ATM Security System Using GSM and MEMS Module

ATM SECURITYUSING GSM AND MEMS

CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION

The overview of this project is to design MEMS and GSM based ATM

SECURITY system using AT89S52.

1.2 AIM OF THE PROJECT

To enhance the security system of present existing ATM machine.

1.3 METHODOLOGY

The Project ‘Atm security system using gsm and mems module ’ is designed

using MEMS technology. According to this technology the communication takes

place between two devices MEMS and microcontroller.

The MEMS is a sensor device which identifies the tilt produced by the atm

machine due to the irregular movement that occur during theft.

This project makes best use of MEMS as a sensor device which identifies the

tilt produced by the atm machine due to the irregular movement that occur..

The project basically consists of a MEMS sensor which identifies the tilt by

the machine and activates the microcontroller to start the following sequence in which

shutting the door using stepper motor and sending sms to vigilance system using gsm

is involved.

S.R.T.I.S.T 1


1.4. SIGNIFICANCE

This System stops any sort of robbery by taking MEMS as its input functional

bock. It’s the MEMS that is activating the total project by identifying the tilt caused

by the thief during breaking down the ATM machine. Once the micro controller is

activated the following sequence is started which involves shutting of the door using

stepper motor and alerting the vigilance system by a sms using GSM .

1.5 BLOCK DIAGRAM

Fig.1.1

Fig 1.1 Block Diagram of the Project

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AT89S52

LCD DISPL

GSM MODEM

MAX232

ADC0804

MEMS SENSOR

RELAY

MOTOR

POWER SUPPLY


1.6 BLOCK DIAGRAM DESCRIPTION

The hardware involved in this project is a Power Supply, a LCD to display the

concerned information, a GSM is interfaced to the Microcontroller through MAX

232, MEMS is interfaced through ADC 0804.

While execution, the tilt identified by the mems activates the microcontroller.

The microcontroller then starts the following sequence, it gives command to shut

down the door in order to avoid the thief to run away and also a sms is sent to the

vigilance system to alert them so that they can approach to the place as soon as

possible to catch the burglar.

This Project mainly consists of Power Supply section, Microcontroller section,

Mems section, GSM section, LCD display section, Max 232 serial driver section,

ADC 0804 section, Motor section and Relay section.

1.6.1 Power Supply Section

This section is meant for supplying Power to all the sections mentioned above.

It basically consists of a Transformer to step down the 230V ac to 9V ac followed by

diodes. Here diodes are used to rectify the ac to dc. After rectification the obtained

rippled dc is filtered using a capacitor Filter. A positive voltage regulator is used to

regulate the obtained dc voltage.

1.6.2 Microcontroller Section

This section forms the control unit of the whole project. This section basically

consists of a Microcontroller with its associated circuitry like Crystal with capacitors,

Reset circuitry, Pull up resistors (if needed) and so on. The Microcontroller forms the

heart of the project because it controls the devices being interfaced and communicates

with the devices according to the program being written.

1.6.3 MEMS Section

This is the input functional block which is used to identify the tilt that are

occurred in the atm machine when a thief tries to break open the atm machine.

S.R.T.I.S.T 3


1.6.4 ADC 0804 Section

The ADC0808 data acquisition component is a monolithic CMOS device with

an 8-bit analog-to-digital converter, 8-channel multiplexer and microprocessor

compatible control logic. The 8-bit A/D converter uses successive approximation as

the conversion technique. The converter features a high impedance chopper stabilized

comparator, a 256R voltage divider with analog switch tree and a successive

approximation register. The 8-channel multiplexer can directly access any of 8-single-

ended analog signals. The device eliminates the need for external zero and full-scale

adjustments.

1.6.5 GSM Section

GSM (Global System for Mobile communications) is a cellular network,

which means that mobile phones connect to it by searching for cells in the immediate

vicinity. GSM networks operate in four different frequency ranges. Most GSM

networks operate in the 900 MHz or 1800 MHz bands.

1.6.6 MAX 232 Section

The microcontroller can communicate with the serial devices using its single

Serial Port. The logic levels at which this serial port operates is TTL logics. But some

of the serial devices operate at RS 232 Logic levels. For example PC and Smart Card

Reader etc. So in order to communicate the Microcontroller with either Smart Card

Reader or PC, a mismatch between the Logic levels occurs. In order to avoid this

mismatch, in other words to match the Logic levels, a Serial driver is used. And MAX

232 is a Serial Line Driver used to establish communication between microcontroller

and PC (or Smart Card Reader)

1.6.7 LCD Display Section

This section is basically meant to show up the status of the project. This

project makes use of Liquid Crystal Display to display / prompt for necessary

information.

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1.6.8 Motor Section

A stepper motor is an electromechanically device which converts electrical

pulses into discrete mechanical movements. The shaft or spindle of a stepper motor

rotates in discrete step increments when electrical command pulses are applied to it in

the proper sequence. The motors rotation has several direct relationships to these

applied pulses is directly related to the direction of motor shafts rotation. The speed of

the motor shafts rotation is directly related to the frequency of the input pulses and the

length of rotation is directly related to the number of input pulses applied.

1.6.9 Relay Section

A relay is an electrical switch that opens and closes under the control of

another electrical circuit. In the original form, the switch is operated by an

electromagnet to open or close one or many sets of contacts. A relay is able to control

an output circuit of higher power than the input circuit, it can be considered to be, in a

broad sense, a form of an electrical amplifier.

S.R.T.I.S.T 5


CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION TO EMBEDDED SYSTEMS

Embedded system is a combination of software and hardware designed and

programmed to perform one/more particular task(s). The hardware is designed for

specific application and then software is embedded in this hardware to perform the

task. Both software and hardware are dedicated to that particular application. The

heart of the system is either processor or controller. Processor / controller may be

general purpose or special purpose that controls whole system.

There may be more than one processor/controller if system is complex. It may

be possible that there is one general purpose processor / controller and one or more

special purpose processors / controllers. For example in 3G (or 4G) cell phones there

is one general purpose processor that handles user commands, memory and display

etc. And there are special purpose processors like DSP for voice communication and

network management, display controller to generate real and reach images on color

LCD screen.

An embedded system is a special-purpose system in which the computer is

completely encapsulated by or dedicated to the device or system it controls.

Physically embedded systems range from portable devices such as digital watches and

MP3 players, to large stationary installations like traffic lights, factory controllers, or

the systems controlling nuclear power plants. In terms of complexity embedded

systems can range from very simple with a single microcontroller chip, to very

complex with multiple units, peripherals and networks mounted inside a large chassis

or enclosure.

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2.1.1 Application Areas

Nearly 99 per cent of the processors manufactured end up in embedded systems.

• Consumer appliances

• Office automation

• Industrial automation:

• Medical electronics.

• Telecommunications

• Wireless technologies

• Security& finance

Examples of embedded systems

Calculators

Laser Printer

Security Systems

Musical Instruments

Medical Equipment's

Automatic Teller Machines (ATMs)

Cellular telephones and telephone switches

Inertial guidance systems for aircraft and missiles

Computer peripherals such as routers and printers

engine controllers and antilock brake controllers for automobiles

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2.2 MICROCONTROLLER AND MICROPROCESSOR

The prime use of a microcontroller is to control the operation of a

machine using fixed programs that is stored in ROM that doesn't change

over the life time of the system

Processors have most of their op-codes moving data from external

memory to the CPU

Generally controllers move data and code from internal memory to

ALU

Processors have most of their instructions operating on a byte

Controllers on the other hand, have many bit handling instructions

making it ideal for control applications.

2.3 MICROCONTROLLER

A Micro controller consists of a powerful CPU tightly coupled with memory

RAM, ROM or EPROM), various I / O features such as Serial ports, Parallel Ports,

Timer/Counters, Interrupt Controller, Data Acquisition interfaces-Analog to Digital

Converter (ADC), Digital to Analog Converter (ADC), everything integrated onto a

single Silicon Chip.

It does not mean that any micro controller should have all the above said

features on chip, Depending on the need and area of application for which it is

designed, the ON-CHIP features present in it may or may not include all the

individual section said above.

Any microcomputer system requires memory to store a sequence of

instructions making up a program, parallel port or serial port for communicating with

an external system, timer / counter for control purposes like generating time delays,

Baud rate for the serial port, apart from the controlling unit called the Central

Processing Unit.

2.4 ADVANTAGES

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If a system is developed with a microprocessor, the designer has to go for

external memory such as RAM, ROM or EPROM and peripherals and hence the size

of the PCB will be large enough to hold all the required peripherals. But, the micro

controller has got all these peripheral facilities on a single chip so development of a

similar system with a micro controller reduces PCB size and cost of the design.

One of the major differences between a micro controller and a microprocessor

is that a controller often deals with bits , not bytes as in the real world application, for

example switch contacts can only be open or close, indicators should be lit or dark

and motors can be either turned on or off and so forth

2.5 PROBLEM STATEMENT

Enhancing the security system of the atm machine. The present existing

system is not sufficient to stop the thief when he tries to break down the atm machine.

2.6 SOLUTION

If we introduce the project then it would be easy to stop the thief. As the thief

tries to open the machine the MEMS is activated this gives signal to the

microcontroller which shuts the door and alerts the vigilance system.

2.7 DESCRIPTION

In this project, the MEMS sensor is placed in the upper or lower panel of the

atm machine, when a thief tries to open the machine he has to break the panel and

open either the upper panel or lower panel. When he does so the MEMS sensor will

be activated as it reads the tilt produced while lifting the panel, this will activate the

microcontroller. As the microcontroller is activated it then has to start a sequence

which should stop the thief from running away from the machine, for this purpose we

need to shut the door, in order to shut the door we are using a stepper motor, also we

have to alert the vigilance system here we are using GSM to send the SMS.

CHAPTER 3

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AT89S52 MICROCONTROLLER

3.1 AT89S52

3.1.1 A BRIEF HISTORY OF 8051

In 1981, Intel corporation introduced an 8 bit microcontroller called 8051. this

microcontroller had 128 bytes of RAM, 4K bytes of chip ROM, two timers, one serial

port, and four ports all on a single chip. At the time it was also referred as “ A

SYSTEM ON A CHIP”

The 8051 is an 8-bit processor meaning that the CPU can work only on 8 bits

data at a time. Data larger than 8 bits has to be broken into 8 bits pieces to be

processed by the CPU. The 8051 has a total of four I\O ports each 8 bit wide.

