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MINI PROJECT REPORT On GLOBAL ALERT AND CONTROL SYSTEM FOR UPS BATTERY MANAGEMENT FOR CORPORATE AUTOMATION (GSM) Submitted in partial fulfillment of the requirements For the award of the degree of BACHELOR OF TECHNOLOGY IN ELECTRONICS & COMMUNICATION ENGINEERING BY Y.SAI NITISH (08C71A04A9) P.CHANDRA SHEKER (08C71A0482) Under the Guidance of P.SURESH REDDY Asst.Prof Department of ECE

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Page 1: Mini Project on Gsm Based Ups Batterys Management Changes

MINI PROJECT REPORT

On

GLOBAL ALERT AND CONTROL SYSTEM FOR UPS BATTERY

MANAGEMENT FOR CORPORATE AUTOMATION (GSM)

Submitted in partial fulfillment of the requirements

For the award of the degree of

BACHELOR OF TECHNOLOGY

IN

ELECTRONICS & COMMUNICATION ENGINEERING

BY

Y.SAI NITISH (08C71A04A9)

P.CHANDRA SHEKER (08C71A0482)

Under the Guidance of

P.SURESH REDDY

Asst.Prof

Department of ECE

ELLENKI COLLEGE OF ENGINEERING & TECHNOLOGY

PATELGUDA, PATANCHERU, MEDAK DISTRICT-502305

AFFILIATED TO JNTU

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ELLENKI COLLEGE OF ENGINEERING & TECHNOLOGY

PATELGUDA, PATANCHERU, MEDAK DISTRICT-502305

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING

CERTIFICATE

This is to certify that project report entitled “GLOBAL ALERT AND

CONTROL SYSTEM FOR UPS BATTERY MANAGEMENT FOR CORPORATE

AUTOMATION (GSM)” of third year in partial fulfillment of requirements for

the award of the degree of bachelor of technology in Electronics &

Communication Engineering under Jawaharlal Nehru technology of University

during the period of 2008-2012.

INTERNAL GUIDE HEAD OF THE DEPARTMENT

Mr.P.SURESH REDDY Mr.T.SRAVAN KUMAR

Asst.Prof Assoc.Prof

DEPARTMENT OF ECE DEPARTMENT OF ECE

EXTERNAL GUIDE

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ACKNOWLEDGEMENT

Taking up the execution of project work was a rich experience by itself as it involved more of my efforts. It was the first opportunity for me to apply my knowledge and skill to work up on and an idea, which certainly will be helpful after stepping in to the actual field work.

My sincere thanks to external project guide SRINIVAS of KREST TECHNOLOGIES HYDERABAD, for the guidance and support pertaining to use lab facilities and carry out this project work.

I express my profound attitude to our guide Mr.P.SURESH REDDY Asst.prof of ECE department for her support and encouragement in completing the project .I thanks her project guidance and help through the development of this project for providing me with required information. Without her guidance, co-operation and encouragement, I couldn’t have learned many things during my project tenure.

I would like to thank Mr.T.SRAVAN KUMAR Assoc.Prof, Head of the department of electronics and communication engineering for his valuable guidance in bringing shape to this dissertation.

I express my special thanks to Principal Prof.MR.AMZAN SHAIK on behalf of our ECE department for his kind co-operation.

Y.SAI NITISH (08C71A04A9)

P.CHANDRA SHEKER (08C71A0482)

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ABSTRACT

In this project, we are using two transformers. One is as mains supply to

corporate and second transformer as secondary (UPS) supply. In the beginning

we are giving the main supply by transformer one, but if due to some reason

mains supply is not working. Then by power detector circuit this information

goes to microcontroller and buzzer will produce an alarming sound.

Microcontroller will send the message to authorized person by GSM modem.

If person wants to continue the power supply by second

transformer then that person has to send message to gsm modem. Whenever

the gsm modem receives sms message to change the power supply connection

it gives instruction to microcontroller. The microcontroller simply connects the

second power supply and disconnects the existing supply using relay based control

circuit.

INDEX

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CH.NO CONTENTS PAGE NO

1. INTRODUCTION

2. BLOCK DIAGRAM

2. 1 BLOCK DIAGRAM DESCRIPTION

3. SCHEMATIC

3. 1 SCHEMATIC DESCRIPTION

4. HARDWARE COMPONENTS

MICROCONTROLLER

GSM MODEM

BUZZER

LED

RELAY

LCD

POWER SUPPLY

TRANSFORMERS

5. SOFTWARE

ABOUT KIEL

EMBEDDED ‘C’

6. SOURCE CODE

7. CONCLUSION (OR) SYNOPSIS

8. ABBREVATIONS

BIBLIOGRAPHY

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CHAPTER 1

INTRODUCTION

Every system is automated in order to face new challenges in the present day

situation. Automated systems have less manual operations, so that the flexibility, reliabilities

are high and accurate. Hence every field prefers automated control systems. Especially in the

field of electronics automated systems are doing better performance increasingly.

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.

In our project the microcontroller continuously monitors the voltage and if the voltage

drops below the present value then this system alerts the local user and the remote personal

through gsm in the form of sms message.

If we want change the existed battery with another battery just we have to send the

sms to gsm modem connected. Whenever the gsm modem receives sms message to change

the battery connection it gives instruction to microcontroller .The microcontroller simply

connects the new battery and disconnects the existing battery using relay based control

circuit.

INTRODUCTION TO GSM TECHNOLOGY

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. Unlike a general-purpose

computer, such as a personal computer, an embedded system performs one or a few pre-

defined tasks, usually with very specific requirements. Since the system is dedicated to

specific tasks, design engineers can optimize it, reducing the size and cost of the product.

Embedded systems are often mass-produced, benefiting from economies of scale.

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What is GSM

Global System for Mobile Communication (GSM) is a set of ETSI standards specifying the

infrastructure for a digital cellular service. The standard is used in approx. 85 countries in the

world including such locations as Europe, Japan and Australia1

GSM Call Routing

Mobile Subscriber Roaming

When a mobile subscriber roams into a new location area (new VLR), the VLR automatically

determines that it must update the HLR with the new location information, which it does

using an SS7 Location Update Request Message. The Location Update Message is routed to

the HLR through the SS7 network, based on the global title translation of the IMSI that is

stored within the SCCP Called Party Address portion of the message. The HLR responds

with a message that informs the VLR whether the subscriber should be provided service in

Fig:Gsm call routing

GSM (Global System for Mobile communication) is a digital mobile telephone

system that is widely used in many parts of the world. GSM uses a variation of Time Division

Multiple Access (TDMA) and is the most widely used of the three digital wireless telephone

technologies. GSM digitizes and compresses data, then sends it down a channel with two

other streams of user data, each in its own time slot. GSM operates in the 900MHz,

1800MHz, or 1900 MHz frequency bands.

