Cellphone Operated Robotcv_2v

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CELLPHONE OPERATED ROBOT

A Project Report

Submitted by

B.VINOD KUMAR (2210409106)

G.PRATAP VAMSI (2210409143)

ELECTRONICS AND COMMUNICATIONengineering

DEPARTMENT

GITAM UNIVERSITY.

At

ECIL-ECIT

(Electronic Corporation of India Limited)

Under the esteemed guidance of

Mr.P.B.RAMAKRISNA (SDGM, CED)


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DECLARATION

I hereby declare that the project entitled CELLPHONE OPERATED

ROBOT submitted for the ELECTRONICS AND COMMUNICATION DEPARTMENT.

This dissertation is our original work and the project has not formed the basis for the award

of any degree, associate ship, fellowship or any other similar titles and no part of it has been

published or sent for publication at the time of submission.

By

B.VINOD KUMAR (2210409106)

G.PRATAP VAMSI (2210409143)


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ECIL was setup under the Department of Atomic Energy on 11th April, 1967 with a

view to generate a strong indigenous capability in the field of professional grade electronics.

The initial accent was on total self-reliance and ECIL was engaged in the design

development, Manufacture and Marketing of several products with emphasis on three

technology lines viz. Computers, Control Systems and Communications. Over the years,

ECIL pioneered the development of various complex electronics products without any

external technology help and scored several firsts in this fields prominent among them

being countrys

First Digital Computer

First Solid State TV

First Control & Instrumentation of Nuclear Power Plants

First Earth Station Antenna

First Computerized Operator Information System

First radiation Monitoring & Detection System

First Automatic Message Switching System

First Operation & Maintenance Center for E-108 Exchange

First Programmable Logic Controller

First Solid state Cockpit Voice Recorder

First Electronics Voting Machines


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The company played a very significant role in the training and growth of high caliber

technical and managerial man power especially in the fields of Computer and Information

Technology. Though the initial thrust was on meeting the Control & Instrumentation

requirements of the Nuclear Power Program, the expand scope of self-reliance pursued by

ECIL enabled the company to develop various products to cater to the needs of Defense,

Civil Aviation, Information & Broadcasting, Telecommunications, Insurance, banking, Police

and Para-Military Forces, Oil & Gas, Power, Space Education, Health, Agriculture Steel and

Coal Sectors and various user departments in the Government domain. ECIL thus evolved as

multi-product company serving multiple sectors of Indian economy with emphasis on import

of country substitution and development of products & services that are of economic and

strategic significance to the country.

Established: 1967

Location: Hyderabad, India

In addition to its primary focus on chosen areas like Strategic Electronics and IT, the

Company took upon itself certain areas with a view to sub serve certain obligations of

enterprises. Mostly, they are confined to the societal and rural sectors focusing on the health

care, education, agriculture and such related areas.


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ABSTRACT

Most of Artificial Intelligence will eventually lead to robotics. Most neural

networking, natural language processing, image recognition, speech recognition/synthesis

research aims at eventually incorporating their technology into the epitome of robotics the

creation of a fully humanoid robot.

The field of robotics has been around nearly as long as Artificial Intelligencebut the

field has made little progress. This is only natural, since the field not only attempts to conquer

intelligence, but also the body that embodies it a formidable task. Robotics, though, is not

just about humanoid robots; but also about their commercial applications in manufacturing,

safety and hundreds of other fields.

It is only relatively recently that robots have started to employ a degree of Artificial

Intelligence in their work many robots required human operators, or precise guidance

throughout their missions. Slowly, robots are becoming more and more autonomous.

Robotics is an absolutely fascinating field that interests most people. Robot is a system that

contains sensors, control systems, manipulators, power supplies and software all working

together to perform a task. Robot should have Sensing, Movement, Energy and Intelligence

characteristics.

This project deals with one of the application of robotics. In this project one moving

object is developed such that it is moved as per commands given by master through Mobile

phone and that command is received by mobile phone which is placed on the robot and give

information to the DTMF IC which is connected to the microcontroller.


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This project is equipped with DC motor GSM mobile phone, DTMF IC, Micro

controller along with the Power supply unit. Robot finds it applications in the real time in

Defense applications, Satellite system, Flight tracking system, car race and Cerebella control.

