GSM BASED SMS DRIVEN AUTOMATIC DISPLAY TOOL KIT

GSM BASED AUTOMATIC DISPLAY TOOLKIT

CHAPTER1

INTRODUCTIONAND

BLOCK DIAGRAM

DEPTT. OF ELECTRONICS AND COMMUNICATION ENGG. Page 1


1.1 INTRODUCTION

Presently, the United States is the most technologically advanced country in the area of

telecommunications with about; 126 million phone lines, 7.5 million cellular phone users,5

thousand AM radio broadcast stations, 5 thousand FM radio stations, 1 thousand television

broadcast stations, 9 thousand cable television systems, 530 million radios, 193 million

television sets, 24 ocean cables, and scores of satellite facilities! This is truly an

"Information Age" and sometimes, you need to look at where we've been in order to see

the future more clearly!

1.1.1 Information

---“A message received and understood” --- Princeton

---“Information is a term with many meanings depending on context, but is as a rule

closely related to such concepts as meaning, knowledge, instruction, communication,

representation, and mental stimulus ”

--- Wikipedia

--- “any communication or representation of knowledge such as facts, data, or opinions in

any medium or form, including textual, numerical, graphic, cartographic, narrative, or

audiovisual forms (OMB Circular A-130). ”

--- Gils.net

--- “Facts, concepts, or instructions; any sort of knowledge or supposition which can be

communicated. “ --- Cedar.Web.Cern

--- “Is organized data that has been arranged for better comprehension or understanding.

What is one person's information can become another person's data.” --- earthlink.net

1.1.2 Information Transfer

A coordinated sequence of user and telecommunications system actions that cause

information present at a source user to become present at a destination user.



Note: An information-transfer transaction usually consists of three consecutive phases

called the access phase, the information-transfer phase, and the disengagement phase.

1.2 Broadcast

A term to describe communication where a piece of information is sent or transmitted from

one point to all other points. There is just one sender, but the information is simultaneously

sent to all connected receivers. In networking, a distinction is made between Broadcasting

and Multicasting.

Broadcasting sends a message to everyone on the network whereas multicasting sends a

message to a select list of recipients .One of the most common examples is broadcast

through a cellular network service. This serves multiple end users at different locations in a

simulcast fashion. Practically every cellular system has some kind of broadcast

mechanism.

This can be used directly for distributing information to multiple mobiles, commonly, for

example in a mobile telephony system, the most important use of broadcast information is

to set up channels for one to one communication between the mobile Trans-receiver and

the base station. This is called Paging. The details of the process of paging vary somewhat

from network to network, but normally we know a limited number of cells where the

phone is located (this group of cells is called a location area in the GSM system or Routing

Area in UMTS).

Paging takes place by sending the broadcast message on all of those cells. Today,

interaction with digital displays is a deskbound or device-dependent experience. However,

developments in display and information sharing technologies may enable a new form of

interaction with digital media: ‘ubiquitous computing’. In ubiquitous computing, the

physical location of data and processing power is not apparent to the user. Rather,

information is made available to the user in a transparent and contextually relevant

manner.



A single display device restricts the repertoire of interactions between the user and digital

media, so ubiquitous computing requires displays wherever the user might need one – in

appliances, tabletops public transport, walls, etc. This project aims at integrating the

expansiveness of a wireless cellular network and the ease of information transfer through

the SMS with the coverage of public display boards. It is thereby a modest effort to realize

the complete potential of public display boards in instantaneous information broadcast in

swift response to events of interests.

1.3 BLOCK DIAGRAM

As explained in the introduction chapter, the realization of complete potential of the

display boards and the wireless medium in information transfer is the major issue that the

following thesis of the following project deals with.

Fig 1.1 Block diagram of GSM based SMS driven Automatic Display Toolkit

As we see in the above figure, there are at least two interfacing circuits:-

GSM Module with Microcontroller

Microcontroller with LCD Display



1.4 DESCRIPTION OF BLOCKS

1.4.1 GSM HANDSET

GSM (Global System for Mobile Communications, originally Group Special

Mobile), is a standard set developed by the European Telecommunications

Standards Institute (ETSI) to describe technologies for second generation (2G)

digital cellular networks. Developed as a replacement for first generation (1G)

analog cellular networks.

GSM handset is used to send the message to the GSM MODULE. The message

which is send through the GSM Mobile will be display on the LCD.

Fig 1.2 GSM Handset

1.4.2 GSM MODULE

GSM modules are similar to modems but there is one difference –A GSM Modem

is an external equipment where as a GSM Module is a module that can be

integrated within an equipment.

GSM Module is an embedded piece of hardware.

GSM Module receives the message from the mobile station.


http://en.wikipedia.org/wiki/Cellular_network

http://en.wikipedia.org/wiki/2G

http://en.wikipedia.org/wiki/European_Telecommunications_Standards_Institute

http://en.wikipedia.org/wiki/European_Telecommunications_Standards_Institute


Fig 1.3 GSM Module

1.4.3 MICROCONTROLLER

The microcontroller which is used in this project is AT89S52.

Microcontroller is a microprocessor designed specifically for control

applications, and is equipped with ROM, RAM and facilities I / O on a

single chip.

AT89S52 is one of the family MCS-51/52 equipped with an internal 8

Kbyte Flash EPROM (Erasable and Programmable Read Only Memory),

which allows memory to be reprogrammed.

Fig 1.4 Microcontroller AT89S52

1.4.4 LCD Display

16*2 Alphanumeric LCD’s are used.

The message which is sent from the mobile phone is displayed on the LCD.



Fig 1.5 16*2 LCD Display

1.5 FEATURES OF PROJECT

The main aim of the project will be to design a SMS driven automatic display

toolkit which can replace the currently used programmable electronic display.

This project deals with the integration of the expansiveness of a wireless cellular

network and the ease of information transfer through the SMS with the coverage of

public display boards.

The message to be displayed is sent through a SMS from a transmitter. The toolkit

receives the SMS and displays the desired information after necessary code

conversion.

It is useful to display the messages in a large geographical area like- college

campus, offices, railway stations, airports etc.

It will display same message on every LCD’s at a time.

1.6 SYSTEM OVERVIEW

The component description of this system can be divided into the following stages-

Definition of all features of our project.

Designing block diagram.



Designing of all circuits.

Implementing circuits and components.

Giving software overview.

Writing the codes of all the functions.

Writing actual codes for microcontroller.

Compiling the code.

Burning the hex file into microcontroller with programmer.

Testing.

Running.

Documentation.

1.7 ADVANTAGES

Information can be transferred at different places at a time.

The electronics displays which are currently used are programmable displays

which need to be reprogrammed each time. This makes it inefficient for

immediate information transfer, and thus the display board loses its

importance where as GSM BASED TOOLKIT replace this problem.

This display board programs itself with the help of the incoming SMS with

proper validation. Such a system proves to be helpful for immediate

information transfer.

The GSM based display toolkit can be used as an add-on to these display

boards and make it truly wireless.

Information can be transferred at different places at a time.

1.8 APPLICATION

The system is made efficient by using ‘clone’ SIMs of same MIN in a

geographical area so that the same SMS can be received by number of display

boards in a locality using techniques of time division multiple access.

This project is already an application of GSM.



1.9 FUTURE ASPECT

The use of microcontroller in place of a general purpose computer allows us to

theorize on many further improvements on this project prototype.

Temperature display during periods wherein no message buffers are empty is one

such theoretical improvement that is very possible.

Another very interesting and significant improvement would be to accommodate

multiple receiver MODEMS at the different positions in a geographical area

carrying duplicate SIM cards.

Multilingual display can be another added variation of the project.

MMS technology along with relatively high end microcontrollers to carry on the

tasks of graphics encoding and decoding along with a more expansive bank of

usable memory can make this task a walk in the park.



HARDWARE SECTION

2.1 BLOCK DIAGRAM OF SETUP BOX



Fig 2.1 The Basic Hardware of the ProjectA – Microcontroller

B – LCD display

C – GSM Module

D – SIM

E –9 Pin Female Plug

F – Transformer

G – Magnet Mount Antenna

H – Power Reset Button

I – LED

J – Diode

K – Capacitor

L – Crystal

M – PCB

N – Resistor

O – Coaxial Cable

2.2 DESCRIPTION OF 8051 MICROCONTROLLER



2.2.1 8051 MICROCONTROLLER

8051 is the name of a big family of microcontrollers. The device which we used in our

project was the 'AT89S52' which is a typical 8051 microcontroller manufactured by Atmel.

2.2.2 FEATURES

1) 8051 have 128 bytes of RAM

2) 8051 have 128 user defined flags

3) It consist of 16 bit address bus

4) It also consist of 3 internal and two external interrupts

5) Less power usage in 8051 with respect to other micro-controller

6) It consist of 16-bit program counter and data pointer

7) 8051 can process 1 million one-cycle instructions per second

8) It also consist of 32 general purpose registers each of 8 bits

9) ROM on 8051 is 4 Kbytes in size

10) It also consist of Two 16 bit Timer/ Counter

2.2.3 TYPES OF MEMORY

The 8051 has three very general types of memory. To effectively program the 8051 it is

necessary to have a basic understanding of these memory types.

Fig 2.2 Memory Configuration of 8051



On-Chip Memory refers to any memory (Code, RAM, or other) that physically

exists on the microcontroller itself. On-chip memory can be of several types, but

we'll get into that shortly.

External Code Memory is code (or program) memory that resides off-chip. This

is often in the form of an external EPROM.

External RAM is RAM memory that resides off-chip. This is often in the form of

standard static RAM or flash RAM.

CODE MEMORY

Code memory is the memory that holds the actual 8051 program that is to be run.

This memory is limited to 64K and comes in many shapes and sizes. Code memory

may be found on-chip, either burned into the microcontroller as ROM or EPROM.

Code may also be stored completely off-chip in an external ROM or, more

commonly, an external EPROM.

Flash RAM is also another popular method of storing a program. Various

combinations of these memory types may also be used--that is to say, it is possible

to have 4K of code memory on-chip and 64k of code memory off-chip in an

EPROM.

When the program is stored on-chip the 64K maximum is often reduced to 4k, 8k,

or 16k. This varies depending on the version of the chip that is being used.

EXTERNAL RAM

As an obvious opposite of Internal RAM, the 8051 also supports what is called

External RAM.

As the name suggests, External RAM is any random access memory which is

found off-chip.

Since the memory is off-chip it is not as flexible in terms of accessing, and is also

slower. For example, to increment an Internal RAM location by 1 requires only 1

instruction and 1 instruction cycle. To increment a 1-byte value stored in External

RAM requires 4 instructions and 7 instruction cycles. In this case, external memory

is 7 times slower!



External RAM loses in speed and flexibility it gains in quantity.

While Internal RAM is limited to 128 bytes the 8051 supports External RAM up to

64K.

2.2.4 BASIC REGISTERS

THE ACCUMULATOR

The Accumulator, as it’s name suggests,is used as a general register to accumulate

the results of a large number of instructions.

It can hold an 8-bit (1-byte) value and is the most versatile register the 8051 has

due to the sheer number of instructions that make use of the accumulator.

More than half of the 8051’s 255 instructions manipulate or use the accumulator in

some way.

THE "R" REGISTERS

The "R" registers are a set of eight registers that are named R0, R1, etc. up to and

including R7.

These registers are used as auxiliary registers in many operations.

The "R" registers are also used to temporarily store values.

THE "B" REGISTER

The "B" register is very similar to the Accumulator in the sense that it may hold an

8-bit (1-byte) value.

The "B" register is only used by two 8051 instructions: MUL AB and DIV AB.

THE DATA POINTER (DPTR)

The Data Pointer (DPTR) is the 8051’s only user-accessable 16-bit (2-byte)

register.

The Accumulator, "R" registers, and "B" register are all 1-byte values.



THE PROGRAM COUNTER (PC)

The Program Counter (PC) is a 2-byte address which tells the 8051 where the next

instruction to execute is found in memory.

When the 8051 is initialized PC always starts at 0000h and is incremented each

time an instruction is executed.

It is important to note that PC isn’t always incremented by one. Since some

instructions require 2 or 3 bytes the PC will be incremented by 2 or 3 in these

cases.

The Program Counter is special in that there is no way to directly modify it’s value.

THE STACK POINTER (SP)

The Stack Pointer, like all registers except DPTR and PC, may hold an 8-bit (1-

byte) value.

The Stack Pointer is used to indicate where the next value to be removed from the

stack should be taken from.

When you push a value onto the stack, the 8051 first increments the value of SP

and then stores the value at the resulting memory location.

When you pop a value off the stack, the 8051 returns the value from the memory

location indicated by SP, and then decrements the value of SP.

2.3 DESCRIPTION OF BLOCKS (SETUP BOX)

2.3.1 AT89S52 MICROCONTROLLER

The AT89S52 has 4 different ports, each one having 8 Input/output lines providing

a total of 32 I/O lines.

Those ports can be used to output DATA and orders do other devices, or to read the

state of a sensor, or a switch.

Most of the ports of the AT89S52 have 'dual function' meaning that they can be

used for two different functions.