There are many versions of 8051 with different speeds and amount of on-chip

ROM and they are all compatible with the original 8051. this means that if you write a

program for one it will run on any of them.

The 8051 is an original member of the 8051 family. There are two other members in the 8051 family of microcontrollers. They are 8052 and 8031. All the

three microcontrollers will have the same internal architecture, but they differ in the

following aspects.

8031 has 128 bytes of RAM, two timers and 6 interrupts.

8051 has 4K ROM, 128 bytes of RAM, two timers and 6

interrupts.

8052 has 8K ROM, 256 bytes of RAM, three timers and 8

interrupts.

3.2 NECESSITY OF MICROCONTROLLERS

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Microprocessors brought the concept of programmable devices and made

many applications of intelligent equipment. Most applications, which do not need

large amount of data and program memory, tended to be costly.

The microprocessor system had to satisfy the data and program requirements

so, sufficient RAM and ROM are used to satisfy most applications .The peripheral

control equipment also had to be satisfied. Therefore, almost all-peripheral chips were

used in the design. Because of these additional peripherals cost will be comparatively

high.

Bulky:

On comparing a board full of chips (Microprocessors) with one chip with all

components in it (Microcontroller).

Debugging:

Lots of Microprocessor circuitry and program to debug. In Micro controller

there is no Microprocessor circuitry to debug.

Slower Development time: As we have observed Microprocessors need a lot of

debugging at board level and at program level, where as, Micro controller do not have

the excessive circuitry and the built-in peripheral chips are easier to program for

operation.

So peripheral devices like Timer/Counter, Parallel programmable port, Serial

Communication Port, Interrupt controller and so on, which were most often used were

integrated with the Microprocessor to present the Micro controller .RAM and ROM

also were integrated in the same chip. The ROM size was anything from 256 bytes to

32Kb or more. RAM was optimized to minimum of 64 bytes to 256 bytes or more.

Microprocessor has following instructions to perform:

1. Reading instructions or data from program memory ROM.

2. Interpreting the instruction and executing it.

3. Microprocessor Program is a collection of instructions stored in a Nonvolatile

memory.

4. Read Data from I/O device

5. Process the input read, as per the instructions read in program memory.

6. Read or write data to Data memory.

7. Write data to I/O device and output the result of processing to O/P device.

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3.3 Introduction to AT89S52

The system requirements and control specifications clearly rule out the use of

16, 32 or 64 bit micro controllers or microprocessors. Systems using these may be

earlier to implement due to large number of internal features. They are also faster and

more reliable but, the above application is satisfactorily served by 8-bit micro

controller. Using an inexpensive 8-bit Microcontroller will doom the 32-bit product

failure in any competitive market place. Coming to the question of why to use 89S52

of all the 8-bit Microcontroller available in the market the main answer would be

because it has 8kB Flash and 256 bytes of data RAM32 I/O lines, three 16-bit

timer/counters, a Eight-vector two-level interrupt architecture, a full duplex serial

port, on-chip oscillator, and clock circuitry.

In addition, the AT89S52 is designed with static logic for operation down to

zero frequency and supports two software selectable power saving modes. The Idle

Mode stops the CPU while allowing the RAM, timer/counters, serial port, and

interrupt system to continue functioning. The Power Down Mode saves the RAM

contents but freezes the oscillator, disabling all other chip functions until the next

hardware reset. The Flash program memory supports both parallel programming and

in Serial In-System Programming (ISP). The 89S52 is also In-Application

Programmable (IAP), allowing the Flash program memory to be reconfigured even

while the application is running.

By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel

AT89S52 is a powerful microcomputer which provides a highly flexible and cost

effective solution to many embedded control applications.

3.4 FEATURES

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Compatible with MCS-51® Products

• 8K Bytes of In-System Programmable (ISP) Flash Memory

– Endurance: 1000 Write/Erase Cycles

• 4.0V to 5.5V Operating Range

• Fully Static Operation: 0 Hz to 33 MHz

• Three-level Program Memory Lock

• 256 x 8-bit Internal RAM

• 32 Programmable I/O Lines

• Three 16-bit Timer/Counters

• Eight Interrupt Sources

• Full Duplex UART Serial Channel

• Low-power Idle and Power-down Modes

• Interrupt Recovery from Power-down Mode

• Watchdog Timer

• Dual Data Pointer

-Power-off Flag

PIN DIAGRAM

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FIG 3.1 PIN DIAGRAM OF AT89S52 IC

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Port Pin Alternate Functions

P1.0 T2 (external count input to Timer/Counter 2), clock-out

P1.1 T2EX (Timer/Counter 2 capture/reload trigger and direction control)


3.5 PIN DESCRIPTION

Pin Description

VCC: Supply voltage.

GND: Ground.

Port 0

Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can

sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-

impedance inputs. Port 0 can also be configured to be the multiplexed low- order

address/data bus during accesses to external pro-gram and data memory. In this mode,

P0 has internal pullups Port 0 also receives the code bytes during Flash program- mi ng an

d ou tpu t s the c o de b y tes du r i n g pr o g r a m verification. External pullups are

required during program verification.

Port 1

Port 1 is an 8-bit bi-directional I/O port with internal pullups. The Port 1

output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins,

they are pulled high by the internal pullups and can be used as inputs. As inputs, Port

1 pins that are externally being pulled low will source current (IIL) because of the

internal pullups. In addition, P1.0 and P1.1 can be configured to be the

timer/counter 2 external count input (P1.0/T2) and the timer/counter 2 trigger

input (P1.1/T2EX), respectively, as shown in the following table.

Port 1 also receives the low-order address bytes during

Flash programming and verification

S.R.T.I.S.T 15


Port 2



they are pulled high by the internal pullups and can be used as inputs. As inputs,

Port 2 pins that are externally being pulled low will source current (IIL) because of

the internal pullups.Port 2 emits the high-order address byte during fetches from

external program memory and during accesses to external data memory that use

16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal

pullups when emitting 1s. During accesses to external data memory that use 8-

bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function

Register.Port 2 also receives the high-order address bits and some control signals

during Flash programming and verification.

Port 3



they are pulled high by the internal pullups and can be used as inputs. As inputs,

Port 3 pins that are externally being pulled low will source current (IIL) because of

the pullups. Port 3 also serves the functions of various special features of the

AT89C51, as shown in the following table.

Port 3 also receives some control signals for Flash programming and verification.

Port Pin Alternate Functions

P3.0 RXD (serial input port)

P3.1 TXD (serial output port)

P3.2 INT0 (external interrupt 0)

P3.3 INT1 (external interrupt 1)

P3.4 T0 (timer 0 external input)

P3.5 T1 (timer 1 external input)

P3.6 WR (external data memory write

P3.7 RD (external data memory read strobe)

S.R.T.I.S.T 16


RST

Reset input. A high on this pin for two machine cycles while the oscillator is

running resets the device.

ALE/PROG

Address Latch Enable is an output pulse for latching the low byte of the

address during accesses to external memory. This pin is also the program pulse

input (PROG) during Flash programming.

In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator

frequency and may be used for external timing or clocking Note, however, that

one ALE pulse is skipped during each access to external data memory. If

desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the

bit set, ALE is active only dur-ing a MOVX or MOVC instruction. Otherwise, the

pin is weakly pulled high. Setting the ALE-disable bit has no effect if the

microcontroller is in external execution mode.

S.R.T.I.S.T 17


FIG-3.2 Functional block diagram of micro controller

3.6 The 8052 Oscillator and Clock

The heart of the 8051 circuitry that generates the clock pulses by which all

the internal all internal operations are synchronized. Pins XTAL1 And XTAL2 is

provided for connecting a resonant network to form an oscillator. Typically a quartz

crystal and capacitors are employed. The crystal frequency is the basic internal clock

frequency of the microcontroller. The manufacturers make 8051 designs that run at

specific minimum and maximum frequencies typically 1 to 16 MHz.

S.R.T.I.S.T 18


Fig-3.3 Oscillator and timing circuit

3.7 MEMORIES

3.7.1 Types of memory:

The 8052 have three general types of memory. They are on-chip memory,

external Code memory and external Ram. On-Chip memory refers to physically

existing memory on the micro controller itself. External code memory is the code

memory that resides off chip. This is often in the form of an external EPROM.

External RAM is the Ram that resides off chip. This often is in the form of standard

static RAM or flash RAM.

a) Code memory

Code memory is the memory that holds the actual 8052 programs that is to be

run. This memory is limited to 64K. Code memory may be found on-chip or off-chip.

It is possible to have 8K of code memory on-chip and 60K off chip memory

simultaneously. If only off-chip memory is available then there can be 64K of off chip

ROM. This is controlled by pin provided as EA

b) Internal RAM

S.R.T.I.S.T 19


The 8052 have a bank of 256 bytes of internal RAM. The internal RAM is

found on-chip. So it is the fastest Ram available. And also it is most flexible in terms

of reading and writing. Internal Ram is volatile, so when 8051 is reset, this memory is

cleared. 256 bytes of internal memory are subdivided. The first 32 bytes are divided

into 4 register banks. Each bank contains 8 registers. Internal RAM also contains 256

bits, which are addressed from 20h to 2Fh. These bits are bit addressed i.e. each

individual bit of a byte can be addressed by the user. They are numbered 00h to FFh.

The user may make use of these variables with commands such as SETB and CLR.

Special Function registered memory:

Special function registers are the areas of memory that control specific

functionality of the 8052 micro controller.

a) Accumulator (0E0h)

As its name suggests, it is used to accumulate the results of large no of

instructions. It can hold 8 bit values.

b) B registers (0F0h)

The B register is very similar to accumulator. It may hold 8-bit value. The b

register is only used by MUL AB and DIV AB instructions. In MUL AB the higher

byte of the product gets stored in B register. In div AB the quotient gets stored in B

with the remainder in A.

c) Stack pointer (81h)

The stack pointer holds 8-bit value. This is used to indicate where the next

value to be removed from the stack should be taken from. When a value is to be

pushed onto the stack, the 8052 first store the value of SP and then store the value at

the resulting memory location

d) Data pointer

The SFRs DPL and DPH work together work together to represent a 16-bit

value called the data pointer. It is a 16-bit SFR and also an addressable SFR.

e) Program counter

The program counter is a 16 bit register, which contains the 2 byte address,

which tells the 8052 where the next instruction to execute to be found in memory.

