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CHAPTER 1
INTRODUCTION
1.1 Introduction to SMS Based Voting Machine
India is world’s largest democracy. Fundamental right to vote or simply voting in
elections forms the basis of Indian democracy. In India all earlier elections a voter
used to cast his vote by using ballot paper. This is a long time-consuming process and
very much prone to errors. This situation continued till election scene was completely
changed by electronic voting machine. No more ballot paper, ballot boxes, stamping,
etc. All this condensed into a simple box called ballot unit of the electronic voting
machine. Cell phone based voting machine is capable of saving considerable printing
stationery and transport of large volumes of electoral material. It is easy to transport,
store, and maintain. It completely rules out the chance of invalid votes. It reduces of
polling time, resulting in fewer problems in electoral preparations, law and order,
candidate’s expenditure, etc. and easy and accurate counting without any mischief at
the counting centre. The aim of our project is to design & develop a mobile based
voting machine. This project focuses onto implement GSM (Global System for
Mobile Communication) based Voting System. This system is implemented using an
embedded microcontroller. The embedded microcontroller used here is Atmega32
microcontroller. Actually, the aim of the project is to implement an Automatic Voting
system. GSM Based voting machine is fully controlled system. There is no chance of
any mistake. Primarily, the system functions with the help of different technologies
like the traditional cellular network such as Global System for Mobile
Communications (GSM) and other radio frequency medium. Today GSM fitted
Banks, cars; ambulances, fleets and police vehicles are common sights. The functional
units of our projects are GSM MODEM, LCD display, keypad and Atmega32.
1.2 Basic Aim of Project
The aim of our project is to design & develop a mobile based voting machine. In this
project user can sms on the specific number from his registered mobile phone to cast
his vote. If he has entered a valid choice & password his vote will be caste. For
invalid password/choice a message is forwarded to the user.
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1.3 Current Market Solution Available
At present Electronic Voting Machines ("EVM") are being used in Indian General and
State Elections to implement electronic voting in part from 1999 elections and in total
since 2004 elections. The EVMs reduce the time in both casting a vote and declaring
the results compared to the old paper ballot system. However, EVMs have been under
a cloud of suspicion over their alleged tamping arability and security problems during
elections (especially after the 2009 general elections). An EVM consists of two units:
• Control Unit • Balloting Unit. The Control Unit is with the Polling Officer and the
Balloting Unit is placed inside the voting compartment
Fig 1.1: Typical Electronic Voting Machine
EVM is very complicated and there is lot of wasting of time and money so SMS
voting machine can be a safer mode of casting vote with respect to Electronic Voting
Machines (EVM).
1.4 Need
Conventional paper-based voting can result in a number of problems like:
Unacceptable percentages of lost, stolen, or miscounted ballots.
Votes lost through unclear or invalid ballot marks.
Limited accommodations for people with disabilities.
The government has to call the day off which can incur huge losses.
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The government has to set voting booths at various places in a limited region
for people to vote.
The electronic voting machines also add to the unacceptable cost of voting.
The security personals which are hired for this job have to be paid heavily
and even then there are chances of some tragedy at the voting booth.
There are many such problems associated with such a voting system. This process
requires a change which should be friendly. Voting is a vital process in democracy.
For such a process, the efficiency, reliability, and security of the technologies
involved are critical. Here comes in the significance of sms based voting system
which offers multiple advantages over traditional paper-based voting systems like
increasing citizen access to democratic processes and encouraging participation. It not
only saves a huge amount of money but also offers mobility which is also an
important aspect.
1.5 Technology Used in Project
The current technology used in the project is SMS (Short Message Service) service
based on GSM (Global System for Mobile).GSM (Global System for Mobile
communications) is an open, digital cellular technology used for transmitting mobile
voice and data service.
GSM supports voice calls and data transfer speeds of up to 9.6 kbps, together with the
transmission of SMS (Short Message Service). GSM operates in the 900MHz and
1.8GHz bands in Europe and the 1.9GHz and 850MHz bands in the US. The use of
harmonized spectrum across most of the globe, combined with GSM‟s international
roaming capability, allows travelers to access the same mobile services at home and
abroad. GSM enables individuals to be reached via the same mobile number in up to
219 countries.
Terrestrial GSM networks now cover more than 90% of the world’s population. GSM
satellite roaming has also extended service access to areas where terrestrial coverage
is not available.
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CHAPTER 2
COMPONENTS AND ITS DESCRIPTION
2.1 Basic components used in this project
Table 2.1 Component list
S.NO. Component Specification Quantity
1 Microcontroller Atmega32 1
2 LCD display 20*4 text 1
3 Resistor 330 ohm 1
4 Voltage regulator IC 7805 1
5 Capacitor 1uf, 10uf 2
6 Keypad 4*4 buttons 1
7 GSM module SIM 900A 1
8 Sim card 1
9 Connecting wires As per need
10. Soldering kit Iron, solder wire 2
2.2 Component Descriptions
2.2.1 Introduction to Atmega32 Microcontroller
A microcontroller is a single chip that contains the processor ( the CPU), non- volatile
memory for the program (ROM or Flash), volatile memory for input and output
(RAM), a clock and an I/O control unit. Also called a “Computer on a Chip”.
ATmega32 is an 8-bit high performance microcontroller of Atmel’s Mega AVR
family with low power consumption. Atmega32 is based on enhanced RISC (Reduced
Instruction Set Computing) architecture with 131 powerful instructions. Most of the
instructions execute in one machine cycle. Atmega32 can work on a maximum
frequency of 16MHz.
ATmega32 has 32 KB programmable flash memory, static RAM of 1 KB and
EEPROM of 1 KB. The endurance cycle of flash memory and EEPROM is 10,000
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and 100,000 respectively. ATmega32 is a 40 pin microcontroller. There are 32 I/O
(input/output) lines which are divided into four 8-bit ports designated as PORTA,
PORTB, PORTC and PORTD.
ATmega32 has various in-built peripherals like USART, ADC, Analog Comparator,
SPI, JTAG etc. Each I/O pin has an alternative task related to in-built peripherals.
