

OUTPUT ON SERIAL MONITOR

Thank You