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COMPACT AND COST EFFECTIVE DIGITAL PRIVATE BRANCH EXCHANGE USING

ARM PROCESSOR

By

M.Muneeswaran (9910108007)

II M.Tech /EST

Guided by

Mr. D.Ganesha Perumal

AP-I/EEE

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PRIVATE BRANCH EXCHANGE

Introduction:• Private Branch Exchange means a private telephone system

which is part of a larger network system [Public Switched Telephone Network (PSTN)] that exchange information.

• PBX is installed in a business location to facilitate communication between people inside the organization while allowing access to adequate external telephone lines.

• Analog PBX shows result in low voice and cross talk errors.

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ABSTRACT

• Design and Implement a Digital PBX system Using 32-Bit ARM processor which supports more than 100-Extension lines and 20-Trunk lines. The ARM 9 (S3C2440A) based DPBX CPU performs:– Establish a connection between two terminals during a

phone call.– Maintain a connection as long as the users require it.– Provide call details for accounting purposes.

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DPBX CPU USING PENTIUM I PROCESSOR

• Availability of Pentium I is difficult(obsolete model).• It support 100-Extension and 12-Trunk lines(support upto 200

MHz)• Larger in CPU size.• High CPU cost.

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DPBX CPU USING ARM-9 PROCESSOR

• Processor Availability.• It support more than 100-Extension and 20-trunk lines(support

upto 533Mhz).• Compact CPU size.• Reduced CPU cost.• Low power Consumption.

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BLOCK DIAGRAM

Extension Circuit

Extension Circuit

PCM Codec

PCM Codec

Digital cross point CPU

ARM 9 Processor

DTMF Transceiver

Tone section

PCM Codec

Trunk Circuit

Trunk line

Phone 2

Phone 1FLASH MEMORY

SDRAM

EEPROM

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DTMF RECEIVER

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PHASE I DTMF RECEIVER OUTPUT

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DIGITAL CROSS POINT CPU CARD

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INTERFACING CIRCUIT FOR DIGITAL CROSS POINT SECTION

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MT8980( DIGITAL CROSS POINT )SECTION

• TDM(Time Division Multiplexing) is used for transmitting several message signals over a single communication channel by dividing the time frame into slots, one slot for each message signal

• It has 8- TDM 2048kbit/s ST-BUS stream input and stream output line.• Each stream has 32-channel.• 4(A0-A4)- address line for selecting channel.• A5 is used to selecting control registers.• In control registers, we can select connection memory high , connection

memory low & data mode.• Every read (or) write operation, data acknowledgement signal received in

DTA.• Necessary clock signal 4.096MHz(C4i) & 8kHz(F0i-Framing 0-type --

frame synchronization pulse for the 2048 kbit/s ST-BUS) is generated by using Frequency divider and 4-bit Synchronous counter.

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CPU control circuit design

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NON-BLOCKING SWITCHING

MT8980#1

MT8980#2

MT8980#3

MT8980#4

STi0-STi7

STi8-STi15

STo0-STo7

STo8-STo15

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READING SPECIFIC CHANNEL INFORMATION

Parallel to serial converter

ChannelSelection

Serial Output to STREAM INPUT

Parallel Input Data from Control circuit

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WRITING SPECIFIC CHANNEL INFORMATION

Serial to Parallel converter

ChannelSelection

Parallel Output Data to Control Circuit

Serial Input from STREAM OUTPUT

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8KHZ & 4.096MHZ FREQUENCY

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OUTPUT STREAM AT POWER UP CONDITION

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OUTPUT STREAM AT INITIALIZATION WITH ALL CHANNEL AS 0XFF

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OUTPUT STREAM WHEN SWITCHING WITH 1MS INPUT STREAM

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ARM PROCESSOR BASED DPBX SYSTEM

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CONCLUSION

• Pentium-I based digital PBX CPU is replaced with 32-bit ARM 9 (S3C2440A) Processor. When this S3C2440A based CPU, it supports more than 100 extension ports and 20 trunk lines.

• In Digital cross point CPU card, Reading information & Writing information & Switching ST-BUS Stream input and output is successfully interfaced with ARM 9 (S3C2440A) Processor to perform the DPBX functionality.

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PUBLICATION

• In National conference on “ Emerging Trends in Nano, Embedded system, Telecommunication’12”(ETNET’12) at Saveetha school of Engineering (Saveetha University), Chennai on 6th April 2012.

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REFERENCES

• Simon Segars, “The ARM9 Family - High Performance Microprocessors for Embedded Applications”, Proceedings ICCD '98. International Conference on, pp. 230 - 235 ,oct 1998.

• Christiensen C. Arandilla, Joseph Bernard A. Constantino, Alvin Oliver M. Glova Anastacia P. Ballesil-Alvarez, Joy Alinda P. Reyes, “High-Level Implementation of the 5-Stage Pipelined ARM9TDM Core”, TENCON 2010 - 2010 IEEE Region 10 Conference, pp. 1696 – 1700, Nov 2010.

• Azlan Bin Sulaiman, Mohd Sharifuddin Bin Mohd Nordin, Namazi Bin Azhari , Dr. Jalil Md. Desa, “Samsung ARM9 S3C2440A Hardware Core Circuit Design”, 2011 IEEE Symposium on Computers & Informatics, pp.352-356, 2011.

• J.M. Kasson, "The Rolm Computerized Branch Exchange: An Advanced Digital PBX," IEEE Transactions on communications, vol. 12, no. 6, pp. 24-31, June 1979, doi:10.1109/MC.1979.1658776

• Mischar schwartz,“History of Communication”,IEEE communication Magazine, pp.13-15, December 2008.

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THANK YOU