PIN DIAGRAM OF ATMEGA32
Fig 2.1: Pin Diagram of Atmega32
Pin Description
Pin no. Pin name Description
1 (XCK/T0)PB0 I/O PORTB, Pin 0
2 (T1) PB1 I/O PORTB, Pin 1
3 (INT2/AIN0)PB2 I/O PORTB, Pin 2
4 (OC0/AIN1)PB3 I/O PORTB, Pin 3
5 (SS)PB4 I/O PORTB, Pin 4
6 (MOSI)PB5 I/O PORTB, Pin 5
7 (MISO)PB6 I/O PORTB, Pin 6
8 (SCK)PB7 I/O PORTB, Pin 7
9 RESET Reset, Active low
10 Vcc Vcc=+5v
11 GND Ground
5
12 XTAL2 External oscillator
13 XTAL1
14 (RXD)PD0 I/O PORTD, Pin 0
15 (TXD)PD1 I/O PORTD, Pin 1
16 (INT0)PD2 I/O PORTD, Pin 2
17 (INT1)PD3 I/O PORTD, Pin 3
18 (OC1B)PD4 I/O PORTD, Pin 4
19 (OC1A)PD5 I/O PORTD, Pin 5
20 (ICP)PD6 I/O PORTD, Pin 6
21 (OC2)PD7 I/O PORTD, Pin 7
22 (SCL)PC0 I/O PORTC, Pin 0
23 (SDA)PC1 I/O PORTC, Pin 1
24 (TCK)PC2 I/O PORTC, Pin 2
25 (TMS)PC3 I/O PORTC, Pin 3
26 (TD0)PC4 I/O PORTC, Pin 4
27 (TD1)PC5 I/O PORTC, Pin 5
28 (TOSC1)PC6 I/O PORTC, Pin 6
29 (TOSC2)PC7 I/O PORTC, Pin 7
30 Avcc Vcc for ADC
31 GND Ground
32 Aref Analog ref. pin
33 (ADC7)PA7 I/O PORTA, Pin 0
34 (ADC6)PA6 I/O PORTA, Pin 0
35 (ADC5)PA5 I/O PORTA, Pin 0
36 (ADC4)PA4 I/O PORTA, Pin 0
37 (ADC3)PA3 I/O PORTA, Pin 0
38 (ADC2)PA2 I/O PORTA, Pin 0
39 (ADC1)PA1 I/O PORTA, Pin 0
40 (ADC0)PA0 I/O PORTA, Pin 0
Table 2.1: Atmega32 Pin Diagram Description
Features of atmega32
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The main features of Atmega32 are:
32K bytes of In-System Programmable Flash Program memory with Read-
While-Write capabilities
1024 bytes EEPROM
2K byte SRAM
32 general purpose I/O lines
32 general purpose working registers
a JTAG interface for Boundary scan
On-chip Debugging support and programming
3 flexible Timer/Counters with compare modes
Internal and External Interrupts
a serial programmable USART
a byte oriented Two-wire Serial Interface
an 8-channel, 10-bit ADC
a programmable Watchdog Timer with Internal Oscillator
an SPI serial port
6 software selectable power saving modes
Interrupts
In short, an interrupt is a way for an external (or, sometimes, internal) event to pause
the current processor's activity, so that it can complete a brief task before resuming
execution where it left off. Atmega32 in total has 21 interrupts available. The
available interrupts are categorized in two classes:
External Interrupts- Out of the twenty one interrupts available, four interrupts are
directly present on controller pins to handle the interrupts generated by external
sources, so they are called as external interrupts. The four available interrupts and
their respective pins are shown in the figure below in their order of priority.
Fig. 2.2: External Interrupts
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Internal Interrupts- The remaining seventeen (17) interrupts are available for
internal use and support the precise and efficient operation of various peripherals like
ADC, Timers, and USARTs etc. The table below describes the available internal
interrupts in the order of their priority.
Fig. 2.3: Internal Interrupts
Following is what happens when an interrupt occurs:
Microcontroller normally completes the instruction which is being executed.
The program control transfers to Interrupt Service Routine (ISR). Each
interrupt have an associated ISR which is a piece of code which tells the
microcontroller what to do when an interrupt has occurred.
Execution of ISR is performed by loading the beginning address of the
corresponding ISR into program counter.
Execution of ISR continues until the return from the interrupt instruction
(RETI) is encountered.
When ISR is complete, the microcontroller resumes processing where it left
off before the interrupt occurred, i.e., program control is reverted back to the
main program.
USART
Communication between two entities is important for the information flow to take
place. In general the information transport system can be parallel in which the
complete byte of data is sent at a time, with each bit having a separate dedicated line
or it can be serial where only one communication line is available which is shared by
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all the bits sequentially. The pros and cons of these two systems are equivalent and
selection between the two depends on the application.
Data can be exchanged using parallel or serial techniques. Setup for parallel data
transfer is not cost effective but is a very fast method of communication. Serial
communication is cost effective because it requires only a single line of connection
but on the other hand is a slow process in comparison to parallel communication.
There are two methods for serial data communication:
(i) Synchronous and
(ii) Asynchronous communication.
In Synchronous communication method complete block (characters) is sent at a time.
It doesn’t require any additional bits (start, stop or parity) to be added for the
synchronization of frame. The devices are synchronized by clock. And in
asynchronous communication data transmission is done byte by byte i.e., one byte at
a time. The additional bits are added to complete a frame.
In synchronous communication the frame consists of data bits while in asynchronous
communication the total number of bits in a frame may be more than the data bits.
There are three ways in which serial communication can be done:
1. Simplex: Transmission is done in one direction.
2. Half duplex: Transmission can be done in both the direction but one side at a
time.
3. Full duplex: Transmission can be done in both the direction simultaneously.
Atmega32 is equipped with three different kinds of serial communication
peripheral systems:
Serial USART
SPI (Serial Peripheral Interface)
TWI (Two wire Interface)
SERIAL USART (universal synchronous asynchronous receiver and
transmission/ transmitter):
Serial USART provides full-duplex communication between the transmitter and
receiver. Atmega16 is equipped with independent hardware for serial USART
communication. Pin-14 (RXD) and Pin-15 (TXD) provide receive and transmit
interface to the microcontroller.
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Fig 2.4: USART Pins
Atmega32 USART provides asynchronous mode of communication and do not have a
dedicated clock line between the transmitting and receiving end. The synchronization
is achieved by properly setting the baud rate, start and stop bits in a transmission
sequence.
Start bit and stop bit: These bits are use to synchronize the data frame. Start bit is
one single low bit and is always given at the starting of the frame, indicating the next
bits are data bits. Stop bit can be one or two high bits at the end of frame, indicating
the completion of frame.
