Pbx (Simple)

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Design and ImplementingDesign and Implementinga 1-to-4 PBX Systema 1-to-4 PBX System

Using a MicrocontrollerUsing a Microcontroller

Behdad Hosseini

University of Isfahan, Iran

May 2003

(Simple version of the presentation)

(Simple version of the presentation)



IntroductionIntroduction



May 20031-to-4 PBX Project3

ContentsContents

Switching Theory

Telephone Switching SystemAbout The Phonesets




Switching TheorySwitching Theory

Network

SwitchingWe have two major kind of switching:

– Circuit

– Packet




Telephone Switching SystemTelephone Switching System

Definition

Types: – Electronic Technology:

• Analog

• Digital

– Domain:• GX

• PBX




Telephone Switching System:Telephone Switching System:

HistoryHistory

Point-to-point phones in 1876 (Bell)

Manual Telephone Switching Center Crossbar (Matrix) Telephone Switching Center

Automated Central Telephone Switching

Analog Telephone Switching System

Digital Telephone Switching System

Exchange System


http://slidepdf.com/reader/full/pbx-simple 7/30May 20031-to-4 PBX Project7


Some Technical WordsSome Technical Words

Line

Trunk Tip & Ring

Inbound Signaling

Outbound SignalingConversation Circuit




GX ConnectionsGX Connections

… GX Switching System

Data Processing

System

Monitor Panel

Power

Trunks&

Another GX

Phone 1Line 1

Phone 2Line 2

Phone ILine I

Signals




PBX ConnectionsPBX Connections

… … PBX Switching System

Trunk 1GX 1

Data Processing

System

Operator Monitor

Panel

Power

Trunk 2GX 2

Trunk JGX J

Phone 1Line 1

Phone 2Line 2

Phone ILine I



About The PhonesetsAbout The Phonesets

On-hook / Off-hook

VoiceDialing

Ringing

Notifying Tones



The ProjectThe Project



ContentsContents

Title

Behavior Design Considerations

Hardware

SoftwareSample Processes



TitleTitle

“Design and Implementing a 1-to-4 PBX System

Using a Microcontroller”.PBX

1-to-4

Microcontroller



Behavior Behavior

Connections

Dialing modeTones

Number assignments

Services



Behavior:Behavior:

ConnectionsConnections

Project’s PBX Switching

System

Trunk 1GX 1

Data Processing

System

Monitor Panel

Power

Phone 1Line 1

Phone 2Line 2

Phone 4

Line 4

Phone 3Line 3



Design ConsiderationsDesign Considerations

Modular design

– Readability, writablity, debugging – Upgrade & development

Circuit switching (analog)

Nonblocking system

Digital controller (microcontroller from MCS-51TM

family)

Trunk ring policy (with absence of operator)



Hardware:Hardware:

StructureStructure

Control Unit

Line Unit

Trunk Unit

Power

Supply

Unit

Switch Unit

Project’sPBX

System

Monitoring

Signals

Data

Signals

L i n e 1

L i n e 2

L i n e 4

L i n e 3

T r unk

1



Hardware:Hardware:

UnitsUnits

Power Supply Unit

Line UnitTrunk Unit

Switch Unit

Control Unit



Hardware:Hardware:

Some ComponentsSome Components

Relays

Open collector not gatesOpto-couplers



Hardware:Hardware:

BoardsBoards

Power Supply board

Line boardsTrunk board

Conversation Circuit boards

Control board



SwitchUnit

C

onversationCirc

uit0board

pbx.dsn

(“

ConversationCkt0”she

et

)

C

onversationCirc

uit1board

pbx.dsn

(“

ConversationCkt1”she

et

)

C

onversationCircuit2board

pbx.dsn

(“

Conversatio

nCkt2”she

et

)

TrunkUnit

T

runk0board

pbx.dsn

(“

Trunk0”she

et

)

Cont

rolUnit

Con

trolboard

pbx.dsn

(“Control” sheet)

