PRESENTED BY:- ARUNAVA PAUL VIJAYKUMAR KULKARNI VIVEKANAND DHAVALE

GUIDED BY:- PROF-V.N.GHODKE

DIGITAL GRAFFITI

Alphanumeric information is commonly entered into microcomputers by typing on a keyboard .

Each key stroke is converted into a coded digital signal ,such as an ASCII code .

Scanning ckt is used to scan the rows & columns of key positions to determine which key position is being touched.

Writing pads enable a user to enter a sketch into the data processor by “writing” on the surface of the pad.

As each point on the sketch is written , the pad senses its location & delivers analog signals corresponding to that location .

The A/D conversion can be done , from which the two coordinate position of the point can be determined.

Existing system Vs Digital graffiti

• Compatible for any computers

• Options selection with help of touch pad

• High accuracy and convenience

• To point out the exact location of the touch

Why to go for digital graffiti?

Research in the field of human computer interaction has led to development of some really smart devices to interface the computer devices like touch screen, touch pad and recently multipoint touch screen are result of that.

These new ways of interaction has also led to development of some really dynamic application & the aim of our project is to propose a design of a touch pad for dedicated customized applications.

Abstract

Touch pad AVR ATmega32

MAX232 PC

Power Supply

Driver circuit

BLOCK DIAGRAM

Multi-point touch pad: It is a grid of passive elements like resistances

mounted on a pcb. Those resistances form a voltage divider circuit. When a position is measured on a touch screen, voltage is applied across the screen in the Y direction; and a touch presses the layers together, where a voltage can be read from one of the X electrodes. The contact made as a result of the touch creates a

voltage divider atthat point, so the Y coordinate can be determined;

The process then repeats with the X direction being driven,

and a reading is taken from one of the Y electrodes.

High-performance, Low-power AVR® 8-bit Microcontroller

32K Bytes of In-System Self-programmable Flash program memory

1024 Bytes EEPROM 2K Byte Internal SRAM 8-channel, 10-bit ADC Write/Erase Cycles: 10,000 Flash/100,000 EEPROM I/O and Packages

ATmega32

Driver circuitry:- It can also be said as a line refreshes circuit because after each cycle

it refreshes the resistive mesh and total voltage is again provided to the mesh i.e.

whatever initial voltage drop reading was taken ,that gets vanished and the grid again become active for detecting the location of touch from the user.

MAX-232:- The MAX232 is a dual driver/receiver that includes a capacitive voltage

generator to supply voltage levels from a single 5-V supply. Each receiver converts inputs to 5-V TTL/CMOS levels. These receivers have a typical threshold of 1.3 V and a typical hysteresis of

0.5 V, and can accept ±30-V inputs. Each driver converts TTL/CMOS input levels into required levels.

Character/Symbol Recognition

Image Processing, Feature Extraction, Template Matching & Pattern Recognition algorithms will be used to recognize the input annotation.

The character or symbol recognition enables us to use special symbols/annotations to control applications or hardware.

• For conveying the message at public places like bus stop , railway station.

• To control interactive gaming application

• To access an application software like ms-paint

APPLICATION

• High reliability and performance ,low cost .

• Always a facility of upgradation.

• Performance per unit cost is good.

• Easiest way to interface with computer.

ADVANTAGE

• VISUAL BASIC 6.0• AVR STUDIO• ORCAD

SOFTWARE USED

LANGUAGE USED• EMBEDDED C

Visual Object Recognition using Template Matching (http:/ / www. araa. asn. au/ acra/ acra2004/ papers/ cole.pdf)

http://en.wikipedia.org/w/index.php?title=Feature_detection_%28 computer_vision%29

www.datasheetcatalog.com Programming and customizing the AVR

microcontroller-D.V.Gadre http://www.senet.com.au/~cpeacock

References

THANK YOU…..