POV Using LED’s

1 | P a g e

PERSISTANCE OF VISION USING LED’S

MSC PROJECT REPORT

M.S.Ramaiah Institute of Technology

Dept. of Electronics and Instrumentation Engineering

Submitted To

Dr.R.Elumalai

Professor & Head

Submitted By,

Rajat R Rokade – 1MS12IT039

Jishnu Gopal – 1MS12IT020

POV Using LED’s

2 | P a g e

CONTENTS

CERTIFICATE PAGE NO: 3

ACKNOWLEDGEMENT PAGE NO: 4

PROJECT ABSTRACT PAGE NO: 5

INTRODUCTION PAGE NO: 6

BLOCK DIAGRAM PAGE NO: 7 – 9

MECHANICAL ASSEMBLY PAGE NO: 10

CIRCUITARY PAGE NO: 11 – 15

SOFTWARE USED PAGE NO: 16

CODING PAGE NO: 17 – 18

PICTURES PAGE NO: 19 – 20

CONCLUSION PAGE NO: 21

POV Using LED’s

3 | P a g e

CERTIFICATE

We hereby certify that the work which is being presented in the MSC Project

report entitled “PERSISTANCE OF VISION USING LED’S” has been submitted to

the Department of Electronics and Instrumentation Engineering, M.S.Ramaiah

Institute of Technology, Bangalore, India is an authentic record of our own work

carried out during a period of November-2014 to December-2014 under the

supervision of Dr.R.Elumalai, Professor & Head, Electronics and Instrumentation

Engineering Department.

Signature of Students

Rajat R Rokade-1MS12IT039

Jishnu Gopal-1MS12IT020

This is to certify that the above statements made by us is correct to the best of

our knowledge.

Signature of Supervisor:

Dr.R.Elumalai Professor & Head Dept. of Electronics and Instrumentation Engineering M.S.Ramaiah Institute of Technology

POV Using LED’s

4 | P a g e

ACKNOWLEDGEMENT

We would like to express our special thanks of gratitude to our Professor Dr.R.Elumalai, Dept. of Electronics and Instrumentation Engineering, M.S.Ramaiah Institute of Technology who gave us an opportunity to do this project on the topic ‘PERSISTANCE OF VISION USING LED’S, which helped us in understanding the subject very well and also gave us an exposure to many new concepts. It has given us a lot of confidence and this will help us in our future projects. It also helped us to understand how a group work is being carried and to work efficiently as a team member. Secondly we would also like to thank our parents and friends who helped us a

lot in finalizing this project within the limited time frame.

Signature By,

Rajat R Rokade – 1MS12IT039

Jishnu Gopal – 1MS12IT020

POV Using LED’s

5 | P a g e

Project Abstract

This project is a special kind of circular LED display. With the help some

mechanical assembly, LED count, hardware requirement, and hence overall cost

is cut to very affordable price. Also, maintenance and repairing of the display is

so easy, that anyone having a little electronics knowledge, can take care of this.

All the synchronizing can be implemented through software.

First of its kind, made using the 20-pin 8051 series microcontroller, this project

use the principle of Persistence of vision. This propeller display is mechanically

scanned and displays the characters in digital format. Made from scrap it can be

used anywhere and everywhere and the most amazing fact about this display is

it’s crystal clear display. This display consists of just 8 bright LEDs which are

rotated to show the display.

This project was started with a simple principle which is frequently encountered

in our everyday life, which is Persistence of Vision. This phenomenon makes one

feel fast moving/changing objects to appear continuous. A television is a

common example, in which image is re-scanned every 25 times, thereby appear

continuous.

Further, a glowing object if rotated in a circle at fast speed, it shows a continuous

circle. By modifying this basic idea, 8 LEDs can be rotated in a circle, showing 8

concentric circles. But if these LEDs are switched at precise intervals, a steady

display pattern can be shown.

Existing Systems:

Existing systems do employ POV principle, but for displaying each pixel,

individual LED is used. This results in a huge number of LEDs even for small sized

displays. By using a propeller type display, LED count can be kept to a bare

minimum. Even 8 LEDs can perform a task of over 525 LEDs.