C 0

_ S

0

C 0

_ S

1

C 0

_ S

2

C 0

_ S

3

C 0

_ T O N E

C 1

_ S

0

C 1

_ S

1

C 1

_ S

2

C 1

_ S

3

C 1

_ T O N E

C 2

_ S

0

C 2

_ S

1

C 2

_ S

2

C 2

_ S

3

C 2

_ T O N E

L 3

_ R N G

L 3

_ I N T R

L 3

_ D T C T

L 2

_ R N G

L 2

_ I N T R

L 2

_ D T C T

Lin

eUnit

L

ine2&3board

pbx.dsn

(“

Line2”shee

t

)

pbx.dsn

(“

Line3”shee

t

)

L

ine0&1board

pbx.dsn

(“

Line0”shee

t

)

pbx.dsn

(“

Line1”shee

t

)

L 1

_ R N G

L 1

_ I N T R

L 1

_ D T C T

L 0

_ R N G

L 0

_ I N T R

L 0

_ D T C T

L 0

_ T I P

L 0

_ R I N G

L 1

_ T I P

L 1

_ R I N G

L 2

_ T I P

L 2

_ R I N G

L 3

_ T I P

L 3

_ R I N G

T 0

_ T I P

T 0

_ R I N G

V C C

+ 1 8

V

R i

n g

1

R i

n g

2

Power

Supply

Unit

Power

Supply

board pbx.dsn (“Power Supply” sheet)

T 0

_ C N C T

T 0

_ R D T C T




Software:Software:

StructureStructure

Trunk Hardware Interface Unit

Trunk Control Unit

Trunk Ports

Ring & Tone Generator

Unit

Central Control Unit

Project’s

Software

Architecture

Switch Hardware Interface Unit

Switch Control Unit

Switch Ports

Line Hardware Interface Unit

Line Control Unit

Line Ports




Software:Software:

UnitsUnits

Line Hardware Interface Unit

Trunk Hardware Interface UnitSwitch Hardware Interface Unit

Line Control Unit

Trunk Control Unit

Switch Control Unit

Central Control Unit

Ring & Tone Generator Unit




Software:Software:

ConsiderationsConsiderations

Concurrency

State-based routinesEvent-driven routines




Software:Software:

Phone StatesPhone States

StIdle

StDialingStTrunk

StTalk

StRing

StDialTone

StInvalidToneStBusyTone

StRingbackTone



StRingback

Tone

E v

C o n v

R e q

E v

T o n e

R e q

( T

n D

i a

l

)

StTalk

StRing

StDialTone

StIdle

StDialing

StInvalid

Tone

StBusy

Tone

StTrunk

E v

P i

c k

u p

E v

P u

t d

o w n

E v

S O D

E v

P u

t d

o

w n

E v

P u

t d

o

w n

E v

P u

t d

o

w n

E v

E O D + E

v N

o I

n v a

l i d

E v

E O D + E

v N

o L

i n e

B u s

y

E v

E O D + E

v N

o T

r u n

k B u

s y

E v

E O D + E

v N

o T

r u n

k O K

E v

E O D + E

v N

o L

i n e

R B

E v

P u

t d

o

w n

E v

P u

t d

o

w n

E v

E O R

E v

S O R

EvPickupEvTalk

Accept

E v

T a

l k

A c c e p

t

E v

A l l

R e

l

E v

T a

l k

C a n c e

l

E v

A l l

R e

l

E v

A l l

R e

l

E v

T r u n

k R

e l

E v

A l l

R e

l

E v

T o n e

R e q

( T

n N

o

)

E v

P u

t d

o w n

EvDigitDialed

E v

T o n e

R e q

( T

n I

n v a

l i d

)

E v

T o n e

R e q

( T

n B

u s y

) E v

T o n e

R e q

( T

n R

i n g

b a c

k

)

E v

A l l

R e

l

E v

T o n e

R e q

( T

n N

o

)




Software:Software:

RoutinesRoutines

Initialize & Timer ISR routines

Timing routines

Memory Access routines

Hardware Access routines

Interfaces routines

Controls routinesDebugging routines




Sample ProcessesSample Processes

Internal connection

External connection



SummarySummary



30

SummarySummary

Upgrade trends

Suggestions & upgrade plansThanks!

Pbx (Simple)

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