Baud Rate: In simple words baud rate is the rate at which serial data is being
transferred.
Atmega32 USART has following features:
Different Baud Rates.
Variable data size with options ranging from 5bits to 9bits.
One or two stop bits.
Hardware generated parity check.
USART can be configured to operate in synchronous mode.
Three separate interrupts for RX Complete, TX complete and TX data register
empty.
USART Registers
To use the USART of Atmega32, certain registers need to be configured.
.UBRR: USART Baud Rate Registers. Basically use to set the baud rate of USART
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atmega32
UDR: USART data register
UCSR: USART control and status register. It’s is basically divided into three parts
UCSRA, UCSRB and UCSRC. These registers are basically used to configure the
USART.
1. UCSRA: (USART Control and Status Register A)
RXC (USART Receive Complete): RXC flag is set to 1 if unread data exists in
receive buffer, and set to 0 if receive buffer is empty.
TXC (USART Transmit complete): TXC flag is set to 1 when data is completely
transmitted to Transmit shift register and no data is present in the buffer register
UDR.
UDRE (USART Data Register Empty): This flag is set to logic 1 when the transmit
buffer is empty, indicating it is ready to receive new data. UDRE bit is cleared by
writing to the UDR register.
2. UCSRB: (USART Control and Status Register B)
RXCIE: RX Complete Interrupt Enable
When 1--RX complete interrupt is enabled.
When 0--RX complete interrupt is disabled.
TXCIE: TX Complete Interrupt Enable
When 1--TX complete interrupt is enabled.
When 0--TX complete interrupt is disabled.
UDRIE: USART Data Register Empty Interrupt Enable
When 1--UDRE flag interrupt is enabled.
When 0--UDRE flag interrupt is disabled.
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RXEN: Receiver Enabled
When 1--USART Receiver is enabled.
When 0--USART Receiver is disabled.
TXEN: Transmitter Enabled
When 1--USART Transmitter is enabled.
When 0--USART Transmitter is disabled.
3. UCSRC: (USART Control and Status Register C)
The transmitter and receiver are configured with the same data features as configured
in this register for proper data transmission.
URSEL: USART Register select. This bit must be set due to sharing of I/O location
by UBRRH and UCSRC
UMSEL: USART Mode Select,
When 1--Synchronous Operation
When 0--Asynchronous Operation
UPM [0:1]: USART Parity Mode, Parity mode selection bits.
USBS: USART Stop Select Bit,
When 0--1 Stop Bit
When 1 --2 Stop Bits
UCSZ [0:1]: The UCSZ[1:0] bits combined with the UCSZ2 bit in UCSRB sets size
of data frame i.e., the number of data bits. The table shows the bit combinations with
respective character size.
UCSZ2 UCSZ1 UCSZ0 Character Size
0 0 0 5-bit
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0 0 1 6-bit
0 1 0 7-bit
0 1 1 8-bit
1 0 0 Reserved
1 0 1 Reserved
1 1 0 Reserved
1 1 1 9-bit
Table 2.3: UCSZ values and their meaning
4. UDR: (USART Data Register)
The USART Data receive and data transmit buffer registers share the same address
referred as USART UDR register, when data is written to the register it is written in
transmit data buffer register (TXB). Received data is read from the Receive data
buffer register (RXB).
5. UBRRH & UBRRL (USART Baud Rate Registers)
The UBRRH register shares the same I/O address with the UCSRC register, The
differentiation is done on the basis of value of URSEL bit.
When URSEL=0; write operation is done on UBRRH register.
When URSEL=1; write operation is done on UCSRC register.
The UBRRH and UBRRL register together stores the 12-bit value of baud rate,
UBRRH contains the 4 most significant bits and UBRRL contains the other 8 least
significant bits. Baud rates of the transmitting and receiving bodies must match for
successful communication to take place.
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UBRR register value is calculated by the following formula:
2.2.2 LCD Display
Fig. 2.5: 20*4 LCD Display
LCD is used to present textual information to the users. A 20x4 LCD means it can
display 20 characters per line and there are 4 such lines. In this LCD each character is
displayed in 5x7 pixel matrix. This LCD has two registers:
1. Command/Instruction Register - stores the command instructions given to
the LCD. A command is an instruction given to LCD to do a predefined task
like initializing, clearing the screen, setting the cursor position, controlling
display etc.
2. Data Register - stores the data to be displayed on the LCD. The data is the
ASCII value of the character to be displayed on the LCD.
LCD has inbuilt controllers which process the commands and displays on the screen.
Functions for LCD are provided in the appendices.
Following is the table showing various command codes for the LCD:
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Hex Code Command to LCD Instruction Register
01 Clear screen display
02 Return home
04 Decrement cursor
06 Increment cursor
0E Display ON, Cursor ON
80 Force the cursor to the beginning of the 1st line
C0 Force cursor to the beginning of the 2nd line
Table 2.4: Commonly used LCD Command codes
Pin configuration of LCD
Following table gives the brief description of LCD pins:
Pin Symbol Description
1 VSS Ground
2 VCC Main power supply
3 VEE Power supply to control contrast
4 RS Register Select
5 R/W Read/write
6 EN Enable
7 DB0 data pins
8 DB1
9 DB2
10 DB3
11 DB4
12 DB5
13 DB6
14 DB7
15 Led+ Backlight VCC
16 Led- Backlight Ground
Table 2.5: Pin Configuration LCD display
Programming the LCD
1. Data pin8 (DB7) of the LCD is busy flag and is read when R/W = 1 & RS = 0.
When busy flag=1, it means that LCD is not ready to accept data since it is
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busy with the internal operations. Therefore before passing any data to LCD,
its command register should be read and busy flag should be checked.
2. To send data on the LCD, data is first written to the data pins with R/W = 0 (to
specify the write operation) and RS = 1 (to select the data register). A high to
low pulse is given at EN pin when data is sent. Each write operation is
performed on the positive edge of the Enable signal.
3. To send a command on the LCD, a particular command is first specified to the
data pins with R/W = 0 (to specify the write operation) and RS = 0 (to select
the command register). A high to low pulse is given at EN pin when data is
sent.
2.2.3. Resistor
A resistor is a passive two-terminal electrical component that implements electrical
resistance as a circuit element. Resistors act to reduce current flow, and, at the same
time, act to lower voltage levels within circuits.