POV Using LED’s

6 | P a g e

Introduction

Propeller is a term associated with a circular rotating object. As this project

needs to rotate the whole circuit assembly, there must be some prime mover

attached to it. So, the term ‘Propeller’. This project using bright light emitting

diodes for displaying the characters and symbols on its assembly. That’s why this

project is named as ‘PROPELLER LED CLOCK‘. This is the phenomenon which is

related to vision capability of human eye by which an afterimage is thought to

persist for approximately 1/25th of a second. So, if someone is observing the

images at a rate of 25 images per second, then they appear to be continuous.

The best example of this property is the red circle we observe when we rotate

the firecracker or incense stick in circle. This project was started with a simple

principle which is frequently encountered in our everyday life, which is

Persistence of Vision. This phenomenon makes one feel fast moving/changing

objects to appear continuous. A television is a common example; in which image

is re-scanned every 25 times, thus making it continuous. Further, a glowing

objects if rotated in a circle at fast speed, it shows a continuous circle. By

modifying this basic idea, 7 LEDs can be rotated in a circle, showing 7 concentric

circles. But if these LEDs are switched at precise intervals, a steady display

pattern can be shown. Existing systems do employ POV principle, but for

displaying each pixel, individual LED is used. This results in a huge number of

LEDs even for small sized displays. By using a propeller type display, LED count

can be kept to a bare minimum. Even 7 LEDs can perform a task of over 525

LEDs. Applications can find their way into cost effective solutions for large public

displays, information systems. It can directly replace Railway station information

displays, bus stands and many more places.

POV Using LED’s

7 | P a g e

BLOCK DIAGRAM

Microcontroller

AT89S52

LED Array

(8 LED’s)

DC POWER SUPPLY

DC MOTOR

(12V 300rpm)

POV Using LED’s

8 | P a g e

Microcontroller: The AT89S52 is a low-power, high-performance CMOS 8-bit

microcontroller with 8K bytes of in-system programmable Flash memory. The

device is manufactured using Atmel’s high-density nonvolatile memory

technology and is compatible with the industry-standard 80C51 instruction set

and pin out. The on-chip Flash allows the program memory to be reprogrammed

in-system or by a conventional non-volatile memory programmer. By combining

a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip,

the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible

and cost-effective solution to many embedded control applications. The

AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes

of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit

timer/counters, a six-vector two-level interrupt architecture, a full duplex serial

port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed

with static logic for operation down to zero frequency and supports two

software selectable power saving modes. The Idle Mode stops the CPU while

allowing the RAM, timer/counters, serial port, and interrupt system to continue

functioning. The Power-down mode saves the RAM contents but freezes the

oscillator, disabling all other chip functions until the next interrupt or hardware

reset.

POV Using LED’s

9 | P a g e

LED ARRAY: LED array consists of 8 bright red LED’s is fixed in another side of

the arm of our project. These LEDs are connected with each of the port pin of

microcontroller, with a series current limiting resistor of 220 ohm. All the LED’s

are connected in active low logic i.e. common anode mode.

DC MOTOR: Repeated scanning of the display is must for continuous vision. This

task is achieved using circular rotation of the whole circuit assembly. So, we used

a DC motor as the prime mover. We are making use 12v 300RPM geared motor

with 6mm shaft.

DC POWER SUPPLY: For microcontroller, as well as the DC motor, a regulated

DC power supply is required. We have to provide +5V to the microcontroller,

while +12V to the motor. For 12v we are making use of an adaptor.

POV Using LED’s

10 | P a g e

MECHANICAL ASSEMBLY

Mechanical assembly plays a vital role in proper functioning of this project. The

display is scanned each time, by rotating the whole assembly in a circular path.

The basic idea we developed is on our own, by implementing and modifying

different ways to do this.

Following diagram shows the most reliable way, that we finally selected. Here,

one major challenge was how to bring +5V supply to the spinning circuit. We

tried the same by adopting two-three different methods, but finally concluded

on the method, as shown in the figure.

Circuit

5V 12V

GND

POV Using LED’s

11 | P a g e

CIRCUITARY

MICROCONTROLLER AT89S52:

POV Using LED’s

12 | P a g e

The basic circuit for the microcontroller is as shown in the above diagram.

It has a crystal of 11.0592 MHz which is connected between two 33pF

capacitors to generate clock frequency. Pin no 19 in input frequency and Pin no

18 is the output frequency. This crystal decides the operating frequency of the

microcontroller.

Since we are not making use any external program we are connecting the Pin

31, i.e. External Access pin to Vcc and make use of the code present in the

program memory of our microcontroller.

