Virtual Simulation and Embedded Module of Mobile

Phone Using Modified Braille Display

Mohamed Iqbal.M, Padma Balaji.L, Jayakar.M , Gokul.P, Karthik Kumar.R, Jairam.R

Department of Electrical and Electronics Engineering

Sri Ramakrishna Institute of Technology

Coimbatore - 641010

Email: mohdiq_m@yahoo.co.in

Abstract— Mobile phone embedded with recent

technologies play a major role in day to day life of everyone

in the world and thus shrinking the world with the well

connected network. Yet there are people who have not been

able to relish and benefit from the advanced technology.

One among those deprived are the visually challenged

people. Therefore an attempt has been made to develop a

simple user friendly and cost effective mobile phone by

which the visually challenged can save the numbers, make

calls, receive calls and the most important is that they can

easily feel the display. Initially, the function of the mobile

phone incorporated with Braille display has been virtually

simulated using LabVIEW. The simulation has been

performed by creating the graphical nodes of mobile phone

set up in LabVIEW front panel. The simulated mobile

phone incorporated with Braille display model has been

implemented using PIC16F877A microcontroller and SIM-

300 GSM module. The embedded hardware module of

mobile phone for the visually challenged people has been

validated for ease of its operation with all possible features.

The details of simulation of mobile phone using LabVIEW,

and embedded module have been furnished in this paper.

Keywords - Mobile phone, Modified Braille display,

LabVIEW, GSM module, Microcontroller, Embedded

module.

I. INTRODUCTION

In India, about 15 million out of 37 million visually

challenged people are found in India. The recent

technologies in Braille displays are found to be very

expensive for a middle class visually challenged person to

afford it. There are lot of features incorporated in the Braille

phones proposed by various mobile phone manufacturing

companies but these features makes it complex to use and

not so user friendly for the visually challenged people. The

phones that are available in the market are user friendly for

normal people yet many of the visually challenged use it

with difficulty and struggle with its basic operation . The

common man avails the basic mobile phone for an affordable

cost while a middle class visually challenged person has to

spend a lot for a basic and compact Braille mobile phone,

since the cost of Braille display by itself is very expensive.

To bridge the gap between the cost of the normal mobile

phones and the expensive Braille compactable mobile

phones, a cost effective and compact mobile phone with

Braille display has been devised. Generally the Braille

system consists of 6 pins which operate in linear motion. We

have devised a module consisting of 5 pins Braille display. It

is cheap, portable and can be operated using a battery.

II. MODIFIED BRAILLE DISPLAY

Braille system was first developed by Louis Braille

in the year 1821 [1]-[4]. Braille system consists of small

rectangular blocks called cells. Each cell can denote a

character. Braille is a system in which the raised dots are

arranged in cells. Any combination of one to six dots may

be raised within each cell and the number and position of

the raised dots within a cell conveys to the reader the letter,

word, number, or symbol the cell represents. There are 64

possible combinations of raised dots within a single cell.

There are three different grades of Braille. In the

grade-1 Braille display, the maximum possible type of

arrangement of the dots within a cell portrays either a letter

or a number, or a punctuation sign, or a special Braille

composition sign. Individual cells in this grade will not be

able to represent words or abbreviations. Due to this flaw to

shorten words, books and other documents composed in

grade-1 Braille are bulky and bigger than generally printed

text. Grade-1 Braille is mentioned in Figure 1

Figure 1 – Grade-1 Braille

Grade-2 Braille system was proposed and introduced

as a space-saving alternative to replace the grade-1 Braille.

In this system a cell is able to represent a brief form of a

word. There are many combinations of cells created to

represent general and common words. This made the Grade-

2 popular than the Grade-1.The Grade-3 Braille system is

essentially a system of Braille shorthand. Since it was not

standardized it is not used in publications. Nevertheless,

they are used by individuals for their personal convenience.

It consists around 300 word contractions. In addition, the

space-spacing between the words and paragraphs is reduced

so as to shorten the length of the final document. Even

though there are so much of advancements in technology to

establish an electronic Braille displays, but they are highly-

priced. The recent technologies in Braille displays are,

Electro-Mechanical Braille displays

EAP Braille displays

Since the above mentioned technologies are very

expensive, it has been proposed to develop a cheap and

portable Braille display in this paper.