The first one is to perform input/output operations and the second one is used to

implement special features of the microcontroller like counting external pulses,

interrupting the execution of the program according to external events, performing

serial data transfer or connecting the chip to a computer to update the software.

Each port has 8 pins, and will be treated from the software point of view as an 8-

bit variable called 'register', each bit being connected to a different Input/ Output

pin.

Fig 2.3 AT89S52 microcontroller

2.3.1.1 FEATURES

Four-port I / O, which each consist of eight bits.

4.0V to 5.5V Operating Range.

Fully Static Operation: 0 Hz to 33 MHz.

Two-level Program Memory Lock.

256 x 8-bit Internal RAM internally.

32 Programmable I/O Lines.

Three 16-bit Timer/Counters.

A CPU (Central Processing Unit) 8 Bit.

The internal oscillator and timing circuits.

Five interrupt lines.

The size of 8 KByte EPROM for program memory.



Maximum speed execution of instructions per cycle is 0.5 s at 24 MHz clock

frequency.

2.3.1.2 CONNECTIONS IN MICROCONTROLLER

Fig 2.4 Connection in microcontroller

CPU (CENTRAL PROCESSING UNIT)

This section serves to control the entire operation on the microcontroller. This unit is

divided into two parts, the control unit, or CU (Control Unit) and the arithmetic and logic

unit or ALU (Arithmetic Logic Unit) The main function control unit is to take instructions

from memory (fetch) and then translate the composition of these instructions into a simple

collection of work processes (decode), and implement instruction sequence in accordance

with the steps that have been determined the program (execute). Arithmetic and logic unit

is the part that deals with arithmetic operations like addition, subtraction, and logical data

manipulation operations such as AND, OR, and comparison.

MEMORY


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There are two different memory types:- RAM and EEPROM. Shortly, RAM is used to

store variable during program execution, while the EEPROM memory is used to store the

program itself, that's why it is often referred to as the 'program memory'. It is clear that the

CPU (Central Processing Unit) is the heart of the micro controllers. It is the CPU that will

Read the program from the FLASH memory and Execute it by interacting with the

different peripherals.

PART INPUT / OUTPUT (I / O)

This section serves as a communication tool with a single chip device outside the system.

Consistent with the name, I / O devices can receive and provide data to / from a single

chip.

There are two kinds of devices I / O is used, ie devices for serial connection UART

(Universal Asynchronous Receiver Transmitter) and device for so-called parallel

relationship with the PIO (Parallel Input Output).Both types of I / O has been available in a

single chip AT89S52.

SOFTWARE

Single flakes MCS-51 family has a special programming language that is not understood

by other types of single flakes. This programming language known by the name of the

assembler language instruction has 256 devices. However, when this can be done with

microcontroller programming using C language .With the C language, microcontroller

programming easier, because the C language format will be automatically converted into

assembler language with a hex file format. Software on a microcontroller can be divided

into five groups as follows:

DATA TRANSFER INSTRUCTIONS

This instruction serves to move the data, between registers, from memory to memory, from

registers to memory, and others.

ARITHMETIC INSTRUCTION



These instructions perform arithmetic operations including addition, subtraction, addition

of one (increments), a reduction of one (decrement), multiplication and division.

LOGIC AND BIT MANIPULATION INSTRUCTIONS

Functions perform logic operations AND, OR, XOR, comparison, shift and complement

data.

BRANCHING INSTRUCTIONS

Serves to alter the normal sequence of execution of a program . With this instruction, the

programs that are implemented will jump to a particular address.

INSTRUCTION STACK, I / O AND CONTROL

These instructions set the stack usage, read / write I / O ports, and controlling.

2.3.1.3 DESCRIPTION

The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K

bytes 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 AT89S52 is a powerful microcontroller which provides a highly-flexible

and cost-effective solution to many embedded control applications.

The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of

RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-



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 con-tents but freezes the

oscillator, disabling all other chip functions until the next interrupt or hardware reset.

2.3.1.4 PIN CONFIGURATION

AT89S52 microcontroller has 40 pins with a single 5 Volt power supply. The pin 40 is

illustrated as follows:

Fig 2.5 Pin Diagram


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2.3.1.5 PIN DESCRIPTION

VCC - Supply voltage.

GND - Ground.

Port 0 -

Port 0 is an 8-bit open drain bidirectional 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 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 bidirectional 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.

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.



Table 2.1 Port 1

Port 2-


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

memory that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2

uses strong internal pull-ups 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 -


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 receives some control signals for Flash programming and

verification.

Port 3 also serves the functions of various special features of the AT89S52, as

shown in the following table:-

Table 2.2 Port 3

RST-

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

running resets the device. This pin drives high for 98 oscillator periods after the

Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be

used to disable this feature. In the default state of bit DISRTO, the RESET

HIGH out feature is enabled.

ALE/PROG-

Address Latch Enable (ALE) 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 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

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

external execution mode.

PSEN-

Program Store Enable (PSEN) is the read strobe to external program memory.

When the AT89S52 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.

Note, however, that if lock bit 1 is programmed, EA will be internally latched

on reset. EA should be strapped to VCC for internal program executions. This

pin also receives the 12-volt programming enable voltage (VPP) during Flash

programming.

XTAL1-

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

operating circuit.



XTAL2-

Output from the inverting oscillator amplifier.

Special Function Registers-

A map of the on-chip memory area called the Special Function Register (SFR)

space. Note that not all of the addresses are occupied, and unoccupied addresses

may not be implemented on the chip.

Read accesses to these addresses will in general return random data, and write

accesses will have an indeterminate effect.

User software should not write 1s to these unlisted locations, since they may be

used in future products to invoke new features. In that case, the reset or inactive

values of the new bits will always be 0.

Timer 2Registers:

Control and status bits are contained in registers T2CON ) and T2MOD for

Timer 2. The register pair (RCAP2H, RCAP2L) are the Capture/Reload

registers for Timer 2 in 16-bit capture mode or 16-bit auto-reload mode.

Interrupt Registers:

The individual interrupt enable bits are in the IE register. Two priorities can be

set for each of the six interrupt sources in the IP register.



2.3.1.6 BLOCK DIAGRAM

Fig 2.6 Block Diagram of AT89S52



2.3.1.7 Memory Organization

All single chip in the family division of MCS-51 has the address space to programs and

data. The separation of program memory and data memory allows data to be accessed by a

memory address 8 bits. Even so, the address memory 16 bits of data can be generated

through the DPTR register (Point Data Register). Program memory can only be read

cannot be written because it is stored in the EPROM. In this case the EPROM is available

in a single chip AT89S52 for 8 Kbyte.

Fig 2.7 AT89S52 Microcontroller memory

Memory Program

If EA’s low value, the program will occupy the address 1000 H to FFFF H to external

programs.

If the EA pin is connected to GND, all program fetches are directed to external memory.

On the AT89S52, if EA is connected to VCC, program fetches to addresses 0000H through

1FFFH are directed to internal memory and fetches to addresses 2000H through FFFFH

are to external memory.


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Data memory

Internal data memory are mapped as shown below memory space is divided into three

blocks of the 128 down, 128 up, and space SFR (Special Function Register) Under Section

128 bytes of RAM mapped into

the 32 bytes are grouped into four banks and eight registers (R0 to R7). In the next 16

bytes, on the banks of register, form a block of memory space that can bit addressable. All

bytes that are within 128 below can be accessed either directly or indirectly.

The AT89S52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a

parallel address space to the Special Function Registers. This means that the upper 128

bytes have the same addresses as the SFR space but are physically separate from SFR

space.

When an instruction accesses an internal location above address 7FH, the address mode

used in the instruction specifies whether the CPU accesses the upper 128 bytes of RAM or

the SFR space. Instructions which use direct addressing access the SFR space.

2.3.1.8 UART-

The UART in the AT89S52 operates the same way as the UART in the AT89C51 and

AT89C52.

2.3.1.9 TIMER 0 AND 1-

Timer 0 and Timer 1 in the AT89S52 operate the same way as Timer 0 and Timer 1 in the

AT89C51 and AT89C52.

2.3.1.10 TIMER 2

Timer 2 is a 16-bit Timer/Counter that can operate as either a timer or an event counter.

The type of operation is selected by bit C/T2 in the SFR T2CON (shown in Table 5-2).

Timer 2 has three operating modes: capture, auto-reload (up or down counting), and baud

rate generator.



The modes are selected by bits in T2CON, as shown in Table 10-1. Timer 2 consists of two

8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is incremented every

machine cycle. Since a machine cycle consists of 12 oscillator periods, the count rate is

1/12 of the oscillator frequency.

Table 2.3 Timer 2 Operating Mode

2.3.1.11 INTERRUPTS-

The AT89S52 has a total of six interrupt vectors: two external interrupts (INT0 and INT1),

three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. These interrupts are

all shown in Figure 2.8.

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. 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.

Fig 2.8 Interrupt Sources

2.3.1.12 TIMERS AND COUNTERS IN AT89S52

Diagram below shows a simplified diagram of the main peripherals present in the

AT89S52 or 8052 / 8051. There are 3 Timers/Counters in the 89S52.

The expression "Timer/Counter" is used because this unit can act as a Counter or as a

Timer as per requirement. Timer/Counter 2 is a special counter that does not behave like

the two others, because of some extra functionality.

The serial port, using a UART (Universal Asynchronous Receive Transmit) protocol can

be used in a wide range of communication applications. With the UART provided in the



AT89S52 it is easy to communicate with a serial port equipped computer, as well as

communicate with another microcontroller.

If all the peripherals described above can generate interrupt signals in the CPU according

to some specific events, it can be useful to generate an interrupt signal from an external

device that may be a sensor or a Digital to Analog converter. For that purpose there are 2

External Interrupt sources (INT0 and INT1).

Fig 2.9 Timers and Counters in AT89S52

2.3.2 LIQUID CRYSTAL DISPLAY

Fig 2.10 16*2 LCD


http://2.bp.blogspot.com/_becES0hCzzM/TByqdA-HL1I/AAAAAAAAAkQ/NAykDOppCUY/s1600/timers_8052.JPG

http://2.bp.blogspot.com/_becES0hCzzM/S7Qd2lrV4yI/AAAAAAAAAas/ttDl-LxEb0I/s1600/untitled.bmp


A liquid crystal display (LCD) is a thin, flat display device made up of any number of

color or monochrome pixels arrayed in front of a light source or reflector. It is prized by

engineers because it uses very small amounts of electric power, and is therefore suitable

for use in battery-powered electronic devices.

LCD’s are passive display having low power consumption and contrast ratio. The

characteristic of LCD’s are given below:

LCD’s operate on the principle of light scattering. They can be operated

either in a reflective or transmissive configuration. There operation

dependent on ambient or back lightering as they do not generate there own

light.

It operates on low voltage around 1v-5v and the power required by LCD to

the scatter or absorbs light is very low in the order of the few

micro-watts/cm.

A transmissive LCD has better visual characteristic than a reflective LCD.

The operation of LCD is base on the use of certain organic material, which

retains a regular crystal like structure even when they have been melted.

Nematic and cholestric are to important liquid crystal material used in

display out of these two NLC has a particular crystal structure. The liquid is

normally transparent, but if subjected to a strong electric field, an ion moves

through it and disturbs the well-ordered crystal structure.

The liquid is normally transparent, but if subjected to a strong electric field,

an ion move through it and disturbs the well ordered crystal structure

causing the liquid to polarized and hence turns opaque.


http://en.wikipedia.org/wiki/Electronics

http://en.wikipedia.org/wiki/Light

http://en.wikipedia.org/wiki/Pixel

http://en.wikipedia.org/wiki/Monochrome

http://en.wikipedia.org/wiki/Display_device

http://en.wikipedia.org/wiki/Liquid_crystal


Basically, LCD consist of thin layer of NLC liquid about 10 micron thick

placed between two glass plates having an electrode at list one electrode is

transparent.

The transmissive type LCD has two transparent glass plates, where as a

reflective type LCD has only one electrode transparent.

2.3.2.1 FEATURES

5 x 8 dots with cursor.

Built-in controller (KS 0066 or Equivalent).

+ 5V power supply (Also available for + 3V).

1/16 duty cycle.

N.V. optional for + 3V power supply.

2.3.2.2 LCD PIN DESCRIPTION

VSS, VDD and VEE

Pin 1 (VSS) is a ground pin and it is certainly needed that this pin should be grounded for

LCD to work properly. VEE and VDD are given +5 vlots normally. However VEE may

have a potentiometer voltage divider network to get the contrast adjusted. But VDD is

always at +5V.

RS, R/W and EN

These three pins are numbered 4, 5 and 6 as shown above. RS is used to make the selection

between data and command register. For RS=0, command register is selected and for RS=1

data register is selected. R/W gives you the choice between writing and reading. If set

(R/W=1) reading is enabled. R/W=0 when writing.



Enable pins is used by the LCD to latch information presented to its data pins. When data

is supplied to data pins, a high to low pulse must be applied to this pin in-order for the

LCD to latch in the data present at the data pins. It may be noted here that the pulse must

be of minimum 450ns wide.

D0-D7

The 8-bit data pins, D0-D7, are used to send information to the LCD or read the contents

of LCD's internal register.