Fig. 2.6: 330 ohm resistor
2.2.4. Voltage regulated IC
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The 78xx (sometimes L78xx, LM78xx, MC78xx...) is a family of self-contained
fixed linear voltage regulator integrated circuit. The 78xx family is commonly used in
electronic circuits requiring a regulated power supply due to their ease-of-use and low
cost. For ICs within the family, the xx is replaced with two digits, indicating the
output voltage (for example, the 7805 has a 5 volt output, while the 7812 produces
12 volts). The 78xx line are positive voltage regulators: they produce a voltage that is
positive relative to a common ground. There is a related line of 79xx devices which
are complementary negative voltage regulators.
Fig.2.7: Pin Diagram 7805
2.2.5 Capacitor
A capacitor (originally known as a condenser) is a passive two-terminal electrical
component used to store energy electrostatically in an electric field. The forms of
practical capacitors vary widely, but all contain at least two electrical
conductors (plates) separated by a dielectric (i.e. insulator). The conductors can be
thin films, foils or sintered beads of metal or conductive electrolyte, etc. The "non
conducting" dielectric acts to increase the capacitor's charge capacity. A dielectric can
be glass, ceramic, plastic film, air, vacuums, paper, mica, oxide layer etc. Capacitors
are widely used as parts of electrical circuits in many common electrical devices.
Unlike a resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor
stores energy in the form of an electrostatic field between its plates.
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Fig 2.8: Capacitor
2.2.6 4*4 keypad
Keypad is most widely used input device to provide input from the outside world to
the microcontroller. The keypad makes an application more users interactive. Keypad
is organized as a matrix of switches in rows and column. The concept of interfacing
keypad with the MCU is simple. Every number is assigned two unique parameters,
i.e., row and column number (n(R, C) for example 6 (2, 3)). Hence every time a key is
pressed the number is identified by detecting the row and column number of the key
pressed.
Initially all the rows are set to zero by the controller and the columns are scanned to
check if any key is pressed. In case no key is pressed the output of all the columns
will be high.
Fig 2.9: Arrangement in Keypad
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Whenever a key is pressed the row and column corresponding to the key will get
short, resulting in the output of the corresponding column goes to go low (since we
have made all the rows zero). This gives the column number of the pressed key.
Once the column number is detected, the controller set’s all the rows to high. Now
one by one each row is set to zero by controller and the earlier detected column is
checked if it becomes zero. The row corresponding to which the column gets zero is
the row number of the digit.
The above process is very fast and even if the switch is pressed for a very small
duration of time the controller can detect the key which is pressed. The controller
displays the number corresponding to the row and column on the LCD.
2.2.7 GSM MODULE
Fig 2.10: GSM Module
A GSM modem is a wireless modem that works with a GSM wireless network. A
wireless modem behaves like a dial- up modem. The main difference between them is
that a dial- up modem sends and receives data through a fixed telephone line while a
wireless modem Sends and receives data through radio waves. GSM modem requires
a SIM card from a wireless carrier in order to operate. GSM modem uses AT
commands to control. Both GSM modems and dial-up modems support a common set
of standard AT commands. In addition to the standard AT commands; GSM modems
support an extended set of AT commands. These extended AT commands are defined
in the GSM standards. With the extended AT commands, we can do things like:
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1. Reading, writing and deleting SMS messages.
2. Sending SMS messages.
3. Monitoring the signal strength.
4. Monitoring the charging status and charge level of the battery.
5. Reading, writing and searching phone book entries.
Features of SIM900A
Quad-Band 850/ 900/ 1800/ 1900 MHz
GPRS multi-slot class 10/8
GPRS mobile station class B
Dimensions: 24*24*3 mm
Weight: 3.4g
Control via AT commands (GSM 07.07 ,07.05 and SIMCOM enhanced AT
Commands)
SIM application toolkit
Supply voltage range 3.4 ... 4.5 V
Low power consumption
Operation temperature: -30 °C to +80 °C
AT Commands
AT commands are instructions used to control a modem. AT is the abbreviation of
Attention. Every command line starts with “AT”. That’s why modem commands are
called AT commands. Many of the commands that are used to control wired dial- up
modems, such as ATD (Dial), ATA (Answer), ATH (Hook control) and ATO (Return
to online data state), are also supported by GSM/GP RS modems and mobile phones.
Besides this common AT command set, GS M/GPRS modems and mobile phones
support an AT command set that is specific to the GSM technology, which includes
SMS-related commands like AT+CMGS (Send SMS message), AT+CMSS (Send
SMS message from storage), AT+CMGL (List SMS messages) and AT+CMGR
(Read SMS messages).
Note that the starting "AT" is the prefix that informs the modem about the start of a
command line. It is not part of the AT command name. For example, D is the actual
AT command name in ATD and +CMGS is the actual AT command name in
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AT+CMGS. However, some books and web sites use them interchangeably as the
name of an AT command. Here are some of the tasks that can be done using AT
commands with a GS M/GPRS modem or mobile phone:
1. Get basic information about the mobile phone or GS M/GPRS modem. For
example, name of manufacturer (AT+CGMI), model number (AT+CGMM), IMEI
number (International Mobile Equipment Identity) (AT+CGSN) and software version
(AT+CGMR).
2. Get basic information about the subscriber. For example MSISDN (AT+CNUM)
and IMSI number (International Mobile Subscriber Identity) (AT+CIMI).
3. Get the current status of the mobile phone or GSM/GP RS modem. For
example, mobile phone activity status (AT+CPAS), mobile network registration
status (AT+CREG), radio signal strength (AT+CSQ), battery charge level and battery
charging status (AT+C BC).
4. Establish a data connection or voice connection to a remote modem (ATD, ATA,
etc.).
5. Send and receive fax (ATD, ATA, AT+F*).
6. Send (AT+CMGS, AT+CMSS), read (AT+CMGR, AT+CMGL), write
(AT+CMGW) or delete (AT+CMGD) SMS messages and obtain notifications of
newly received SMS messages (AT+CNMI).
7. Read (AT+CP BR), write (AT+CPBW) or search (AT+CPBF) phonebook entries.
8. Perform security-related tasks, such as opening or closing facility locks
(AT+CLCK), checking whether a facility is locked (AT+CLCK) and changing
passwords (AT+CPWD). (Facility lock examples: SIM lock [a password must be
given to the SIM card every time the mobile phone is switched on] and P H-SIM lock
[a certain SIM card is associated with the mobile phone. To use other S IM cards
with the mobile phone, a password must be entered.])