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GSM together with other technologies is part of an evolution of wireless

mobile telecommunication that includes High-Speed Circuit-Switched Data (HCSD), General

Packet Radio System (GPRS), Enhanced Data GSM Environment (EDGE), and Universal

Mobile Telecommunications Service (UMTS). GSM security issues such as theft of service,

privacy, and legal interception continue to raise significant interest in the GSM community.

The purpose of this portal is to raise awareness of these issues with GSM security.

Digital containers offer an alternative way of securely delivering content to

consumers. They can offer many advantages, particularly for content delivery over mobile

phone networks:

1. Scalability

2. Micro transactions/Micro payments compatibility

3. Content channel neutrality (heterogeneous networks, uni cast

/multicast/broadcast etc)

4. Possibility of DRM

5. Consumer anonymity

Etc.

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CHAPTER 2

BLOCK DIAGRAM:

LCD

MICRO

CONTROLLER

RELAY

LED INDICATOR

Transformer 1

Transformer 2

POWER SUPPLY

BUZZER

GSM

MODEM

Power detector ckt

MAX232

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Fig: block diagram of microcontroller

2.1 BLOCK DIAGRAM EXPLANATION:

Micro Controller:

In this project work the micro-controller is plays major role. Micro-controllers were originally used as components in complicated process-control systems. However, because of their small size and low price, Micro-controllers are now also being used in regulators for individual control loops. In several areas Micro-controllers are now outperforming their analog counterparts and are cheaper as well.

Gsm Modem

Here we are using GSM MODEM to communicate with the mobile phone to which we are going to send the message. Whenever an authorized person wants to know the status of parameter or whenever parameters values increases above the threshold value then a message will be sent through modem. This fault is indicated by displaying in LCD. This project will facilitates us to monitor as well as control different parameters at a time which increase accuracy and speed.

POWER SUPPLY

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 18V 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.

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But here in this project two power supplies are used one is meant to supply operating

voltage for Microcontroller and the other is to supply control voltage for Relays.

LCD:

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.

5

Buzzer:

A buzzer or beeper is a signaling device, usually electronic, typically used in

automobiles, household appliances such as a microwave ovens, & game shows.

The word "buzzer" comes from the rasping noise that buzzers made when they were

electromechanical devices, operated from stepped-down AC line voltage at 50 or 60 cycles.

Other sounds commonly used to indicate that a button has been pressed are a ring or a beep...

Leds:

A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices, and are increasingly used for lightning. Introduced as a practical electronic component in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet and infrared wavelengths, with very high brightness.

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6

CHAPTER 3

SCHEMATIC DIAGRAM:

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3.1 SCHEMATIC DESCRIPTION

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, 8-bit micro controller satisfactorily serves the above application. Using an inexpensive 8-

bit Microcontroller will doom the 32-bit product failure in any competitive market place.

A capacitor (formerly known as condenser) is a device for storing electric charge.

The forms of practical capacitors vary widely, but all contain at least two conductors

separated by a non-conductor. Capacitors used as parts of electrical systems, for example,

consist of metal foils separated by a layer of insulating film. 7

A resistor is a two-terminal passive electronic component that implements electrical

resistance as a circuit element. When a voltage V is applied across the terminals of a resistor,

a current I will flow through the resistor in direct proportion to that voltage.

 A diode is a two-terminal electronic component. A semiconductor diode, the most

common type today, is a crystalline piece of semiconductor material connected to two

electrical terminals.[1] A vacuum tube diode (now little used except in some high-power

technologies) is a vacuum with two electrodes: a plate and a cathode. 

The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with

4Kbytes of in-system programmable Flash memory. The device is manufactured using

Atmel’s high-density nonvolatile memory technology and is compatible with the industry-

Standard 80C51 instruction set and pin out. The on-chip Flash allows the program

Memory to be reprogrammed in-system or by a conventional nonvolatile memory

programmer.

By combining a versatile 8-bit CPU with in-system programmable Flash on a

Monolithic chip, the Atmel AT89S51 is a powerful microcontroller which provides a

Highly-flexible and cost-effective solution to many embedded control applications.

The required operating voltage for Microcontroller 89C51 is 5V. Hence the 5V D.C. power

supply is needed. This regulated 5V is generated by stepping down the voltage from 230V to

12V using step down transformer. Now the step downed a.c voltage is being rectified by the

Bridge Rectifier using 1N4007 diodes. 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

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regulator provides/allows us to have a Regulated constant Voltage which is of +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 89c51 microcontroller

to supply operating voltage. The microcontroller 89C51 with Pull up resistors at Port0 and

crystal oscillator of 11.0592 MHz crystal in conjunction with couple of 30-33pf capacitors is

placed at 18th& 19th pins of 89c51 to make it work (execute) properly.

8

Gsm Modem

A GSM modem can be an external modem device, such as the Wavecom FASTRACK

Modem. Insert a GSM SIM card into this modem, and connect the modem to an available

serial port on your computer. A GSM modem could also be a standard GSM mobile phone

with the appropriate cable and software driver to connect to a serial port on your computer.

Phones such as the Nokia 7110 with a DLR-3 cable, or various Ericsson phones, are often

used for this purpose.

When you install your GSM modem, or connect your GSM mobile phone to the computer, be

sure to install the appropriate Windows modem driver from the device manufacturer. To

simplify configuration, the Now SMS/MMS Gateway will communicate with the device via

this driver. An additional benefit of utilizing this driver is that you can use Windows

diagnostics to ensure that the modem is communicating properly with the computer.

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9

CHAPTER 4

Hardware Components

MICROCONTROLLER

GSM MODEM

BUZZER

LED

RELAY

LCD

POWER SUPPLY

TRANSFORMERS

4.1 MICRO CONTROLLER 89C51

Introduction

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

I/O interfaces such as serial port, parallel port timer or counter, interrupt controller, data

acquisition interfaces-Analog to Digital converter, Digital to Analog converter, integrated on

to a single silicon chip.

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

memory such as RAM, ROM, EPROM and peripherals. But controller is provided all these

facilities on a single chip. Development of a Micro controller reduces PCB size and cost of

design.

One of the major differences between a Microprocessor and a Micro controller is that a

controller often deals with bits not bytes as in the real world application.

Intel has introduced a family of Micro controllers called the MCS-51.