TOPICS INDEX

1. INTRODUCTION

1.1. How to build Cell phone Operated Robot

1.2. Block Diagram

2. INTRODUCTION TO MICROCONTROLLER

2.1. Major features of Microcontrollers

2.1.1. Why AT89S52?

2.2. AT89S52 Microcontroller Architecture

2.3. Pin Description

2.3.1. AT89S52 Oscillator and Clock

2.4. Special Function Registers

2.4.1. SFR Types

2.4.2. SFR Descriptions

2.5. Conclusion

3. LIQUID CRYSTAL DISPLAY

3.1. Specifications of LCD

3.1.1.16*2 Alphanumeric LCD module features

3.2. Types of LCDs

3.3. Interfacing LCD to 8051 Microcontroller

3.4. Schematic Diagram of LCD

3.5. Circuit Description

4. INTRODUCTION TO EMBEDDED SYSTEMS

4.1. Introduction

4.1.1. Definition of Embedded system


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4.1.2. Features of Embedded system

4.1.3. Characteristics of Embedded system

4.1.4. Overview of Embedded system Architecture

4.1.5. Applications of Embedded system

4.2. Types of Embedded system

4.2.1. Standalone Embedded system

4.2.2. Networked information appliances

4.2.3. Mobile devices

4.3. Programming Language

5. HARDWARE DESCRIPTION

5.1. Schematic Block diagram

5.2. DTMF (Dual Tone Multi frequency)

5.2.1. Introduction

5.2.2. HT917D/B features

5.2.3. Pin Description

5.2.4. Circuit Diagram

5.3. Motor Driver (L293D)

5.3.2. Pin Description

5.3.3. Circuit description

5.4. DC Motor

6. REGULATED POWER SUPPLY

6.1.1. Transformer

6.1.2. Rectifier

6.1.3. Filter

6.1.4. Regulator

7. KEIL SOFTWARE

7.1. Introduction

7.1.1. Keil Software Program Procedure


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8. FUTURE SCOPE

9. CONCLUSION

10. REFERENCES

FIGURES INDEX

2.1. Functional Block Diagram of AT89S52

2.2. Pin Diagram of AT89S52

2.3. Oscillator & Timing Circuit

2.4. Special Function Register Address Range

2.5.16-bit Registers

2.6. Special Function Registers

2.6.1. PCON Register

2.6.2. TCON Register

2.6.3. TMOD Register

2.6.4. SCON Register

2.6.5. IE Register

2.6.6. IP Register

3.1. Interfacing LCD to 8051 Microcontroller

3.2. Schematic Diagram of LCD

3.3.2*16 Character LCD with Backlighting

3.4. Typical pin out on a display with 1*16 pin connector

3.5. Circuit Diagram of LCD

4.1. Overview of an embedded system Architecture

4.2. Basic form of ALP

5.1. Schematic Block Diagram

5.2. General Block Diagram

5.3. Pin Diagram of HT9170D/B

5.4. Circuit diagram of HT9170d/B


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5.5. Pin Diagram of L293D

5.6. Robot Directions

5.7. Circuit Diagram of L293D

5.8. Figure of DC motor

6.1. Circuit Diagram of Power Supply

6.2. Electrical Transformer

6.3. Bridge Rectifier Circuit

6.4. Positive half cycle operation

6.5. Negative half cycle operation

6.6. Three Terminal Voltage Regulator 78xx

TABLE INDEX

2.1. Port pins and their alternate functions

2.2. SFRs

2.2.1. TCON Register

2.2.2. TMOD Register

2.2.3. SCON Register

3.1. Pin Description of LCD

5.1. Pin Description of HT9170D/B

5.2. Pin Description of L293D


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1. INTRODUCTION

In this project the robot, is controlled by a mobile phone that makescall to the mobile phone attached to the robot in the course of the call, ifany button is pressed control corresponding to the button pressed isheard at the other end of the call. This tone is called dual tone multi

frequency tone (DTMF) robot receives this DTMF tone with the help ofphone stacked in the robot

The received tone is processed by the atmega16 microcontrollerwith the help of DTMF decoder MT8870 the decoder decodes the DTMFtone in to its equivalent binary digit and this binary number is send to themicrocontroller, the microcontroller is preprogrammed to take a decisionfor any give input and outputs its decision to motor drivers in order todrive the motors for forward or backward motion or a turn.