9. Control the presentation of result codes / error messages of AT commands. For
example, you can control whether to enable certain error messages (AT+CMEE) and
whether error messages should be displayed in numeric format or verbose format
(AT+CMEE=1 or AT+CMEE=2).
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10. Get or change the configurations of the mobile phone or GSM/GPRS modem.
For example, change the GSM network (AT+COPS), bearer service type (AT+CBS
T), radio link protocol parameters (AT+CRLP), SMS center address (AT+CSCA) and
storage of SMS messages (AT+CPMS).
11. Save and restore configurations of the mobile phone or GSM/GP RS modem. For
example, save (AT+CSAS) and restore (AT+CRES) settings related to SMS
messaging such as the SMS center address.
Note that mobile phone manufacturers usually do not implement all AT commands,
command parameters and parameter values in their mobile phones. Also, the
behaviour of the implemented AT commands may be different from that defined in
the standard. In general, GSM/GPRS modems designed for wireless applications have
better support of AT commands than ordinary mobile phones. In addition, some AT
commands require the support of mobile network operators. For example, SMS over
GP RS can be enabled on some GP RS mobile phones and GPRS modems with the
+CGSMS command (command name in text: Select Service for MO SMS Messages).
But if the mobile network operator does not support the transmission of SMS over
GP RS, you cannot use this features .There are two types of AT commands:
basic commands and extended commands. Basic commands are AT commands that
do not start with "+". For example, D (Dial), A (Answer), H (Hook control) and O
(Return to online data state) are basic commands. Extended commands are AT
commands that start with "+". All GSM AT commands are extended commands. For
example, +CMGS (Send SMS message), +CMSS (Send SMS message from storage),
+CMGL (List SMS messages) and +CMGR (Read SMS messages) are extended
commands.
General Syntax of Extended AT Commands
The general syntax of extended AT commands is straightforward. The syntax rules
are provided below. The syntax of basic AT commands is slightly different. We will
not cover the syntax of basic AT commands in this SMS tutorial since all SMS
messaging commands are extended AT commands.
Syntax rule 1: All command lines must start with "AT" and end with a carriage
return character. (We will use <C R> to represent a carriage return character in this
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SMS tutorial.) In a terminal program like HyperTerminal of Microsoft Windows, you
can press the Enter key on the keyboard to output a carriage return character.
Example: To list all unread inbound SMS messages stored in the message storage
area, type "AT", then the extended AT command "+CMGL", and finally a carriage
return character, like this:
AT+CMGL<CR>
Syntax rule 2: A command line can contain more than one AT command. Only the
first AT command should be prefixed with "AT". AT commands in the same
command- line string should be separated with semicolons. Example: To list all
unread inbound SMS messages stored in the message storage area and obtain the
manufacturer name of the mobile device, type "AT", then the extended AT command
"+CMGL", followed by a semicolon and the next extended AT command
"+CGMI":
AT+CMGL; +CGMI<CR>
An error will occur if both AT commands are prefixed with "AT", like this:
AT+CMGL; AT+C GMI<CR>
Syntax rule 3: A string is enclosed between double quotes.
Example: To read all SMS messages from message storage in SMS text mode (at this
time you do not need to know what SMS text mode is. More information will be
provided later in this SMS tutorial), you need to assign the string "ALL" to the
extended AT command +CMGL, like this:
AT+CMGL="ALL"<CR>
Syntax rule 4: Information responses and result codes (including both final result
codes and unsolicited result codes) always start and end with a carriage return
character and a linefeed character. Example: After sending the command line
"AT+CGMI<CR>“to the mobile device, the mobile device should return a response
similar to this:
The first line is the information response of the AT command +CGMI and the second
line is the final result code. <C R> and <LF> represent a carriage return character and
23
a line feed character respectively. The final results code "OK” marks the end of the
response. It indicates no more data will be sent from the mobile device to the
computer / PC. When a terminal program such as HyperTerminal of Microsoft
Windows sees a carriage return character, it moves the cursor to the beginning of the
current line. When it sees a linefeed character, it moves the cursor to the same
position on the next line. Hence, the command line "AT+CGMI<CR> " that you
entered and the corresponding response will be displayed like this in a terminal
program such as HyperTerminal of Microsoft Windows:
AT+CGMI Nokia OK
The OK Final Result Code: The OK final result code indicates that a command
line has been executed successfully by the GSM/GP RS modem or mobile phone. It
always starts and ends with a carriage return character and a linefeed character. Here
is an example for illustration. Let's say you send the command line "AT+CMGL;
+CGMI<C R>“to your GSM/GPRS modem. The AT command "+CMGL" is
used to list SMS messages stored in the message storage area and the AT command
“+CGMI" is used to get the manufacturer name of the GS M/GPRS modem. If
everything works properly without any errors, the command line, together with the
response returned, should be something similar to this: AT+CMGL; +CGMI<CR>
<CR><LF>+CMGL: 1,"REC UNREAD","+85291234567",”06/11/11,
00:30:29+32"<C R><LF>Welcome to our SMS tutorial. <CR><LF> <CR><LF>
Nokia <CR><LF><CR><LF>OK<CR><LF> As mentioned earlier, when a terminal
program such as HyperTerminal of Microsoft Windows sees a carriage return
character, it moves the cursor to the beginning of the current line. When it sees a
linefeed character, it moves the cursor to the same position on the next line. Hence,
the command line you entered, together with the response returned, will be displayed
like this in a terminal program such as HyperTerminal of Microsoft Windows:
AT+CMGL; +CGMI
+CMGL: 1,"REC UNREAD","+7568501753",”06/11/11, 00:30:29+32" Welcome to
our SMS tutorial”. Nokia
OK
24
The following table lists the AT commands that are related to the writing and sending
of SMS messages:
+CMGS Send message
+CMSS Send message from storage
+CMGW Write message to memory
+CMGD Delete message
+CMGC Send command
+CMMS More messages to send
One way to send AT commands to a mobile phone or GSM/GP RS modem is to use a
terminal program. A terminal program's function is like this: It sends the character
you typed to the mobile phone or GSM/GP RS modem. It then displays the response it
receives from the mobile phone or GSM/GPRS modem on the screen. The terminal
program on Microsoft Windows is called HyperTerminal. Below shows a simple
example that demonstrates how to use AT commands and the HyperTerminal
program of Microsoft Windows to send an SMS text message. The lines in bold type
are the command lines that should be entered in HyperTerminal. The other lines are
responses returned from the GSM / GP RS modem or mobile phone.
