PROJECT TITLE:

PERSISTENCE OF VISION DISPLAY

SUMMARY: WHEN SOMETHING HAPPENS AT A FASTER RATE EVERYTHING APPEARS TO BE

MERGED, LIKE WHEN A FAN IS ROTATING THEN ALL IT’S WINGS APPEAR AS ONE , AS WE

PEDAL MORE AND MORE THEN THE SPOKES OF THE BICYCLE APPEAR AS ONE,WHEN

DROP BY DROP WATER FLOWS AT FASTER RATE WE FEEL THE CONTINUOUS FLOW OF IT

ETC... THESE EVENTS ALL APPEAR CONTINUOUS TO HUMAN’S EYES THOUGH THEY TAKE

PLACE DISCRETLY AT SEPARATE TIME INTERVALS. THIS IS DUE TO CONCEPT OF

PERSISTENCE OF VISION. USING THIS IDEA I HAVE BUILT A MODEL WHICH IS CALLED AS

PERSISTENCE OF VISON DISPLAY. THIS SETUP CREATES A VISION(MAY ALSO BE CALLED

AS ILLUSION) USING JUST FEW LEDS WHICH IS SET UP ON A TABLE FAN AND HAS ONLY

8 LEDS MOUNTED ON IT. AND AS THE FAN ROTATES, THE WINGS(ON WHICH LEDS ARE

MOUNTED) START DISPLAYING AS PER THE PROGRAMING WRITTEN IN THE

MICROCONTROLLER 8051 WHICH IS USED. IT WILL DISPLAY LETTERS, WORDS, IMAGES

JUST USING 8 LEDS WITHOUT MAKING ANY CHANGES IN THE NUMBER OF LEDS AND

THE SETUP.

DESCRIPTION:

BLOCK DIAGRAM:

MICROCONTRO

LLER 8051

POWER SUPPLY

8 BLUE LEDS

TOGETHER MOUNTED ON TABLE FAN

DESCRIPTION:

THE OCCURRENCE OF DISCRETE EVENTS AS “ONE” IS CALLED AS “CONTINUOUS OR

PERSISTENCE”. WHEN ANY EVENT TAKES PLACE AT A RATE OF SAY LESS THAN 15MS

THEN, EVERY HAPPENING OF THE EVENT APPEARS CONTINUOUS THOUGH IN REALITY

IT IS NOT.THE MYSTERY BEHIND THIS IS THAT OUR BRAIN CANNOT DETECT SIGNALS

FASTER THAN 15MS SO ANY EVENTS HAPPENING WITH A TIME WHICH EVEN TAKES

LESS THAN 15MS IS PRESUMED AS ONE BY OUR BRAIN.USING THIS CONCEPT I HAVE

BUILT A MODEL ON A TABLE FAN FOR THIS PROJECT ANY ROTATING OBJECT CAN BE

TAKEN BUT, THE SPEED OF THE FAN IS SUPPOSED TO BE AROUND 1000RPM OR MORE

FOR THE VISION TO PREVAIL. ALSO 8 BLUE LEDS ARE USED WITH MICROCONTROLLER

8051 , IR LED SENSOR IS ALSO USED TO DETECT THE MOTION OF THE FAN AND A 9V

BATTERY TO POWER THE SETUP AND WHOLE THING MOUNTED ON A CARDBOARD

WHICH IS MOUNTED ON THE SHAFT OF THE TABLE FAN.

THERE IS AN IR PHOTODIODE CIRCUIT INTERFACED AT THE P3.3 PIN OF 8051

MICROCONTROLLER AND AN IR LED PLACED ON THE TABLE. AS THE FAN ROTATES IR

PHOTODIODE RECEIVED PULSES FORM THE IR LED PLACED ON THE TABLE AND THIS LED

ACTS AS A REFERENCE POINT FOR THE MICROCONTROLLER TO BEGIN IT’S DISPLAY.

SO IN THE PROGRAM THERE ARE TWO DELAYS GIVEN ONE IS OF 20MS AND ANOTHER OF

1.5MS.

THE ONE WITH 20MS IS TO BEGINE THE DISPLAY AT 1/4TH OF THE CIRCUMFERENCE AS

SHOWN BELOW:

Ir transmitter

placed on table

Ir photodiode along

with dev board

continuously rotating

Rotating

1/4th of the

circumference

Ir rays

AND 1.5MS IS THE TIME FOR WHICH LED WILL BE LIT UP AT A PARTICULAR POSITION

ON THE CIRCUMFERENCE.