And is incremented each time an instruction is executes. It is not addressable SFR.

f) PCON (power control, 87h)

S.R.T.I.S.T 20


The power control SFR is used to control the 8051’s power control modes.

Certain operation modes of the 8051 allow the 8051 to go into a type of “sleep

mode” which consumes much lee power.

g) TCON (timer control, 88h)

The timer control SFR is used to configure and modify the way in which the

8051’s two timers operate.. Additionally, some non-timer related bits are located in

TCON SFR. These bits are used to configure the way in which the external interrupt

flags are activated, which are set when an external interrupt occurs.

h) TMOD (Timer Mode, 89h)

The timer mode SFR is used to configure the mode of operation of each of the

two timers. Using this SFR your program may configure each timer to be a 16-bit

timer, or 13 bit timer, 8-bit auto reload timer, or two separate timers. Additionally

you may configure the timers to only count when an external pin is activated or to

count “events” that are indicated on an external pin.

i) TO (Timer 0 low/high, address 8A/8C h)

These two SFRs taken together represent timer 0. Their exact behavior

depends on how the timer is configured in the TMOD SFR; however, these timers

always count up. What is configurable is how and when they increment in value.

j) T1 (Timer 1 Low/High, address 8B/ 8D h)

These two SFRs, taken together, represent timer 1. Their exact behavior

depends on how the timer is configured in the TMOD SFR; however, these timers

always count up..

k) P0 (Port 0, address 90h, bit addressable)

S.R.T.I.S.T 21


This is port 0 latch. Each bit of this SFR corresponds to one of the pins on a

micro controller. Any data to be outputted to port 0 is first written on P0 register. For

e.g., bit 0 of port 0 is pin P0.0, bit 7 is pin p0.7. Writing a value of 1 to a bit of this

SFR will send a high level on the corresponding I/O pin whereas a value of 0 will

bring it to low level.

l) P1 (port 1, address 90h, bit addressable)

This is port latch1. Each bit of this SFR corresponds to one of the pins on a


e.g., bit 0 of port 0 is pin P1.0, bit 7 is pin P1.7. Writing a value of 1 to a bit of this


bring it to low level

m) P2 (port 2, address 0A0h, bit addressable):

This is a port latch2. Each bit of this SFR corresponds to one of the pins on a





n) P3 (port 3, address B0h, bit addressable) :

This is a port latch3. Each bit of this SFR corresponds to one of the pins on a





o) IE (interrupt enable, 0A8h):

The Interrupt Enable SFR is used to enable and disable specific interrupts. The

low 7 bits of the SFR are used to enable/disable the specific interrupts, where the

MSB bit is used to enable or disable all the interrupts. Thus, if the high bit of IE is 0

all interrupts are disabled regardless of whether an individual interrupt is enabled by

setting a lower bit.

S.R.T.I.S.T 22


p) IP (Interrupt Priority, 0B8h)

The interrupt priority SFR is used to specify the relative priority of each

interrupt. On 8051, an interrupt maybe either low or high priority. An interrupt may

interrupt interrupts. For e.g., if we configure all interrupts as low priority other than

serial interrupt. However, if a serial interrupt is executing no other interrupt will be

able to interrupt the serial interrupt routine since the serial interrupt routine has the

highest priority.

q) PSW (Program Status Word, 0D0h)

The program Status Word is used to store a number of important bits that are

set and cleared by 8052 instructions. The PSW SFR contains the carry flag, the

auxiliary carry flag, the parity flag and the overflow flag. Additionally, it also

contains the register bank select flags, which are used to select, which of the “R”

register banks currently in use.

r) SBUF (Serial Buffer, 99h)

SBUF is used to hold data in serial communication. It is physically two

registers. One is writing only and is used to hold data to be transmitted out of 8052 via

TXD. The other is read only and holds received data from external sources via RXD.

Both mutually exclusive registers use address 99h.

I/O ports:

One major feature of a microcontroller is the versatility built into the

input/output (I/O) circuits that connect the 8052 to the outside world. The main

constraint that limits numerous functions is the number of pins available in the 8051

circuit. The DIP had 40 pins and the success of the design depends on the flexibility

incorporated into use of these pins.

PORT 0

S.R.T.I.S.T 23


Port 0 pins may serve as inputs, outputs, or, when used together, as a bi

directional low-order address and data bus for external memory. When used for

interfacing with the external memory, the lower byte of address is first sent via

PORT0, latched using Address latch enable (ALE) pulse and then the bus is turned

around to become the data bus for external memory.

PORT 1

Port 1 is exclusively used for input/output operations. PORTS 1 pin have no

dual function. When a pin is to be configured as input, 1 is to be written into the

corresponding Port 1 latch.

PORT 2

Port 2 maybe used as an input/output port. It may also be used to supply a

high –order address byte in conjunction with Port 0 low-order byte to address external

memory.. Port 2 latches remain stable when external memory is addressed, as they do

not have to be turned around (set to 1) for data input as in the case for Port 0.

PORT 3

Port 3 may be used to input /output port. The input and output functions can be

programmed under the control of the P3 latches or under the control of various special

function registers. Unlike Port 0 and Port 2, which can have external addressing

functions and change all eight-port b se, each pin of port 3 maybe individually

programmed to be used as I/O or as one of the alternate functions.

3.8

INTERRUPTS:

The AT89S52 has a total of six interrupt vectors: two external interrupts

(INT0 and INT1), three timer interrupts (Timers0, 1, and 2), and the serial port

S.R.T.I.S.T 24

Pin (SFR) Alternate Use

P3.0-RXD (SBUF) Serial data input

P3.1-TXD (SBUF) Serial data output

P3.2-INTO 0 (TCON.1) External interrupt 0

P3.3 - INTO 1 (TCON.3) External interrupt 1

P3.4 - T0 (TMOD) External Timer 0 input

P3.5 – T1 (TMOD) External timer 1 input

P3.6 - WR External memory write pulse

P3.7 - RD External memory read pulse


interrupt. These interrupts are all shown in Figure 10. Each of these interrupt sources

can be individually enabled or disabled by setting or clearing a bit in Special Function

Register IE. IE also contains a global disable bit, EA, which disables all interrupts at

once. Note that Table 5 shows that bit position IE.6 is unimplemented. In the

AT89S52, bit position IE.5 is also unimplemented.Timer 2 interrupt is generated by

the logical OR of bits TF2 and EXF2 in register T2CON. Neither of these flags is

cleared by hardware when the service routine is vectored to. In fact, the service

routine may have to determine whether it was TF2 or EXF2 that generated the

interrupt, and that bit will have to be cleared in software.The Timer 0 and Timer 1

flags, TF0 and TF1, are set at S5P2 of the cycle in which the timers overflow. The

values are then polled by the circuitry in the next cycle. However, the Timer 2 flag,

TF2, is set at S2P2 and is polled in the same cycle in which the timer overflows

S.R.T.I.S.T 25


. S.R.T.I.S.T 26


CHAPTER 4

MEMS(Micro electro mechanical system)

4.1 Introduction

MEMS which is abbreviated as Micro electro mechanical system is a

combination of mechanical and electrical systems. Its fabricated using micro

fabrication technique. This acts as main functional block in our project. Its sensor

device it has the capability of sensing the slightest tilt produced.

4.2 How it is applied in our project

The mems module is placed in the upper or the lower panel present in the

ATM machine. When a thief tries to open the panels of the ATM machine the tilt

produced during opening the panel is read by the MEMS, this activates the

microcontroller then the following sequence is initiated which includes shutting the

door and alerting the vigilance system by sending a sms through GSM.

4.3 Applications

Scrolling of documents, maps and images larger than the display window.

Web page browsing.

Menu navigation.

Automatic portrait-landscape adaption.

Motion control

S.R.T.I.S.T 27


CHAPTER 5

ADC 0804

5.1 Introduction

The ADC0808 data acquisition component is a monolithic CMOS device

with an 8-bit analog-to-digital converter, 8-channel multiplexer and microprocessor

compatible control logic. The 8-bit A/D converter uses successive approximation as

the conversion technique. The converter features a high impedance chopper stabilized

comparator, a 256R voltage divider with analog switch tree and a successive

approximation register. The 8-channel multiplexer can directly access any of 8-single-

ended analog signals. The device eliminates the need for external zero and full-scale

adjustments. Easy interfacing to microprocessors is provided by the latched and

decoded multiplexer address inputs and latched TTL tri-state outputs. The design of

the ADC0808 has been optimized by incorporating the most desirable aspects of

several A/D conversion techniques. The ADC0808 offers high speed, high accuracy,

minimal temperature dependence, excellent long-term accuracy and repeatability, and

consumes minimal power. These features make this device ideally suited to

applications from process and machine control to consumer and automotive

applications.

5.2 Features

1. Easy interface to all microprocessors

2. Operates ratio metrically or with 5 VDC or analog span

adjusted voltage reference

3. No zero or full-scale adjust required

4. 8-channel multiplexer with address logic

5. 0V to 5V input range with single 5V power supply

6. Outputs meet TTL voltage level specifications

7. Standard hermetic or molded 28-pin DIP package

8. 28-pin molded chip carrier package

9. ADC0808 equivalent to MM74C949

S.R.T.I.S.T 28


5.3 Key Specifications

1. Resolution 8 Bits

2. Total Unadjusted Error ±1/2 LSB and ±1 LSB

3. Single Supply 5 VDC

4. Low Power 15 mW

5. Conversion Time 100 µs

Figure 5.1 Pin diagram:

S.R.T.I.S.T 29


Fig 5.2 Molded chip carrier package

5.4 Types of ADC

Digital-Ramp ADC

Successive Approximation ADC

Flash ADC

5.4.1 Digital-Ramp ADC:

Conversion from analog to digital form inherently involves comparator

action where the value of the analog voltage at some point in time is compared with

some standard. A common way to do that is to apply the analog voltage to one

terminal of a comparator and trigger a binary counter which drives a DAC. The output

of the DAC is applied to the other terminal of the comparator. Since the output of the

DAC is increasing with the counter, it will trigger the comparator at some point when

its voltage exceeds the analog input. The transition of the comparator stops the binary

counter, which at that point holds the digital value corresponding to the analog

voltage.

S.R.T.I.S.T 30


Fig 5.3 Digital Ramp adc

5.4.2 Successive Approximation ADC:The successive approximation ADC is much faster than the digital ramp ADC

because it uses digital logic to converge on the value closest to the input voltage. A

comparator and a DAC are used in the process. A flowchart explaining the working is

shown in the figure below.

