pc based appliances

8/2/2019 Pc Based Appliances

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GROUP NO.:_________________

SYNOPSIS

INFRARED TRANSRECEIVER

FOR PC

Submitted by

GUIDED BY ________________________


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INTRODUCTION

This project can be used for the controlling INFRARED TRANSRECEIVER FOR

PC . It consist a circuit for using the printer port of a PC,

for control application using software and some interface hardware.


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The interface circuit along with the given software can be used with the

parallel port of any PC for controlling up to eight equipment. Parallel port is

a simple and inexpensive tool for building computer controlled devices and

projects. The simplicity and ease of programming makes parallel port

popular.

SCOPE OF PROJECT

This project can be used in industries as well as in houses to control the

various appliances through PC. Devices can be controlled from the desktop

while working on it.

DESRIPTION OF PROJECT

BASIC COMPONENTS REQUIRED

1. Personal Computer

2. Optocoupler

3. ULN 2803

4. Electro-mechanical Relay(SPDT)

5. Transformer(15v)

6. Voltage Regulator 78XX

7. Diode(IN4007), Resistors, capacitors


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BRIEF INTRODUCTION TO PARALLEL PORT

Hardware

The pin outs of DB25 connector is shown in the picture below:

The lines in DB25 connector are divided into three groups, they are:

1. Data lines (data bus)

2. Control lines

3. Status lines.

As the name refers, data is transferred over data lines. Control lines are used

to control the peripheral, and of course, the peripheral returns status signals

back to the computer through Status lines. These lines are connected to Data,Control and Status registers internally.

Parallel port registers

The Data, Control and Status lines are connected to there corresponding

registers inside the computer. So, by manipulating these registers in

program, one can easily read or write to parallel port with programming

languages like 'C' and BASIC.

The registers found in a standard parallel port are:

1. Data register

2. Status register

3. Control register


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POWER SUPPLY

REGULATOR IC (78XX)

It is a three pin IC used as a voltage regulator. It converts unregulated DC

current into regulated DC current.

BRIDGE RECTIFIER

A bridge rectifier makes use of four diodes in a bridge arrangement to

achieve full-wave rectification. This is a widely used configuration, both

with individual diodes wired as shown and with single component bridges

where the diode bridge is wired internally.

CIRCUIT DIAGRAM OF POWER SUPPLY


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I have divided complete circuit into three major blocks

1. DTMF decoder2. Micro controller3. DC motor driver

DTMF decoder: -

As shown in figure it is made up form readily available MT8870 chip that iswidely used for DTMF based application. It receives DTMF tones and generates4-bit digital output corresponding to received DTMF signal of digits 0 - 9 and

other signals (like *, # etc) also. It receives input form cell phone to its pin no 2. Itamplifies it through internal op-amp amplifier. If it receives valid DTMF tone, itwill produce pulse output on StD (pin no 15). This is indicated by green LEDconnected as shown. The 4-bit digital output is latched on pins 11 - 14 and that isgiven to micro controller. The StD output is also given to interrupt pin of microcontroller through transistor that will generate negative pulse every time whenDTMF signal is received. This negative pulse will generate an interrupt. All themovements of robotic arm are controlled by cell phone digit switches 1 to 8. The 4bit digital output corresponding to these switches form MT8870 are as given here

Keypad

switch oncellphone

4 bit digital

outputD C B A

1 0 0 0 12 0 0 1 03 0 0 1 14 0 1 0 05 0 1 0 16 0 1 1 07 0 1 1 18 1 0 0 0


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Micro-controller: -

As shown in figure a 40 pin, 8-bit micro controller 89C51 is used for controllingpurpose. It receives 4-bit digital output from DTMF decoder on its port P1 pinsP1.0 - P1.3. And interrupt signal is given to P3.3 (external interrupt 1) pin. It

drives two DC motors through port P2 pins P2.0 - P2.3. A 12 MHz crystal withtwo 33pf capacitors is connected to crystal pins (18 & 19) to provide basic clocksignal to micro controller. One push button switch (RST) in parallel with 100nFcapacitor forms power on reset circuit to reset the micro controller. it will controlthe motion of land rover depending upon the code it receives from DTMFdecoder as given in table

4 bit digitalinput

Hexcode

Movement controllingaction

D C B A0 0 1 0 F2h starts moving forward0 1 0 0 F4h Take a left turn0 1 0 1 F5h Stop moving0 1 1 0 F6h Take a right turn1 0 0 0 F8h Start moving backward

DC Motor driver: -


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As shown in figure L293D is quadruple H-Bridge driver chip that is widely usedfor DC motor and stepper motor driver applications. It receives inputs from

micro controller as shown on its input pins 2,7,10 & 15 and rotates two DCmotors in either direction as per given table

W (pin no 2) X (pin no 7) Y (pin no 10) Z (pin no 15) Motor

1 0 0 0 left motor rotates

0 1 0 0 left motor rotates

0 0 1 0 Right motor rotate

0 0 0 1 Right motor rotate


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So to move the land rover forward or backward - left or right one has to sendfollowing data on port

Motion W

(P2.0)

X

(P2.1)

Y

(P2.2)

Z

(P2.3)

dat

a

Move forward rotate bothmotors CW

1 0 1 0 05h

Move backward rotate bothmotors CCW

0 1 0 1 0Ah

Turn left rotate right motor CW 0 0 1 0 04hTurn right rotate left motor CW 1 0 0 0 01h

Go to next page for software logic and program

HIGH VOLTAGE HIGH CURRENT DARLINGTON TRANSISTOR

ARRAY (ULN2003):

The eight NPN Darlington connected transistors in this family of arrays areideally suited for interfacing between low logic level digital circuitry (such

as TTL, CMOS or PMOS/NMOS) and the higher current/voltage

requirements of lamps, relays, printer hammers or other similar loads for a

broad range of computer, industrial, and consumer applications. All devices

feature opencollector outputs and free wheeling clamp diodes for transient

suppression.

The ULN2803 is designed to be compatible with standard TTL families

while the ULN2804 is optimized for 6 to 15 volt high level CMOS or PMOS
http://multyremotes.com/land-rover-C-program.htmhttp://multyremotes.com/land-rover-C-program.htm


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ULN 2003

RELAY:

A relay is an electrical switch that opens and closes under the control of

another electrical circuit. In the original form, the switch is operated by an

electromagnet to open or close one or many sets of contacts. It was inventedby Joseph Henry in 1835. Because a relay is able to control an output circuit

of higher power than the input circuit, it can be considered to be, in a broad

sense, a form of an electrical amplifier.

Here relay is used for the isolation of various heavy appliances to the PC.

Since the PC operates on very low current, but the current in various

appliances is in Amperes therefore isolation is necessary and relay is

required. Here we have used single pole dual through relay for the purpose.


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CIRCUIT DIAGRAM OF PROJECT

CONCLUSION

The greatest learning experience in this project comes from the design and

construction of PC Based Appliance Controller which answer a lot of

questions regarding the real implementation of Embedded system, Electro-

mechanical relays and Opto-couper, ULN 2803, Parallel Port of PC .

During the development of our project we studied and analyzed many real

world applications

of Electronics and Software Engineering. Some of the theoretical knowledge

that was inculcated in us within our engineering program, which we haveapplied practically, are:

1. Use of voltage regulation and filtering in power supply.

2. Study of parallel ports.

3. Study of C-Language.

4. Study of ULN.

5. Understanding of single pole dual through relay.

6. Study of Optocoupler.

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