CIRCUIT DIAGRAM:

CIRCUIT DISCRIPTION:

MICROCONTROLLER 8051:

FEATURES:

1) 8051 have 128 bytes of RAM

2) 8051 have 128 user defined flags

3) it consist of 16 bit address bus

4) it also consist of 3 internal and two external interrupts

5) less power usage in 8051 with respect to other micro-controller

6) it consist of 16-bit program counter and data pointer

7) 8051 can process 1 million one-cycle instructions per second

8) it also consist of 32 general purpose registers each of 8 bits

9) ROM on 8051 is 4 Kbytes in size

10) it also consist of Two 16 bit Timer/ Counter

PORT P1:8 LEDS ARE CONNECTED TO THIS PORT

8051

MICRO

CONTROLLER

8

L

E

D

S

P1.0

P1.1

P1,2

P1.3

P1.4

P1.5

P1.6

P1.7

CALCULATIONS:

THERE ARE THREE SPEEDS ON FAN:

1)480RPM 2)950RPM 3)1120RPM

SO I PROGRAMMED FOR 2)SPEED THAT IS 950RPM

i.e 63.15ms/rotation

pixel size:5*6

size of each led:5mm

distance of leds from centre of shaft is:15cm

so min time for which led remains in position on the circumference is:1.5ms

THE SETUP IS AS SHOWN:

Nuts placed to avoid

wobbling of the setup

Micro controller

8051

9v battery

connector

8leds (blue)

Ir transmitter

TABLE FAN SHAFT

Ir led

(transmitter)

Ic 7805

Ir receiver

Ir receiver

Ir

transmitter

Circuit dig of ir transmitter :

Circuit dig of ir receiver :

Here only one photdiode is connected to 8051

P3.3 pin

VIEW WHEN DISLAY IS DONE:

MANY SUCH DISPLAYS ARE MADE BUT THE CODE FOR “I LOVE ELECTRONICS” IS GIVEN

org 0030h

main:mov p1,#00h //leds connected to port p1

mov p3,#0ffh //p3.3 takes sensor ir photodiode as input as a refrence to start display

mov p1,#00h

mov tmod,#11h

up:

j1:jb p3.3,j1 //wait till refernce point is got and then start display

lcall delay1 //1.5ms(minmimum time for which an led remains in position on the circle)

lcall delay //20ms display should start at 1/4th distacnce on circle from the 1st sensor i/p.

mov p1,#4ch //letter s

lcall delay1

mov p1,#54h

lcall delay1

lcall delay1

mov p1,#64h

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#44h // letter c

lcall delay1

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#44h // letter i

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#44h

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#7ch // letter n

lcall delay1

mov p1,#8h

lcall delay1

mov p1,#10h

lcall delay1

mov p1,#20h

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#7ch // letter o

lcall delay1

mov p1,#44h

lcall delay1

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#74h // letter r

lcall delay1

mov p1,#58h

lcall delay1

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#40h // letter t

lcall delay1

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#40h

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#44h // letter c

lcall delay1

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#54h // letter e

lcall delay1

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#4h // letter l

lcall delay1

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#54h // letter e

lcall delay1

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#18h //heart symbol

lcall delay1

mov p1,#24h

lcall delay1

mov p1,#22h //or 12h

lcall delay1

mov p1,#10h

lcall delay1

mov p1,#5h

lcall delay1

mov p1,#10h

lcall delay1

mov p1,#22h //or 12h

lcall delay1

mov p1,#24h

lcall delay1

mov p1,#18h

lcall delay1

mov p1,#00h

lcall delay1

lcall delay1

mov p1,#44h // letter i

lcall delay1

mov p1,#7ch

lcall delay1

mov p1,#44h

lcall delay1

mov p1,#00h

ljmp up

delay:

mov th0,#0b8h //20ms (to create a delay to start display from 1/4th

of the cicumference)

mov tl0,#015h

setb tr0

j:jnb tf0,j

clr tr0

clr tf0

ret

delay1: //1.5ms (already given under calculations subsection)

mov th0,#0feh

mov tl0,#0fh

setb tr0

b1:jnb tf0,b1

clr tr0

clr tf0

ret

delay12: //1.5ms

mov th0,#0ffh

mov tl0,#1fh

setb tr0 //this delay is only for v&w

cvb:jnb tf0,cvb

clr tr0

clr tf0

ret

end

PROGRAMING OVERVIEW :

1. SENSOR INPUT

2. PROGRAM EXECUTION

3. LED DISPLAYING

BEGINS

4. DISPLAYING LEDS AT

SPECIFIC TIME INTERVALS

5. IMAGE CREATION (VISION) &

BACK TO STEP1.

Video: