Aim

To Study the 8085 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 8085 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

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

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.

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, 8085 kits and receiver module (sw1).
• Connect PC to PC cable between 8085Kit 1 to transmitter Module P5 connector and receiver module P8 connecter to 8085Kit 2.
• Connect the 1 m Plastic fiber cable between transmitter Module 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 side 8085 Kit.

8085 Transmitter Program

Address	Opcode	Mnemonics
9100	21 00 92	LXI H,9200
9103	3E B6	MVI A,B6
9105	D3 23	OUT 23
9107	3E 40	MVI A,40
9109	D3 22	OUT 22
910B	3E 01	MVI A,01
910D	D3 22	OUT 22
910F	0E 05	RELOAD : MVI C,05
9111	DB 01	CHECK : IN 01
9113	E6 04	ANI 04
9115	CA 11 91	JZCHECK
9118	7E	MOV A,M
9119	D3 00	OUT 00
911B	23	INX H
911C	FE 3F	CPI 3F
911E	C2 0F 91	JNZ RELOAD
9121	0D	DCR C
9122	C2 11 91	JNZ CHECK
9125	CF	RST 1

8085 Receiver Program

Address	Opcode	Mnemonics
9100	21 00 92	LXI H,9200
9103	3E B6	MVI A,B6
9105	D3 23	OUT 23
9107	3E 40	MVI A,40
9109	D3 22	OUT 22
910B	3E 01	MVI A,01
910D	D3 22	OUT 22
910F	0E 05	RELOD : MVI C,05
9111	DB 01	CHECK : IN 01
9113	E6 02	ANI 04
9115	CA 11 91	JZ CHECK
9118	DB 00	IN 00
911A	77	MOV M,A
911B	23	INX H
911C	FE 3F	CPI 3F
911E	C2 0F 91	JNZ RELOAD
9121	0D	DCR C
9122	C2 11 91	JNZ CHEAK
9125	CF	RST 1
9126	CF	RST 1

☞First execute the receiver side 8085 kit.

☞Give the transmitting data from 9200 address and execute the transmitter side 8085 kit.

☞Now received data verified from 9200 address in receiver side 8085 kit.