Table 2.4 Pin Description



2.3.2.3 LCD CODES

Table 2.5 LCD Codes



2.3.2.4 16*2 CHARACTER LCD

Table 2.6 Character LCD

2.3.3 GSM MODULE

Fig 2.11 GSM Module



The GSM module is a GSM terminal for transmitting data, faxes and SMS (short

message service) text messages in GSM networks (GSM = global system for

mobile communication).

GSM modules are similar to modems but there is one difference –A GSM Modem

is an external equipment where as a GSM Module is a module that can be

integrated within an equipment.

When the GSM Module M1 is registered in the network, it serves as a standard

modem for fax and data transmission for a computer connected to the V.24

interface. Special AT+C commands as per GSM 07.07 or GSM 07.05 for

controlling GSM-related functions (PIN entry, network selection, etc.) and for the

short message service are available via the V.24 interface.

2.3.3.1 The GSM Module comprises the following components

• GSM transceiver.

• Data and power supply unit.

• Serial interface (V.24) for data transmission and control.

• Manufacturer-specific interface for DC power supply, external antenna and audio signals.

2.3.3.2 The GSM module offers the advantages

Ultra small size (22x22x3 mm), lightweight (3.2 g) and easy to integrate.

Low power consumption.

R&TTE type approval plus CE, GCF, FCC, PTCRB, IC.

Full RS232 on CMOS level with flow control (RX, TX, CTS, RTS, CTS, DTR,

DSR, DCD, RI).

Embedded TCP/IP Stack UDP/IP Stack , Embedded FTP and SMTP Client.

High performance on low price.

2.3.3.3 INTERFACES

Power supply nominal 3,8 V.

10 general purposes I/O ports and serial bi-directional bus on CMOS 2,8 V.

External SIM.



Analogue audio for microphone, speaker and hands free set plus digital voice

interface.

RS232 on CMOS 2,8 V (One RS232 (2,8V) with flow control (RX, TX, CTS, RTS,

CTS, DTR, DSR, DCD, RI), baud rate 300 - 115.200 bps, auto bauding 1200 -

57.600 bps.

50 Ohm antenna connector.

2.3.3.4 The GSM Module offers the following features

Short message service mobile originated (SMS MO, TS22).

Short message service mobile terminated (SMS MT, TS21).

SIM Phonebook management.

Fixed Dialling Number (FDN).

SIM Toolkit class 2

Real time clock

Alarm management.

2.4 SUBSCRIBER IDENTITY MODULE (SIM)

Fig 2.12 BSNL SIM

Simcom offers this information as a service to its customers, to support application

and engineering efforts that use Simcom products. The information provided is

based upon requirements specifically provided to Simcom by the customers.

Simcom has not undertaken any independent search for additional relevant

information, including any information that may be in the customer’s possession.



The GSM Module M1 must have a SIM card to operate in the GSM network. To

install this card, press the yellow button to eject the carrier and insert the SIM in the

carrier. Then push the carrier into the housing, making sure that it locks into place.

A subscriber identity module or subscriber identification module (SIM) is an

integrated circuit that securely stores the International Mobile Subscriber Identity

(IMSI) and the related key used to identify and authenticate subscribers on mobile

telephony devices (such as mobile phones and computers).

There are three operating voltages for SIM cards: 5 V, 3 V and 1.8 V. The

operating voltage of the majority of SIM cards launched before 1998 was 5 V. SIM

cards produced subsequently are compatible with 3 V and 5 V. Modern cards

support 5 V, 3 V and 1.8 V.

The microcontrollers used for SIM cards come in different configurations. The

typical ROM size is between 64 KB and 512 KB, typical RAM size is between 1

KB and 8 KB, and typical EEPROM size is between 16 KB and 512 KB.

The ROM contains the operating system of the card and might contain applets

where the EEPROM contains the so called Personalisation, which consists of

security keys, phone book, SMS settings, etc., and operating system patches.

SIM cards store network-specific information used to authenticate and identify

subscribers on the network. The most important of these are the ICCID, IMSI,

Authentication Key (Ki), Local Area Identity (LAI) and Operator-Specific

Emergency Number.

The SIM also stores other carrier-specific data such as the SMSC (Short Message

Service Center) number, Service Provider Name (SPN), Service Dialing Numbers

(SDN), Advice-Of-Charge parameters and Value Added Service (VAS)

applications.SIM cards can come in at least two capacity types: 32 KB and 64 KB.

Both allow a maximum of 250 contacts to be stored on the SIM, but while the 32

KB has room for 33 mobile network codes (MNCs) or "network identifiers", the 64

KB version has room for 80 MNCs.


http://en.wikipedia.org/wiki/Mobile_network_code

http://en.wikipedia.org/wiki/Subscriber_identity_module#Authentication_key

http://en.wikipedia.org/wiki/IMSI

http://en.wikipedia.org/wiki/Operating_system

http://en.wikipedia.org/wiki/EEPROM

http://en.wikipedia.org/wiki/RAM

http://en.wikipedia.org/wiki/ROM

http://en.wikipedia.org/wiki/Microcontroller

http://en.wikipedia.org/wiki/Computer

http://en.wikipedia.org/wiki/Mobile_phone

http://en.wikipedia.org/wiki/Telephony

http://en.wikipedia.org/wiki/Subscriber_identity_module#Authentication_key

http://en.wikipedia.org/wiki/International_Mobile_Subscriber_Identity

http://en.wikipedia.org/wiki/Integrated_circuit


2.4.1 SIM300 KEY FEATURES



Table 2.7 SIM300 Key Features

2.5 FEMALE 9 PIN PLUG

There are different types of connectors required for serial communication like 9 or 25 pin

female and male plug etc.Serial communication is a way enables different equipments to

communicate with their outside world. It is called serial because the data bits will be sent

in a serial way over a single line.

A personal computer has a serial port known as communication port or COM Port used to

connect a modem for example or any other device, there could be more then one COM

Port in a PC.

Serial ports are controlled by a special chip called UART (Universal Asynchronous

Receiver Transmitter). Different applications use different pins on the serial port and this

basically depend of the functions required.



Serial communication has some advantages over the parallel communication. One of the

advantages is transmission distance, serial link can send data to a remote device more far

then parallel link. Also the cable connection of serial link is simpler then parallel link and

uses less number of wires.

Serial link is used also for Infrared communication, now many devices such as laptops &

printers can communicate via inferred link.

Types of connectors

There are two sizes of connectors 9 pin and 25 pin, both they called D-Type plug. D-Type

plug could be either Male or Female. Here we will discuss only about the female 9 pin

plug.

2.5.1 PIN DESCRIPTION OF FEMALE 9 PIN PLUG

Fig 2.13 Female 9 Pin Plug



Table 2.8 Pin description of Female 9 Pin plug

2.5.2 FEATURES OF FEMALE 9 PIN PLUG

Supports PCI bus, Plug and Play.

Provides 1 isolated RS-422/485 port and 1 RS-232 port.

Provides surge protection.

LED diagnostic indicators.

DOS, Windows NT/2K/XP/2003 and Linux driver supported.

2.5.3 ADVANTAGES

Built-in COM-Selector.

Self-Tuner inside.

3KV isolated RS-422/485 port.

Up to 128KB software FIFO for each COM port under Windows.

Short Card Design.

2.6 TRANSFORMER



Fig 2.14 Transformer

A transformer is a device (that was invented by NIKOLA TESLA) that transfers

electrical energy from one circuit to another through inductively coupled conductors—the

transformer's coils.

A varying current in the first or primary winding creates a varying magnetic flux in the

transformer's core and thus a varying magnetic field through the secondary winding.

This varying magnetic field induces a varying electromotive force (EMF), or "voltage", in

the secondary winding. This effect is called inductive coupling.

If a load is connected to the secondary, current will flow in the secondary winding, and

electrical energy will be transferred from the primary circuit through the transformer to the

load.

In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion

to the primary voltage (Vp) and is given by the ratio of the number of turns in the

secondary (Ns) to the number of turns in the primary (Np) as follows:


http://en.wikipedia.org/wiki/Electrical_load

http://en.wikipedia.org/wiki/Inductive_coupling

http://en.wikipedia.org/wiki/Volt

http://en.wikipedia.org/wiki/Electromotive_force

http://en.wikipedia.org/wiki/Electromagnetic_induction

http://en.wikipedia.org/wiki/Magnetic_field

http://en.wikipedia.org/wiki/Magnetic_flux

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Inductive_coupling

http://en.wikipedia.org/wiki/Electrical_network

http://en.wikipedia.org/wiki/Electrical_energy

http://en.wikipedia.org/wiki/Image:Transformer.filament.agr.jpg


By apprpriate selection of the ratio of turns, a transformer thus enables an alternating

current (AC) voltage to be "stepped up" by making Ns greater than Np, or "stepped down"

by making Ns less than Np.

2.6.1 COUPLING BY MUTUAL INDUCTION

A simple transformer consists of two electrical conductors called the primary winding

and the secondary winding. Energy is coupled between the windings by the time-varying

magnetic flux that passes through (links) both primary and secondary windings.

When the current in a coil is switched on or off or changed, a voltage is induced in a

neighboring coil. The effect, called mutual inductance, is an example of electromagnetic

induction

2.6.2 BASIC PRINCIPLES

The transformer is based on two principles: first, that an electric current can produce a

magnetic field (electromagnetism) and second that a changing magnetic field within a coil

of wire induces a voltage across the ends of the coil (electromagnetic induction).

Changing the current in the primary coil changes the magnetic flux that is developed. The

changing magnetic flux induces a voltage in the secondary coil.

Fig 2.15 An ideal transformer

The secondary current arises from the action of the secondary EMF on the load

impedance


http://en.wikipedia.org/wiki/Electromagnetic_induction

http://en.wikipedia.org/wiki/Electromagnetism


http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Inductance#Mutual_inductance

http://en.wikipedia.org/wiki/Magnetic_flux

http://en.wikipedia.org/wiki/Electrical_conduction

http://en.wikipedia.org/wiki/Alternating_current


http://en.wikipedia.org/wiki/File:Transformer3d_col3.svg


An ideal transformer is shown in the adjacent figure. Current passing through the

primary coil creates a magnetic field. The primary and secondary coils are wrapped

around a core of very high magnetic permeability, such as iron, so that most of the

magnetic flux passes through both the primary and secondary coils. If a load is

connected to the secondary winding, the load current and voltage will be in the

directions indicated, given the primary current and voltage in the directions indicated

(each will be alternating current in practice).

2.6.3 IDEAL POWER EQUATION

Fig 2.16 The ideal transformer as a circuit element

If the secondary coil is attached to a load that allows current to flow, electrical power is

transmitted from the primary circuit to the secondary circuit. Ideally, the transformer is

perfectly efficient. All the incoming energy is transformed from the primary circuit to the

magnetic field and into the secondary circuit. If this condition is met, the input electric

power must equal the output power:

giving the ideal transformer equation

This formula is a reasonable approximation for most commercial built transformers today.


http://en.wikipedia.org/wiki/Electric_power

http://en.wikipedia.org/wiki/Electric_power



http://en.wikipedia.org/wiki/Iron

http://en.wikipedia.org/wiki/Permeability_(electromagnetism)

http://en.wikipedia.org/wiki/Magnetic_core


http://en.wikipedia.org/wiki/File:Transformer_under_load.svg


If the voltage is increased, then the current is decreased by the same factor. The impedance

in one circuit is transformed by the square of the turns ratio.

For example, if an impedance Zs is attached across the terminals of the secondary coil, it

appears to the primary circuit to have an impedance of (Np/Ns)2Zs. This relationship is

reciprocal, so that the impedance Zp of the primary circuit appears to the secondary to be

(Ns/Np)2Zp.

2.6.4 THE UNIVERSAL EMF EQUATION

If the flux in the core is sinusoidal, the relationship for either winding between its number

ofturns, voltage, magnetic flux density and core cross-sectional area is given by the

universal emf equation (from Faraday's law):

Where,

E= is the sinusoidal rms or root mean square voltage of the winding.

f= is the frequency in hertz

N= is the number of turns of wire on the winding

a= is the cross-sectional area of the core in square metres

B =is the peak magnetic flux density in teslas

2.6.5 CLASSIFICATION

Transformers are adapted to numerous engineering applications and may be classified in

many ways:

By power level (from fraction of a volt-ampere(VA) to over a thousand MVA).

By application (power supply, impedance matching, circuit isolation).

By frequency range (power, audio, radio frequency(RF)).

By voltage class (a few volts to about 750 kilovolts).

By cooling type (air cooled, oil filled, fan cooled, water cooled, etc.).

By purpose (distribution, rectifier, arc furnace, amplifier output, etc.).

By ratio of the number of turns in the coils.


http://en.wikipedia.org/wiki/Tesla_(unit)

http://en.wikipedia.org/wiki/Hertz

http://en.wikipedia.org/wiki/Frequency

http://en.wikipedia.org/wiki/Root_mean_square

http://en.wikipedia.org/wiki/Magnetic_flux_density

http://en.wikipedia.org/wiki/Sinusoidal


STEP-UP

The secondary has more turns than the primary.

STEP-DOWN

The secondary has fewer turns than the primary.