Fig 5.4 Illustration of 4-bit SAC with 1 volt step size

S.R.T.I.S.T 31


Fig 5.5 Flash ADC:

S.R.T.I.S.T 32


Illustrated is a 3-bit flash ADC with resolution 1 volt (after Tocci). The

resistor net and comparators provide an input to the combinational logic circuit, so the

conversion time is just the propagation delay through the network - it is not limited by

the clock rate or some convergence sequence. It is the fastest type of ADC available,

but requires a comparator for each value of output (63 for 6-bit, 255 for 8-bit, etc.)

Such ADCs are available in IC form up to 8-bit and 10-bit flash ADCs (1023

comparators) are planned. The encoder logic executes a truth table to convert the

ladder of inputs to the binary number output.

5.5 Applications

AD converters are used virtually everywhere where an analog signal has to be

processed, stored, or transported in digital form. Fast video ADCs are used, for

example, in TV tuner cards. Slow on-chip 8, 10, 12, or 16 bit ADCs are common in

microcontrollers. Very fast ADCs are needed in digital oscilloscopes, and are crucial

for new applications like software defined radio and in music recording. ADC's

dynamic range is also important.

S.R.T.I.S.T 33

http://www.8051projects.net/adc-interfacing/introduction.php

http://www.8051projects.net/adc-interfacing/introduction.php


CHAPTER 6

GSM (Global System for Mobile communications)

6.1 Introduction

GSM (Global System for Mobile communications) is a cellular network,

which means that mobile phones connect to it by searching for cells in the immediate

vicinity. GSM networks operate in four different frequency ranges. Most GSM

networks operate in the 900 MHz or 1800 MHz bands. Some countries in the

Americas use the 850 MHz and 1900 MHz bands because the 900 and 1800 MHz

frequency bands were already allocated.The rarer 400 and 450 MHz frequency bands

are assigned in some countries, where these frequencies were previously used for

first-generation systems.GSM-900 uses 890–915 MHz to send information from the

mobile station to the base station (uplink) and 935–960 MHz for the other direction

(downlink), providing 124 RF channels (channel numbers 1 to 124) spaced at 200

kHz. Duplex spacing of 45 MHz is used. In some countries the GSM-900 band has

been extended to cover a larger frequency range. This 'extended GSM', E-GSM, uses

880–915 MHz (uplink) and 925–960 MHz (downlink), adding 50 channels (channel

numbers 975 to 1023 and 0) to the original GSM-900 band. Time division

multiplexing is used to allow eight full-rate or sixteen half-rate speech channels per

radio frequency channel. There are eight radio timeslots (giving eight burst periods)

grouped into what is called a TDMA frame. Half rate channels use alternate frames in

the same timeslot. The channel data rate is 270.833 kbit/s, and the frame duration is

4.615 ms.

6.2 GSM Advantages

GSM also pioneered a low-cost, to the network carrier, alternative to voice

calls, the Short t message service (SMS, also called "text messaging"), which is now

supported on other mobile standards as well. Another advantage is that the standard

includes one worldwide Emergency telephone number, 112. This makes it easier for

international travelers to connect to emergency services without knowing the local

emergency number.

S.R.T.I.S.T 34


6.3 The GSM Network

GSM provides recommendations, not requirements. The GSM specifications

define the functions and interface requirements in detail but do not address the

hardware. The GSM network is divided into three major systems: the switching

system (SS), the base station system (BSS), and the operation and support system

(OSS).

Fig 6.1 GSM Network

S.R.T.I.S.T 35


6.3.1 The Switching System:

The switching system (SS) is responsible for performing call processing and

subscriber-related functions. The switching system includes the following functional

units.

Home location register (HLR): The HLR is a database used for storage and

management of subscriptions. The HLR is considered the most important

database, as it stores permanent data about subscribers, including a

subscriber's service profile, location information, and activity status. When an

individual buys a subscription from one of the PCS operators, he or she is

registered in the HLR of that operator.

Mobile services switching center (MSC): The MSC performs the telephony

switching functions of the system. It controls calls to and from other telephone

and data systems. It also performs such functions as toll ticketing, network

interfacing, common channel signaling, and others.

Visitor location register (VLR): The VLR is a database that contains

temporary information about subscribers that is needed by the MSC in order to

service visiting subscribers. The VLR is always integrated with the MSC.

When a mobile station roams into a new MSC area, the VLR connected to that

MSC will request data about the mobile station from the HLR. Later, if the

mobile station makes a call, the VLR will have the information needed for call

setup without having to interrogate the HLR each time.

Authentication center (AUC): A unit called the AUC provides authentication

and encryption parameters that verify the user's identity and ensure the

confidentiality of each call. The AUC protects network operators from

different types of fraud found in today's cellular world.

Equipment identity register (EIR): The EIR is a database that contains

information about the identity of mobile equipment that prevents calls from

stolen, unauthorized, or defective mobile stations. The AUC and EIR are

implemented as stand-alone nodes or as a combined AUC/EIR node.

S.R.T.I.S.T 36


6.3.2 The Base Station System (BSS):

All radio-related functions are performed in the BSS, which consists of base

station controllers (BSCs) and the base transceiver stations (BTSs).

BSC: The BSC provides all the control functions and physical links between

the MSC and BTS. It is a high-capacity switch that provides functions such as

handover, cell configuration data, and control of radio frequency (RF) power

levels in base transceiver stations. A number of BSCs are served by an MSC.

BTS: The BTS handles the radio interface to the mobile station. The BTS is

the radio equipment (transceivers and antennas) needed to service each cell in

the network. A group of BTSs are controlled by a BSC.

6.3.3 The Operation and Support System

The operations and maintenance center (OMC) is connected to all equipment

in the switching system and to the BSC. The implementation of OMC is called the

operation and support system (OSS). The OSS is the functional entity from which the

network operator monitors and controls the system. The purpose of OSS is to offer the

customer cost-effective support for centralized, regional and local operational and

maintenance activities that are required for a GSM network. An important function of

OSS is to provide a network overview and support the maintenance activities of

different operation and maintenance organizations.

6.4 Additional Functional Elements

Message center (MXE): The MXE is a node that provides integrated voice,

fax, and data messaging. Specifically, the MXE handles short message service,

cell broadcast, voice mail, fax mail, e-mail, and notification.

Mobile service node (MSN): The MSN is the node that handles the mobile

intelligent network (IN) services.

Gateway mobile services switching center (GMSC): A gateway is a node

used to interconnect two networks. The gateway is often implemented in an

MSC. The MSC is then referred to as the GMSC.

S.R.T.I.S.T 37


GSM inter-working unit (GIWU): The GIWU consists of both hardware

and software that provides an interface to various networks for data

communications. Through the GIWU, users can alternate between speech and

data during the same call. The GIWU hardware equipment is physically

located at the MSC/VLR.

6.5 GSM Network Areas

The GSM network is made up of geographic areas. As shown in bellow figure, these

areas include cells, location areas (LAs), MSC/VLR service areas, and public land

mobile network (PLMN) areas.

Fig 6.2 GSM Network Areas

6.5.1 Location Areas

The cell is the area given radio coverage by one base transceiver station. The GSM

network identifies each cell via the cell global identity (CGI) number assigned to each

cell. The location area is a group of cells. It is the area in which the subscriber is

paged. Each LA is served by one or more base station controllers, yet only by a single

MSC Each LA is assigned a location area identity (LAI) number.

6.5.2 MSC/VLR service areas

An MSC/VLR service area represents the part of the GSM network that is covered by

one MSC and which is reachable, as it is registered in the VLR of the MSC.

S.R.T.I.S.T 38


6.5.3 PLMN service areas

The PLMN service area is an area served by one network operator.

6.6 GSM Specifications

Specifications for different personal communication services (PCS) systems vary among the different PCS networks. Listed below is a description of the specifications and characteristics for GSM.

Frequency band: The frequency range specified for GSM is 1,850 to 1,990

MHz (mobile station to base station).

Duplex distance: The duplex distance is 80 MHz. Duplex distance is the

distance between the uplink and downlink frequencies. A channel has two

frequencies, 80 MHz apart.

Channel separation: The separation between adjacent carrier frequencies. In

GSM, this is 200 kHz.

Modulation: Modulation is the process of sending a signal by changing the

characteristics of a carrier frequency. This is done in GSM via Gaussian

minimum shift keying (GMSK).

Transmission rate: GSM is a digital system with an over-the-air bit rate of

270 kbps.

Access method: GSM utilizes the time division multiple access (TDMA)

concept. TDMA is a technique in which several different calls may share the

same carrier. Each call is assigned a particular time slot.

Speech coder: GSM uses linear predictive coding (LPC). The purpose of

LPC is to reduce the bit rate. The LPC provides parameters for a filter that

mimics the vocal tract. The signal passes through this filter, leaving behind a

residual signal. Speech is encoded at 13 kbps.

6.7 GSM Subscriber Services

Dual-tone multifrequency (DTMF): DTMF is a tone signaling scheme often used

for various control purposes via the telephone network, such as remote control of an

answering machine. GSM supports full-originating DTMF.

S.R.T.I.S.T 39


Facsimile group III—GSM supports CCITT Group 3 facsimile. As standard fax

machines are designed to be connected to a telephone using analog signals, a special

fax converter connected to the exchange is used in the GSM system. This enables a

GSM–connected fax to communicate with any analog fax in the network.

Short message services: A convenient facility of the GSM network is the short

message service. A message consisting of a maximum of 160 alphanumeric characters

can be sent to or from a mobile station. This service can be viewed as an advanced

form of alphanumeric paging with a number of advantages. If the subscriber's mobile

unit is powered off or has left the coverage area, the message is stored and offered

back to the subscriber when the mobile is powered on or has reentered the coverage

area of the network. This function ensures that the message will be received.

Cell broadcast: A variation of the short message service is the cell broadcast facility.

A message of a maximum of 93 characters can be broadcast to all mobile subscribers

in a certain geographic area. Typical applications include traffic congestion warnings

and reports on accidents.

Voice mail: This service is actually an answering machine within the network, which

is controlled by the subscriber. Calls can be forwarded to the subscriber's voice-mail

box and the subscriber checks for messages via a personal security code.

Fax mail: With this service, the subscriber can receive fax messages at any fax

machine. The messages are stored in a service center from which they can be

retrieved by the subscriber via a personal security code to the desired fax number

Supplementary Services:

Call forwarding: This service gives the subscriber the ability to forward incoming

calls to another number if the called mobile unit is not reachable, if it is busy, if there

is no reply, or if call forwarding is allowed unconditionally.

