GUIDING VISUALLY CHALLENGED USING AVR MICROCONTROLLER

Presentation byDig Vijay Kumar Yarlagadda

dy5kc@mail.umkc.edu

Contents• Introduction• Block Diagram• Sensor Module• Microcontroller Section• Voice Module• Operation• Advantages And Disadvantages• Applications• Project Overview• Conclusion• References

Introduction

• Disability is a curse to a person especially if the person is blind.

• Every five seconds a person turns in the world to blind.

• The number of the blind in the world is currently estimated at 45 million

people.

• Nine million blind and visually impaired people live in India.

Current technologies

Electronic Eye Laser caneWalking stick

• "Guiding Visually Challenged Using AVR Microcontroller" mainly focuses on

providing guidance system for blind people to avoid any stationary obstacles.

• In contrast to many existing technologies, the device is designed to be portable,

user friendly and inexpensive.

Project overview

Block diagram

Voice moduleSensor moduleMicrocontroller

section

Fig. Block diagram of Guiding Visually Challenged using AVR Microcontroller

Sensor module

Fig. Circuit Diagram of Sensor module

Sensor module(contd.)• Sensor module mainly consists of a quad operational amplifier LM324 and

three IR Transmitter-Receiver pairs.

• The light is illuminated from IR Transmitter continuously and if any obstacle is

encountered, the light is reflected back and corresponding receiver receives

the signal.

• Op-amp compares the received output to a preset value and if the received

output is greater, it sends a HIGH voltage to Microcontroller section for

processing.

Microcontroller section

Microcontroller section(contd.)• ATmega8 is a 8-bit Microcontroller based on the

AVR RISC Architecture.

• It can execute powerful instructions in a single clock

cycle.

• In order to maximize performance and parallelism,

the AVR uses Harvard architecture, which separates

memories and buses for program and data.

Features of ATmega8• High-performance 8 bit Microcontroller

• 32 x 8 General Purpose Working Registers

• Six ADC channels in PDIP package

• Internal Calibrated Oscillator

Voice module

Voice module(contd.)• Voice module consists of IC AP89042 and IC LM386.

• The IC AP89042 is a high performance Voice OTP with embedded 1M bits

EPROM.

• It can store up to 42 sec voice messages with 4-bit ADPCM compression at 6KHz

sampling rate.

• The LM386 is a low voltage audio power amplifier consisting of with a gain of 20-

200.

Operation• The IR transmitter-receiver pairs are mounted on the left, front and right side

of the hand stick and they transmit IR signals regularly.

• The corresponding receiver receives back the signal if it is reflected by some

obstacle in that particular direction.

• The received signal is fed to corresponding operational amplifier of IC LM324.

• Output of each operational amplifier is limited to 3.3V by zener diodes and is

given to Microcontroller for further processing.

• The AVR Microcontroller detects the direction from which the signal is

received and issues suitable audio message.

• The audio message is amplified in voice module and fed to the speaker.

Operation(contd.)

Circuit

• Inexpensive

• Portable

• User friendly

Advantages

• Device may not work when obstacles are mobile

Disadvantages

Applications

Project

ConclusionThe device can be employed as an guidance system for visually impaired and blind

people.

References[1]. Sunil kumar, "Guiding visually challenged using Raspberry Pi", Electronics for

you, March 2014.

THANK YOU