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Aim

To Study the 8051 kit to kit communication using Optic Digital link

Apparatus Required

Fiber Optics Digital Transmitter Module- 01

Fiber Optics Digital Receiver Module- 01

☞Plastic Fiber cable 1 meter - 01

☞PS 8051 kit - 02

☞Adapter +15V/ DC - 02

☞Patch Chords - 04

☞PC to PC cable - 02

Theory

Kit to Kit communication

Fiber optic digital link was used to transmit and receive the data from one place another place .In this digital link will be supporting 1Mbd speed data communication. It will be act as an optical data modem. So we can use this digital link system in various sectors. And this digital link was used RS 232 serial port for communication.

Transmitter

The heart of the transmitter is a light source. The major function of a light source is to convert an information signal from its electrical form into light. Today's fiber-optic communications systems use, as a light source, either light-emitting diodes (LEDs) or laser diodes (LDS). Both are miniature semiconductor devices that effectively convert electrical signals into light. They need power-supply connections and modulation circuitry. All these components are usually fabricated in one integrated package.

Transmitting LED HFBR 1251



Transmitting LED HFBR 1251

This type LEDs needs external Driver circuits. Here we used IC 75451 for drive the LED.

Optical fiber

The transmission medium in fiber-optic communications systems is an optical fiber. The optical fiber is the transparent flexible filament that guides light from a transmitter to a receiver. An optical information signal entered at the transmitter end of a fiber - optic communications system is delivered to the receiver end by the optical fiber.

Model Diagram for Plastic Fiber cable



Model Diagram for Plastic Fiber cable

This is multi mode plastic fiber cable, in this fiber cable core diameter 1000 micron and fiber cladding index 1.402.

Receiver

The key component of an optical receiver is its photo detector. The major function of a photo detector is to convert an optical information signal back into an electrical signal (Photocurrent). The photo detector in today's fiber - optic communications systems is a semiconductor photodiode (PD). This miniature device is usually fabricated together with its electrical circuitry to from an integrated package that provides power-supply connections and signal amplification.

Receiving Photo Diode HFBR 2521


Receiving Photo Diode HFBR 2521

In this type Photo Diode have internal driver circuits. So no need any external driver.

 

Procedure

☞Connect +15V adapter to both transmitter and receiver module.

☞Switch (sw1) ON the transmitter Module,  8051 kits and receiver module (sw1).

☞Connect PC to PC cable between 8051 kit 1 to transmitter module P5 connector and receiver module P8 connecter to 8051 kit 2.

☞Connect the 1 m Plastic fiber cable between transmitter modules LED to receiver module Photo Diode.

☞Connect P7 and P9 using patch chord at transmitter module.

☞Connect P3 and P7 using patch chord at receiver module.

☞Now type the transmitter program in transmitter side kit and receiver program in receiver side8051 Kit.

8051 Transmitter Program

Memory Address

Opcode

Mnemonics

8500

75,89,21

MOV TMOD,#21

8503

75 8D FD

MOV TH1,#FD

8506

75 98 52

MOV SCON,#52

8509

D2 8E

SETB TR1

850B

74 41

H:MOV A,#41

850D

B1 00

ACALL TXMT

850F

74 42

MOV A,#42

8511

D1 00

ACALL TXMT

8513

80 FE

SJMP 8517

8600

F5 99

MOV 99,A

8602

30 99 FD

JNB 99,8602

8605

C2 99

CLR 99

8607

22

RET

 

8051 Receiver Program

Memory Address

Opcode

Mnemonics

8500

90 87 00

MOV DPTR,#8700

8503

75,89,21

MOV TMOD,#21

8506

75 8D FD

MOV TH1,#FD

8509

75 98 52

MOV SCON,#52

850C

D2 8E

SETB TR1

850E

30 98 FB

JNB RI,850C

8511

E5 99

MOV A,99

8513

F0

MOVX @DPTR,A

8514

A3

INC DPTR

8515

80 F5

SJMP 850C

8516

F5 99

MOV SBUF,A

8518

22

RET


☞First execute the receiver side 8051 Kit, then transmitter side 8051 Kit.

☞Now received data verified from 8700 address in receiver side 8051 kit.

Refer below links for more experiments:

Fiber Optic Digital Link

PC TO PC COMMUNICATION USING OPTICAL DIGITAL LINK

BIT RATE OF OPTICAL DIGITAL LINK SYSTEM