The Major Features:

Compatible with MCS-51 products

4k Bytes of in-system Reprogrammable flash memory

Fully static operation: 0HZ to 24MHZ

10

128 * 8 –bit timer/counters

Six interrupt sources

Label1

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Functional block diagram of micro controller

The 89C51 oscillator and clock:

The heart of the 89C51 circuitry that generates the clock pulses by which all the

internal all internal operations are synchronized. Pins XTAL1 and XTAL2 are

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

and capacitors are employed. The manufacturers make 89C51 designs that run at specific

minimum and maximum frequencies typically 1 to 16 MHz 11

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Fig 3.7.2: - Oscillator and timing circuit

Types of memory:

The 89C51 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

Code memory

Code memory is the memory that holds the actual 89C51 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 4K 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

12

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a) Internal RAM

The 89C51 have a bank of 128 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 89C51 is reset, this memory is cleared. 128 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 128 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 7Fh. The user may make use of these variables with

commands such as SETB and CLR.

Fig 3.7.3: - Pin diagram of AT89C51

Pin Description:

VCC: Supply voltage.

GND: Ground.

13

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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 one’s are written to port 0 pins, the pins can be used as high

impedance inputs. Port 0 may also be configured to be the multiplexed low order address/data

bus during accesses to external program and data memory. In this mode P0 has internal pull-

ups. Port 0 also receives the code bytes during Flash programming, and outputs the code

bytes during program verification. External pull-ups are required during program verification.

Port 1:

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

also receives the low-order address bytes during Flash programming and verification.

Port 2:

Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output

buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled

high by the internal pull-ups 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 pull-ups. Port 2

emits the high-order address byte during fetches from external program memory and during

accesses to external data memories that use 16-bit addresses (MOVX @DPTR). In this

application, it uses strong internal pull-ups when emitting 1s. During accesses to external data

memories 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.

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14

Port 3:

Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output

buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled

high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are

externally being pulled low will source current (IIL) because of the pull-ups.

Port 3 also serves the functions of various special features of the AT89C51 as listed below:

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

Tab 6.2.1 Port pins and their alternate functions

RST:

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

resets the device.

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15

ALE/PROG:

Address Latch Enable 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 1/6the oscillator

frequency, and may be used for external timing or clocking purposes. 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 during a MOVX or MOVC instruction. Otherwise, the pin is pulled high. Setting

the ALE-disable bit has no effect if the microcontroller is in external execution mode.

PSEN:

Program Store Enable is the read strobe to external program memory. When the

AT89C51 is executing code from external program memory, PSEN is activated twice each

machine cycle, except that two PSEN activations are skipped during each access to external

data memory.

EA/VPP:

External Access Enable EA must be strapped to GND in order to enable the device to

fetch code from external program memory locations starting at 0000H up to FFFFH.

EA should be strapped to VCC for internal program executions. This pin also receives

the 12-volt programming enable voltage (VPP) during Flash programming, for parts that

require 12-volt VPP.

XTAL1:

Input to the inverting oscillator amplifier and input to the internal clock operating

circuit.

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16

XTAL2:

It is the Output from the inverting oscillator amplifier.

Oscillator Characteristics:

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier

which can be configured for use as an on-chip oscillator, as shown in Figs 6.2.3. Either a

quartz crystal or ceramic resonator may be used. To drive the device from an external clock

source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure

6.2.4.There are no requirements on the duty cycle of the external clock signal, since the input

to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and

maximum voltage high and low time specifications must be observed.

Fig 6.2.3 Oscillator Connections Fig 6.2.4 External Clock Drive Configuration

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17

8051 Register Banks and Stack

RAM memory space allocation in the 8051

There are 128 bytes of RAM in the 8051. The 128 bytes of RAM inside the 8051

are assigned addresses 00 to7FH. These 128 bytes are divided into three different groups as

follows:

1. A total of 32 bytes from locations 00 to 1FH hex are set aside for register banks

and the stack.

2. A total of 16 bytes from locations 20 to 2FH hex are set aside for bit-addressable

read/write memory.

3. A total of 80 bytes from locations 30H to 7FH are used for read and write storage,

or what is normally called Scratch pad. These 80 locations of RAM are widely

used for the purpose of storing data and parameters nu 8051 programmers.

Register banks in the 8051

A total of 32bytes of RAM are set aside for the register banks and stack. These 32

bytes are divided into 4 banks of registers in which each bank has registers, R0-R7. RAM

locations 0 to 7 are set aside for bank 0 of R0-R7 where R0 is RAM location 0, R1 is RAM

location 1, and R2 is location 2, and so on, until memory location7, which belongs to R7 of

bank0. The second bank of registers R0-R7 starts at RAM location 08 and goes to location

0FH. The third bank of R0-R7 starts at memory location 10H and goes to location 17H.

Finally, RAM locations 18H to 1FH are set aside for the fourth bank of R0-R7. Fig shows

how the 32 bytes are allocated into 4 banks.

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As we can see from fig 1, the bank 1 uses the same RAM space as the stack. This is

a major problem in programming the 8051. we must either not use register bank1, or allocate

another area of RAM for the stack.

18

Default register bank

If RAM locations 00-1F are set aside for the four register banks, which register

bank of R0-R7 do we have access to when the 8051 is powered up? The answer is register

bank 0; that is , RAM locations 0, 1,2,3,4,5,6, and 7 are accessed with the names R0, R1, R2,

R3, R4, R5, R6, and R7 when programming the 8051. It is much easier to refer to these

RAM locations with names such as R0, R1 and so on, than by their memory locations as

shown in fig 2.

The register banks are switched by using the D3 & D4 bits of register PSW.

FIG: RAM Allocation in the 8051

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19

Fig: 8051 Register Banks and their RAM Addresses

PSW Register (Program Status Word)

This is one of the most important SFRs. The Program Status Word (PSW) contains several

status bits that reflect the current state of the CPU. This register contains: Carry bit, Auxiliary

Carry, two register bank select bits, Overflow flag, parity bit, and user-definable status flag.

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The ALU automatically changes some of register’s bits, which is usually used in regulation

of the program performing.

P - Parity bit. If a number in accumulator is even then this bit will be automatically set (1),

otherwise it will be cleared (0). It is mainly used during data transmission and receiving via

serial communication.

20

- Bit 1. This bit is intended for the future versions of the microcontrollers, so it is not

supposed to be here.

OV Overflow occurs when the result of arithmetical operation is greater than 255 (decimal),

so that it can not be stored in one register. In that case, this bit will be set (1). If there is no

overflow, this bit will be cleared (0).

RS0, RS1 - Register bank selects bits. These two bits are used to select one of the four

register banks in RAM. By writing zeroes and ones to these bits, a group of registers R0-R7

is stored in one of four banks in RAM.