The mobile that makes a call to the mobile phone stacked in therobot acts as a remote. So this simple robotic project does not require theconstruction of receiver and transmitter units.

DTMF signaling is used for telephone signaling over the line in the voicefrequency band to the call switching center. The version of DTMF used fortelephone dialing is known as touch tone.

DTMF assigns a specific frequency (consisting of two separate tones) toeach key s that it can easily be identified by the electronic circuit. Thesignal generated by the DTMF encoder is the direct al-gebric submission,in real time of the amplitudes of two sine (cosine) waves of differentfrequencies, i.e. ,pressing 5 will send a tone made by adding 1336hz and770hz to the other end of the mobile.


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1.1.How to build cell phone operated Robot ?

Robot, is controlled by a mobile phone that makes call to the mobile phone attachedto the robot in the course of the call, if any button is pressed control corresponding to thebutton pressed is heard at the other end of the call. This tone is called dual tone multifrequency tome (DTMF) robot receives this DTMF tone with the help of phone stacked in therobot,The received tone is processed by the Arduino with the help of DTMF decoder HT7190D thedecoder decodes the DTMF tone in to its equivalent binary digit and this binary number is

send to the Arduino, the Arduino is preprogrammed to take a decision for any give input andoutputs its decision to motor drivers in order to drive the motors for forward or backwardmotion or a turn.

The mobile that makes a call to the mobile phone stacked in the robot acts as aremote. So you do not require the construction of receiver and transmitter units.DTMF signaling is used for telephone signaling over the line in the voice frequency band tothe call switching center. The version of DTMF used for telephone dialing isknown as touch tone.

DTMF assigns a specific frequency to each keys that it can easily be identified by theelectronic circuit. The signal generated by the DTMF encoder is the direct al-gebricsubmission, in real time of the amplitudes of two sine waves of different frequencies, i.e.,

pressing 5 will send a tone made by adding 1336 Hz and 770 Hz to the other end of themobile.

This output is connected to the second port of the Microcontroller. With the help of port3

special function pins, to which motor driver L293D is connected will drive the motors andmove the Robot in indicated direction.


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1.2. BLOCKDIAGRAM

Power Supply:

The power supply unit is used to provide a constant 5V supply to different ICs this is

a standard circuits using external 12VDC adapter and fixed 3-pin voltage regulator. Diode is

added in series to avoid Reverse voltage.

Micro controller:

The 89C51 is a low cost Micro controller from either ATMEL or PHILIPS. It has a

40-pin configuration and other components are interfaced to its ports. The entire functionality

of the CLIP device is under the control of Micro controller. The Micro controller takes input

from the external sources and routes them to the appropriate devices as programmed in it to

Controls the direction of the robot.

GSM:

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

that is widely used in Europe and other parts of the world. GSM uses a variation of time

division multiple access (TDMA) and is the most widely used of the three digital wireless

telephone technologies (TDMA, GSM, and CDMA). GSM digitizes and compresses data,

then sends it down a channel with two other streams of user data, each in its own time slot. It

operates at either the 900 MHz or 1800 MHz frequency band.

DTMF transceiver:

The MT8888C/C-1 is a monolithic DTMF transceiver with call progress filter. The

transceiver consists of transmitter and receiver. The DTMF signals are transmitted through


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transmitter over the telephone lines and can be received and decoded using a DTMF

receiver/decoder ICs.

Motors:

By far the vast majority of robots use electric motors, of which there are several kinds.

DC motors, which are familiar to many people, spin rapidly when electric current is passed

through them. They will spin backwards if the current is made to flow in the opposite

direction.


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Introduction to Microcontroller 89S52:

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

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

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

to a single silicon chip.

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

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

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

design.

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

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

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

Criteria for Choosing Microcontroller:

The first and foremost criterion for choosing a Microcontroller is that if

Microcontroller based project we must first see whether an 8-bit, 16-bit or 32-bit.

Microcontroller can best handle the computing needs of the task most effectively.