ISOLATING

Intended to transform from one voltage to the same voltage. The two coils have

approximately equal numbers of turns, although often there is a slight difference in the

number of turns, in order to compensate for losses (otherwise the output voltage would be

a little less than, rather than the same as, the input voltage).

VARIABLE

The primary and secondary have an adjustable number of turns which can be

selected without reconnecting the transformer.

2.7 MAGNET MOUNT ANTENNA

Magnet Mount or Mag Mount Antennas stick to the sheet metal of your vehicle's roof or

trunk via a strong circular magnet and utilizes the body metal as an integral part of the

antenna (ground plane). The antenna pictured to the right is a Dual Band Mag Mount

antenna.

These antennas work particularly well for people who have several vehicles or do not want

to install an antenna either permanently or semi-permanently on their vehicle.

Installation of these antennas is as simple as setting the antenna on the trunk lid or roof

and running the included cable in through the trunk lid, door or window.

Care must be taken to run the cable in such a way so that water cannot get through where

the cable enters the vehicle interior. Also care must be taken not to crush or severely bend

the cable.

These antennas can also be used in a home or office but must be applied to a metal surface

(file cabinet, desk or refrigerator are some examples) in order to work effectively.



A ground plane can also be made out of sheet metal (12" Square for 1900 MHz and 28"

Square for 800MHz and Dual Band).

Your local Hardware store carries pieces of sheet metal also known as flashing (for roofs)

that are very inexpensive.

This antenna would be a good choice at home where signal is sometimes good and

sometimes marginal. If reception is not sufficient to make ANY calls, a panel antenna

might be a better solution.

The primary purpose of the magnet antenna mount is to allow the CB’er the means to gain

temporary or emergency communications capability.

The fact that the user doesn’t need to drill holes in the vehicle should be of secondary

importance.Magnetic mounts should always be treated as a temporary solution to an

immediate or short-term communications need.

If you don’t plan to use your CB on a regular basis, don’t want to drill holes in your

vehicle for permanent mounts, or don’t expect the maximum performance from your

equipment, than a magnetic mount may be all you need.

But remember, in spite of their convenience, a magnetic mount antenna will rarely meet

the performance that is realized from a properly installed permanent antenna. However, for

short-range caravan type communications or emergency use, magnetic mount antennas are

sufficient.



Fig 2.17 Magnet Mount Anteena BMAX824/1850




2.7.1 GENERAL CONSIDERATIONS

1. Like all other transmit antennas, those mounted on magnet mounts must be tuned on

the vehicle in the location that it will always be used. If you tune the antenna in the

middle of the roof then decide to use it on the hood or truck, or a different vehicle, it

will require re-tuning at its new location.

2. Always place your magnet on the flattest surface available.

3. Do not abuse the coax cable. It is extremely important. Sharp bends, tight pinches and

holes rubbed through outer jacket will affect performance.

4. Always place your magnet on a clean, dry surface.

5. If avoidable, do not use on a vinyl roof. (Adds capacitance and diminishes holding

strength).

6. Never leave the mount in one location for extended periods of time. (The vehicle

paint will fade at various rates and moisture under mount can cause rust to form under

the painted surface.)

7. If you drop a ferrite magnet on a hard surface the magnetic strength may be reduced,

or the material could shatter into many pieces.

8. Magnet mounts rely on high resistance, capacitance grounding. If you use power

amplification, there is a good chance that heat will discolor the vehicles paint. We do

not recommend the use of amplifiers with any magnet-mounted antenna.

9. At highway speeds there are considerable forces acting upon the mount. Even if the

antenna is holding fast, a side burst of air from a passing 18-wheeler can hit the

antenna with a force from another direction causing it to loose its grip. For that

reason, it is always a good idea to have a spring between the antenna and the magnet

mount.

10. When removing the magnetic mount from the vehicle, do not slide it to the edge to

make it more convenient. Dirt between the magnet and the vehicle paint will surely

leave scratches.

11. Never place your magnet mount near your audio and/or video tapes, or computer

disks of any type. The strong magnetic field will destroy them. And, if you want to

wreck the magnetic strip on your credit card, set them on the magnet for 1 second or

more.


2.7.2 FEATURES

Molded polymer base provides ruggedness and durability in harsh mobile

environments.

Wideband performance (Wi-Fi and WiMAX models) provide coverage of 2.2 GHz

to 2.9GHz frequencies without tuning. WiMAX model covers 2.3-3.8 GHz

frequencies.

3 dB or 5 dB models available for most frequency ranges.

Most models available in bright chrome or black finish.

Antenna is ready to install; no rod cutting is required (unless otherwise noted).

Designed to mate with all 1-1/8”-18 thread mounts, including 3/4” mounts.

Spring-loaded gold plated contact pin.

2.7.3 TECHNICAL DATA

Table 2.9 Technical data of magnet mount antenna



2.8 POWER RESET BUTTON

A Power-ON Reset allows togenerate a reset signal after a power supply level detection.

Fig 2.18 Power ON RESET

The output reset signal is low-active and must be efficient during a precise time (Trst)

after the input signal level detection. The Power-ON Reset must detect a voltage level

smaller than a constant value and generate the reset signal at every moment. This circuit is

only supplied by the general power supply, so by the same voltage on which we have to

perform the detection.

In our case, the power supply voltage is 5V and the reference voltage (Vref.) is 3,75V. As

soon as the power supply voltage (Vsupply) is superior to Vref, the reset output voltage

stays at a 0V level during the time Trst needed by the user; then, it gets to the high digital

voltage value (here 5V). The same reset will occur for a glitch. The reset time Trst is

chosen using external components.



2.8.1 DISCHARGE

To have a constant reset time, especially for re-reset conditions, we have to discharge very

quickly the RC bridge capacitor. So, we use a huge PMOS transistor as a switch, 1rter and

a small NMOS switch which allows to empty the capacitor at the beginning of the cycle

(when the power supply voltage is getting high)because when Vcc is inferior to the PMOS

threshold voltage, the PMOS doesn’t empty the full charge.

2.9 LIGHT EMITTING DIODE

A light-emitting diode (LED) is a semiconductor light source.[3] LEDs are used as

indicator lamps in many devices and are increasingly used for other lighting. Introduced as

a practical electronic component in 1962,[4] early LEDs emitted low-intensity red light, but

modern versions are available across the visible, ultraviolet, and infrared wavelengths,

with very high brightness.

When a light-emitting diode is forward-biased (switched on), electrons are able to

recombine with electron holes within the device, releasing energy in the form of photons.

This effect is called electroluminescence and the color of the light (corresponding to the

energy of the photon) is determined by the energy gap of the semiconductor.

LEDs are often small in area (less than 1 mm2), and integrated optical components may be

used to shape its radiation pattern. LEDs present many advantages over incandescent light

sources including lower energy consumption, longer lifetime, improved robustness,

smaller size, and faster switching.Light-emitting diodes are used in applications as diverse

as aviation lighting, automotive lighting, advertising, general lighting, and traffic signals.

LEDs have allowed new text, video displays, and sensors to be developed, while their high

switching rates are also useful in advanced communications technology.

Fig 2.19 Symbol of LED


http://en.wikipedia.org/wiki/Traffic_signal

http://en.wikipedia.org/wiki/Automotive_lighting#Light_emitting_diodes_.28LED.29

http://en.wikipedia.org/wiki/Navigation_light#Aviation_navigation_lights

http://en.wikipedia.org/wiki/Service_life

http://en.wikipedia.org/wiki/Energy_conservation

http://en.wikipedia.org/wiki/Light-emitting_diode#Advantages

http://en.wikipedia.org/wiki/Energy_gap

http://en.wikipedia.org/wiki/Color

http://en.wikipedia.org/wiki/Electroluminescence

http://en.wikipedia.org/wiki/Photon

http://en.wikipedia.org/wiki/Electron_hole

http://en.wikipedia.org/wiki/Carrier_generation_and_recombination

http://en.wikipedia.org/wiki/Electrons

http://en.wikipedia.org/wiki/Voltage_bias

http://en.wikipedia.org/wiki/Semiconductor_diode

http://en.wikipedia.org/wiki/Infrared

http://en.wikipedia.org/wiki/Ultraviolet

http://en.wikipedia.org/wiki/Visible_spectrum

http://en.wikipedia.org/wiki/Lighting

http://en.wikipedia.org/wiki/Semiconductor

http://en.wikipedia.org/wiki/File:LED_symbol.svg


Fig 2.20 LED

2.9.1 THE INNER WORKINGS OF AN LED

The LED consists of a chip of semiconducting material doped with impurities to create a p-

n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side,

or cathode, but not in the reverse direction. Charge-carriers—electrons and holes—flow

into the junction from electrodes with different voltages. When an electron meets a hole, it

falls into a lower energy level, and releases energy in the form of a photon.

The wavelength of the light emitted, and thus its color depends on the band gap energy of

the materials forming the p-n junction. In silicon or germanium diodes, the electrons and

holes recombine by a non-radiative transition, which produces no optical emission,

because these are indirect band gap materials. The materials used for the LED have a direct

band gap with energies corresponding to near-infrared, visible, or near-ultraviolet light.

LED development began with infrared and red devices made with gallium arsenide.

Advances in materials science have enabled making devices with ever-shorter

wavelengths, emitting light in a variety of colors.

LEDs are usually built on an n-type substrate, with an electrode attached to the p-type

layer deposited on its surface. P-type substrates, while less common, occur as well. Many

commercial LEDs, especially GaN/InGaN, also use sapphire substrate.

Most materials used for LED production have very high refractive indices. This means that

much light will be reflected back into the material at the material/air surface interface.


http://en.wikipedia.org/wiki/Refractive_index

http://en.wikipedia.org/wiki/Sapphire

http://en.wikipedia.org/wiki/Materials_science

http://en.wikipedia.org/wiki/Gallium_arsenide

http://en.wikipedia.org/wiki/Direct_band_gap

http://en.wikipedia.org/wiki/Direct_band_gap

http://en.wikipedia.org/wiki/Indirect_band_gap

http://en.wikipedia.org/wiki/Germanium

http://en.wikipedia.org/wiki/Silicon

http://en.wikipedia.org/wiki/Band_gap

http://en.wikipedia.org/wiki/Wavelength

http://en.wikipedia.org/wiki/Photon

http://en.wikipedia.org/wiki/Energy

http://en.wikipedia.org/wiki/Energy_level

http://en.wikipedia.org/wiki/Electrode

http://en.wikipedia.org/wiki/Electron_hole

http://en.wikipedia.org/wiki/Electron

http://en.wikipedia.org/wiki/Cathode

http://en.wikipedia.org/wiki/Anode

http://en.wikipedia.org/wiki/P-n_junction

http://en.wikipedia.org/wiki/P-n_junction

http://en.wikipedia.org/wiki/Doping_(semiconductor)


Thus, light extraction in LEDs is an important aspect of LED production, subject to much

research and development.

Fig 2.21 The inner workings of an LED

2.9.2 ADVANTAGES

Efficiency: LEDs emit more light per watt than incandescent light bulbs.[93] Their

efficiency is not affected by shape and size, unlike fluorescent light bulbs or tubes.

Color: LEDs can emit light of an intended color without using any color filters as

traditional lighting methods need. This is more efficient and can lower initial costs.

Size: LEDs can be very small (smaller than 2 mm2]) and are easily populated onto

printed circuit boards.

On/Off time: LEDs light up very quickly. A typical red indicator LED will achieve

full brightness in under a microsecond.[95] LEDs used in communications devices

can have even faster response times.

Cycling: LEDs are ideal for uses subject to frequent on-off cycling, unlike

fluorescent lamps that fail faster when cycled often, or HID lamps that require a

long time before restarting.

Dimming: LEDs can very easily be dimmed either by pulse-width modulation or

lowering the forward current.


http://en.wikipedia.org/wiki/Pulse-width_modulation

http://en.wikipedia.org/wiki/Dimmer

http://en.wikipedia.org/wiki/HID_lamp

http://en.wikipedia.org/wiki/Microsecond

http://en.wikipedia.org/wiki/Incandescent_light_bulb

http://en.wikipedia.org/wiki/Light_extraction_in_LEDs

http://upload.wikimedia.org/wikipedia/commons/d/d7/PnJunction-LED-E.svg


Cool light: In contrast to most light sources, LEDs radiate very little heat in the

form of IR that can cause damage to sensitive objects or fabrics. Wasted energy is

dispersed as heat through the base of the LED.

Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt

failure of incandescent bulbs.

Lifetime: LEDs can have a relatively long useful life. One report estimates 35,000

to 50,000 hours of useful life, though time to complete failure may be longer.

Fluorescent tubes typically are rated at about 10,000 to 15,000 hours, depending

partly on the conditions of use, and incandescent light bulbs at 1,000–2,000 hours.

Shock resistance: LEDs, being solid state components, are difficult to damage

with external shock, unlike fluorescent and incandescent bulbs, which are fragile.

Focus: The solid package of the LED can be designed to focus its light.

Incandescent and fluorescent sources often require an external reflector to collect

light and direct it in a usable manner

2.9.3 APPLICATIONS

In general, all the LED products can be divided into two major parts, the public lighting

and indoor lighting. LED uses fall into four major categories:

Visual signals where light goes more or less directly from the source to the human

eye, to convey a message or meaning.