RS1 RS2 Space in RAM

0 0 Bank0 00h-07h

0 1 Bank1 08h-0Fh

1 0 Bank2 10h-17h

1 1 Bank3 18h-1Fh

F0 - Flag 0. This is a general-purpose bit available to the user.

CY - Carry Flag is the (ninth) auxiliary bit used for all arithmetical operations and shift

instructions.

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DPTR Register (Data Pointer)

These registers are not true ones because they do not physically exist. They consist of two

separate registers: DPH (Data Pointer High) and (Data Pointer Low). Their 16 bits are used

for external memory addressing. They may be handled as a 16-bit register or as two

independent 8-bit registers. Besides, the DPTR Register is usually used for storing data and

intermediate results which have nothing to do with memory locations.

21

SP Register (Stack Pointer)

The stack is a section of RAM used by the CPU to store information temporarily.

This information could be data or an address. The CPU needs this storage area since there

are only a limited number of registers.

Program counter:

The important register in the 8051 is the PC (Program counter). The program

counter points to the address of the next instruction to be executed. As the CPU fetches the

OPCODE from the program ROM, the program counter is incremented to point to the next

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instruction. The program counter in the 8051 is 16bits wide. This means that the 8051 can

access program addresses 0000 to FFFFH, a total of 64k bytes of code. However, not all

members of the 8051 have the entire 64K bytes of on-chip ROM installed, as we will see

soon.

22

Types of instructions

Depending on operation they perform, all instructions are divided in several groups:

Arithmetic Instructions

Branch Instructions

Data Transfer Instructions

Logical Instructions

Logical Instructions with bits

The first part of each instruction, called MNEMONIC refers to the operation an instruction

performs (copying, addition, logical operation etc.). Mnemonics commonly are shortened

form of name of operation being executed. For example:

INC R1; Increment R1 (increment register R1)

LJMP LAB5 ; Long Jump LAB5 (long jump to address specified as LAB5)

JNZ LOOP; Jump if Not Zero LOOP (if the number in the accumulator is not 0, jump to

address specified as LOOP)

Another part of instruction, called OPERAND is separated from mnemonic at least by one

empty space and defines data being processed by instructions. Some instructions have no

operand; some have one, two or three. If there is more than one operand in instruction, they

are separated by comma. For example:

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RET - (return from sub-routine)

JZ TEMP - (if the number in the accumulator is not 0, jump to address specified as TEMP)

ADD A, R3 - (add R3 and accumulator)

CJNE A, #20, LOOP - (compare accumulator with 20. If they are not equal, jump to address

specified as LOOP)

23

TIMERS

On-chip timing/counting facility has proved the capabilities of the microcontroller for

implementing the real time application. These includes pulse counting, frequency

measurement, pulse width measurement, baud rate generation, etc, having sufficient number

of timer/counters may be a need in a certain design application. The 8051 has two

timers/counters. They can be used either as timers to generate a time delay or as counters to

count events happening outside the microcontroller. Let discuss how these timers are used to

generate time delays and we will also discuss how they are been used as event counters.

PROGRAMMING 8051 TIMER

The 8051 has timers: Timer 0 and Timer1.they can be used either as timers or as event

counters. Let us first discuss about the timers’ registers and how to program the timers to

generate time delays.

TIMER 0 REGISTERS

The 16-bit register of Timer 0 is accessed as low byte and high byte. the low byte

register is called TL0(Timer 0 low byte)and the high byte register is referred to as TH0(Timer

0 high byte).These register can be accessed like any other register, such as

A,B,R0,R1,R2,etc.for example, the instruction ”MOV TL0, #4F”moves the value 4FH into

TL0,the low byte of Timer 0.These registers can also be read like any other register.

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24

TIMER 1 REGISTERS

Timer 1 is also 16-bit register is split into two bytes, referred to as TL1 (Timer 1

low byte) and TH1 (Timer 1 high byte).these registers are accessible n the same way as the

register of Timer 0.

TMOD (timer mode) REGISTER

Both timers TIMER 0 and TIMER 1 use the same register, called TMOD, to set the

various timer operation modes. TMOD is an 8-bit register in which the lower 4 bits are set

aside for Timer 0 and the upper 4 bits for Timer 1.in each case; the lower 2 bits are used to

set the timer mode and the upper 2 bits to specify the operation.

MODES:

M1, M0:

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M0 and M1 are used to select the timer mode. There are three modes: 0, 1, 2.Mode

0 is a 13-bit timer, mode 1 is a 16-bit timer, and mode 2 is an 8-bit timer. We will concentrate

on modes 1 and 2 since they are the ones used most widely. We will soon describe the

characteristics of these modes, after describing the reset of the TMOD register.

GATE Gate control when set. The timer/counter is enabled only

While the INTx pin is high and the TRx control pin is.

Set. When cleared, the timer is enabled.

C/T Timer or counter selected cleared for timer operation

(Input from internal system clock).set for counter

Operation (input TX input pin). 25

M 1 Mode bit 1

M0 Mode bit 0

M1 M0 MODE Operating Mode

0 0 0 13-bit timer mode

8-bit timer/counter THx with TLx as

5 - Bit pre-scaler.

0 1 1 16-bit timer mode

16-bit timer/counters THx with TLx are

Cascaded; there is no prescaler

1 0 2 8-bit auto reload

8-bit auto reload timer/counter; THx

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Holds a value that is to be reloaded into

TLx each time it overflows.

1 1 3 Split timer mode.

C/T (Clock / Timer)

This bit in the TMOD register is used to decide whether the timer is used as a delay

generator or an event counter. If C/T=0, it is used as a timer for time delay generation. The

clock source for the time delay is the crystal frequency of the 8051. This section is concerned

with this choice. The timer’s use as an event counter is discussed in the next section.

27

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

possible fast data transfer using only a few wires.

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,

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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.

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 ends.

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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 bits. 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. 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).

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. 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

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be noted that in asynchronous serial data communication, the baud rate is generally limited to

100,000bps.

RS232 Standards

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. 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.

29

RS232 pins

Pin Functions:

Pin Description

1 Data carrier detect (DCD)

2 Received data (RXD)

3 Transmitted data (TXD)

4 Data terminal ready(DTR)

5 Signal ground (GND)

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6 Data set ready (DSR)

7 Request to send (RTS)

8 Clear to send (CTS)

9 Ring indicator (RI)

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

30

8051 connection to RS232

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

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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.

CONNECTING μC to PC using MAX 232

31

INTERRUPTS

A single microcontroller can serve several devices. There are two ways to do that:

INTERRUPTS or POLLING.