AT
.OK
AT+CMGF=1 .
.OK
AT+CMGW="+7568501753"
> A simple demo of SMS text messaging.
+CMGW:
.OK
AT+CMSS=1
25
+CMSS:
.OK
To send SMS messages from an application, you have to write the source code for
connecting to and sending AT commands to the mobile phone or GS M/GPRS
modem, just like what a terminal program does. You can write the source code in C,
C++.
How to receive SMS messages
In general, there are three ways to receive SMS messages using your computer / PC:
1. Connect a mobile phone or GSM/GPRS modem to a computer / PC. Then use the
computer / PC and AT commands to get the received SMS messages from the mobile
phone or GSM/GP RS modem. 2. Get access to the SMS center (SMSC) or SMS
gateway of a wireless carrier. Any SMS messages received will be forwarded to your
computer / PC using a protocol / interface supported by the S MSC or SMS gateway.
3. Get access to the SMS gateway of an SMS service provider. Any SMS messages
received will be forwarded to your computer / PC using a protocol / interface
supported by the SMS gateway.
3.2.3.7 The 1st Way: Using a Computer to Receive SMS Messages through a Mobile
Phone or GSM/GP RS Modem Receiving SMS messages through a mobile phone or
GSM/GP RS modem has a major advantage over the other two ways -- wireless
carriers usually do not charge any fees for receiving incoming SMS messages with
their SIM cards. The disadvantage of receiving SMS messages this way is that a
mobile phone or GSM/GP RS modem cannot handle
a large amount of SMS traffic. One way to overcome this is to load balance the S MS
traffic with a pool of mobile phones or GSM/GP RS modems. Each mobile phone or
GS M/GPRS modem will have its own SIM card and mobile phone number. In terms
of programming, sending and receiving SMS messages through a mobile phone or
GSM/GP RS modem are similar. What you need to do is to send instructions (in the
form of AT commands) to the mobile phone or GSM/GP RS modem. The following
table lists the AT commands that are related to the receiving and reading of SMS
messages: Table 3.5: AT Command RX
26
AT command Meaning
+CNMI New message indications
+CMGL List messages
+CMGR Read messages
+CNMA New message acknowledgement
Below shows a simple example that demonstrates how to use AT commands and the
HyperTerminal program of Microsoft Windows to read SMS text messages received
by a GSM / GP RS modem or mobile phone. The lines in bold type are the command
lines that should be entered in HyperTerminal. The other lines are responses returned
from the GSM / GP RS modem or mobile phone. AT OK AT+CMGF=1 OK
AT+CMGL=" ALL" +CMGL: 1,"REC READ","+7568501753",”06/11/11,
00:30:29+32" Hello, welcome to our SMS tutorial. +CMGL: 2,"REC
READ","+7568501753",”06/11/11, 00:32:20+32" A simple demo of SMS text
messaging. OK
2.2.8 Sim card
A subscriber identity module or subscriber identification module (SIM) is an
integrated circuit that securely stores the international mobile subscriber identity
(IMSI) and the related key used to identify and authenticate subscribers on mobile
telephony devices (such as mobile phones and computers). A SIM card contains its
unique serial number (ICCID), international mobile subscriber identity (IMSI),
security authentication and ciphering information, temporary information related to
the local network
Fig. 2.11: Sim card
27
2.2.9. Connecting wires
They are the building block of the circuit. They are used to create current/signal path
between various components on the circuit board.
2.2.10 Soldering kit
Fig.2.12: Soldering kit
Soldering is a process in which two or more metal items are joined together by
melting and flowing a filler metal (solder) into the joint, the filler metal having a
lower melting point than the adjoining metal. Soldering differs from welding in that
soldering does not involve melting the work pieces. In brazing, the filler metal melts
at a higher temperature, but the work piece metal does not melt. In the past, nearly all
solders contained lead, but environmental concerns have increasingly dictated use of
lead-free alloys for electronics and plumbing purposes.
28
CHAPTER 3
CIRCUIT AND BLOCK DIAGRAM OF PROJECT
3.1 Block Diagram of Project
VV
Fig 3.1: Block Diagram of Project
3.1.1 Block Diagram Description
1. POWER SUPPLY UNIT
7805 VOLTAGE REGULATOR The 78xx (also sometimes known as LM78xx)
series of devices is a family of self-contained fixed linear voltage regulator integrated
circuits. The 78xx family is a very popular choice for many electronic circuits which
require a regulated power supply, due to their ease of use and relative cheapness.
When specifying individual ICs within this family, the xx is replaced with a two-digit
number, which indicates the output voltage the particular device is designed to
provide (for example, the 7805 has a 5 volt output, while the 7812 produces 12 volts).
The 78xx line is positive voltage regulators, meaning that they are designed to
produce a voltage that is positive relative to a common ground. There is a related line
of 79xx devices which are complementary negative voltage regulators. 78xx and 79xx
ICs can be used in combination to provide both positive and negative supply voltages
in the same circuit, if necessary.78xx ICs have three terminals and are most
commonly found in the TO220 form factor, although smaller surface- mount and
larger TO3 packages are also available from some manufacturers. These devices
typically support an input voltage which can be anywhere from a couple of volts over
29
2- ATMEGA32
uC
1- POWER SUPPLY
4- KEYPAD 5-LCD
3- GSM MODULE
6- MOBILE
the intended output voltage, up to a maximum of 35 or 40 volts, and can typically
provide up to around 1 or 1.5 amps of current .
Fig 3.2: 7805 Voltage Regulator IC
2. ATMEGA32 Microcontroller
In this project we interfaced ATMEGA32 microcontroller with LCD, KEYPAD AND
GSM MODULE. The ATMEGA32 is 40 pin IC packaged in DIP package. It is
derivative of AVR family, from Atmel
ATMEGA32 Microcontroller is the heart of the circuit as it controls all the functions
of the system.
3. GSM MODEM
A GSM modem is a wireless modem that works with a GSM wireless network. A
GSM modem can be an external device or a PC Card PCMCIA Card. In this project
GSM modem is connected to the microcontroller through a cable. A GSM modem
requires a SIM card from a wireless carrier in order to operate computers use AT
commands to control modems. These extended AT commands are defined in the
GSM standards. With the extended AT commands Reading, writing, deleting and
Sending SMS messages are monitored.