The important part of the microcontroller is the reset circuit. Reset is the active

High input. When RESET is set to high, 8051 goes back to the power on state.

The 8051 is reset by holding the RST high for at least two machine cycles and

returning it low.

There are two method of reset circuit:

1. Power on Reset

Initially charging of capacitor makes RST high.

When capacitor charges fully it blocks DC

2. Manual Reset: losing the switch momentarily will make RST high.

We make use of Power on reset in our Project.

POV Using LED’s

13 | P a g e

POWER SUPPLY

The microcontroller in our project requires a 5v as power to the Vcc. Therefore

we make use of the voltage regulator 7805. This IC has very good internal

current-limiting and thermal shutdown features. We made use of 7805 as a

source of power to our microcontroller.

LED CIRCUIT

POV Using LED’s

14 | P a g e

We are using LED’s in active low i.e. common anode mode. This mode will help

to make use of the sink current of the microcontroller without any driver

circuit to drive the LED’s. We have the current limiting resistors of 220 ohm

each connected to the 8 LED’s. These LED’s can be connected to any port of

the Microcontroller. We have made use of the PORT 1.

MOTOR CIRCUIT

His circuit is used to control the speed of the motor. This will act as

safety circuit for motor as it control the current to the motor and hence

avoids burn out.

300 RPM

DC

MOTOR

100 OHM

TRIM POT

12 V….1A

ADAPTOR

POV Using LED’s

15 | P a g e

FLASH PROGRMMER CIRCUIT

In Serial programming single bit is transferred at a time using ISP protocol

therefore Serial programmers also called ISP programmers. The hardware

needed is very simple and small. There is no need to take out the target

microcontroller from the circuit. ISP programming requires 6 pin of the target

microcontroller (including Vcc and GND).

1. Vcc (Pin No. 40): Connected to +5V supply. 2. GND (Pin No. 20): Connected to Ground. 3. RESET (Pin No. 9): Made high (1). It tells the target controller that it is under

the programming mode. 4. SCK (clock pin, Pin No. 8): This pin is used to supply clock to the target

microcontroller. 5. MISO: Master In Slave Out (output pin, Pin No. 7): This is the output pin of the

target microcontroller which sends the acknowledgement signals to the master controller.

6. MOSI: Master Out Slave In (input pin, Pin No. 6): This is the input pin of the target microcontroller. Every signal including data, address and control are received on this pin of the target microcontroller.

POV Using LED’s

16 | P a g e

SOFTWARES USED

KEIL C51: The Keil C51 C Compiler for the 8051 microcontroller is the most popular 8051 C compiler in the world. It provides more features than any other 8051 C compiler available today. The C51 Compiler allows you to write 8051 microcontroller applications in C that, once compiled, have the efficiency and speed of assembly language. Language extensions in the C51 Compiler give you full access to all resources of the 8051.The C51 Compiler translates C source files into relocatable object modules which contain full symbolic information for debugging with the µVision Debugger or an in-circuit emulator. In addition to the object file, the compiler generates a listing file which may optionally include symbol table and cross reference information. We used the keil compiler to write the program code. The code is written in c language.

PROGSIP 1.72: This software is used to load flash into the microcontroller using

the 8051 programmer. This loads the hex file into the microcontroller and also has the feature to verify the loaded flash.

POV Using LED’s

17 | P a g e

CODING

Coding can be done with two types of notation i.e. active high and active low. Let us consider 5*7 matrix

ACTIVE LOW:

ACTIVE HIGH:

POV Using LED’s

18 | P a g e

PROTOTYPE OF THE CODE:

Void Delay( )

{

}

Main ()

{

While(1)

{

P1=0x81;

Delay();

P1=0x6f;

Delay();

P1=0x6f;

Delay();

P1=0f81;

Delay();

.

.

.

}

}

POV Using LED’s

19 | P a g e

PICTURES

POV Using LED’s

20 | P a g e

POV Using LED’s

21 | P a g e

CONCLUSION

This is a cost effective solution for large public displays, information systems. It

can directly replace Railway station information displays, bus stands and many

more places.

Future improvements can involve the RGB colours of an image and display

image using this.

These systems are the latest and the most practical way creating semi-

transparent displays which can also be used to create three dimensional

effects by controlling the intensity of each display unit (LED).

This idea can be taken into the concept of 3D image.