POLLING:

In polling the microcontroller continuously monitors the status of a given device;

when the status condition is met, it performs the service .After that, it moves on to monitor

the next device until each one is serviced. Although polling can monitor the status of several

devices and serve each of them as certain condition are met.

INTERRUPTS:

In the interrupts method, whenever any device needs its service, the

device notifies the microcontroller by sending it an interrupts signal. Upon receiving an

interrupt signal, the microcontroller interrupts whatever it is doing and serves the device. The

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program associated with the interrupts is called the interrupt service routine (ISR).or interrupt

handler.

INTERRUPTS Vs POLLING:

The advantage of interrupts is that the microcontroller can serve many devices (not

all the same time, of course); each device can get the attention of the microcontroller based

on the priority assigned to it. The polling method cannot assign priority since it checks all

devices in round-robin fashion. More importantly, in the interrupt method the

microcontroller can also ignore (mask) a device request for service. This is again not

possible with the polling method. The most important reason that the interrupt method is

preferable is that the polling method wastes much of the microcontroller’s time by polling

devices that do not need service. So, in order to avoid tying down the microcontroller,

interrupts are used.

32

INTERRUPT SERVICE ROUTINE

For every interrupt, there must be an interrupt service routine (ISR), or interrupt

handler. When an interrupt is invoked, the microcontroller runs the interrupts service routine.

For every interrupt, there is a fixed location in memory that holds the address of its ISR. The

group of memory location set aside to hold the addresses of ISR and is called the Interrupt

Vector Table. Shown below:

Six Interrupts in the 8051:

In reality, only five interrupts are available to the user in the 8051, but many

manufacturers’ data sheets state that there are six interrupts since they include reset .the six

interrupts in the 8051 are allocated as above.

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1. Reset. When the reset pin is activated, the 8051 jumps to address location 0000.this is

the power-up reset.

2. Two interrupts are set aside for the timers: one for Timer 0 and one for Timer

1.Memory location 000BH and 001BH in the interrupt vector table belong to Timer 0

and Timer 1, respectively.

3. Two interrupts are set aside for hardware external harder interrupts. Pin number

12(P3.2) and 13(P3.3) in port 3 are for the external hardware interrupts INT0 and

INT1,respectively.These external interrupts are also referred to as EX1 and

EX2.Memory location 0003H and 0013H in the interrupt vector table are assigned to

INT0 and INT1, respectively.

4. Serial communication has a single interrupt that belongs to both receive and transmit.

The interrupt vector table location 0023H belongs to this interrupt.

33

Interrupt Enable Register

D7 D6 D5 D4 D3 D2 D1 D0

EA IE.7 disables all interrupts. If EA=0, no interrupts is acknowledged.

If EA=1, each interrupt source is individually enabled disabled

By setting or clearing its enable bit.

EA -- ET2 ES ET1 EX1 ET0 EX0

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-- IE.6 Not implemented, reserved for future use.*

ET2 IE.5 Enables or disables Timer 2 overflow or capture interrupt (8052

Only)

ES IE.4 Enables or disables the serial port interrupts.

ET1 IE.3 Enables or disables Timers 1 overflow interrupt

EX1 IE.2 Enables or disables external interrupt 1

ET0 IE.1 Enables or disables Timer 0 overflow interrupt.

EX0 IE.0 Enables or disables external interrupt.

34

4.2 GSM Modems

A GSM modem can be an external modem device, such as the Wavecom

FASTRACK Modem. Insert a GSM SIM card into this modem, and connect the modem to

an available serial port on your computer.

A dedicated GSM modem (external or PC Card) is usually preferable to a GSM mobile

phone. This is because of some compatibility issues that can exist with mobile phones.

When you install your GSM modem, or connect your GSM mobile phone to the computer, be

sure to install the appropriate Windows modem driver from the device manufacturer. To

simplify configuration, the Now SMS/MMS Gateway will communicate with the device via

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this driver. An additional benefit of utilizing this driver is that you can use Windows

diagnostics to ensure that the modem is communicating properly with the computer.

The Now SMS/MMS gateway can simultaneously support multiple modems, provided that

your computer hardware has the available communications port resources.

Fig:16 GSM smart modem

SMART MODEM (GSM/GPRS)SMART MODEM (GSM/GPRS)

INTRODUCTION:

Analogic’s GSM Smart Modem is a multi-functional, ready to use, rugged and versatile

modem that can be embedded or plugged into any application. The Smart Modem can be

customized to various applications by using the standard AT commands. The modem is fully

type-approved and can directly be integrated into your projects with any or all the features of

Voice, Data, Fax, SMS, and Internet etc.

35

Smart Modem kit contains the following items:

Analogic’s GSM/GPRS Smart Modem

SMPS based power supply adapter.

3 dBi antenna with cable (optional: other types)

Data cable (RS232)

User Manual

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PRODUCT DESCRIPTION:

The connectors integrated to the body, guarantee the reliable output and input connections.

An extractible holder is used to insert the SIM card (Micro-SIM type). Status LED indicates

the operating mode.

Fig 17: Block diagram of modem with key connections

Installing the modem:

To install the modem, plug the device on to the supplied SMPS Adapter.

Inserting/ Removing the SIM Card:

To insert or Remove the SIM Card, it is necessary to press the SIM holder ejector button with

Sharp edged object like a pen or a needle. With this, the SIM holder comes out a little, then

pulls it out and insert or remove the SIM Card

36

Fig 19: Inserting/Removing the sim card into the modem

Make sure that the ejector is pushed out completely before accessing the SIM Card holder do

not remove the SIM card holder by force or tamper it (it may permanently damage). Place the

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SIM Card Properly as per the direction of the installation. It is very important that the SIM is

placed in the right direction for its proper working condition

Connecting External Antenna:

Connect GSM Smart Modem to the external antenna with cable end with SMA male. The

Frequency of the antenna may be GSM 900/1800 MHz. The antenna may be (0 dbi, 3 dbi or

short length L-type antenna) as per the field conditions and signal conditions.

Connectors:

Connector Function

SMA RF Antenna connector

15 pin or 9 pin D-SUB USB (optional) RS232 link Audio link (only for 15 D-

SUB) Reset (only for 15 D-SUB) USB

communication port (optional)

2 pin Phoenix tm Power Supply Connector

SIM Connector SIM Card Connection

RJ11 (For 9 D-SUB and USB only) Audio link Simple hand set connection

(4 wire) 2 wire desktop phone

connection

37

Description of the interfaces:

The modem comprises several interfaces:

LED Function including operating Status

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External antenna (via SMA)

Serial and control link

Power Supply (Via 2 pin Phoenix tm contact)

SIM card holder

Services provided by GSM

GSM was designed having interoperability with ISDN in mind, and the services provided by GSM are

a subset of the standard ISDN services. Speech is the most basic, and most important, teleservice

provided by GSM.