4. KEYPAD
A keypad is a set of buttons arranged in a block or "pad" which usually bear digits,
symbols and usually a complete set of alphabetical letters. If it mostly contains
numbers then it can also be called a numeric keypad. Keypad is interfaced to provide
numeric input.
30
5. LCD
In this project 20*4 LCD is used. This LCD is interface with ATmega32 at port B. It
is used to display all the relevant information.
6. MOBILE
Here mobile is the user mobile who‟s SIM card number has been priory registered in
voting machine. Through mobile user will have to cast his\her vote in specific format
using Short Message Service (SMS).
3.2 Circuit Diagram
Fig: 3.3: Circuit Diagram
31
3.2.1 Circuit Description
Here PORT B is connected to the LCD to display data from the microcontroller to the
LCD. PORT D ( 0th and 1st) is used to send and receive data via serial port and is
used for GSM module. PORT A and PORT C are used for interfacing of keypad with
the controller. PORT A’s pins (PA0-PA3) are internally pulled up and PORT C’s pins
(PC0-PC3) are used to provide ground to detect the pressed button of keypad.
The HEX file of the program is loaded into the controller and the clock frequency and
baud rates of all the devices are adjusted so that they work in synchronization.
DC voltage is supplied with the help of 9v battery to the voltage regulator IC 7805
with the help of two capacitors to reduce the heating of IC. 7805 produce 5v DC from
9v supply. A led is placed with the output pin with a series resistor of 330 ohm.
From this power supply circuit, 5v and ground is connected to the various circuit
components.
32
CHAPTER 4
FLOW CHART AND ALGORITHMS
4.1 Flow Chart of Project
Fig.4.1: Flow chart of Voting System
33
INITIALIZE GMS
4.2 flow of Microcontroller Programming
Step 1: Power supply ON.
Step 2: Initializing LCD, GSM and USART
Step 3: Display initial menu on LCD and let user enter his choice
Choices available are:
1. Register
2. Generate password
2.1 for all user
2.2 for specific user
3. Display results
Step 4: display user choice on lcd
Step 5: If choice is 1, then let the user enter his 5 digit voter id number and 10 digit
mobile number, then using usart send data to gsm module to send a register
confirmation message to the user on his entered number while registering.
No voter id number can have two number associated with it.
Step 6: If choice of user is 2, then display the other menu for user asking about
whether he want to generate password for all user or a specific user.
User will enter 1 for all users and 2 for specific user.
Step 7: If choice of user is 3, then display the results of election.
Before this display, Messages received from registered users are decoded and counter
of there voted candidate is increased.
34
CHAPTER 5
SOFTWARE & HARDWARE TOOL
5.1 Software Tools:
5.1.1 AVR studio 6
AVR Studio was created by Atmel in order to help developers to create applications
for AVR microcontrollers using C/C++ programming languages. This piece of
software comes with a large number of tutorials, which allow the users to get familiar
with the application. The program stands as a complete pack for programmers that use
C++ and other programming languages.
5.1.2 Proteus Professional V7.10
Proteus is software for microprocessor simulation, schematic capture, and printed
circuit board (PCB) design. It is developed by Lab center Electronics. The X Game
Station Micro Edition was designed using Lab center‟s Proteus schematic entry and
PCB layout tools.
5.1.3 Programming language
The programming language used in this project is “embedded C”.
5.2 Hardware Tools:
1. USBasp
USBasp is a USB in-circuit programmer for Atmel AVR controllers. It simply
consists of an ATMega88 or an ATMega8 and a couple of passive components. The
programmer uses a firmware-only USB driver, no special USB controller is needed.
Features
Works under multiple platforms. Linux, Mac OS X and Windows are tested.
No special controllers or smd components are needed.
Programming speed is up to 5kBytes/sec.
SCK option to support targets with low clock speed (< 1,5MHz).
Planned: serial interface to target (e.g. for debugging).
35
Fig.5.1: USBasp programmer
2. Com to serial connector
Fig.5.2: serial connector
A serial cable is a cable used to transfer information between two devices using a
serial communication protocol. The form of connectors depends on the particular
serial port used. A cable wired for connecting two DTEs directly is known as a null
modem cable
36
CHAPTER 6
APPLICATIONS & ADVANTAGES
6.1 Applications
The EVM system is a longtime-consuming process and very much prone to
errors.
This situation continued till election scene was completely changed by
electronic voting machine.. Cell phone based voting machine is capable of
saving considerable printing stationery and transport of large volumes of
electoral material.
SMS based voting system can be used in remote areas where manual voting
system is difficult to implement.
This system can be used in colleges, society and various other places for
elections.
Fast track voting which could be used in small scale elections, like resident
welfare association, “panchayat” level election and other society level
elections.
It could also be used to conduct opinion polls during annual shareholders
meeting.
It could also be used to conduct general assembly elections where number of
candidates are less than or equal to eight in the current situation.
It is used in various TV serials as for public opinion.
6.2 Advantages
Voting system using sms offer multiple advantages over traditional paper-based
voting systems- advantages that increase citizen access to democratic processes and
encourage participation.
Reduced costs- SMS voting systems reduce the materials required for printing and
distributing ballots. GSM based voting, in particular, offers superior economies of
scale in regard to the size of the electoral roll.
37
Increased participation and voting options- SMS voting offers increased convenience
to the voter, encourages more voters to cast their votes remotely, and increases the
likelihood of participation for mobile voters. Additionally, it permits access to more
information regarding voting options.
Greater speed and accuracy placing and tallying votes- SMS voting's step-by-step
processes help minimize the number of miscast votes. The electronic gathering and
counting of ballots reduces the amount of time spent tallying votes and delivering
results.
Flexibility – SMS voting can support few languages, and the flexible design allows
up-to-the minute ballot modifications.
38
CHAPTER 7
FUTURE SCOPE & LIMITATIONS
7.1 Future Scope
The system can be further modified to enhance its utility. The enhancements are:
Number of candidates could be increased.
It can be interfaced with printer to get the hard copy of the result almost
instantly from the machine itself.
It can also be interfaced with the personal computer and result can be stored in
the central server.
Once the result is on the server it could be relayed on the network to various
offices of the election conducting authority. Thus our project can make results
available at any corner of the world in a matter of seconds.
7.2 Limitations
Number of candidates is less.
Major limitation is network problem.
Less storage of data.