Barring of outgoing calls: This service makes it possible for a mobile subscriber to

prevent all outgoing calls.

S.R.T.I.S.T 40


Barring of incoming calls: This function allows the subscriber to prevent incoming

calls. The following two conditions for incoming call barring exist: baring of all

incoming calls and barring of incoming calls when roaming outside the home PLMN.

Advice of charge (AoC): The AoC service provides the mobile subscriber with an

estimate of the call charges. There are two types of AoC information: one that

provides the subscriber with an estimate of the bill and one that can be used for

immediate charging purposes. AoC for data calls is provided on the basis of time

measurements.

Call hold: This service enables the subscriber to interrupt an ongoing call and then

subsequently reestablish the call. The call hold service is only applicable to normal

telephony.

Call waiting: This service enables the mobile subscriber to be notified of an

incoming call during a conversation. The subscriber can answer, reject, or ignore the

incoming call. Call waiting is applicable to all GSM telecommunications services

using a circuit-switched connection.

Multiparty service: The multiparty service enables a mobile subscriber to establish a

multiparty conversation—that is, a simultaneous conversation between three and six

subscribers. This service is only applicable to normal telephony.

Calling line identification presentation/restriction: These services supply the

called party with the integrated services digital network (ISDN) number of the calling

party. The restriction service enables the calling party to restrict the presentation. The

restriction overrides the presentation.

Closed user groups (CUGs): CUGs are generally comparable to a PBX. They are a

group of subscribers who are capable of only calling themselves and certain numbers

S.R.T.I.S.T 41


CHAPTER 7

MAX 232

7.1 INTRODUCTION

To allow compatibility among data communication equipment made by

various manufacturers, an interfacing standard called RS232 was set by the

Electronics Industries Association (EIA) in 1960. In 1963 it was modified and called

RS232A. RS232B AND RS232C were issued in 1965 and 1969, respectively. Today,

RS232 is the most widely used serial I/O interfacing standard. This standard is used

in PCs and numerous types of equipment. However, since the standard was set long

before the advert of the TTL logic family, its input and output voltage levels are not

TTL compatible. In RS232, a 1 is represented by -3 to -25V, while a 0 bit is +3 to

+25V, making -3 to +3 undefined. For this reason, to connect any RS232 to a

microcontroller system we must use voltage converters such as MAX232 to convert

the TTL logic levels to the RS232 voltage levels, and vice versa. MAX232 IC chips

are commonly referred to as line drivers.

7.2 SERIAL COMMUNICATION

Computers can transfer data in two ways: parallel and serial. In parallel data

transfers, often 8 or more lines (wire conductors) are used to transfer data to a device

that is only a few feet away. Examples of parallel data transfer are printers and hard

disks; each uses cables with many wire strips. Although in such cases a lot of data

can be transferred in a short amount of time by using many wires in parallel, the

distance cannot be great. To transfer to a device located many meters away, the serial

method is used. In serial communication, the data is sent one bit at a time, in contrast

to parallel communication, in which the data is sent a byte or more at a time. Serial

communication of the 8051 is the topic of this chapter.

S.R.T.I.S.T 42


The 8051 has serial communication capability built into it, there by making

possible fast data transfer using only a few wires.

If data is to be transferred on the telephone line, it must be converted from

0s and 1s to audio tones, which are sinusoidal-shaped signals. A peripheral device

called a modem, which stands for “modulator/demodulator”, performs this

conversion.

Serial data communication uses two methods, asynchronous and

synchronous. The synchronous method transfers a block of data at a time, while the

asynchronous method transfers a single byte at a time.

In data transmission if the data can be transmitted and received, it is a

duplex transmission. This is in contrast to simplex transmissions such as with

printers, in which the computer only sends data. Duplex transmissions can be half or

full duplex, depending on whether or not the data transfer can be simultaneous. If

data is transmitted one way at a time, it is referred to as half duplex. If the data can go

both ways at the same time, it is full duplex. Of course, full duplex requires two wire

conductors for the data lines, one for transmission and one for reception, in order to

transfer and receive data simultaneously.

7.2.1 Asynchronous serial communication and data framing

The data coming in at the receiving end of the data line in a serial data

transfer is all 0s and 1s; it is difficult to make sense of the data unless the sender and

receiver agree on a set of rules, a protocol, on how the data is packed, how many bits

constitute a character, and when the data begins and endsbits. This is called framing.

In the data framing for asynchronous communications, the data, such as ASCII

characters, are packed between a start bit and a stop bit.

S.R.T.I.S.T 43


7.2.2 Start and stop bits

Asynchronous serial data communication is widely used for character-

oriented transmissions, while block-oriented data transfers use the synchronous

method. In the asynchronous method, each character is placed between start and stop

The start bit is always one bit, but the stop bit can be one or two bits. The start bit is

always a 0 (low) and the stop bit (s) is 1 (high)

7.2.3 Data transfer rate

The rate of data transfer in serial data communication is stated in bps (bits

per second). Another widely used terminology for bps is baud rate. However, the

baud and bps rates are not necessarily equal. This is due to the fact that baud rate is

the modem terminology and is defined as the number of signal changes per second.

In modems a single change of signal, sometimes transfers several bits of data. As far

as the conductor wire is concerned, the baud rate and bps are the same, and for this

reason we use the bps and baud interchangeably.

The data transfer rate of given computer system depends on communication

ports incorporated into that system. For example, the early IBMPC/XT could transfer

data at the rate of 100 to 9600 bps. In recent years, however, Pentium based PCS

transfer data at rates as high as 56K bps. It must be noted that in asynchronous serial

data communication, the baud rate is generally limited to 100,000bps.

7.3 RS232 PINS

RS232 cable is commonly referred to as the DB-25 connector. In labeling,

DB-25P refers to the plug connector (male) and DB-25S is for the socket connector

(female). Since not all the pins are used in PC cables, IBM introduced the DB-9

Version of the serial I/O standard, which uses 9 pins only, as shown in table.

S.R.T.I.S.T 44


7.3.1 DB-9 pin connector

1 2 3 4 5

6 7 8 9

Table 7.1: Pin Functions of DB-9 Pin Connector

(Note: DCD, DSR, RTS and CTS are active low pins.)

The method used by RS-232 for communication allows for a simple

connection of three lines: Tx, Rx, and Ground.

The three essential signals for 2-way RS-232 Communications are these:

TXD: carries data from DTE to the DCE.

RXD: carries data from DCE to the DTE.

SG: signal ground

S.R.T.I.S.T 45

Pin Description

1 Data carrier detect (DCD)

2 Received data (RXD)

3 Transmitted data (TXD)

4 Data terminal ready(DTR)

5 Signal ground (GND)

6 Data set ready (DSR)

7 Request to send (RTS)

8 Clear to send (CTS)

9 Ring indicator (RI)


The RS232 standard is not TTL compatible; therefore, it requires a line

driver such as the MAX232 chip to convert RS232 voltage levels to TTL levels, and

vice versa. The interfacing of 8051 with RS232 connectors via the MAX232 chip is

the main topic.

The 8051 has two pins that are used specifically for transferring and receiving

data serially. These two pins are called TXD and RXD and a part of the port 3 group

(P3.0 and P3.1). Pin 11 of the 8051 is assigned to TXD and pin 10 is designated as

RXD. These pins are TTL compatible; therefore, they require a line driver to make

them RS232 compatible. One such line driver is the MAX232 chip.

MAX232 converts from RS232 voltage levels to TTL voltage levels, and

vice versa. One advantage of the MAX232 chip is that it uses a +5V power source

which, is the same as the source voltage for the 8051. In the other words, with a

single +5V power supply we can power both the 8051 and MAX232, with no need for

the power supplies that are common in many older systems. The MAX232 has two

sets of line drivers for transferring and receiving data. The line drivers used for TXD

are called T1 and T2, while the line drivers for RXD are designated as R1 and R2. In

many applications only one of each is used.

7.3.2 8051 connection to RS232

Fig.7.1: Connection of Microcontroller with Serial Port Using MAX 232

S.R.T.I.S.T 46


The RS232 standard is not TTL compatible; therefore, it requires a Line

Driver such as the MAX232 chip to convert RS232 voltage levels to TTL levels, and

vice versa.

The 8051 has two pins that are used specifically for transferring and receiving

data serially. These two pins are TXD and RXD and are a part of the port 3 (P3.0 and

P3.1). Pin 11 of the 8051 is designated as TXD and pin 10 as RXD. These pins are

TTL compatible; therefore, they require a line driver to make them RS232 compatible.

One such line driver is the MAX232 chip.

MAX232 converts from RS232 voltage levels to TTL voltage levels, and vice

versa. One advantage of the MAX232 chip is that it uses a +5V power source which,

is the same as the source voltage for the 8051. In the other words, with a single +5V

power supply we can power both the 8051 and MAX232, with no need for the power

supplies. The MAX232 has two sets of line drivers for transferring and receiving data.

The line drivers used for TXD are called T1 and T2, while the line drivers for RXD

are designated as R1 and R2. In many applications only one of each is used.

7.4 MAX 232 SERIAL LINEDRIVER

The pin-out diagram of MAX 232 is shown below.

Fig.7.2: MAX 232E Dual Driver/Receiver

S.R.T.I.S.T 47


7.4.1 MAX 232 Operating Circuit

Fig.7.3: MAX 232 Operating Circuit

S.R.T.I.S.T 48


Table 7.2: Function Tables of MAX 232

Pin 10, 11 form the dual inputs with TTL logic whereas 14, 7 form the outputs

for RS 232 logic. And the 12, 9, 13, 8 form the vice versa inputs and outputs as shown

in fig.

The inputs and outputs of the drivers and receivers are shown in fig above.

CHAPTER 8

LIQUID CRYSTAL DISPLAY

8.1 INTRODUCTION

Liquid crystal displays (LCDs) have materials which combine the properties

of both liquids and crystals. Rather than having a melting point, they have a

temperature range within which the molecules are almost as mobile as they would be

in a liquid, but are grouped together in an ordered form similar to a crystal.

An LCD consists of two glass panels, with the liquid crystal material sand

witched in between them. The inner surface of the glass plates are coated with

transparent electrodes which define the character, symbols or patterns to be displayed

polymeric layers are present in between the electrodes and the liquid crystal, which

makes the liquid crystal molecules to maintain a defined orientation angle.