Illumination where light is reflected from objects to give visual response of these

objects.

Measuring and interacting with processes involving no human vision.[109]

Narrow band light sensors where LEDs operate in a reverse-bias mode and respond

to incident light, instead of emitting light.


http://en.wikipedia.org/wiki/Lighting

http://en.wikipedia.org/wiki/Infrared


2.10 DIODE

Fig 2.22 Diode 1N4007

In electronics, a diode is a type of two-terminal electronic component with nonlinear

resistance and conductance (i.e., a nonlinear current–voltage characteristic), distinguishing

it from components such as two-terminal linear resistors which obey Ohm’s law. A

semiconductor diode, the most common type today, is a crystalline piece of

semiconductor material connected to two electrical terminals. A vacuum tube diode (now

rarely used except in some high-power technologies) is a vacuum tube with two electrodes:

a plate and a cathode.

The most common function of a diode is to allow an electric current to pass in one

direction (called the diode’s forward direction), while blocking current in the opposite

direction (the reverse direction). Thus, the diode can be thought of as an electronic version

of a check valve. This unidirectional behavior is called rectification, and is used to convert

alternating current to direct current, and to extract modulation from radio signals in radio

receivers—these diodes are forms of rectifiers.

However, diodes can have more complicated behavior than this simple on–off action.

Semiconductor diodes do not begin conducting electricity until a certain threshold voltage

is present in the forward direction (a state in which the diode is said to be forward-biased).

The voltage drop across a forward-biased diode varies only a little with the current, and is

a function of temperature; this effect can be used as a temperature sensor or voltage

reference.

FEATURES

• Low forward voltage drop.

• High surge current capability.


http://en.wikipedia.org/wiki/Voltage_reference

http://en.wikipedia.org/wiki/Voltage_reference

http://en.wikipedia.org/wiki/Diode#Temperature_measurements

http://en.wikipedia.org/wiki/P%E2%80%93n_junction#Forward_bias

http://en.wikipedia.org/wiki/Rectifier

http://en.wikipedia.org/wiki/Modulation

http://en.wikipedia.org/wiki/Direct_current


http://en.wikipedia.org/wiki/Rectification_(electricity)

http://en.wikipedia.org/wiki/Check_valve

http://en.wikipedia.org/wiki/Cathode

http://en.wikipedia.org/wiki/Plate_electrode

http://en.wikipedia.org/wiki/Electrode

http://en.wikipedia.org/wiki/Vacuum_tube

http://en.wikipedia.org/wiki/Semiconductor

http://en.wikipedia.org/wiki/Crystalline

http://en.wikipedia.org/wiki/Ohm's_law

http://en.wikipedia.org/wiki/Linear_resistor

http://en.wikipedia.org/wiki/Current%E2%80%93voltage_characteristic

http://en.wikipedia.org/wiki/Electrical_resistance_and_conductance

http://en.wikipedia.org/wiki/Nonlinear_element

http://en.wikipedia.org/wiki/Electronic_component

http://en.wikipedia.org/wiki/Terminal_(electronics)



2.11 CAPACITOR

It is an electronic component whose function is to accumulate charges and then release it.

Fig 2.23 Capacitor

Capacitors are of two types: - (1) fixed type like ceramic, polyester, electrolytic

capacitors-these names refer to the material they are made of aluminium foil. (2) Variable

type like gang condenser in radio or trimmer. In fixed type capacitors, it has two leads and

its value is written over its body and variable type has three leads. Unit of measurement of

a capacitor is farad denoted by the symbol F.

It is a very big unit of capacitance. Small unit capacitor are pico-farad denoted by pf

(Ipf=1/1000,000,000,000 f) Above all, in case of electrolytic capacitors, it’s two terminal

are marked as (-) and (+) so check it while using capacitors in the circuit in right direction.

Mistake can destroy the capacitor or entire circuit in operational.

In this project two types of capacitors are used:

Ceramic Capacitor (22 pF, 15pF, 47pF)

Electrolytic Capacitor (10 microF)

2.11.1 CERAMIC CAPACITOR

Fig 2.24 Ceramic Capacitor



In electronics, a ceramic capacitor is a capacitor constructed of alternating layers of metal

and ceramic, with the ceramic material acting as the dielectric. The temperature coefficient

depends on whether the dielectric is Class 1 or Class 2. A ceramic capacitor (especially the

class 2) often has high dissipation factor, high frequency coefficient of dissipation.

2.11.2 CLASSES OF CERAMIC CAPACITORS

Class I capacitors: accurate, temperature-compensating capacitors. They are the

most stable over voltage, temperature, and to some extent, frequency. They also

have the lowest losses. On the other hand, they have the lowest volumetric

efficiency. A typical class I capacitor will have a temperature coefficient of 30

ppm/°C. This will typically be fairly linear with temperature. These also allow for

high Q filters—a typical class I capacitor will have a dissipation factor of 0.15%.

Very high accuracy (~1%) class I capacitors are available (typical ones will be 5%

or 10%). The highest accuracy class 1 capacitors are designated C0G or NP0.

Class II capacitors: better volumetric efficiency, but lower accuracy and stability.

A typical class II capacitor may change capacitance by 15% over a −55 °C to 85 °C

temperature range. A typical class II capacitor will have a dissipation factor of

2.5%. It will have average to poor accuracy (from 10% down to +20/-80%).

Class III capacitors: high volumetric efficiency, but poor accuracy and stability. A

typical class III capacitor will change capacitance by -22% to +56% over a

temperature range of 10 °C to 55 °C. It will have a dissipation factor of 4%. It will

have fairly poor accuracy (commonly, 20%, or +80/-20%). These are typically used

for decoupling or in other power supply applications.

2.11.3 ELECTROLYTIC CAPACITOR

An electrolytic capacitor is a type of capacitor that uses an electrolyte (an ionic

conducting liquid) as one of its plates to achieve a larger capacitance per unit volume than

other types, but with performance disadvantages.


http://en.wikipedia.org/wiki/Capacitance

http://en.wikipedia.org/wiki/Electrolyte

http://en.wikipedia.org/wiki/Capacitor

http://en.wikipedia.org/wiki/Decoupling_capacitor

http://en.wikipedia.org/wiki/NP0

http://en.wikipedia.org/wiki/Dissipation_factor

http://en.wikipedia.org/wiki/EIA_Class_2_dielectric

http://en.wikipedia.org/wiki/EIA_Class_1_dielectric

http://en.wikipedia.org/wiki/Temperature_coefficient

http://en.wikipedia.org/wiki/Dielectric

http://en.wikipedia.org/wiki/Ceramic

http://en.wikipedia.org/wiki/Metal

http://en.wikipedia.org/wiki/Capacitor



All capacitors conduct alternating current (AC) and block direct current (DC) and can be

used, amongst other applications, to couple circuit blocks allowing AC signals to be

transferred while blocking DC power, to store energy, and to filter signals according to

their frequency.

The large capacitance of electrolytic capacitors makes them particularly suitable for

passing or bypassing low-frequency signals and storing large amounts of energy. They are

widely used in power supplies and for decoupling unwanted AC components from DC

power connections.

Fig 2.25 Electrolytic Capacitor

2.12 CRYSTAL

Crystal has the property of durability, reliability, easy installation, low maintenance,

precision of frequency and high end output frequencies.

Fig 2.26 Quartz Crystal


http://en.wikipedia.org/wiki/Power_supply

http://en.wikipedia.org/wiki/Electronic_filter

http://en.wikipedia.org/wiki/Electronic_circuit

http://en.wikipedia.org/wiki/Coupling_(electronics)




2.12.1 FEATURES

Nominal frequency 1.000~125.000MHz

Mode of vibration Fundament 1.0~30.0MHz 3rd Overtone 24.0~60.0MHz

60.0~125.0MHz

CRT type AT

Frequency tolerance + -20ppm, + -30ppm, + -50ppm

Frequency stability + -20ppm, + -30ppm, + -50ppm

Load capacitance 8pf~33pf, series

Shunt capacitance 7.0pf max

Drive level 0.01~2.0mw max

Insulation resistance 500MΩMin/100+ -15VDC

2.13 PRINTED CIRCUIT BOARD (PCB)

A printed circuit board, or PCB, is used to mechanically support and electrically connect

electronic components using conductive pathways, tracks or signal traces etched from

copper sheets laminated onto a non-conductive substrate. It is also referred to as printed

wiring board (PWB) or etched wiring board.

A PCB populated with electronic components is a printed circuit assembly (PCA), also

known as a printed circuit board assembly or PCB Assembly (PCBA). Printed circuit

boards are used in virtually all but the simplest commercially produced electronic devices.

Alternatives to PCBs include wire wrap and point-to-point construction. PCBs are often

less expensive and more reliable than these alternatives, though they require more layout

effort and higher initial cost.

PCBs are much cheaper and faster for high-volume production since production and

soldering of PCBs can be done by automated equipment. Much of the electronics

industry’s PCB design, assembly, and quality control needs are set by standards that are

published by the IPC organization.Conducting layers are typically made of thin copper

foil.


http://en.wikipedia.org/wiki/IPC_(electronics)

http://en.wikipedia.org/wiki/Point-to-point_construction

http://en.wikipedia.org/wiki/Wire_wrap

http://en.wikipedia.org/wiki/Substrate_(electronics)

http://en.wikipedia.org/wiki/Laminated

http://en.wikipedia.org/wiki/Copper

http://en.wikipedia.org/wiki/Industrial_etching

http://en.wikipedia.org/wiki/Electrical_conductor

http://en.wikipedia.org/wiki/Electronic_component


Insulating layers dielectric are typically laminated together with epoxy resin prepreg.The

board is typically coated with a solder mask that is green in color. Other colors that are

normally available are blue, black, white and red. There are quite a few different dielectrics

that can be chosen to provide different insulating values depending on the requirements of

the circuit.

Fig 2.27 PCB

The vast majority of printed circuit boards are made by bonding a layer of copper over the

entire substrate, sometimes on both sides, (creating a “blank PCB”) then removing

unwanted copper after applying a temporary mask (e.g., by etching), leaving only the

desired copper traces.

A few PCBs are made by adding traces to the bare substrate (or a substrate with a very thin

layer of copper) usually by a complex process of multiple electroplating steps. The PCB


http://en.wikipedia.org/wiki/Electroplating

http://en.wikipedia.org/wiki/Prepreg

http://en.wikipedia.org/wiki/Epoxy_resin

http://en.wikipedia.org/wiki/Dielectric

http://www.google.co.in/imgres?q=PCB&hl=en&safe=off&sa=X&biw=1311&bih=646&tbm=isch&prmd=imvnsur&tbnid=JxTLZf73_IHvBM:&imgrefurl=http://www.newburyelectronics.co.uk/products-and-services/electronic-design-and-development/what-is-the-electronic-design-process/&docid=utl9xaNvEVB0IM&imgurl=http://www.newburyelectronics.co.uk/products-and-services/electronic-design-and-development/what-is-the-electronic-design-process/uploaded/BGA%20bare%20pcb(red).jpg&w=2575&h=1938&ei=xp91T_WcLInRrQep2fi3DQ&zoom=1&iact=hc&vpx=670&vpy=330&dur=956&hovh=195&hovw=259&tx=160&ty=129&sig=104489412808236203766&page=3&tbnh=132&tbnw=176&start=40&ndsp=24&ved=1t:429,r:3,s:40


manufacturing method primarily depends on whether it is for production volume or

sample/prototype quantities. Double-sided boards or multi-layer boards use plated-through

holes, called vias, to connect traces on either side of the substrate.

2.13.1 LARGE VOLUME

Silk screen printing–the main commercial method.

Photographic methods–used when fine line widths are required.

2.13.2 SMALL VOLUME

Print onto transparent film and use as photomask along with photo-sensitized

boards. (i.e., pre-sensitized boards), then etch. (Alternatively, use a film photo

plotter).

Laser resist ablation: Spray black paint onto copper clad laminate, place into CNC

laser plotter. The laser raster-scans the PCB and ablates (vaporizes) the paint where

no resist is wanted. Etch. (Note: laser copper ablation is rarely used and is

considered experimental.)

2.14 RESISTOR (10KΩ ,11kΩ)

Resistance is the opposition of a material to the current. It is measured in Ohms (Ω). All

conductors represent a certain amount of resistance, since no conductor is 100% efficient.

To control the electron flow (current) in a predictable manner, we use resistors.

Fig 2.28 Symbol of Resistor

Electronic circuits use calibrated lumped resistance to control the flow of current. Broadly

speaking, resistor can be divided into two groups viz. fixed & adjustable (variable)

resistors. In fixed resistors, the value is fixed & cannot be varied. In variable resistors, the

resistance value can be varied by an adjuster knob.

It can be divided into (a) Carbon composition (b) Wire wound (c) Special type.


http://en.wikipedia.org/wiki/Silk_screen

http://en.wikipedia.org/wiki/Via_(electronics)


The most common type of resistors used in our projects is carbon type. The resistance

value is normally indicated by colour bands. Each resistance has four colours, one of the

band on either side will be gold or silver, this is called fourth band and indicates the

tolerance, others three band will give the value of resistance.