Among other consideration in this category are:

Cost: The cost of the part, Microcontrollers are usually very cheap, sometimes evenless than $1 each.

Speed: The frequency clock often stated in megahertz or gigahertz. Microcontrollersare typically slow, less than 20MHz.

Bits: This usually means the number of bits that can be processed at one time by eachinstruction. Microcontrollers are almost always 8 bit or maybe 16 bit devices.


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The second criterion in choosing a Microcontroller is how easy it is to develop

products around it. Key considerations include the availability of an assembler, debugger, a

code efficient C language complier, emulator, technical support and both in hose and outside

expertise.

The third criterion in choosing Microcontrollers is its ready availability in needed

qualities both now and in future. For some designers this is even more important that first two

criteria. Currently, of leading 8 bit Microcontrollers, the MS-51 family has the largest number

of diversified suppliers. By Suppliers meant a producer besides the originator of

Microcontroller in the case of the MS- 51, which was originator by INTEL; several

companies are also currently producing the MS-51: INTEL, ATMEL

.

2.1. THE MAJOR FEATURES OF MICRO CONTROLLER:

Compatible with MCS-51 Products 8K Bytes of In-System Programmable (ISP) Flash Memory Endurance: 10,000 Write/Erase Cycles 4.0V to 5.5V Operating Range Fully Static Operation: 0 Hz to 33 MHz Three-level Program Memory Lock 256 x 8-bit Internal RAM 32 Programmable I/O Lines Three 16-bit Timer/Counters Eight Interrupt Sources Full Duplex UART Serial Channel Low-power Idle and Power-down Modes

Interrupt Recovery from Power-down Mode


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Fast Programming Time Flexible ISP Programming (Byte and Page Mode)

2.1.1 Why AT89S52?

The system requirements and control specifications clearly rule out the use of 16, 32

or 64 bit micro controllers or microprocessors. Systems using these may be earlier to

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

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

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

Coming to the question of why to use AT89S52 of all the 8-bit microcontroller

available in the market the main answer would be because it has 4 Kb on chip flash memory

which is just sufficient for our application. The on-chip Flash ROM allows the program

memory to be reprogrammed in system or by conventional non-volatile memory

Programmer. Moreover ATMEL is the leader in flash technology in todays market place and

hence using AT 89S52 is the optimal solutio

2.2 AT89S52 MICRO CONTROLLER ARCHITECHTURE:


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The 89S52 architecture consists of these specific features:

FIGURE 2.1 FUNCTIONAL BLOCK DIAGRAM OF AT89S52

2.3 PIN DESCRIPTION:


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FIGURE 2.2: PIN DIAGRAM OF AT89S52

VCC: Supply voltage. GND: Ground. Port 0:

Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin cansink eight TTL inputs. When ones are written to port 0 pins, the pins can be used as high

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

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

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

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

Port 1:


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

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

high by the internal pull-ups and can be used as inputs. Port 1 also receives the low-order

address bytes during Flash programming and verification.

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

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

high by the internal pull-ups and can be used as inputs. Port 2 also receives the high-order

address bits and some control signals during Flash programming and verification.

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

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

the internal pull-ups and can be used as inputs. Port 3 also receives some control signals for

Flash programming and verification

Port 3 also serves the functions of various special features of the AT89S52.as listed below

TABLE 2.1: PORT3 PINS AND THEIR ALTERNATE FUNCTIONS

RST(Reset):A high on this pin for two machine cycles while the oscillator is running resets the

device.


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ALE/PROG:Address Latch Enable output pulse for latching the low byte of the address during

accesses to external memory. This pin is also the program pulse input (PROG) during Flash

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

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

ALE pulse is skipped during each access to external Data Memory.

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

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

AT89S52 is executing code from external program memory, PSEN is activated twice eachmachine 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, for parts

that require 12-volt VPP.

XTAL1:Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2:It is the Output from the inverting oscillator amplifier.

