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Presented By:

Internal Guide: Md.Akheel AhmedMr.Prashanth S. Pise 05621A0484

N.Narender Reddy

05621A0485

Department of Electronics and Communication Engineering,

Auroras engineering college,bhongir

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AIM OF THE PROJECT:

The aim of the project is the design and construction of an interface

between the CMOS camera and a computer, using the AVRmicrocontroller.

The proposed tasks for the project:

Make the AVR Atmega128 and its environment work

Communicate the AVR Atmega128 with the computer

Interfacing CMOS image sensor to AVR Atmega128

Make the camera work and see images in the TV

Read and write the registers of the camera using the I2C protocol

Read a line from the camera and send it to the computerRead a whole image from the camera and send it to the computer

Image processing on the system is done using MATLAB software

Make a little process of the image inside the AVR and send the

result to the computer or color graphical lcd

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BLOCK DIAGRAM:

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BLOCK DIAGRAM EXPLANATION:

The information flows in two ways: on the one hand there arecommands from the computer to the camera to change different

characteristics of it, on the other images from the camera should be

sent to the computer.

The communication between the computer and the AVR

Microcontroller is through the serial port.

The communication between the camera and the microcontroller is:

using the I2Cprotocol to access to the different registers of the

camera and using an 8-bit port to read the images. In addition the

camera will be connected to a TV with its analog output for

debugging purpose.

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AVR MICROCONTROLLER:

The AVR is a Modified Harvard architecture machine with program

and data stored in separate physical memory systems that appear indifferent address spaces but having the ability to read data items from

program memory using special instructions.

ATMEGA 128:

The ATmega128 is a low-power CMOS 8-bit microcontroller based on

the AVR enhanced RISC architecture. By executing powerful

instructions in a single clock cycle, the ATmega128 achieves

throughputs approaching 1 MIPS perMHz allowing the system

designer to optimize power consumption versus processing speed.

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Pin Diagram of AVR AT Mega 128:

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FEATURESOFAVR:

RISC / Harvard

Powerful microcontroller designed for small applications

Very low power operation

118 instructions

1 instruction per clock cycle (pipelined)

Register-to-register operation

RISC core with ~100 instructions Modest clock speeds (4-16 MHz)

8-bit bus, 32 GP 8-bit registers

Intended as single chip solutions

In-circuit programmable Flash(~1000 cycles)

Small amount of EEPROM and SRAM

Single-cycle execution of most instructions

Several on-chip peripherals

(UART, SPI,TWI, ADC, PWM, WDT..)

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CMOS Image Sensor:

Until recently,CCD sensors were only image sensors used in digitalcameras, now new type image sensors has entered the market i.e.,

CMOS.

The C3088 is the color camera module used here in this project withdigital output. It usesOmni visions CMOS image sensorOV6620.

Combining CMOS technology with an easy to use digital interfacemakes C3088 a low cost solution for higher quality video imageapplication.

The digital video port supplies a continuous 8/16 bit-wide imagedata stream. All camera functions such as exposure ,gamma ,gain,white balancing ,color matrix ,windowing are programmable throughTWI .

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CMOS IMAGE SENSOR(OV6620)

Image sensor is a device that converts avisual image to an electric signal.

ComplementaryM

etalO

xideSemiconductor image sensor is heart ofthe camera.

It produces a digital/analog outputrepresenting each pixel.

It contains a crystal oscillator whichworks at a frequency of 16MHz.

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FEATURES OF OV 6620:

101,376 pixels, 1/4 lens.Small size-40x28mm

Data format - RGB Raw Data.

8/16 bit video data.

Wide dynamic range.

Anti-blooming.White balance control.

Single 5-Volt supply, low power dissipation.

Lens-4.9mm.

Array size-176x144

Signal to noise ratio-48db

I2C interface.

Image enhancement - brightness, contrast, saturation, sharpness.

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INTER-INTEGRATED CIRCUIT (I2C)PROTOCOL:

I2C devices include EEPROMs, thermal sensors, and real-time

clocks

Used as a control interface to signal processing devices that haveseparate data interfaces, e.g. RF tuners, video decoders andencoders, and audio processors.