In addition, various data services are supported, with user bit rates up to 9600 bps. Specially

equipped GSM terminals can connect with PSTN, ISDN, Packet Switched and Circuit Switched Public

Data Networks, through several possible methods, using synchronous or asynchronous transmission.

Also supported are Group 3 facsimile service, videotext, and teletex. Other GSM services include a

cell broadcast service, where messages such as traffic reports, are broadcast to users in particular

cells.

A service unique to GSM, the Short Message Service, allows users to send and receive point-to-point

alphanumeric messages up to a few tens of bytes. It is similar to paging services, but much more

comprehensive, allowing bi-directional messages, store-and-forward delivery, and

acknowledgement of successful delivery.

Supplementary services enhance the set of basic teleservices. In the Phase I specifications,

supplementary services include variations of call forwarding and call barring, such as Call Forward on

Busy or Barring of Outgoing International Calls. Many more supplementary services, including

multiparty calls, advice of charge, call waiting, and calling line identification presentation will be

offered in the Phase 2 specifications.

38

AT commands features:

Line settings:

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A serial link handler is set with the following default values Auto baud, 8 bits data, 1 stop bit,

no parity, flow control.

Command line

Commands always start with AT (which means attention) and finish with a <CR> character.

Information responses and result codes

Responses start and end with <CR><LF>,

If command syntax is incorrect, an ERROR string is returned.

If command syntax is correct but with some incorrect parameters, the +CME ERROR: <Err>

or +CMS ERROR: <SmsErr> strings are returned with different error codes.

If the command line has been performed successfully, an OK string is returned.

In some cases, such as “AT+CPIN?” or (unsolicited) incoming events, the product does not

return the OK string as a response.

Architecture of the GSM network

A GSM network is composed of several functional entities, whose functions and interfaces

are specified. Figure 1 shows the layout of a generic GSM network. The GSM network can

be divided into three broad parts. Subscriber carries the Mobile Station. The Base Station

Subsystem controls the radio link with the Mobile Station. The Network Subsystem, the main

part of which is the Mobile services Switching Center (MSC), performs the switching of calls

between the mobile users, and between mobile and fixed network users. The MSC also

handles the mobility management operations. Not shown is the Operations intendance Center,

which oversees the proper operation and setup of the network.

39

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Fig 20: General architecture of a GSM network

4.3 BUZZER

The "Piezoelectric sound components" introduced herein operate on an innovative

principle utilizing natural oscillation of piezoelectric ceramics. These buzzers are offered in

lightweight compact sizes from the smallest diameter of 12mm to large piezoelectric

sounders. Today, piezoelectric sound components are used in many ways such as home

appliances, OA equipment, audio equipment telephones, etc. And they are applied widely, for

example, in alarms, speakers, telephone ringers, receivers, transmitters, beep sounds, etc.

FIG: Types of Buzzers

4.4 LIGHT EMITING DIODES

It is a semiconductor diode having radioactive recombination. It requires a definite

amount of energy to generate an electron-hole pair.

40

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4.5 RELAYS

Relay is an electrically operated switch. Current flowing through the coil of the relay

creates a magnetic field which attracts a lever and changes the switch contacts. The coil

current can be on or off so relays have two switch positions and they are double throw

(changeover) switches.

Relays allow one circuit to switch a second circuit which can be completely separate

from the first. For example a low voltage battery circuit can use a relay to switch a 230V AC

mains circuit. There is no electrical connection inside the relay between the two circuits; the

link is magnetic and mechanical.

The coil of a relay passes a relatively large current, typically 30mA for a 12V relay,

but it can be as much as 100mA for relays designed to operate from lower voltages. Most ICs

(chips) cannot provide this current and a transistor is usually used to amplify the small IC

current to the larger value required for the relay coil. The maximum output current for the

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popular 555 timer IC is 200mA so these devices can supply relay coils directly without

amplification. 41

Most relays are designed for PCB mounting but you can solder wires directly to the

pins providing you take care to avoid melting the plastic case of the relay. The supplier's

catalogue should show you the relay's connections. The coil will be obvious and it may be

connected either way round. Relay coils produce brief high voltage 'spikes' when they are

switched off and this can destroy transistors and ICs in the circuit.

The relay's switch connections are usually labelled COM, NC and NO:

COM = Common, always connect to this; it is the moving part of the switch.

NC = Normally Closed, COM is connected to this when the relay coil is off.

NO = Normally Open, COM is connected to this when the relay coil is on.

Connect to COM and NO if you want the switched circuit to be on when the relay

coil is on.

Connect to COM and NC if you want the switched circuit to be on when the relay coil

is off.

Advantages of relays:

Relays can switch AC and DC, transistors can only switch DC.

Relays can switch high voltages, transistors cannot.

Relays are a better choice for switching large currents (> 5A).

Relays can switch many contacts at once.

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Disadvantages of relays:

Relays are bulkier than transistors for switching small currents.

Relays cannot switch rapidly (except reed relays), transistors can switch many times

per second.

42

Relays require more current than many chips can provide, so a low power

transistor may be needed to switch the current for the relay's coil.

4.6 Liquid crystal display

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 polarizer’s are pasted outside the two glass panels. This polarizer’s would

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

When the LCD is in the off state, light rays are rotated by the two polarizer’s 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 polarizer’s, 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.

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43

TABLE 1:Pin description for LCD:

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

8 DB1 I/O The 8-bit data bus

9 DB2 I/O The 8-bit data bus

10 DB3 I/O The 8-bit data bus

11 DB4 I/O The 8-bit data bus

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12 DB5 I/O The 8-bit data bus

13 DB6 I/O The 8-bit data bus

14 DB7 I/O The 8-bit data bus

44

TABLE 2: LCD Command Codes

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

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C0 Force cursor to beginning of 2nd line

38 2 lines and 5x7 matrix

45

The LCD’s don’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.

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

and interface an LCD to 8051 using Assembly and C.

LCD operation

In recent years the LCD is finding widespread use replacing LEDs (seven-segment

LEDs or other multi segment LEDs).This is due to the following reasons:

1. The declining prices of LCDs.

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

Contract to LEDs, which are 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 contrast,

The LED must be refreshed by the CPU to keep displaying the data.

4. Ease of programming for characters and graphics.

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

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

used in telecommunications and entertainment electronics.