The basic concept behind the Braille display is to make

the visually challenged person feel the motion of the pins

and sense the number or an alphabet. In the proposed Braille

display, the linear motion of the pins has been changed into

rotational motion using small size motors so that the visually

challenged person can feel the letter or an alphabet. Motor is

a cheap and best electro-mechanical device which will make

the visually challenged person sense the character. Motor

works on the principle of Electro-magnetic induction and so

it requires an electrical input which can even be fed by a

battery source. Small and low rated DC motors are used so

that the overall size and power consumption of the Single

cell Braille display are reduced.Usually Braille system

consists of 6 pins but for a Simple Basic Mobile 5 pins will

be sufficient to convey the message to the visually

challenged people. In the proposed Braille display 4 pins are

used to denote the letter or the number and the last pin is

used to denote various call commands as shown in Figure 2.

Figure 2 - Modified Braille code list

III. LABVIEW

LabVIEW is a graphical software that uses

graphical programming language [5]-[8]. It uses graphical

icons to write program instead of text line programming,

The graphical language is a dataflow programming

language. LabVIEW creates user interfaces, also known as

front panels in the program, into the development cycle[5]

.

The subroutines are precisely known as virtual instrument

generally termed as VI in LabVIEW. The virtual

instruments consist of three parts namely a block diagram,

front panel and connector pane. Data can be inserted or

extracted from the running virtual instrument, and the front

panel can be used as a programming interface. The VI can

run as a program. It also define the inputs and outputs of

the block. In other words, a software engineer has the option

to either program certain parts by themselves or use the

already pre-programmed components that LabVIEW offers.

Also the graphical option makes it possible for

nonprogrammers to build programs by simply connecting

and moving the virtual representation of the tools that they

are familiar with.

Simulation of Mobile phone in LabVIEW

LabVIEW2012 has been used to simulate the

working of mobile phone with Braille display because there

is no skill level restriction in LabVIEW. LabVIEW has been

chosen for the basic understanding as it is a graphical

programming language. The Front panel of the phone as

shown in Figure 3.The front panel consists of simulated

mobile phone with three main parts viz.,

Keypad

Braille display

Alpha numeric display to show the AT commands

Figure 3 - Front panel of the simulation model of the mobile

phone

Keypad

Keypad consists of fifteen Boolean keys placed

like 4x4 matrix keypad. An event structure that senses the

mouse down action is used. So, when a key is pressed using

the mouse its corresponding character is sent to the Alpha

numeric display in the front panel and at the same time it is

stored in a string. This block is placed inside a while loop to

get multiple data.

Braille display

Braille display consists of five Virtual LEDs

which are the five pins of modified Braille display. When

the key is pressed, the key is sensed and its corresponding

data is sent to the five Virtual LEDs that resembles the

Braille display. Inbuilt block event structure is used to

convert the alphabets and numbers into modified Braille

code.

Alpha numeric display to show the AT commands

Alpha numeric display is used to check the AT

command output and to check the keypad’s functionality.

When the call command keys viz., Call connect and Call

end keys are pressed, the number is concatenated with the

phone number that is entered and sent to the Alpha numeric

display. Thus, any error in the programming part can be

detected using the Alpha numeric display.

IV. EMBEDDED MODULE

The Embedded module of the Mobile phone consists of

the following major components [9].

Micro controller

GSM Module

Braille Keypad

Single cell Braille display

Buzzer

Speaker and microphone

Micro controller

A Micro controller is a programmable integrated

chip. Generally micro controller has registers, I/O ports,

memory, USART, timer, interrupts and some other features

based on type of chip. It is usually programmed based on the

application it is used. It is an important part in any embedded

system. It finds it's application in controlling devices,

monitoring systems, embedded system and in various other

areas. The microtroller is programmed using PIC C

Compiler and then this programmed chip is installed in the

system.