I2

C bus has three speeds:Slow (under 100 Kbps)

Fast (400 Kbps)

High-speed (3.4 Mbps) I2C v.2.0

Limited to about 10 feet for moderate speeds

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I2C Bus Configuration

2-wire serial bus Serial data (SDA) and Serial clock (SCL)

Half-duplex, synchronous, multi-master bus

No chip select or arbitration logic required Lines pulled high via resistors, pulled down via open-drain

drivers (wired-AND)

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I2C Protocol

1.Master sends start condition (S) and controls the clock signal

2.Master sends a unique 7-bit slave device address

3.Master sends read/write bit (R/W) 0 - slave receive, 1 - slavetransmit

4. Receiver sends acknowledge bit (ACK)

5. Transmitter (slave or master) transmits 1 byte of data

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I2C Protocol (cont.)

6. Receiver issues an ACK bit for the byte received

7. Repeat 5 and 6 if more bytes need to be transmitted.

8.a) For write transaction (master transmitting), master issues stop

condition (P) after last byte of data.

8.b) For read transaction (master receiving), master does not

acknowledge final byte, just issues stop condition (P) to tell the

slave the transmission is done

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Two Wire InterfaceTWI Registers

TWBR (bit rate register)-Controls the period ofSCL when the TWI module is

operating in Master mode.TWAR (address register)

-Used when TWI module is receiving data to identify its address.

TWCR (control register)-Controls operation of the TWI unit-Used to generate START, STOP, ACK pulse-Also enables TWI operation including interrupt enables

TWSR (status register)-Reflects the status of the TWI logic bus via codes.-Holds the prescale value for the TWI SCL pulse generator

TWDR (data register)-In transmit mode, it holds the data to send-In receive mode, it holds the data received

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USART

Universal Synchronous and Asynchronous serial Receiver and

Transmitter

A standard I/O device that provides conversions between serial

and parallel data

Provides a basic protocol for serial communication

Speed, framing, error control

USART ON AVR (ATMega128)

USART - The Universal Synchronous and Asynchronous

serial Receiver and Transmitter

(USART) is a highly flexible serial communication device

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Features:

Full Duplex Operation (Independent Serial Receive and Transmit

Registers)

Asynchronous orSynchronous Operation

Master orSlave Clocked Synchronous Operation

High Resolution Baud Rate Generator

Supports Serial Frames with 5, 6, 7, 8, or 9 Data Bits and 1 or 2

Stop Bits

Odd or Even Parity Generation and Parity CheckSupported by

Hardware

Data Overrun Detection

Framing Error Detection

Noise Filtering Includes False Start Bit Detection and Digital Low

Pass Filter

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Three Separate Interrupts on TX Complete, TX Data Register

Empty, and RX Complete

Multi-processor CommunicationMode

Double Speed Asynchronous Communication Mode

USART Initialization:

The USART has to be initialized before any communication can take

place. The initialization process normally consists of setting the baud

rate, setting frame format and enabling the Transmitter or the Receiver

depending on the usage. For interrupt driven USART operation, the

global interrupt flag should be cleared (and interrupts globallydisabled)

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IMAGE PROCESSING:

A method for adjusting the color reproduction of a color image

composed of pixels provided in a plurality of color channels is based

on generating a reference image from a combination of the color

channels, whereby each spatial coordinate of the reference image is

characterized by a reference image level.

A method for processing Bayer images method comprising:

Receiving a raw image from a sensor with Bayer color arrays.

Determining a corresponding dot in the raw image that corresponds

to each pixel in a final image.

Locating color reference pixels in the raw image according to the

corresponding dot.Selecting interpolation pixels in the raw image according to the

color reference pixels and interpolating color values of the each pixel

in the final image according to color values of the interpolation pixels.

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BAYERFORMAT:

Color filters used in most single-chip digital image sensors used in

digital cameras, camcorders, and scanners to create a color image.

The filter pattern is 50% green, 25% red and 25% blue, hence is also

called RGBG orGRGB.

This Bayer format is processed in MATLAB to obtain true RGB

picture.

To create a full color image, the camera's image processor calculates,

or interpolates, the actual color of each pixel by looking at the

brightness of the colors recorded by it and others around it.