One each polarizers are pasted outside the two glass panels. These polarisers

would rotate the light rays passing through them to a definite angle, in a particular

direction

S.R.T.I.S.T 49


When the LCD is in the off state, light rays are rotated by the two polarisers

and the liquid crystal, such that the light rays come out of the LCD without any

orientation, and hence the LCD appears transparent.

When sufficient voltage is applied to the electrodes, the liquid crystal

molecules would be aligned in a specific direction. The light rays passing through the

LCD would be rotated by the polarizers, which would result in activating /

highlighting the desired characters.

The LCD’s are lightweight with only a few millimeters thickness. Since the

LCD’s consume less power, they are compatible with low power electronic circuits,

and can be powered for long durations.

The LCD s doesn’t generate light and so light is needed to read the display. By

using backlighting, reading is possible in the dark. The LCD’s have long life and a

wide operating temperature range.

Changing the display size or the layout size is relatively simple which makes

the LCD’s more customer friendly.

The LCDs used exclusively in watches, calculators and measuring instruments

are the simple seven-segment displays, having a limited amount of numeric data. The

recent advances in technology have resulted in better legibility, more information

displaying capability and a wider temperature range. These have resulted in the LCDs

being extensively used in telecommunications and entertainment electronics. The

LCDs have even started replacing the cathode ray tubes (CRTs) used for the display

of text and graphics, and also in small TV applications.

This section describes the operation modes of LCD’s then describe how to

program and interface an LCD to 8051 using Assembly and C.

8.2 LCD OPERATION

In recent years the LCD is finding widespread use replacing LED s (seven-

segment LED s or other multi-segment LED s).This is due to the following reasons:

1. The declining prices of LCDs.

S.R.T.I.S.T 50


2. The ability to display numbers, characters and graphics. This is in contrast to

LED which is limited to numbers and a few characters.

3. Incorporation of a refreshing controller into the LCD, there by relieving the

CPU of the task of refreshing the LCD. In the case of LED s, they must be

refreshed by the CPU to keep on displaying the data.

4. Ease of programming for characters and graphics.

S.R.T.I.S.T 51


8.3 LCD PIN DESCRIPTION

The LCD discussed in this section has 14 pins. The function of each pin is

given in table.

Fig.8.1: Connection of LCD with Microcontroller

The LCD can display a character successfully by placing the

1. Data in Data Register

2. Command in Command Register of LCD

1. Data corresponds to the ASCII value of the character to be printed. This can

be done by placing the ASCII value on the LCD Data lines and selecting the

Data Register of the LCD by selecting the RS (Register Select) pin.

2. Each and every display location is accessed and controlled by placing

respective command on the data lines and selecting the Command Register of

LCD by selecting the (Register Select) RS pin.

S.R.T.I.S.T 52


Pin symbol I/O Description

1 Vss -- Ground

2 Vcc -- +5V power supply

3 VEE -- Power supply to control

contrast

4 RS I RS=0 to select command

register

RS=1 to select data register

5 R/W I R/W=0 for write

R/W=1 for read

6 E I/O Enable

7 DB0 I/O The 8-bit data bus








Table 8.1: Pin Description for LCD

S.R.T.I.S.T 53


Code (hex) Command to LCD Instruction Register

1 Clear display screen

2 Return home

4 Decrement cursor

6 Increment cursor

5 Shift display right

7 Shift display left

8 Display off, cursor off

A Display off, cursor on

C Display on, cursor off

E Display on, cursor on

F Display on, cursor blinking

10 Shift cursor position to left

14 Shift cursor position to right

18 Shift the entire display to the left

1C Shift the entire display to the right

80 Force cursor to beginning of 1st line

C0 Force cursor to beginning of 2nd line

38 2 lines and 5x7 matrix

Table 8.2: LCD Command Codes

8.4 Uses

The LCDs used exclusively in watches, calculators and measuring instruments

are the simple seven-segment displays, having a limited amount of numeric data. The

recent advances in technology have resulted in better legibility, more information

displaying capability and a wider temperature range. These have resulted in the LCDs

being extensively used in telecommunications and entertainment electronics.

So in this project, the LCD is used to display the instantaneous information. The

information may be prompting or alerting or instructing the user.

S.R.T.I.S.T 54


CHAPTER 9

MOTOR

9.1 Introduction

A stepper motor is an electromechanically device which converts electrical

pulses into discrete mechanical movements. The shaft or spindle of a stepper motor

rotates in discrete step increments when electrical command pulses are applied to it in

the proper sequence. The motors rotation has several direct relationships to these

applied pulses is directly related to the direction of motor shafts rotation. The speed of

the motor shafts rotation is directly related to the frequency of the input pulses and the

length of rotation is directly related to the number of input pulses applied.

9.2 Stepper motor advantages

1. The rotation angle of the motor is proportional to the input pulse

2. The motor has full torque at standstill (if the windings are energized)

3. Precise positioning and repeatability of movement since good stepper motors

have an accuracy of 3-5% of a step and this error is non cumulative from one

step to the next.

4. Excellent response to starting/stopping/reversing.

5. Very reliable since there are no contact brushes in the motor. Therefore the life

of the motor is simply dependant on the life of the bearing.

6. The motors response to digital input pulses provides open-loop control,

making the motor simpler and less costly to control.

7. It is possible to achieve very low speed synchronous rotation with a load that

is directly coupled to the shaft.

8. A wide range of rotational speeds can be realized as the speed is proportional

to the frequency of the input pulses.

9.3 Stepper motor disadvantages

1. Resonances can occur if not properly controlled.

2. Not easy to operate at extremely high speeds.

S.R.T.I.S.T 55


9.4 Stepper Motor Types

There are three basic stepper motor types. They are :

• Variable-reluctance

• Permanent-magnet

• Hybrid

9.5 When to Use a Stepper Motor

A stepper motor can be a good choice whenever controlled movement is

required. They can be used to advantage in applications where you need to control

rotation angle, speed, position and synchronism. Because of the inherent advantages

listed previously, stepper motors have found their place in many different

applications. Some of these include printers, plotters, highend office equipment, hard

diskdrives, medical equipment, fax machines, automotive and many more.

S.R.T.I.S.T 56


CHAPTER 10

RELAYS

10.1 Introduction

A relay is an electrical switch that opens and closes under the control of another

electrical circuit. In the original form, the switch is operated by an electromagnet to

open or close one or many sets of contacts. A relay is able to control an output circuit

of higher power than the input circuit, it can be considered to be, in a broad sense, a

form of an electrical amplifier.

Fig 10.1 Relay

Relays are usuallly SPDT (single pole double through switch)or DPDT (double

pole double through switch) but they can have many more sets of switch contacts, for

example relays with 4 sets of changeover contacts are readily available.

S.R.T.I.S.T 57


10.2 Basic operation of a relay

An electric current through a conductor will produce a magnetic field at right

angles to the direction of electron flow. If that conductor is wrapped into a coil shape,

the magnetic field produced will be oriented along the length of the coil. The greater

the current, the greater the strength of the magnetic field, all other factors being equal.

Fig 10.2 Relay circuit

Inductors react against changes in current because of the energy stored in this

magnetic field. When we construct a transformer from two inductor coils around a

common iron core, we use this field to transfer energy from one coil to the other.

However, there are simpler and more direct uses for electromagnetic fields than the

applications we've seen with inductors and transformers. The magnetic field produced

by a coil of current-carrying wire can be used to exert a mechanical force on any

magnetic object, just as we can use a permanent magnet to attract magnetic objects,

except that this magnet (formed by the coil) can be turned on or off by switching the

current on or off through the coil.

S.R.T.I.S.T 58


If we place a magnetic object near such a coil for the purpose of making that object

move when we energize the coil with electric current, we have what is called a

solenoid. The movable magnetic object is called an armature, and most armatures can

be moved with either direct current (DC) or alternating current (AC) energizing the

coil. The polarity of the magnetic field is irrelevant for the purpose of attracting an

iron armature. Solenoids can be used to electrically open door latches, open or shut

valves, move robotic limbs, and even actuate electric switch mechanisms and is used

to actuate a set of switch contacts

10.3 Relays can be categorized according to the magnetic system and operation

10.3.1 Neutral Relays

This is the most elementary type of relay. The neutral relays have a magnetic

coil, which operates the relay at a specified current, regardless of the polarity of the

voltage applied.

10.3.2 Biased Relays

Biased relays have a permanent magnet above the armature. The relay

operates if the current through the coil winding establishes a magneto-motive force

that opposes the flux by the permanent magnet. If the fluxes are in the same direction,

the relay will not operate, even for a greater current through the coil.

10.3.3 Polarized Relays

Like the biased relays, the polarized relays operate only when the current

through the coil in one direction. But there the principle is different. The relay coil has

a diode connected in series with it. This blocks the current in the reverse direction.The

major difference between biased relays and polarized relays is that the former allows

the current to pass through in the reverse direction, but does the not operate the relay

and the later blocks the current in reverse direction. You can imagine how critical

these properties when relays are connected in series to form logic circuits.

S.R.T.I.S.T 59


10.3.4 Magnetic Stick Relays or Perm polarized Relays

These relays have a magnetic circuit with high permanence. Two coils, one to

operate (pick up) and one to release (drop) are present. The relay is activated by a

current in the operate coil. On the interruption of the current the armature remains in

picked up position by the residual magnetism. The relay is released by a current

through the release coil.

10.3.5 Slow Release Relays

These relays have a capacitor connected in parallel to their coil. When the

operating current is interrupted the release of relay is delayed by the stored charge in

the capacitor. The relay releases as the capacitor discharges through the coil.

10.3.6 Relays for AC

These are neutral relays and picked up for a.c. current through their coil. These

are very fast in action and used on power circuits of the point motors, where high

current flows through the contacts. A normal relay would be slow and make sparks

which in turn may weld the contacts together.All relays have two operating values

(voltages), one pick-up and the other other drop away. The pick-up value is higher

than the drop away value.