GSM module

A GSM module is an mini mobile because it does most of

the job of a mobile.By using this, one can make calls, send

message, access internet through GPRS, manage phonebook

and many other features [10]-[12]. The module is controller

by software using a PC or by a microcontroller. It is

controlled by AT commands which are send through

USART and module also replies the status and incoming

call, message and various other notifications through its

USART. It is simple to program a microcontroller to control

GSM module through At commands[7]

.

Braille Keypad

It is an arrangement where a set of buttons are

present through which the numbers can be dialed and the

calling commands are operated. A 4x4 matrix keypad with

buttons upon which the Braille codes are embedded is

provided. This makes the user feel the keypad and making it

user friendly for dialing and calling purpose.

Single cell Braille Display

It is a single character display unit which epresents

the key entered by user. This display cell consists of

electromechanical pins which gets activated and rotates to

indicate the character or number entered.The user can feel

the rotation of these pins Visually impaired people have a

contact live with those pins to feel and identify the number.

Buzzer

An electrical signaling device which produces

sounds based on the inputs is given to the device. Buzzer is

used here for alerting the user with ringtones when the

mobile phone receives an incoming call. It is an economical

buzzer that is used rather than the high end buzzer available

in the market.

Microphone and speaker

These are the audio input and audio output devices

that provide the interface for communication of voice calls.

The speakers and microphones are accompanied with filter

circuits. The filter circuits enhance the voice clarity in the

communication process between users.

V. EMBEDDED ‘C’ PROGRAM

Embedded C program is used to program this phone.

The Programming part consists of few functions,

initialization of ports and GSM module registers and few

arrays to store numbers [13]. Interrupts, Serial

communication and Ports of the Micro controller are used.

The functions that are incorporated in the program and the

description of each function are given below. The sequence

of operation of mobile phone using embedded C program is

also been shown in flowchart as Figure 4

SenseKey()

Convert2Braille()

Storeph_no()

Serial_recieve()

ATcommands()

Figure 4 - Flow chart of Embedded C program

A. “SenseKey()”

The key pressed in the 4x4 Matrix keypad is sent to the

Micro controller using this function. A 8-bit port is used to

interface the keypad with the micro controller. It performs

two actions. The first operation is to fetch the 4-bit input data

from the keypad and the second operations is to send the data

to the Micro controller via ports.

B. “Convert2Braille()”

The key pressed is sensed and stored in a 8-bit digital

data. A 5-bit digital data is needed as a input to the single

cell Braille display. This work is done by the function stored

in the micro controller and it sends the 5-bit data to the

Braille display through the ports. The Braille displays the

key pressed instantaneously.

C. “Storeph_no()”

The keys pressed must be stored in a memory in order to

send it to the GSM Module. So, the function “Storeph_no()”

stores the phone number pressed in a array and saves it so

that it can be retrieved whenever necessary.

D. “Serial_recieve()”

The communication with the GSM module is via a serial

communication and hence it is necessary to use serial receive

function. Its function is to receive everything from the GSM

module. It detects the incoming call and other messages from

the GSM module.

E. “AT Commands()”

The AT command function is used to send the data

serially to the GSM module. It attaches the phone number

and other data into AT commands and sends it to the GSM

module. The GSM module processes it to make calls and

other call commands

Programming for Microcontroller

#include<headerfile1.h>

#include<headerfile2.h>

SenseKey();

Convert2Braille();

Storeph_no();

Serial_recieve();

ATcommands();

/* Function definitions*/

void main()

{

Initialization of variables;

While (1)

{

If (keypress==1)

{

SenseKey (); /*senses which key is pressed*/

Storeph_no (); /*stores sensed key in memory*/

Convert2braille (); /*access the memory & sends signal to

the brailledisplay*/

//this takes for every key pressed and braille display reacts

for every key

}else{

Serial_recieve();

If (UART==”ring”)

{

SenseKey();

If (keypress==callkey)

ATCommands(callkey);

If (keypress==endkey)

ATCommands (endkey);

}

Sensekey();

If (keypress==callkey)

ATCommands(callkey);