46

LCD INTERFACING

Sending commands and data to LCDs with a time delay:

Fig 21: Interfacing of LCD to a micro controller

To send any command from table 2 to the LCD, make pin RS=0.

For data, make RS=1.Then sends a high –to-low pulse to the E pin to enable the internal latch of the LCD.

4.7 Power supply

The power supplies are designed to convert high voltage AC mains

electricity to a suitable low voltage supply for electronic circuits and other devices. A power

supply can by broken down into a series of blocks, each of which performs a particular

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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”

47

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

4.8 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

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high voltage mains supply, and a small number of turns on its secondary (output) coil to give

a low output voltage.

48

An Electrical Transformer

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 regulator ICs has 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.

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Fig 6.1.6 A Three Terminal Voltage Regulator

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78XX:

The Bay Linear LM78XX is integrated linear positive regulator with three terminals.

The LM78XX offer several fixed output voltages making them useful in wide range of

applications. When used as a zener diode/resistor combination replacement, the LM78XX

usually results in an effective output impedance improvement of two orders of magnitude,

lower quiescent current. The LM78XX is available in the TO-252, TO-220 & TO-

263packages,

Features:

• Output Current of 1.5A

• Output Voltage Tolerance of 5%

• Internal thermal overload protection

• Internal Short-Circuit Limited

• No External Component

• Direct Replacement for LM78XX

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50

CHAPTER 5

SOFTWARE

5.1 ABOUT KEIL SOFTWARE:

It is possible to create the source files in a text editor such as Notepad, run the Compiler on each C source file, specifying a list of controls, run the Assembler on each Assembler source file, specifying another list of controls, run either the Library Manager or Linker and finally running the Object-HEX Converter to convert the Linker output file to an Intel Hex File.

Once that has been completed the Hex File can be downloaded to the target hardware and debugged. Alternatively KEIL can be used to create source files; automatically compile, link and covert using options set with an easy to use user interface and finally simulate or perform debugging on the hardware with access to C variables and memory. Unless you have to use the tolls on the command line, the choice is clear. KEIL Greatly simplifies the process of creating and testing an embedded application.

Simulator/Debugger:

The simulator/ debugger in KEIL can perform a very detailed simulation of a micro controller along with external signals. It is possible to view the precise execution time of a single assembly instruction, or a single line of C code, all the way up to the entire application, simply by entering the crystal frequency. A window can be opened for each peripheral on the device, showing the state of the peripheral. This enables quick trouble shooting of mis-configured peripherals. Breakpoints may be set on either assembly instructions or lines of C code, and execution may be stepped through one instruction or C line at a time. The contents of all the memory areas may be viewed along with ability to find specific variables. In

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addition the registers may be viewed allowing a detailed view of what the microcontroller is doing at any point in time.

The Keil Software 8051 development tools listed below are the programs you use to compile your C code, assemble your assembler source files, link your program together, create HEX files, and debug your target program. µVision2 for Windows™ Integrated Development Environment: combines Project Management, Source Code Editing, and Program Debugging in one powerful environment.

C51 ANSI Optimizing C Cross Compiler: creates relocatable object modules from your C source code,

BL51 Linker/Locator: combines relocatable object modules created by the compiler and assembler into the final absolute object module,

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LIB51 Library Manager: combines object modules into a library, which may be used by the linker,

OH51 Object-HEX Converter: creates Intel HEX files from absolute object modules.

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.

Building an Application in µVision2

To build (compile, assemble, and link) an application in µVision2, you must:

1. Select Project - (forexample, 166\EXAMPLES\HELLO\HELLO.UV2).2. Select Project - Rebuild all target files or Build target.

µVision2 compiles, assembles, and links the files in your project

Creating Your Own Application in µVision2

To create a new project in µVision2, you must:

1. Select Project - New Project.2. Select a directory and enter the name of the project file.3. Select Project - Select Device and select an 8051, 251, or C16x/ST10 device from the

Device Database™.4. Create source files to add to the project.5. Select Project - Targets, Groups, and Files. Add/Files, select Source Group1, and add

the source files to the project.6. Select Project - Options and set the tool options. Note when you select the target

device from the Device Database™ all special options are set automatically. You typically only need to configure the memory map of your target hardware. Default memory model settings are optimal for most applications.

7. Select Project - Rebuild all target files or Build target.

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Debugging an Application in µVision2

To debug an application created using µVision2, you must:

1. Select Debug - Start/Stop Debug Session.2. Use the Step toolbar buttons to single-step through your program. You may enter G,

main in the Output Window to execute to the main C function.3. Open the Serial Window using the Serial #1 button on the toolbar.

Debug your program using standard options like Step, Go, Break, and so on.

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Starting µVision2 and creating a Project

µVision2 is a standard Windows application and started by clicking on the program icon. To create a new project file select from the µVision2 menu

Project – New Project…. This opens a standard Windows dialog that asks you

For the new project file name.

We suggest that you use a separate folder for each project. You can simply use

The icon Create New Folder in this dialog to get a new empty folder. Then

Select this folder and enter the file name for the new project, i.e. Project1.

µVision2 creates a new project file with the name PROJECT1.UV2 which contains

A default target and file group name. You can see these names in the Project

Window – Files.

Now use from the menu Project – Select Device for Target and select a CPU

For your project. The Select Device dialog box shows the µVision2 device

Database. Just select the micro controller you use. We are using for our examples the Philips 80C51RD+ CPU. This selection sets necessary tool

Options for the 80C51RD+ device and simplifies in this way the tool Configuration

Building Projects and Creating a HEX Files

Typical, the tool settings under Options – Target are all you need to start a new

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Application. You may translate all source files and line the application with a

Click on the Build Target toolbar icon. When you build an application with

Syntax errors, µVision2 will display errors and warning messages in the Output

Window – Build page. A double click on a message line opens the source file

On the correct location in a µVision2 editor window.

Once you have successfully generated your application you can start debugging.

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After you have tested your application, it is required to create an Intel HEX file to download the software into an EPROM programmer or simulator. µVision2 creates HEX files with each build process when Create HEX files under Options for Target – Output is enabled. You may start your PROM programming utility after the make process when you specify the program under the option Run User Program #1.

CPU Simulation:

µVision2 simulates up to 16 Mbytes of memory from which areas can be

Mapped for read, write, or code execution access. The µVision2 simulator traps

And reports illegal memory accesses.

In addition to memory mapping, the simulator also provides support for the

Integrated peripherals of the various 8051 derivatives. The on-chip peripherals

Of the CPU you have selected are configured from the Device.