For example if a resistor has the following marking on it say red, violet, gold. Comparing

these coloured rings with the colour code, its value is 27000 ohms or 27 kilo ohms and its

tolerance is ±5%. Resistor comes in various sizes (Power rating). The bigger, the size, the

more power rating of ¼ watts. The four colour rings on its body tells us the value of

resistor value as given below.

2.14.1 COLOURS CODE

Black-----------------------------------------------------0

Brown----------------------------------------------------1

Red-------------------------------------------------------2

Orange---------------------------------------------------3

Yellow---------------------------------------------------4

Green-----------------------------------------------------5

Blue-------------------------------------------------------6

Violet-----------------------------------------------------7

Grey------------------------------------------------------8

White-----------------------------------------------------9

The first rings give the first digit. The second ring gives the second digit. The third ring

indicates the number of zeroes to be placed after the digits. The fourth ring gives tolerance

(gold ±5%, silver ± 10%, No colour ± 20%).

Fig 2.29 Resistor



2.15 OTHER HARDWARE REQUIRMENTS

2.15.1 SERIAL PORT CABLE

The serial port cable is used to connect computer from 9 pin plug.

A null modem cable will enable you to connect two computers together for serial

communications It is a particularly designed cable that permits anyone to connect two

computers directly to each other via their communications ports called RS-232 ports.

Serial communications with RS232 is one of the oldest and most widely spread

communication methods in computer realm.

Null modems are specially helpful with portable computers because they enable the

portable computer to exchange data with a bigger machine.

Null modem cables have the TD (Transmit Data) and RD ( Receive Data) lines crossed

over, permitting information to be sent from one computer to the other.

They are similar to a crossover cable where it is the CTS (clear to send) and RTS (ready to

send) lines are crossed over. Null-modem cables are particularly used for serial port

connections.

Fig 2.30 Serial Port Cable



2.15.2 COAXIAL CABLE

Coaxial cable is used to provide connection to antenna.

Coaxial cables are a type of cable that is used by cable TV and that is common for data

communications.

Taking a round cross-section of the cable, one would find a single center solid wire

symmetrically surrounded by a braided or foil conductor. Between the center wire and foil

is a insulating dielectric. This dielectric has a large affect on the fundamental

characteristics of the cable. In this lab, we show the how the permittivity and permeability

of the dielectric contributes to the cable’s inductance and capacitance. Also, these values

affect how quickly electrical data is travels through the wire.

Data is transmitted through the center wire, while the outer braided layer serves as a line to

ground. Both of these conductors are parallel and share the same axis. This is why the wire

is called coaxial!

Just like all electrical components, coaxial cables have a characteristic impedance. This

impedance depends on the dielectric material and the radii of each conducting material. As

shown in this lab, the impedance affects how the cable interacts with other electrical

components.

Fig 2.31 Coaxial Cable



2.15.3 POWER SUPPLY

Power supply is a reference to a source of electrical power. A device or system that

supplies electrical or other types of energy to an output load or group of loads is called a

power supply unit or PSU. The term is most commonly applied to electrical energy

supplies, less often to mechanical ones, and rarely to others.

Fig 2.32 Circuit of Power Supply

2.15.3.1 ELECTRICAL POWER SUPPLIES

This term covers the power distribution system together with any other primary or

secondary sources of energy such as:

Conversion of one form of electrical power to another desired form and voltage.

This typically involves converting 120 or 240 volt AC supplied by a utility

company (see electricity generation) to a well-regulated lower voltage DC for

electronic devices. For examples, see switched-mode power supply, linear

regulator, rectifier and inverter (electrical).

Batteries

Chemical fuel cells and other forms of energy storage systems

Solar power

Generators or alternators (particularly useful in vehicles of all shapes and sizes,

where the engine has torque to spare, or in semi-portable units containing an

internal combustion engine and a generator) (For large-scale power supplies, see

electricity generation.) Low voltage, low power DC power supply units are

commonly integrated with the devices they supply, such as computers and

household electronics.


http://en.wikipedia.org/wiki/Computer

http://en.wikipedia.org/wiki/Electricity_generation

http://en.wikipedia.org/wiki/Internal_combustion_engine

http://en.wikipedia.org/wiki/Alternator

http://en.wikipedia.org/wiki/Electrical_generator

http://en.wikipedia.org/wiki/Solar_power

http://en.wikipedia.org/wiki/Energy_storage

http://en.wikipedia.org/wiki/Fuel_cell

http://en.wikipedia.org/wiki/Battery_(electricity)

http://en.wikipedia.org/wiki/Inverter_(electrical)

http://en.wikipedia.org/wiki/Rectifier

http://en.wikipedia.org/wiki/Linear_regulator

http://en.wikipedia.org/wiki/Linear_regulator

http://en.wikipedia.org/wiki/Switched-mode_power_supply


http://en.wikipedia.org/wiki/Electricity_generation


http://en.wikipedia.org/wiki/External_electric_load

http://en.wikipedia.org/wiki/Energy

http://en.wikipedia.org/wiki/Electrical

http://en.wikipedia.org/wiki/Electrical_power


Constraints that commonly affect power supplies are the amount of power they can supply,

how long they can supply it without needing some kind of refueling or recharging, how

stable their output voltage or current is under varying load conditions, and whether they

provide continuous power or pulses.

The regulation of power supplies is done by incorporating circuitry to tightly control the

output voltage and/or current of the power supply to a specific value. The specific value is

closely maintained despite variations in the load presented to the power supply’s output, or

any reasonable voltage variation at the power supply’s input. This kind of regulation is

commonly categorized as a Stabilized power supply.

TYPES OF POWER SUPPLY

There are many types of power supply. Most are designed to convert high voltage AC

mains electricity to a suitable low voltage supply for electronics circuits and other devices.

A power supply can by broken down into a series of blocks. For example a 5V regulated

supply:

Fig 2.33 Block Diagram of Regulated Power Supply

Each of the blocks is described in more detail below:

Transformer — steps down high voltage AC mains to low voltage AC.

Rectifier — converts AC to DC, but the DC output is varying.

Smoothing — smoothes the DC from varying greatly to a small ripple.

Regulator — eliminates ripple by setting DC output to a fixed voltage.


http://en.wikipedia.org/wiki/Stabilized_power_supply

http://en.wikipedia.org/wiki/Current_(electricity)

http://en.wikipedia.org/wiki/Voltage


CONNECTIONS

AND

INTERFACING



3.1 CIRCUIT DIAGRAM

Fig 3.1 Circuit Diagram of GSM Based SMS Driven Automatic Display Toolkit



3.2 CONNECTING MICROCONTROLLER AND COMPUTER WITH USB COMMUNICATION

There are many advantages to connecting hardware via the Universal Serial Bus (USB),

but there are also many obstacles to be overcome. In this series of articles, we provide you

with a map to help you find your way along the stony path of developing USB

applications.

DIY hardware for the PC is usually connected to the serial RS232 interface. After several

decades of use, this interface is very well documented and easy to use. Of course, it also

has certain disadvantages One of these is that you can only connect a device to it before

booting the PC, and another is that powering an attached circuit from the serial interface is

awkward (and only a small amount of power can be drawn this way).

The USB interface is free of these disadvantages. However, most users – including

experienced PC hobbyists – know little or nothing about the USB interface. The objective

of this series of article is to enable you to connect homemade USB devices to a PC. The

key factor here is that almost everything you need can be downloaded from the Internet for

free.

3.2.1 THERE ARE THREE ELEMENTS TO THE DEVELOPMENT OF A

PERIPHERAL USB CIRCUIT:

1. The hardware and a program that runs in the USB IC.

2. A program that communicates with the USB IC and displays responses on the screen.

3. A device driver (SYS file) that provides communication between the USB port and the

program.

3.3 CONNECTING MICROCONTROLLER AND MOBILE PHONES

In communicating the cell phone / cell phone with the microcontroller to be used as a

remote-controlled device required an interface that can synchronize the two devices so

they can exchange data. Interface system in this study using phone data port

communication lines embedded on the bottom of the phone to be able to communicate

with a microcontroller series, the serial communication there are two main points that must


http://electricly.com/communication-between-the-microcontroller-and-mobile-phones-using-the-rs232/


be adjusted i.e: stress levels and speed data rate (baud rate), after the second this is then

adjusted so that both devices can communicate with these devices can be used as a remote-

controlled device.

It was made by using micro controller as the main module, which will read incoming SMS

to your mobile phone as an order issued by the control of the realization of micro-, and

ordered the phone to send SMS reply to the mobile sender’s output status. In this script you

can use almost any type of mobile phone data cable original specifications which are

connected in series with the instrument, while the controller can be used for any phone

with SMS facility.

Remote control technology has been developed by using various transmission media.

Some of them are remote control using infrared media, radio, internet and phone lines.

Remote control system via the telephone line has an advantage in terms of range and

practicality compared with other media.

The presence of mobile phone (cellular) or mobile phones that have been known and used

a lot of people that are able to communicate wherever they are without being limited by

space and the span length of the cord could be a solution for the needs of remote control

(remote control) as was described above.

One of the most popular cell phone function is to send and receive SMS. SMS is very

suitable for real time control system for wireless data transfer speed, efficiency and breadth

of coverage, but the excess mobile phone with its SMS facility is still to be connected to a

control device to be able to control the on / off electrical devices remotely.

We have one of the control device which is practical and widely used microcontroller is a

chip that serves as an electronic circuit and the controller can store the program inside. The

major advantage is tersediannya RAM and microcontroller I / O support, so have a very

compact size and more flexibility to be connected and controlling



Fig 3.2 Block Diagram Mobile Phone and Microcontroller Communication

3.4 DESIGN OF CONTROL UNIT MICROCONTROLLER

Microcontroller is the main module in this case the micro controller strand consists of

microcontroller IC AT89S51, AT89S51 micro controller oscillator strand, strand AT89S51

micro controller reset. Strand consists of a crystal oscillator and two capacitors. This strand

with XTAL1 and XTAL2, used capacitor values of 33 pF and crystal that is used has a

value of 11.0592 MHz. strand has the ability to reset the realization of the power-on reset,

which is also accompanied with the reset button, this strand consists of a capacitor, a

resistor and a push Botton. Value of used 10 UF capacitor resistor values used 8.2 Kohm.

PORT 2 of the microstructure is used as the output of the tool, this output will be

connected to the relay. PORT 3 of the micro used for a variety of needs in accordance with

the usefulness of the port 3.

Use of port 3 are as follows:

-P3.0 (RXD) is used as input from serial communication between devices with

microcontroller.

- P3.1 (TXD) is used as output to serial communication between a mobile and

microcontroller.


http://electricly.com/wp-content/uploads/2010/04/mobile-phone-and-microcontroller-communication-block-diagram.jpg


Fig 3.3 Circuit Diagram Mobile Phone and Microcontroller Communication

3.5 SERIAL COMMUNICATIONS UNIT

Communication between the mobile phone by means done serially, with the voltage levels

to RS232. Voltage level because of differences between the micro with a serial port data

cable cell phones that have been compatible with the RS232 standard, we need a voltage

converter.

Max232 IC is used as a modifier on the micro-TTL voltage levels to RS232 voltage levels.

Asynchronous communication is done with the amount of data to 8 bits, noparity, and use

a baud rate of ± 57 600 bps, used for data transmission facilities that exist on micro

controller which is a facility at 3.0 ports (RXD), port 3.1 (TXD) and GND.


http://electricly.com/wp-content/uploads/2010/04/mobile-phone-and-microcontroller-communication-schematic-diagram.jpg


Fig 3.4 Mobile Phone and Microcontroller Communication (RS232 Serial

Communication Schematic Diagram)

3.6 POWER-DOWN MODE

In the Power-down mode, the oscillator is stopped, and the instruction that invokes Power-

down is the last instruction executed. The on-chip RAM and Special Function Registers

retain their values until the Power-down mode is terminated.

Exit from Power-down mode can be initiated either by a hardware reset or by an enabled

external interrupt. Reset redefines the SFRs but does not change the on-chip RAM. The

reset should not be activated before VCC is restored to its normal operating level and must

be held active long enough to allow the oscillator to restart and stabilize.


http://electricly.com/wp-content/uploads/2010/04/mobile-phone-and-microcontroller-communication-rs232-serial-communication-schematic-diagram.jpg


Fig 3.5 Crystal Connections

3.7 INTERFACING

3.7.1 GSM MODULE WITH MICROCONTROLLER

3.7.1.1 DTE and DCE

The terms DTE and DCE are very common in the data communications market. DTE is

short for Data Terminal Equipment and DCE stands for Data Communications Equipment.

But what do they really mean? As the full DTE name indicates this is a piece of device that

ends a communication line, whereas the DCE provides a path for communication.

Let’s say we have a computer on which wants to communicate with the Internet through a

modem and a dial-up connection. To get to the Internet you tell your modem to dial the

number of your provider. After your modems has dialed the number, the modem of the

provider will answer your call and your will hear a lot of noise.

Then it becomes quiet and you see your login prompt or your dialing program tells you the

connection is established. Now you have a connection with the server from your provider

and you can wander the Internet.