}}}}

VI. VIRTUAL SIMULATION AND IMPLEMENTATION

Mobile phones with modified Braille display

concept have been programmed using graphical nodes in

LabVIEW. After the completion of arrangements of

graphical nodes in front panel and connector pane, the VI is

ready for virtual simulation. The complete block diagram of

the simulation of mobile phone is shown in the Figure 5. If

the button is pressed in the front panel the corresponding

Braille code is displayed by the virtual LED. After the call

or end key is pressed the AT commands are generated for

serial communication to the GSM module which is seen in

the alpha numeric display. In addition to validate the key

pressed, voice is added which gives voice output for each

key pressed which is still more helps to confirm the working

of the program. In order to implement the proposed model a

PIC16F877A- Micro controller and Sim 300 module as the

GSM module are used. The PIC 16F877A is an 8-bit

controller with inbuilt ADC (Analog Digital Converter),

USART (Universal Synchronous Asynchronous Receiver

and Transmitter), Timers, Comparators, CCP (Capture

Compare and Pulse Wave Modulation) modules, SSP

(Synchronous Serial Port) with SPI (Serial Port Interface)

and I2C (Inter-Integrated Circuits) [14].

Embedded C is used to program it. The keypad is

connected to the Port B of the PIC. The Sim300 module is

connected to the USART of the PIC 16F877A through the

pins RC6 (Transmission) and RC7 (Reception). The Braille

display is connected to the Port D. 5 pins of the Port D are

utilized. The GSM module - Sim300 has a SIM slot and a

GPRS options too [12]. It has the provision to connect the

module directly to the speaker and the microphone via a

filter circuit. The Sim300 module responds to the AT

commands that are sent to it from the PIC 16F877A through

a serial transmission. First the PIC 16F877A and Sim300

must be initialized. CCS Compiler is used to program the

Microcontroller. In PIC Microcontroller initialization of the

ports B, C and D is done using the registers Port B, Port C

and Port D respectively. The Ports are configured as input

and output ports using their respective TRIS Registers [14].

Next, initialization of the USART is done. Through USART

the SIM300 is initialized by sending the AT commands. The

complete hardware setup consisting of PIC16F877A, GSM

module- SIM 300 along with the modified Braille display

has been shown in the Figure 6.

The PIC 16F877A controls the whole system.

When a key is pressed, the Microcontroller senses the

number or the command that is assigned to the key through

Port B. When the pressed key represents a number the

controller stores that number in an array, and sends the

Braille code to the Braille display. After entering the

number the user can connect the call by sending the AT

command that contains the entered the number with it

through serial communication. This is achieved by

concatenating the AT command with the entered phone

number. When there is an incoming call to the phone, the

Sim300 sends a signal that is received by the

Microcontroller. The signal from Sim300 consists of the

caller’s identity that is stored in an array. Meanwhile the

buzzer rings and the vibrator connected to the phone start s

to vibrate so that the visually challenged person can sense it.

The caller’s identity stored in the array is sent to the Braille

display. If the visually challenged user press the call connect

key, the call is connected by sending the AT command

“ATA” to the Sim300 module.

Figure 5 - Block Diagram of the Virtual Simulation Model of the mobile Phone

Figure 6 - Complete Hardware Setup

The keypad has a key to correct the edit number the

number dialed earlier. When the phone number is entered the

user can modify the phone number using this key. This is

done by erasing the last content of the array which stores the

phone number and the array index is decremented. Thus, the

proposed mobile phone with Braille display has been found

through simulation and hardware implementation that, it is

simple, user friendly and cost effective for the visually

challenged people.

VII. CONCLUSION

In this paper, an attempt has been made to develop the

user friendly and cost effective mobile phone for the visually

challenged people. The module consisting mobile phone

along with Braille display has been created in the front panel

environment and simulated using LabVIEW platform. Then

the embedded module comprising of the same components

has been implemented using microcontroller and GSM

module by programming the microcontroller using

embedded C program. Using this embedded module the

mobile phone for the visually challenge people has been

validated. It has been found from simulation results and

hardware implementation that the visually challenged people

can also be well connected with the people across the globe

with the proposed mobile phones using modified Braille

display. Efforts are still made to incorporate more features in

the proposed mobile phone so as to compete with the mobile

phones available in market without compromising the ease

of use.

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