39
CHAPTER 8
CONCLUSION
We proposed a GSM mobile voting scheme, where the GSM authentication
Infrastructure is used to provide voter authentication and improve voter mobility.
Authentication is always a difficult requirement to fulfil for remote voting schemes,
most of which apply a public-key based signature scheme for voter authentication. In
our scheme, by using the existing GSM authentication infrastructure, the public-key
overhead is largely reduced. Our scheme also enhances the security and provides
more mobility and convenience to voters. Where the voters‟ privacy is protected by
applying a blind signature scheme. In this report, we presented the basic structure and
protocol of our GSM based mobile voting system.
40
REFERENCES
1) Book:Elliot Williams. Make - AVR Programming. Washington, DC : O'Reilly, 2014
2) Article in a Journal:Akshay Verma. “GSM module interfacing”. GSM module, Feb, 2009
3) World Wide Web:Avinash Gupta. “SMS based voting system. Internet: http://extremeelectronics.co.in/avr-projects/sms-based-voting-system, 28 aug, 2002 [sep. 16, 2014].
41
Appendices
A.1 Functions for LCD
void lcd_cmd(int);
void lcd_data(int);
void dis_cmd(int);
void dis_data(int);
void lcd(void);
void string(char *str);
void lcd_num(unsigned int abc)
{
dis_cmd(0x04);
unsigned int d=0;
while(abc!=0)
{
d=abc%10;
dis_data(d+48);
abc=abc/10;
}
dis_cmd(0x06);
}
void lcd_cmd(int a)
{
PORTB=a;
42
PORTB&=~(1<<rs);
PORTB&=~(1<<rw);
PORTB|=(1<<en);
_delay_ms(1);
PORTB&=~(1<<en);
}
void lcd_data(int a)
{
PORTB=a;
PORTB|=(1<<rs);
PORTB&=~(1<<rw);
PORTB|=(1<<en);
_delay_ms(1);
PORTB&=~(1<<en);
}
void dis_cmd(int a)
{
int div;
div=a&0xF0;
lcd_cmd(div);
div=((a<<4)&0xF0);
lcd_cmd(div);
}
43
void dis_data(int a)
{
int div;
div=a&0xF0;
lcd_data(div);
div=((a<<4)&0xF0);
lcd_data(div);
}
void lcd(void)
{
dis_cmd(0x02);
dis_cmd(0x28);
dis_cmd(0x0C);
dis_cmd(0x06);
}
void string (char *str)
{
for(int i=0;str[i]!='\0';i++)
{
dis_data(str[i]);
}
}
44
A.2 Functions for USART
void uart_init()
{ UCSRB|=(1<<RXEN)|(1<<TXEN)|(1<<RXCIE);
UCSRC|=(1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);
UBRRL=51;
}
int uart_recieve()
{
while((UCSRA&(1<<RXC))==0);
return(UDR);
}
void uart_transmit(char data)
{ while((UCSRA&(1<<UDRE))==0);
UDR=data;
}
45
A.3 Function for sending sms
void send_sms_option1(char str1[])
{
uart_transmit('A');
uart_transmit('T');
uart_transmit('+');
uart_transmit('C');
uart_transmit('M');
uart_transmit('G');
uart_transmit('F');
uart_transmit('=');
uart_transmit('1');
uart_transmit(0x0d);
_delay_ms(1000);
uart_transmit('A');
uart_transmit('T');
uart_transmit('+');
uart_transmit('C');
uart_transmit('M');
uart_transmit('G');
uart_transmit('S');
uart_transmit('=');
int i=0;
46
uart_transmit('"');
while(i!=10)
{
uart_transmit(mob[x][i]);
i++;
}
uart_transmit('"');
uart_transmit(';');
uart_transmit(0x0d);
i=0;
_delay_ms(2000);
while(str1[i]!= '\0')
{
uart_transmit(str1[i]);
i++;
}
uart_transmit(0x1a);
uart_transmit(0x0D);
}
47
A.4 Function for entering mobile num/voter id
void getnum(int m)
{
int q=0;
int i=0xc0;
while (q<10)
{
PORTC=0b11111110;
_delay_ms(10);
if ((PINA&0b00000001)==0)
{
while((PINA&0b00000001)==0);
dis_cmd(i);
dis_data('1');
mob[m][q]='1';
i++;
q++;
}
if ((PINA&0b00000010)==0)
{
while((PINA&0b00000010)==0);
48
dis_cmd(i);
dis_data('2');
mob[m][q]='2';
i++;
q++;
}
if ((PINA&0b00000100)==0)
{
while((PINA&0b00000100)==0);
dis_cmd(i);
dis_data('3');
mob[m][q]='3';
i++;
q++;
}
PORTC=0b11111101;
_delay_ms(10);
if ((PINA&0b00000001)==0)
{
49
while((PINA&0b00000001)==0);
dis_cmd(i);
dis_data('4');
mob[m][q]='4';
i++;
q++;
}
if ((PINA&0b00000010)==0)
{
while((PINA&0b00000010)==0);
dis_cmd(i);
dis_data('5');
mob[m][q]='5';
i++;
q++;
}
if ((PINA&0b00000100)==0)
{
while((PINA&0b00000100)==0);
dis_cmd(i);
dis_data('6');
50
mob[m][q]='6';
i++;
q++;
}
PORTC=0b11111011;
_delay_ms(10);
if ((PINA&0b00000001)==0)
{
while((PINA&0b00000001)==0);
dis_cmd(i);
dis_data('7');
mob[m][q]='7';
i++;
q++;
}
if ((PINA&0b00000010)==0)
{
while((PINA&0b00000010)==0);
dis_cmd(i);
51
dis_data('8');
mob[m][q]='8';
q++;
i++;
}
if ((PINA&0b00000100)==0)
{
while((PINA&0b00000100)==0);
dis_cmd(i);
dis_data('9');
mob[m][q]='9';
i++;
q++;
}
PORTC=0b11110111;
_delay_ms(10);
if ((PINA&0b00000010)==0)
{
52
while((PINA&0b00000010)==0);
dis_cmd(i);
dis_data('0');
mob[m][q]='0';
i++;
q++;
}
}
if (q==10)
{
_delay_ms(1000);
dis_cmd(0x01);
_delay_ms(1);
dis_cmd(0x80);
string("wait.. registering");
}
}
53
A.5 AT commands for GSM
SMS Text mode:
54