In this example you PC is a Data Terminal (DTE). The two modems (yours and that one of

your provider) are DCEs, they make the communication between you and your provider



possible. But now we have to look at the server of your provider. Is that a DTE or DCE?

The answer is a DTE.

It ends the communication line between you and the server. When you want to go from

your provided server to another place it uses another interface. So DTE and DCE are

interfacing dependent.

It is e.g. possible that for your connection to the server, the server is a DTE, but that that

same server is a DCE for the equipment that it is attached to on the rest of the Net.

3.7.1.2 RS-232

In telecommunications, RS-232 is a standard for serial binary data signals connecting

between a DTE (Data terminal equipment) and a DCE (Data Circuit-terminating

Equipment). It is commonly used in computer serial ports.

In RS-232, data is sent as a time-series of bits. Both synchronous and asynchronous

transmissions are supported by the standard. In addition to the data circuits, the standard

defines a number of control circuits used to manage the connection between the DTE and

DCE.

Each data or control circuit only operates in one direction that is, signaling from a DTE to

the attached DCE or the reverse. Since transmit data and receive data are separate circuits,

the interface can operate in a full duplex manner, supporting concurrent data flow in both

directions. The standard does not define character framing within the data stream, or

character encoding.

3.7.1.3 RS-232 SIGNALS

Transmitted Data (TxD)

Data sent from DTE to DCE.



Received Data (RxD)

Data sent from DCE to DTE.

Request To Send (RTS)

Asserted (set to 0) by DTE to prepare DCE to receive data. This may require action on the

part of the DCE, e.g. transmitting a carrier or reversing the direction of a half-duplex line.

Clear To Send (CTS)

Asserted by DCE to acknowledge RTS and allow DTE to transmit.

Data Terminal Ready (DTR)

Asserted by DTE to indicate that it is ready to be connected.If the DCE is a modem, it

should go “off hook” when it receives this signal. If this signal is deasserted ,the modem

should respond by immediately hanging up.

Data Set Ready (DSR)

Asserted by DCE to indicate an active connection.If DCE is not a modem (e.g. a null-

modem cable or other equipment), this signal should be permanently asserted (set to 0),

possibly by a jumper to another signal.

Carrier Detect (CD)

Asserted by DCE when a connection has been established with remote equipment.

Ring Indicator (RI)

Asserted by DCE when it detects a ring signal from the telephone line.

3.7.2 MICROCONTROLLER WITH LCD DISPLAY

As we’ve mentioned, the LCD requires either 8 or 11 I/O lines to communicate with. For

the sake of this tutorial, we are going to use an 8-bit data bus—so we’ll be using 11 of the

8051’s I/O pins to interface with the LCD. Let’s draw a sample pseudo-schematic of how

the LCD will be connected to the 8051.



Fig 3.6 Interfacing of Microcontroller with LCD

8051 microcontroller have 4 ports. For the interfacing of microcontroller to LCD

port 1 and port 3 are used.

The 8 pins of port 1 is connected to the 8 pin of LCD i.e. from DB0 to DB7 where

DB stands for DATA BUS.

DB0 to DB7 are used to send information to the LCD or read the contents of the

LCD’s internal registers.

The 3 pins of port 3 are connected with 3 different CONTROL PINS of the LCD.

Pin 7 of port 3 is connected with EN pin of the LCD to latch information presented

to its data pins. This control line is used to tell the LCD that you are sending data.

Pin 6 of port 3 is connected with RS i.e. REGISTER SELECT pin of the LCD. RS

pin is used for the selection of the two important registers inside the LCD-

-If RS=0 the Instruction command register is selected which allows the user to send

a command such as clear display etc.

-If RS=1 the Data register is selected which allows the user to send data to be

displayed on the LCD.

Pin 5 of port 3 is connected with the RW i.e. READ WRITE pin of the LCD.

-When RW =1 it allow the user to write information to the LCD.

-When RW= 0 it allows the user to read information from the LCD.

There are 16 pins connection on the LCD display module.

Pin NO. Symbol Level Description 1 VSS 0V Ground 2 VDD 5.0V Supply voltage for logic 3 VO --- Input voltage for LCD 4 RS H/L H : Data, L : Instruction code 5 R/W H/L H : Read mode, L : Write mode 6 E H, H → L Chip enable signal



7 DB0 H/L Data bit 0 8 DB1 H/L Data bit 1 9 DB2 H/L Data bit 2 10 DB3 H/L Data bit 3 11 DB4 H/L Data bit 4 12 DB5 H/L Data bit 5 13 DB6 H/L Data bit 6 14 DB7 H/L Data bit 7 15 BLA 4.2V Back light anode 16 BLK 0V Back light cathode

Table 3.1 Pins connection on the LCD display module

3.7.3 ANTENNA INTERFACE

The RF interface has an impedance of 50Ω. To suit the physical design of individual

applications SIM300 offers two alternatives:

Recommended approach: antenna connector on the component side of the PCB

Antenna pad and grounding plane placed on the bottom side.

To minimize the loss on the RF cable, it need be very careful to choose RF cable.

We recommend the insertion loss should be meet following requirement:

- GSM900<1dB

-DCS1800/PCS1900<1.5dB

3.7.4 SIM CARD INTERFACE

You can use AT Command to get information in SIM card. The SIM interface supports the

functionality of the GSM Phase 1 specification and also supports the functionality of the

new GSM Phase 2+ specification for FAST 64 kbps SIM (intended for use with a SIM

application Tool-kit). Both 1.8V and 3.0V SIM Cards are supported.

The SIM interface is powered from an internal regulator in the module having nominal

voltage 2.8V. All pins reset as outputs driving low. Logic levels are as described in table



Table 3.2 Signal of SIM interface (board-to-board connector)

3.7.5 SERIAL INTERFACES

SIM300 provides two unbalanced asynchronous serial ports. The GSM module is designed

as a DCE (Data Communication Equipment), following the traditional DCE-DTE (Data

Terminal Equipment) connection, the module and the client (DTE) are connected through

the following signal (as following figure shows). Autobauding supports baud rate from

1200 bps to 115200bps.

Serial port 1

Port/TXD @ Client sends data to the RXD signal line of module.

Port/RXD @ Client receives data from the TXD signal line of module.

Serial port 2

Port/TXD @ Client sends data to the DBGRX signal line of module.

Port/RXD @ Client receives data from the DBGTX signal line of module.



All pins of two serial ports have 8mA driver, the logic levels are described in following

table

Table 3.3 Logic levels of serial ports pins



SOFTWARE



4.1 PROGRAMMING FOR ANALOG TO DIGITAL CONVERSION

#include<regx51.h>

#define rd P2_7

#define wr P3_6

#define intr P3_7

#define cs P2_6

char adcdata;

unsigned char readadc(void);

unsigned char readadc()

{

cs=0;

wr=0;

wr=1;

cs=1;

while(intr);

cs=0;

rd=0;

adcdata=P1;

rd=1;

cs=1;

return adcdata;

}

4.2 PROGRAMMING FOR BTS

#include<lcd.h>

////////////////////////////////////////////////

void sendmat1();

void read_msg();

void sendc(unsigned char ch);



void sends(unsigned char *str);

void enter();

void serial_init();

void modem_init(); // initialize modem

unsigned char recvb();

void read_sms() ;

////////////////////////////////////////////////

unsigned char data i=0,j=0,k=0;

unsigned char data com[15],com1[63];

unsigned char data cmd[6];

int flag,f ;

////////////////////////////////////////////////

void main()

{

flag=0;

serial_init();

LCD_init();

LCD_row1();

LCD_puts(" Automatic ") ;

LCD_row2();

LCD_puts(" GSM Toolkit ") ;

delay(1000);

LCD_row1();

LCD_puts("Project Done By:") ;

LCD_row2();

LCD_puts("Monika Tulasyan ") ;

delay(1000);

modem_init();

sends("AT+CMGL=");

sendc('"');

sends("ALL");

sendc('"');



enter();

read_sms();

if(cmd[3]=='+')

{

sends("AT+CMGL=");

sendc('"');

sends("ALL");

sendc('"');

enter(); // read sms

read_msg();

LCD_row1();

for(i=1;i<17;i++)

{

LCD_putc(com1[i]);

}

LCD_row2();

for(i=17;i<33;i++)

{

LCD_putc(com1[i]);

} // display

}

else

{

sends("no matchat"); // do nothing

}

//IE=0x90; // ENABLE SERIAL INTERRUPT ES

i=0;j=0;

while(1)

{

serial_init();

read_sms();

if(cmd[2]=='+')

{



if(cmd[14]=='1')

{

sends("message one");

enter();

sends("AT+CMGD=2");

enter();

sends("AT+CMGR=");

sendc(cmd[14]);

enter(); // autoamtically reads sms. read new message

//display

read_msg();

LCD_row1();

for(i=1;i<17;i++)

{

LCD_putc(com1[i]);

}

LCD_row2();

for(i=17;i<33;i++)

{

LCD_putc(com1[i]);

}

}

else if(cmd[14]=='2')

{

sends("message two");

enter();

sends("AT+CMGD=1");

enter();

sends("AT+CMGR=");

sendc(cmd[14]);

enter(); // autoamtically reads sms. read new message

//display

read_msg();



LCD_row1();

for(i=1;i<17;i++)

{

LCD_putc(com1[i]);

}

LCD_row2();

for(i=17;i<33;i++)

{

LCD_putc(com1[i]);

}

}

else

{

sends("AT+CMGD=");

sendc(cmd[14]);

enter();

}

}

else

{

sends("invalid");

}

i=0;j=0;

modem_init();

serial_init();

delay(2000);

}

}

void sendc(unsigned char ch)

{

TI = 0;

SBUF = ch;

while(!TI);



delay(1);

}

void sends(unsigned char *str)

{

while(*str != '\0')

sendc(*str++);

}

void enter()

{

sendc(0x0d);

}

void modem_init()

{

sendc('A');

sendc('T');

enter();

delay(20);

sends("AT+CMGF=1");

enter();

}

unsigned char recvb()

{

unsigned char c;

RI=0;

while(!RI);

RI = 0;

c = SBUF;

return(c);

}

void sendmat()

{

for(j=0;j<15;j++)

{



SBUF=cmd[j];

while(TI==0); //wait for transmit

TI=0;

}

j=0;

}

void read_sms()

{

com[0]=recvb();

com[1]=recvb();

com[2]=recvb();

com[3]=recvb();

com[4]=recvb();

com[5]=recvb();

com[6]=recvb();

com[7]=recvb();

com[8]=recvb();

com[9]=recvb();

com[10]=recvb();

com[11]=recvb();

com[12]=recvb();

com[13]=recvb();

com[14]=recvb();

for(i=0;i<15;i++,j++)

{

cmd[j]=com[i];

}

delay(500);

sendc('$');

sendmat();

delay(100);



}

void read_msg() //

{

com1[0]=recvb();

com1[1]=recvb();

com1[2]=recvb();

com1[3]=recvb();

com1[4]=recvb();

com1[5]=recvb();

com1[6]=recvb();

com1[7]=recvb();

com1[8]=recvb();

com1[9]=recvb();

com1[10]=recvb();

com1[11]=recvb();

com1[12]=recvb();

com1[13]=recvb();

com1[14]=recvb();

com1[15]=recvb();

com1[16]=recvb();

com1[17]=recvb();

com1[18]=recvb();

com1[19]=recvb();

com1[20]=recvb();

com1[21]=recvb();

com1[22]=recvb();

com1[23]=recvb();

com1[24]=recvb();

com1[25]=recvb();

com1[26]=recvb();

com1[27]=recvb();



com1[28]=recvb();

com1[29]=recvb();

com1[30]=recvb();

com1[31]=recvb();

com1[32]=recvb();

com1[33]=recvb();

com1[34]=recvb();

com1[35]=recvb();

com1[36]=recvb();

com1[37]=recvb();

com1[38]=recvb();

com1[39]=recvb();

com1[40]=recvb();

com1[41]=recvb();

com1[42]=recvb();

com1[43]=recvb();

com1[44]=recvb();

com1[45]=recvb();

com1[46]=recvb();

com1[47]=recvb();

com1[48]=recvb();

com1[49]=recvb();

com1[50]=recvb();

com1[51]=recvb();

com1[52]=recvb();

com1[53]=recvb();

com1[54]=recvb();

com1[55]=recvb();

com1[56]=recvb();

com1[57]=recvb();

com1[58]=recvb();

com1[59]=recvb();

com1[60]=recvb();



com1[61]=recvb();

com1[0]=recvb();

com1[1]=recvb();

com1[2]=recvb();

com1[3]=recvb();

com1[4]=recvb();

com1[5]=recvb();

com1[6]=recvb();

com1[7]=recvb();

com1[8]=recvb();

com1[9]=recvb();

com1[10]=recvb();

com1[11]=recvb();

com1[12]=recvb();

com1[13]=recvb();

com1[14]=recvb();

com1[15]=recvb();

com1[16]=recvb();

com1[17]=recvb();

com1[18]=recvb();

com1[19]=recvb();

com1[20]=recvb();

com1[21]=recvb();

com1[22]=recvb();

com1[23]=recvb();

com1[24]=recvb();

com1[25]=recvb();

com1[26]=recvb();

com1[27]=recvb();

com1[28]=recvb();

com1[29]=recvb();

com1[30]=recvb();

com1[31]=recvb();



com1[32]=recvb();

delay(400);

sendmat1();

delay(100);