10.4 Applications To control a high-voltage circuit with a low-voltage signal, as in some types of

modems or audio amplifiers,

To control a high-current circuit with a low-current signal, as in the starter

solenoid of an automobile,

To detect and isolate faults on transmission and distribution lines by opening

and closing circuit breakers (protection relays),

To isolate the controlling circuit from the controlled circuit when the two are

at different potentials, for example when controlling a mains-powered device

from a low-voltage switch. They may also be controlled by room occupancy

detectors in an effort to conserve energy,

S.R.T.I.S.T 60


To perform logic functions. For example, the boolean AND function is

realised by connecting NO relay contacts in series, the OR function by

connecting NO contacts in parallel. The change-over or Form C contacts

perform the XOR (exclusive or) function. Similar functions for NAND and

NOR are accomplished using NC contacts. The Ladder programming language

is often used for designing relay logic networks.

o Early computing. Before vacuum tubes and transistors, relays were

used as logical elements in digital computers. See ARRA (computer),

Harvard Mark II, Zuse Z2, and Zuse Z3.

o Safety-critical logic. Because relays are much more resistant than

semiconductors to nuclear radiation, they are widely used in safety-

critical logic, such as the control panels of radioactive waste-handling

machinery.

To perform time delay functions. Relays can be modified to delay opening or

delay closing a set of contacts. A very short (a fraction of a second) delay

would use a copper disk between the armature and moving blade assembly.

Current flowing in the disk maintains magnetic field for a short time,

lengthening release time. For a slightly longer (up to a minute) delay, a

dashpot is used. A dashpot is a piston filled with fluid that is allowed to escape

slowly. The time period can be varied by increasing or decreasing the flow

rate. For longer time periods, a mechanical clockwork timer is installed

S.R.T.I.S.T 61


CHAPTER 11

REGULATED POWER SUPPLY

11.1 INTRODUCTION

The power supplies are designed to convert high voltage AC mains electricity

to a suitable low voltage supply for electronics circuits and other devices. A RPS

(Regulated Power Supply) is the Power Supply with Rectification, Filtering and

Regulation being done on the AC mains to get a Regulated power supply for

Microcontroller and for the other devices being interfaced to it.

A power supply can by broken down into a series of blocks, each of which

performs a particular function. A d.c power supply which maintains the output voltage

constant irrespective of a.c mains fluctuations or load variations is known as

“Regulated D.C Power Supply”

For example a 5V regulated power supply system as shown below:

Fig.11.1: Block Diagram of the Power Supply

S.R.T.I.S.T 62


11.2 TRANSFORMER

A transformer is an electrical device which is used to convert electrical power

from one Electrical circuit to another without change in frequency. Transformers

convert AC electricity from one voltage to another with little loss of power.

Transformers work only with AC and this is one of the reasons why mains electricity

is AC. Step-up transformers increase in output voltage, step-down transformers

decrease in output voltage. Most power supplies use a step-down transformer to

reduce the dangerously high mains voltage to a safer low voltage. The input coil is

called the primary and the output coil is called the secondary. There is no electrical

connection between the two coils; instead they are linked by an alternating magnetic

field created in the soft-iron core of the transformer. The two lines in the middle of

the circuit symbol represent the core. Transformers waste very little power so the

power out is (almost) equal to the power in. Note that as voltage is stepped down

current is stepped up. The ratio of the number of turns on each coil, called the turn’s

ratio, determines the ratio of the voltages. A step-down transformer has a large

number of turns on its primary (input) coil which is connected to the high voltage

mains supply, and a small number of turns on its secondary (output) coil to give a low

output voltage.

Fig.11.2: An Electrical Transformer

Turns ratio = Vp/ VS = Np/NS

Power Out= Power InVS x IS=VP x IP

Vp = primary (input) voltageNp = number of turns on primary coilIp = primary (input) current

S.R.T.I.S.T 63


11.3 RECTIFIER

A circuit which is used to convert a.c to dc is known as RECTIFIER. The

process of conversion a.c to d.c is called “rectification”.

11.3.1 Types of Rectifiers

1. Half wave Rectifier

2. Full wave Rectifier

1. Centre tap full wave rectifier.

2. Bridge type full bridge rectifier.

11.3.2 Comparison of rectifier circuits

Parameter

Type of Rectifier

Half wave Full wave Bridge

Number of diodes 1 2 4

PIV of diodes Vm 2Vm Vm

D.C output voltage Vm/ 2Vm/ 2Vm/

Vdc,at no-load 0.318Vm 0.636Vm 0.636Vm

Ripple factor 1.21 0.482 0.482

Ripple frequency f 2f 2f

Rectification

efficiency

0.406 0.812 0.812

Transformer

Utilization

Factor(TUF)

0.287 0.693 0.812

RMS voltage Vrms Vm/2 Vm/√2 Vm/√2

Table 11.1: Comparison of Rectifier Circuits

11.3.3 Full-wave Rectifier

From the above comparison we came to know that full wave bridge rectifier

as more advantages than the other two rectifiers. So, in our project we are using full

wave bridge rectifier circuit.

S.R.T.I.S.T 64


11.3.4 Bridge Rectifier

A bridge rectifier makes use of four diodes in a bridge arrangement to

achieve full-wave rectification. This is a widely used configuration, both with

individual diodes wired as shown and with single component bridges where the diode

bridge is wired internally.

A bridge rectifier makes use of four diodes in a bridge arrangement as shown

in fig (a) to achieve full-wave rectification. This is a widely used configuration, both

with individual diodes wired as shown and with single component bridges where the

diode bridge is wired internally.

Fig.11.3: Circuit diagram of Bridge Rectifier

11.3.5 Operation

During positive half cycle of secondary, the diodes D2 and D3 are in

forward biased while D1 and D4 are in reverse biased as shown in the fig(b). The

current flow direction is shown in the fig (b) with dotted arrows.

Fig.11.4. (a): Operation Circuit of Bridge Rectifier

S.R.T.I.S.T 65


During negative half cycle of secondary voltage, the diodes D1 and D4 are in

forward biased while D2 and D3 are in reverse biased as shown in the fig(c). The

current flow direction is shown in the fig (c) with dotted arrows.

Fig.11.4. (b): Operation Circuit of Bridger Rectifier

11.4 FILTER

A Filter is a device which removes the a.c component of rectifier output but

allows the d.c component to reach the load

11.4.1 Capacitor Filter

We have seen that the ripple content in the rectified output of half wave

rectifier is 121% or that of full-wave or bridge rectifier or bridge rectifier is 48%

such high percentages of ripples is not acceptable for most of the applications.

Ripples can be removed by one of the following methods of filtering.

(a) A capacitor, in parallel to the load, provides an easier by –pass for the

ripples voltage though it due to low impedance. At ripple frequency and

leave the D.C. to appear at the load.

(b) An inductor, in series with the load, prevents the passage of the ripple

current (due to high impedance at ripple frequency) while allowing the d.c

(due to low resistance to d.c)

(c) Various combinations of capacitor and inductor, such as L-section filter

section filter, multiple section filter etc. which make use of both the

properties mentioned in (a) and (b) above. Two cases of capacitor filter, one

applied on half wave rectifier and another with full wave rectifier.

S.R.T.I.S.T 66


Filtering is performed by a large value electrolytic capacitor connected across

the DC supply to act as a reservoir, supplying current to the output when the varying

DC voltage from the rectifier is falling. The capacitor charges quickly near the peak

of the varying DC, and then discharges as it supplies current to the output. Filtering

significantly increases the average DC voltage to almost the peak value (1.4 × RMS

value).

To calculate the value of capacitor(C),

C = ¼*√3*f*r*Rl

Where,

f = supply frequency,

r = ripple factor,

Rl = load resistance

Note: In our circuit we are using 1000µF hence large value of capacitor is

placed to reduce ripples and to improve the DC component.

11.5 REGULATOR

Voltage regulator ICs is available with fixed (typically 5, 12 and 15V) or

variable output voltages. The maximum current they can pass also rates them.

Negative voltage regulators are available, mainly for use in dual supplies.

Most regulators include some automatic protection from excessive current

('overload protection') and overheating ('thermal protection'). Many of the fixed

voltage regulators ICs have 3 leads and look like power transistors, such as the 7805

+5V 1A regulator shown on the right. The LM7805 is simple to use. You simply

connect the positive lead of your unregulated DC power supply (anything from 9VDC

to 24VDC) to the Input pin, connect the negative lead to the Common pin and then

when you turn on the power, you get a 5 volt supply from the output pin.

Fig. 11.5: A Three Terminal Voltage Regulator

S.R.T.I.S.T 67


CHAPTER 12

CIRCUIT DESCRIPTION

12.1 INTRODUCTION

ATM security system using GSM and MEMS Modules is one of the hot topics

in embedded systems industry. For providing Security at ATMs GSM and MEMS

Modules are controlled by using ATMEL Processor based AT89S52 Microcontroller.

Probably the most useful thing to know about the global system for mobile

communication is that it is an international standard. If you travel in parts of world,

GSM is only type of cellular service available. Instead of analog services, GSM was

developed as a digital system using TDMA technology.

Micro Electrical Mechanical Systems (MEMS) is the integration of

mechanical elements, sensors, actuators, and electronics on a common silicon

substrate through micro fabrication technology. The broadest requirement for these

very small devices is ability to sense the environment, to collect necessary data and to

create a signal or action to make desired changes to the environment.

In this project ATMEL based AT89S52 Microcontroller monitors MEMS Module ,

GSM and motor. MEMS module is placed on the outer panel of the ATM Machine, if

any tilt is identified by this block, MEMS send a signal to AT89S52 and as the signal

is received, it locks the ATM door and Alert message is send to the Security using

GSM Module.

S.R.T.I.S.T 68


12.2 SCHEMATIC DIAGRAM OF THE PROJECT

Fig.12.1: Schematic Diagram of the Project

S.R.T.I.S.T 69


12.3 SCHEMATIC DESCRIPTION

Firstly, the required operating voltage for Microcontroller 89S52 is 5V. Hence

the 5V D.C. power supply is needed by the same. This regulated 5V is generated by

first stepping down the 230V to 9V by the step down transformer.

The step downed a.c. voltage is being rectified by the Bridge Rectifier. The

diodes used are 1N4007. The rectified a.c voltage is now filtered using a ‘C’ filter.

Now the rectified, filtered D.C. voltage is fed to the Voltage Regulator. This voltage

regulator allows us to have a Regulated Voltage which is +5V.The rectified; filtered

and regulated voltage is again filtered for ripples using an electrolytic capacitor

100μF. Now the output from this section is fed to 40 th pin of 89S52 microcontroller to

supply operating voltage.

The microcontroller 89S52 with Pull up resistors at Port0 and crystal oscillator

of 11.0592 MHz crystal in conjunction with couple of capacitors of is placed at 18 th

& 19th pins of 89S52 to make it work (execute) properly.

