Experiment 5 Telephone Switching System Circuit Switched Network

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Experiment 5Telephone Switching System(Circuit
Switched Network)

• YOUNGIK SEO
• March 29, 2005
• Communication Networks Research Lab.
• Division of Electrical Engineering
• Dept. of EECS, KAIST

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Introduction

• Objective
• Design the Telephone Switching System.
• Study the Circuit Switched Network.
• Control the system using PC program.
• Understand the TDM (Time Division Multiplexing)
  scheme.
• Primary Components of the System
• PCM codec/filter (TP3054)
• Conversion Analog signal ? PCM data
• TSAC (Time-Slot Assignment Circuit) (TP3155)
• Control the PCM codec/filter
• PC Interface
• Connect the printer port of PC with
• the telephone switching system via PC Interface

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Equipment of the System

• Power Supply
• Function Generator
• Input the signal (e.g. sine wave) using Function
  Generator
• Oscilloscope
• Observe the output signal using Oscilloscope
• Telephone Switching System Kit
• 2.048MHz Oscillator Main Clock
• TP3155 chip TSAC
• Four TP3054 chips PCM Codec/Filters
• Two PALC22V10 chips
• Shift Register, Divider of Clock

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Overview of the System
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Telephone Switching System

• PC
• C Programming using Turbo C
• Program control the output signal of the Printer
  Port
• Printer Port
• Parallel output port of the PCL 812G Board
• PC Interface
• Receive 8bit parallel signal of the printer port
• 8bit Shift Register (PALC22V10)
• Convert parallel signal to serial signal
• Transmit this 8bit serial signal to TSAC (TP3155)
• TSAC
• Using control signal transmitted by Shift
  Register,
• Control the circuit switching of four PCM
  Codec/Filters

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Telephone Switching System
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TSAC (TP3155) (1/3)

• Time-Slot Assignment Circuit
• 4 channel, One-directional mode (Mode 1)
• Mode 1 4 channel
• Mode 2 8 channel
• This experiment use Mode 1.
• 32 Time Slot per 1 Frame

1 TS (Time Slot) 0.125 / 32 ms
1- frame 0.125ms ( 1/8kHz)
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TSAC (TP3155) (2/3)

• DC Data Format of TSAC
• Control signal transmitted by Shift Register

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TSAC (TP3155) (3/3)

• Channel Assignment
• Control Data from PC to TSAC

Channel selected
CH1
CH0
Assigned to FSx0 and FSr0 Assigned to FSx1 and
FSr1 Assigned to FSx2 and FSr2 Assigned to FSx3
and FSr3
0 0 1 1
0 1 0 1
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Operation of TSAC (TP3155)

• Terminal 1 ? Terminal 2
• Control Data 01 000001 01 ? 10 000001 10

• Terminal 2 ? Terminal 1
• Control Data 01 000111 10 ? 10 000111 01

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PCM Codec/Filter (TP3054)

• Using 2.048MHz clock, A/D conversion
• MCLKx pin, BLCKx pin
• Input 2.048MHz signal
• FSr, FSx
• From FSx, FSr pin of TSAC
• Input 8kHz pulse (synchronization)
• Input pulse to FSx
• PCM encoding ? Dx ? XMT
• Input pulse to FSr
• RCV ? Dr ? PCM decoding

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TSAC PCM Code/Filter
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Printer Port

• PC transmit Control Signal via Printer Port
• Address 378h
• Register data register, status register,
  control register
• But, this experiment uses only data register.
• 8bit parallel data D0 D7

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C Programming (1/3)

• Using functions related to Printer Port
• Example (for Connection)
• define ADDR_data 0x378
• void main (void)
• sl 0 // Shift/Load
• x 0 // X
• r 1 // R
• data 128sl 64x 32r 4slota
  chaa // Control Data
• data inverse (data) // Inverse the sequence
• outportb(ADDR,data) // Output signal via
  Printer Port
• delay(100)
• sl 1 // Shift/Load
• data 128sl 64x 32r 4slota
  chaa // Control Data
• data inverse (data) // Inverse the sequence
• outportb(ADDR,data) // Output signal via
  Printer Port

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C Programming (2/3)

• Main Function Flow Chart

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C Programming (3/3)

• Connection Function Disconnection Function Flow
  Chart

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Pre-lab Report (1/2)

• 1. C Programming the following functions.
• connect, disconnect, display status, multicast,
  reset
• 2. Fill in a blank.
• Digital Output to Printer Port
• 128 _ 64_ 32_ 16_ 8_ 4_ 2_ _
• Hint S/L, X, R, Timeslot, Channel or 0
• 3. (1) Explain the role of Dr, Dx pin of TP 3054
  chip.
• (2) Suppose that phone 0 and 2 are connected,
  and phone 1 and 3 are connected. (timeslot
  0,1,2 or 3) -gt Fill in a blank.

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Pre-lab Report (2/2)

• (3) Fill in blanks
• (channeli of terminal which is connected
  with terminal i)
• (sloti of time slot for transmission by
  terminal i)
• channel0_ channel1_ channel2_
  channel3_
• slot0_ slot1_ slot2_ slot3_
• (4) Explain the role of Fsr, Fsx pin of TP 3155
  chip and TP 3054 chip.

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Main Lab Report(1/3)

• Assemble the testbench in page 4
• Set the SW1 and SW2 to TX0 and TR0
• Test the connect, disconnect, display status,
  multicast, and reset functions using IN0IN3 and
  OUT0OUT3
• Draw timing diagram among CLK,XMT,RCV,TSx,
  IN0IN3, and OUT0OUT3 using Oscilloscope
• Explain the operation of the chips using the
  timing diagram

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Main Lab Report(2/3)

• If you use timeslot 0 and 1 to communicate
  Terminal 2 and 3, what is the procedure for
  connection setup? Fill the blanks of the table.

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Main Lab Report(3/3)

• Draw the telephony system expanding the telephone
  switching kit
• Any comment

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Experiment tips

• References
• National Semiconductor, TP3155 data sheet
• National Semiconductor, TP3054 data sheet
• Cypress, PALC22V10 data sheet
• These materials are uploaded in this lecture
  homepage
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