}

void sendmat1()

{

for(j=0;j<33;j++)

{

SBUF=com1[j];

while(TI==0); //wait for transmit

TI=0;

}

}

void serial_init()

{

SCON = 0x50; //mode 1 serial

communication

TMOD = 0x20; //timer 1 auto reload

mode

TH1 = 0xfd; //9600 baudrate at 11.0592

MHz

TR1 = 1;

}



4.3 PROGRAMMING FOR DELAY

extern void delay(unsigned int y);

4.4 PROGRAMMING FOR LCD

#include<regxx51.h>

#include<delay.h>

#define LCD_en P2_4

#define LCD_rs P2_5

#define LCD_row1() LCD_command(0x80) /* Begin at Line 1 */

#define LCD_row2() LCD_command(0xC0) /* Begin at Line 2 */

/***************************************************

* Prototype(s) *

***************************************************/

void LCD_enable();

void LCD_command(unsigned char command);

void LCD_putc(unsigned char ascii);

void LCD_puts(unsigned char *lcd_string);

void LCD_init();

void convrt(unsigned char var);

int a,b,c;

/***************************************************

* Sources *

***************************************************/

void LCD_enable()

{

LCD_en = 0; /* Clear bit P2.4 */



delay(1);

LCD_en = 1; /* Set bit P2.4 */

}

void LCD_command(unsigned char command)

{

LCD_rs = 0; /* Clear bit P2.5 */

P2 = (P2 & 0xF0)|((command>>4) & 0x0F);

LCD_enable();

P2 = (P2 & 0xF0)|(command & 0x0F);

LCD_enable();

delay(1);

}

void LCD_putc(unsigned char ascii)

{

LCD_rs = 1; /* Set bit P2.5 */

P2 = (P2 & 0xF0)|((ascii>>4) & 0x0F);

LCD_enable();

P2 = (P2 & 0xF0)|(ascii & 0x0F);

LCD_enable();

delay(1);

}

void LCD_puts(unsigned char *lcd_string)

{

while (*lcd_string)

{

LCD_putc(*lcd_string++);

}

}

void LCD_init()



{

LCD_en = 1; /* Set bit P2.4 */

LCD_rs = 0; /* Clear bit P2.5 */

LCD_command(0x33);

LCD_command(0x32);

LCD_command(0x28);

LCD_command(0x0C);

LCD_command(0x06);

LCD_command(0x01); /* Clear */

delay(2);

}

4.5 PROGRAMMING OF REGISTER XX51

/*--------------------------------------------------------------------------

AT89XX51.H

-------------------------------------------------------------------------*/

////

#ifndef __AT89XX51_H__

#define __AT89XX51_H__

/*------------------------------------------------

Byte Registers

------------------------------------------------*/

sfr P0 = 0x80;

sfr SP = 0x81;

sfr DPL = 0x82;

sfr DPH = 0x83;

sfr PCON = 0x87;

sfr TCON = 0x88;

sfr TMOD = 0x89;

sfr TL0 = 0x8A;

sfr TL1 = 0x8B;



sfr TH0 = 0x8C;

sfr TH1 = 0x8D;

sfr P1 = 0x90;

sfr SCON = 0x98;

sfr SBUF = 0x99;

sfr P2 = 0xA0;

sfr IE = 0xA8;

sfr P3 = 0xB0;

sfr IP = 0xB8;

sfr PSW = 0xD0;

sfr ACC = 0xE0;

sfr B = 0xF0;

/*------------------------------------------------

P0 Bit Registers

------------------------------------------------*/

sbit P0_0 = 0x80;

sbit P0_1 = 0x81;

sbit P0_2 = 0x82;

sbit P0_3 = 0x83;

sbit P0_4 = 0x84;

sbit P0_5 = 0x85;

sbit P0_6 = 0x86;

sbit P0_7 = 0x87;

/*------------------------------------------------

PCON Bit Values

------------------------------------------------*/

#define STOP_ 0x02

#define PD_ 0x02 /* Alternate definition */

#define GF0_ 0x04

#define GF1_ 0x08

#define SMOD_ 0x80

/*------------------------------------------------



TCON Bit Registers

------------------------------------------------*/

sbit IT0 = 0x88;

sbit IE0 = 0x89;

sbit IT1 = 0x8A;

sbit IE1 = 0x8B;

sbit TR0 = 0x8C;

sbit TF0 = 0x8D;

sbit TR1 = 0x8E;

sbit TF1 = 0x8F;

/*------------------------------------------------

P1 Bit Registers

------------------------------------------------*/

sbit P1_0 = 0x90;

sbit P1_1 = 0x91;

sbit P1_2 = 0x92;

sbit P1_3 = 0x93;

sbit P1_4 = 0x94;

sbit P1_5 = 0x95;

sbit P1_6 = 0x96;

sbit P1_7 = 0x97;

/*------------------------------------------------

SCON Bit Registers

------------------------------------------------*/

sbit RI = 0x98;

sbit TI = 0x99;

sbit RB8 = 0x9A;

sbit TB8 = 0x9B;

sbit REN = 0x9C;

sbit SM2 = 0x9D;

sbit SM1 = 0x9E;

sbit SM0 = 0x9F;



/*------------------------------------------------

P2 Bit Registers

------------------------------------------------*/

sbit P2_0 = 0xA0;

sbit P2_1 = 0xA1;

sbit P2_2 = 0xA2;

sbit P2_3 = 0xA3;

sbit P2_4 = 0xA4;

sbit P2_5 = 0xA5;

sbit P2_6 = 0xA6;

sbit P2_7 = 0xA7;

/*------------------------------------------------

IE Bit Registers

------------------------------------------------*/

sbit EX0 = 0xA8; /* 1=Enable External interrupt 0 */

sbit ET0 = 0xA9; /* 1=Enable Timer 0 interrupt */

sbit EX1 = 0xAA; /* 1=Enable External interrupt 1 */

sbit ET1 = 0xAB; /* 1=Enable Timer 1 interrupt */

sbit ES = 0xAC; /* 1=Enable Serial port interrupt */

sbit ET2 = 0xAD; /* 1=Enable Timer 2 interrupt */

sbit EA = 0xAF; /* 0=Disable all interrupts */

/*------------------------------------------------

P3 Bit Registers (Mnemonics & Ports)

------------------------------------------------*/

sbit P3_0 = 0xB0;

sbit P3_1 = 0xB1;

sbit P3_2 = 0xB2;

sbit P3_3 = 0xB3;

sbit P3_4 = 0xB4;

sbit P3_5 = 0xB5;

sbit P3_6 = 0xB6;

sbit P3_7 = 0xB7;



/*------------------------------------------------

Interrupt Vectors:

Interrupt Address = (Number * 8) + 3

------------------------------------------------*/

#define IE0_VECTOR 0 /* 0x03 External Interrupt 0 */

#define TF0_VECTOR 1 /* 0x0B Timer 0 */

#define IE1_VECTOR 2 /* 0x13 External Interrupt 1 */

#define TF1_VECTOR 3 /* 0x1B Timer 1 */

#define SIO_VECTOR 4 /* 0x23 Serial port */

#endif



APPENDICES



APPENDIX 1

DATA SHEET OF LCD

The Extended Concise LCD Data Sheet for HD44780 Version: 25.6.1999

Instruction RS RW D7 D6 D5 D4 D3 D2 D1 D0 DescriptionClock-Cycles

NOP 0 0 0 0 0 0 0 0 0 0 No Operation

Clear Display 0 0 0 0 0 0 0 0 0 1 Clear display & set address counter to zero

Cursor Home 0 0 0 0 0 0 0 0 1 xSet adress counter to zero, return shifted display to original position.DD RAM contents remains unchanged.

Entry Mode Set 0 0 0 0 0 0 0 1 I/D S Set cursor move direction (I/D) and specify automatic display shift (S).

Display Control

0 0 0 0 0 0 1 D C B Turn display (D), cursor on/off (C), and cursor blinking (B).

Cursor / Display shift

0 0 0 0 0 1 S/C R/L x x Shift display or move cursor (S/C) and specify direction (R/L).

Function Set 0 0 0 0 1 DL N F x x Set interface data width (DL), number of display lines (N) and character font (F).

Set CGRAM Address

0 0 0 1 CGRAM Address Set CGRAM address. CGRAM data is sent afterwards.

Set DDRAM Address

0 0 1 DDRAM Address Set DDRAM address. DDRAM data is sent afterwards.

Busy Flag & Address

0 1 BF Address Counter Read busy flag (BF) and address counter

Write Data 1 0 Data Write data into DDRAM or CGRAM

Read Data 1 1 Data Read data from DDRAM or CGRAM

x : Don't care I/D10

IncrementDecrement

R/L10

Shift to the rightShift to the left

S10

Automatic display shiftDL

10

8 bit interface4 bit interface

D10

Display ONDisplay OFF

N10

2 lines1 line

C10

Cursor ONCursor OFF

F10

5x10 dots5x7 dots

B10

Cursor blinkingDDRAM : Display Data RAM

CGRAM : Character Generator RAMS/C10

Display shiftCursor move

LCD Display with 2 lines x 16 characters :



Pin No Name Function Description1 Vss Power GND2 Vdd Power + 5 V3 Vee Contrast Adj. (-2) 0 - 5 V4 RS Command Register Select5 R/W Command Read / Write6 E Command Enable (Strobe)7 D0 I/O Data LSB8 D1 I/O Data9 D2 I/O Data

10 D3 I/O Data11 D4 I/O Data12 D5 I/O Data13 D6 I/O Data14 D7 I/O Data MSB

Bus Timing Characteristics

( Ta = - 20 to + 75°C )

Write-Cycle VDD 2.7 - 4.5 V (2) 4.5 - 5.5 V (2) 2.7 - 4.5 V (2) 4.5 - 5.5 V (2)

Parameter Symbol Min(1) Typ(1) Max(1) Unit

Enable Cycle Time tc 1000 500 - - - ns

Enable Pulse Width (High) tw 450 230 - - - ns

Enable Rise/Fall Time tr, tf - - - 25 20 ns

Address Setup Time tas 60 40 - - - ns

Address Hold Time tah 20 10 - - - ns

Data Setup Time tds 195 80 - - - ns

Data Hold Time th 10 10 - - - ns



(1) The above specifications are indications only (based on Hitachi HD44780).

Timing will vary from manufacturer to manufacturer.

(2) Power Supply : HD44780 S : VDD = 4.5 - 5.5 V

HD44780 U : VDD = 2.7 - 5.5 V

This data sheet refers to specifications for the Hitachi HD44780 LCD Driver chip, which is

used for most LCD modules.

Common types are : 1 line x 20 characters

2 lines x 16 characters





APPENDIX 2

DATASHEET OF MICROCONTROLLER













APPENDIX 3

DATASHEET OF LINEAR INTEGRATED CIRCUIT



APPENDIX 4

NPN GENERAL PURPOSE AMPLIFIER





APPENDIX 5

AT COMMANDS

THE AT STANDARD

With the development of intelligent modems, an command language was introduced in the

U.S. called the AT standard. Over the past few years, this language has been consistently

enhanced and has gained international acceptance. Most modems and communication

programs work with this command language or can be set to use it.

AT COMMAND LINE PREFIX

The AT standard is a line-oriented command language. Each command line must begin

with the letters AT, with the sole exception of the A/ command. The commands are

introduced at the end of this section.

The letters AT are also known as the attention code. The attention code signals your GSM

module that one or more commands will follow. The GSM module examines this

command line prefix.

CONNECTING TO YOUR GSM MODULE

You have connected your GSM module to your PC. You can now connect to your GSM

module. To do so, start up a communication program on your PC. Set the following

transmission parameters (characteristics):

COM interface: 1 - 4, depending on which one the M1 is connected to

Rate: 2400 - 19200 baud

Data bits: 8

Parity: None

Stop bits: 1

Duplex: Full



The GSM module supports auto bauding on the V.24 interface with transfer rates from

2400 to 19200 baud and the data format 8N1.

COMMAND SYNTAX OF THE AT STANDARD

• Command lines must always begin with AT.

• Multiple commands can be combined on one command line. To improve legibility ,you

can enter spaces between the individual commands. The GSM module ignores these

spaces.

• Commands that are specified in this manual with "0" in the last position can also be

entered without this "0". Example: ATQ has the same effect as ATQ0.

• A command line must end with a <CR> character, which is entered by pressing "Enter"

on the keyboard. This fact will not be mentioned again in this manual.



GENERAL AT COMMANDS



REFERENCE

WEBSITES

http://www.datasheetcatalog.com

http://matrixtelesol.com

http://www.8051.com

www.wikipedia.org

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http://www.alldatasheet.co.kr/datasheetpdf/

www.embeddedrelated.com

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GSM BASED SMS DRIVEN AUTOMATIC DISPLAY TOOL KIT