The LCD is interfaced to Microcontroller. The data pins and control pins of

LCD are connected to Port 0 as shown in schematic. The GSM is interfaced to

microcontroller through a voltage level converter i.e. MAX 232.

The GSM o/p & i/p pins i.e. RX and TX are connected to MAX 232 serial

drivers 7th and 13th pins and its output to Microcontroller from 11th & 12th of MAX to

TX and RX pins of Microcontroller.

A Motor is connected across port 2 at 24th pin.

And the main functional input block MEMS is interfaced at port 1,at p1.0 to

p1.7 with 18th to 11th pins of ADC 0804 and in turn this ADC 0804 is connected with

mems at 2nd 3rd and 5th pins.

S.R.T.I.S.T 70


12.4 HARDWARE COMPONENTS

The Hardware components used in this project are

Regulated Power Supply

Microcontroller

MEMS Sensor

ADC 0804

GSM

MAX 232

LCD

Motor

Relay

12.5 SOFTWARE COMPONENTS

12.5.1 About Software

Software used is:

*Keil software for C programming

*Express PCB for lay out design

*Express SCH for schematic design

12.5.2 KEIL µVision3

What's New in µVision3?

µVision3 adds many new features to the Editor like Text Templates, Quick

Function Navigation, and Syntax Coloring with brace high lighting Configuration

Wizard for dialog based startup and debugger setup. µVision3 is fully compatible to

µVision2 and can be used in parallel with µVision2.

What is µVision3?

µVision3 is an IDE (Integrated Development Environment) that helps you write, compile, and debug embedded programs. It encapsulates the following components:

A project manager.

A make facility.

Tool configuration.

Editor.

A powerful debugger.

S.R.T.I.S.T 71


12.5.3 Express PCB

Express PCB is a Circuit Design Software and PCB manufacturing service.

One can learn almost everything you need to know about Express PCB from the help

topics included with the programs given.

Details: Express PCB, Version 5.6.0

12.5.4 Express SCH

The Express SCH schematic design program is very easy to use. This software

enables the user to draw the Schematics with drag and drop options.

A Quick Start Guide is provided by which the user can learn how to use it.

Details:

Express SCH, Version 5.6.0

12.6 EMBEDDED C

The programming Language used here in this project is an Embedded C

Language. This Embedded C Language is different from the generic C language in

few things like

a) Data types

b) Access over the architecture addresses.

The Embedded C Programming Language forms the user friendly language

with access over Port addresses, SFR Register addresses etc.

Embedded C Data types:

Data Types Size in Bits Data Range/Usage

unsigned char 8-bit 0-255

signed char 8-bit -128 to +127

unsigned int 16-bit 0 to 65535

signed int 16-bit -32,768 to +32,767

sbit 1-bit SFR bit addressable only

Bit 1-bit RAM bit addressable only

sfr 8-bit RAM addresses 80-FFH only

S.R.T.I.S.T 72


12.6.1 8051 project development cycle

1. Create source files in C or assembly.

2. Compile or assemble source files.

3. Correct errors in source files.

4. Link object files from compiler and assembler.

5. Test linked application.

The steps to develop 8051 project using keil are

1. Click on the Keil uVision Icon on Desktop

2. Click on the Project menu from the title bar

3. Then Click on New Project

4. Save the Project by typing suitable project name with no extension in u r

own folder sited in either C:\ or D:\

5. Then Click on save button above.

6. Select the component for u r project. i.e. Atmel……

7. Click on the + Symbol beside of Atmel

8. Select AT89C51 as shown below

9. Then Click on “OK”

10. Then Click either YES or NO………mostly “NO”

11. Now your project is ready to USE

12. Now double click on the Target1, you would get another option “Source

group 1” as shown in next page.

13. Click on the file option from menu bar and select “new”

14. The next screen will be as shown in next page, and just maximize it by

double clicking on its blue boarder.

15. Now start writing program in either in “C” or “ASM”

16. For a program written in Assembly, then save it with extension “. asm”

and for “C” based program save it with extension “ C”

S.R.T.I.S.T 73


17. Now right click on Source group 1 and click on “Add files to Group

Source”

18. Now you will get another window, on which by default “C” files will

appear.

19. Now select as per your file extension given while saving the file

20. Click only one time on option “ADD”

21. Now Press function key F7 to compile. Any error will appear if so happen.

22. If the file contains no error, then press Control+F5 simultaneously.

23. Then Click “OK”.

24. Now Click on the Peripherals from menu bar, and check your required port

as shown in fig below.

25. Drag the port a side and click in the program file.

26. Now keep Pressing function key “F11” slowly and observe.

27. You are running your program successfully

S.R.T.I.S.T 74


12.7 SOURCE CODE

============================================================

//<<<<<<<<<<ATM Security System Using GSM and MEMS MODULE>>>>>>>>>>//

============================================================

#include<reg52.h>#include<lcd.h>#include<intrins.h>sbit motor=P0^0;sbit sw=P0^1;

void SEND_CHR(unsigned char);void RECEIVE_CHR();void SEND_SMS(unsigned char *nm);void GSM_INIT(void);unsigned char rch; unsigned char buff[40];

void print(char *str){while(*str){SBUF = *str++;while(TI == 0);TI = 0;}}/*void RECEIVE_MEM(){unsigned int i=0;while(1){do{RECEIVE_CHR();}while(rch != '$');RECEIVE_CHR();if(rch == '3')

{RECEIVE_CHR();if(rch == 'A')

{RECEIVE_CHR();

S.R.T.I.S.T 75


if(rch == '0'){RECEIVE_CHR();if(rch == 'M')

{RECEIVE_CHR();if(rch == 'D')

{RECEIVE_CHR();if(rch == 'S'){i = 0;do{RECEIVE_CHR();buff[i] = rch;}while(buff[i++]!='$');goto nex;}}

}}

}}

}nex:;} */

void main(){unsigned char i=0;motor=0;sw=1;TMOD = 0x20;SCON = 0x50;TH1 = 0xFA; TR1 = 1;init_lcd();display_lcd("MAES BASED");cmd_lcd(0xC0);display_lcd("SECURITY SYSTEM");delay_ms(300);init_lcd();//GSM_INIT();print("AT+CMGF=1\r\n");delay_ms(300);TH1 = 0xFD; init_lcd();while(1)

S.R.T.I.S.T 76


{TH1=0xFD;delay_ms(75);init_lcd();display_lcd("MEMS BASED");cmd_lcd(0xC0);display_lcd("SECURITY SYSTEM");for(i=0;i<32;i++){RECEIVE_CHR();buff[i]=rch;}//init_lcd();if(buff[29]=='L' || buff[29]=='R' || buff[29]=='S' || buff[29]=='I'){TH1=0xFA;delay_ms(75);motor=1;SEND_SMS("9032323048");//SEND_SMS("9701515557");motor=0;delay_ms(200);init_lcd();display_lcd("WAIT FOR DOOR");cmd_lcd(0xC0);display_lcd("OPEN");while(sw==1);motor=1;init_lcd();display_lcd("DOOR OPENED");delay_ms(300);motor=0; TH1=0xFD;}}}void RECEIVE_CHR(){while(RI==0);rch = SBUF;RI=0;}void SEND_CHR(unsigned char c){SBUF = c;while(TI==0);TI=0;}void SEND_SMS(unsigned char *nm)

S.R.T.I.S.T 77


{unsigned int i=0,j=0;TH1=0xFA;cmd_lcd(0x01);display_lcd("SENDING SMS...");print("AT+CMGS=");SEND_CHR('"');print(nm);SEND_CHR('"');print("\r\n");delay_ms(500);print("SOMEBODY IS TRYING TO ROBERY");print("\r\n");print("\r\n");i=0;SEND_CHR(0x1A);SEND_CHR(0x1A); //END OF MESSAGE INDICATION. (ctrl + z)delay_ms(500);}

void GSM_INIT(void){

cmd_lcd(0x01);display_lcd("GSM INITIALIZING");cmd_lcd(100);print("AT\r\n");delay_ms(300);print("AT\r\n");delay_ms(300);print("AT\r\n");delay_ms(300);print("AT+IPR=4800\r\n");delay_ms(300);print("AT+CMGF=1\r\n");delay_ms(300);print("AT+CNMI=0,1,0,0,0\r\n");delay_ms(300);print("ATE0\r\n");delay_ms(300);print("AT&W\r\n");delay_ms(300);print("AT+CREG?\r\n");delay_ms(300);print("AT+CREG?\r\n");delay_ms(300);

}

S.R.T.I.S.T 78


CHAPTER 13

FUTURE ASPECTS

1. The microcontroller in this project can be interfaced with smoke sensor to identify

fire accidents and can be approached in time.

2. A smart card system can be developed that which helps in opening the door after

locking down the door when MEMS is activated. This smart card will be available

only with the authorized person.

S.R.T.I.S.T 79


CHAPTER 14

CONCLUSION

The project “ATM SECURITY SYSTEM USING GSM AND MEMS

MODULE” has been successfully designed and tested. Integrating features of all the

hardware components used have developed it. Presence of every module has been

reasoned out and placed carefully thus contributing to the best working of the unit.

Secondly, using highly advanced IC’s and with the help of growing technology the

project has been successfully implemented.

S.R.T.I.S.T 80


S.R.T.I.S.T 81


REFERENCES

TEXT BOOKS

S.NO TITLE OF THE

TEXT BOOK

AUTHOR PUBLICATIONS YEAR

01. 8051 Microcontroller

and embedded

systems (2nd Edition)

MAZIDI

&MAZIDI

Prentice Hall

Publications

2009

02. 8051 Microcontroller

(3rd Edition)

KENNETH

J.AYALA

Thomson

Publications

2004

03. Embedded controller

hardware design

KEN

ARNOLD

Newness

Publications

2007

WEB PREFERENCES

http://www.aaroncake.net/circuits/supply.asp http://www.8052.com/tut 8051

http://electrosofts.com/serial/

http://www.8052.com/tuttimer.phtml www.tkk.fi/Misc/Electronics/circuits/ ir _send.html

S.R.T.I.S.T 82

http://www.tkk.fi/Misc/Electronics/circuits/ir_send.html

http://www.8052.com/tuttimer.phtml

http://electrosofts.com/serial/

http://www.8052.com/tut8051

http://www.aaroncake.net/circuits/supply.asp

ATM Security System Using GSM and MEMS Module

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