Database selection:

You have made when you create your project target. Refer to page 58 for more

Information about selecting a device. You may select and display the on-chip peripheral components using the Debug menu. You can also change the aspects of each peripheral using the controls in the dialog boxes.

Start Debugging:

You start the debug mode of µVision2 with the Debug – Start/Stop Debug

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Session command. Depending on the Options for Target – Debug

Configuration, µVision2 will load the application program and run the startup

Code µVision2 saves the editor screen layout and restores the screen layout of the last debug session. If the program execution stops, µVision2 opens an

Editor window with the source text or shows CPU instructions in the disassembly window. The next executable statement is marked with a yellow arrow. During debugging, most editor features are still available.

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Disassembly Window

The Disassembly window shows your target program as mixed source and assembly program or just assembly code. A trace history of previously executed instructions may be displayed with Debug – View Trace Records. To enable the trace history, set Debug – Enable/Disable Trace Recording.

If you select the Disassembly Window as the active window all program step commands work on CPU instruction level rather than program source lines. You can select a text line and set or modify code breakpoints using toolbar buttons or the context menu commands.

You may use the dialog Debug – Inline Assembly… to modify the CPU instructions. That allows you to correct mistakes or to make temporary changes to the target program you are debugging.

5.2 Embedded C:

What is an embedded system?

An embedded system is an application that contains at least one programmable

computer and which is used by individuals who are, in the main, unaware that the system is

computer-based.

Which programming language should you use?

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Having decided to use an 8051 processor as the basis of your embedded system, the next

key decision that needs to be made is the choice of programming language. In order to

identify a suitable language for embedded systems, we might begin by making the following

observations:

Computers (such as microcontroller, microprocessor or DSP chips) only accept

instructions in ‘machine code’ (‘object codes’). Machine code is, by definition, in the

language of the computer, rather than that of the programmer. Interpretation of the

code by the programmer is difficult and error prone.

All software, whether in assembly, C, C++, Java or Ada must ultimately be translated

into machine code in order to be executed by the computer.

Embedded processors – like the 8051 – have limited processor power and very limited

memory available: the language used must be efficient.

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Summary of C language Features:

It is ‘mid-level’, with ‘high-level’ features (such as support for functions and modules), and

‘low-level’ features (such as good access to hardware via pointers).

It is very efficient.

It is popular and well understood.

Even desktop developers who have used only Java or C++ can soon understand C

syntax.

Good, well-proven compilers are available for every embedded processor (8-bit to 32-

bit or more).

Basic C program structure:

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

//Basic blank C program that does nothing

// Includes

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//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

#include <reg51.h> // SFR declarations

Void main (void)

{

While (1);

{

Body of the loop // Infinite loop

}

} // match the braces

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6. SOURCE CODE

1. Click on the Keil u Vision Icon on Desktop

2. The following fig will appear

3. Click on the Project menu from the title bar

4. Then Click on New Project

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5. Save the Project by typing suitable project name with no extension in u r own folder sited in either C:\ or D:\

57

6. Then Click on Save button above.

7. Select the component for u r project. i.e. Atmel……

8. Click on the + Symbol beside of Atmel

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9. Select AT89C51 as shown below

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10. Then Click on “OK”

11. The Following fig will appear

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12. Then Click either YES or NO………mostly “NO”

13. Now your project is ready to USE

14. Now double click on the Target1, you would get another option “Source group 1”

as shown in next page.

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15. Click on the file option from menu bar and select “new”

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16. The next screen will be as shown in next page, and just maximize it by double

clicking on its blue boarder.

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17. Now start writing program in either in “C” or “ASM”

18. For a program written in Assembly, then save it with extension “. asm” and for

“C” based program save it with extension “ .C”

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19. Now right click on Source group 1 and click on “Add files to Group Source”

20. Now you will get another window, on which by default “C” files will appear.

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21. Now select as per your file extension given while saving the file

22. Click only one time on option “ADD”

23. Now Press function key F7 to compile. Any error will appear if so happen.

24. If the file contains no error, then press Control+F5 simultaneously.

25. The new window is as follows

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62

26. Then Click “OK”

27. Now Click on the Peripherals from menu bar, and check your required port as

shown in fig below

28. Drag the port a side and click in the program file.

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63

29. Now keep Pressing function key “F11” slowly and observe.

30. You are running your program successfully

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64

CHAPTER 7

7. Conclusion

The project “global alert and control system for ups battery management for corporate automation (gsm)” has been successfully designed and tested.

It has been developed by integrating features of all the hardware components used.

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.

7.1 FUTURE ASPECTS

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65

ABBREVATIONS

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Symbol Name Symbol Name

ACC Accumulator TL1 Timer/counter 1 low byte

B B register TH2 Timer/counter 2 high byte

PSW Program status word TL2 Timer/counter 2 low byte

SP Stack pointer SCON Serial control

DPTR Data pointer 2 bytes SBUF Serial data buffer

DPL Low byte MAX MAXIM (IC manufacturer )

DPH High byte TTL Transistor to Transistor Logic

P0 Port0 ATM Automatic Teller Machine

P1 Port1 RS 232 Recommended Standard

P2 Port2 AC Alternating Current

P3 Port3 DC Direct Current

IP Interrupt priority control LCD Liquid Crystal Display

IE Interrupt enable control PC Personal Computer

TMOD Timer/counter mode

control

RPS Regulated Power Supply

TCON Timer/counter control RMS Root Mean Square

T2CON Timer/counter 2 control EEPROM Electrically Erasable

Programmable ROM

T2MOD Timer/counter mode2

control

ROM Read Only Memory

TH0 Timer/counter 0high byte RAM Random Access Memory

TL0 Timer/counter 0 low byte BIOS Basic Input Output System

TH1 Timer/counter 1 high byte SRAM Static RAM

TL1 Timer/counter 1 low byte EPROM Erasable Programmable

ROM

DRAM Dynamic Random Access Memory

ISR Interrupt Service Routine

CAD Card Acceptance Device

IFD Interface Device

IDE Integrated Development Environment

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Bibliography

The 8051 Micro controller and Embedded Systems

-Muhammad Ali MazidiJanice Gillispie Mazidi

The 8051 Micro controller Architecture, Programming & Applications

-Kenneth J.Ayala

Fundamentals of Micro processors and Micro computers

-B.Ram

Micro processor Architecture, Programming & Applications

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-Ramesh S. Gaonkar

Electronic Components

-D.V. Prasad

Wireless Communications- Theodore S. Rappaport

Mobile Tele Communications - William C.Y. Lee

References on the Web:

www.national.comwww.atmel.comwww.microsoftsearch.comwww.geocities.com