2.3.1 AT89S52 Oscillator and Clock:


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The heart of the 89S52 circuitry that generates the clock pulses by which all internal

operations are synchronized. Pins XTAL1 and XTAL2 is provided for connecting a resonant

network to form an oscillator. Typically a quartz crystal and capacitors are employed. The

crystal frequency is the basic internal clock frequency of the microcontroller. The

manufacturers make 89S52 designs that run at specific minimum and maximum frequencies

typically 1 to 16 MHzs

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

can be configured for use as an on-chip oscillator. Either a quartz crystal or ceramic resonator

may be used. To drive the device from an external clock source, XTAL2 should be left

unconnected while XTAL1 is driven.

.

FIGURE 2.3: OSILLATOR AND TIMING CIRCUIT

2.4 SPECIAL FUNCTION REGISTERS:


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The 8051 is a flexible microcontroller with a relatively large number of modes of

operations. Your program may inspect and/or change the operating mode of the 8051 by

manipulating the values of the 8051's Special Function Registers (SFRs).

SFRs are accessed as if they were normal Internal RAM. The only difference is that

Internal RAM is from address 00h through 7Fh whereas SFR registers exist in the address

range

of 80h through FFh.Each SFR has an address (80h through FFh) and a name. The followingchart provides a graphical presentation of the 8051's SFRs, their names, and their address.

FIG 2.4: SPECIAL FUNCTION REGISTERS ADDRESS RANGE

As you can see, although the address range of 80h through FFh offers 128 possible

addresses, there are only 21 SFRs in a standard 8051. All other addresses in the SFR range

(80h through FFh) are considered invalid. Writing to or reading from these registers may

produce undefined values or behaviour.


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Programming Tip: It is recommended that you not read or write to SFR addresses that have

not been assigned to an SFR. Doing so may provoke undefined behaviour and may cause

your program to be incompatible with other 8051-derivatives that use the given SFR for some

other purpose.

2.4.1. SFR Types:

As mentioned in the chart itself, the SFRs that have a blue background are SFRs

related to the I/O ports. The 8051 has four I/O ports of 8 bits, for a total of 32 I/O lines.

Whether a given I/O line is high or low and the value read from the line are controlled by the

SFRs in green. The SFRs with yellow background are SFRs which in some way control the

operation or the configuration of some aspect of the 8051. For example, TCON controls the

timers, SCON controls the serial port.

The remaining SFRs, with green backgrounds, are "other SFRs." These SFRs can

be thought of as auxiliary SFRs in the sense that they don't directly configure the 8051 but

obviously the 8051 cannot operate without them. For example, once the serial port has been

configured using SCON, the program may read or write to the serial port using the SBUF

register.

Programming Tip: The SFRs whose names appear in red in the chart above are SFRs that

may be accessed via bit operations (i.e., using the SETB and CLR instructions). The other

SFRs cannot be accessed using bit operations. As you can see, all SFRs that whose addresses

are divisible by 8 can be accessed with bit operations.

2.4.2. SFR Descriptions:

This section will endeavour to quickly overview each of the standard SFRs found in

the above SFR chart map. It is not the intention of this section to fully explain thefunctionality of each SFR--this information will be covered in separate chapters of the

tutorial. This section is to just give you a general idea of what each SFR does.

P0 (Port 0, Address 80h, Bit-Addressable): This is input/output port 0. Each bit of this SFR

corresponds to one of the pins on the microcontroller. For example, bit 0 of port 0 is pin P0.0,


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bit 7 is pin P0.7. Writing a value of 1 to a bit of this SFR will send a high level on the

corresponding I/O pin whereas a value of 0 will bring it to a low level.

Programming Tip: While the 8051 has four I/O port (P0, P1, P2, and P3), if your hardware

uses external RAM or external code memory (i.e., your program is stored in an external ROMor EPROM chip or if you are using external RAM chips) you may not use P0 or P2. This is

because the 8051 uses ports P0 and P2 to address the external memory. Thus if you are using

external RAM or code memory you may only use ports P1 and P3 for your own use.

SP (Stack Pointer, Address 81h): This is the stack pointer of the microcontroller. This SFR

indicates where the next value to be taken from the stack will be read from in Internal RAM.

If you push a value onto the stack, the value will be written to the address of SP + 1. That is

to say, if SP holds the value 07h, a PUSH instruction will push the value onto the stack at

address 08h. This SFR is modified by all instructions which modify the stack, such as PUSH,

POP, and LCALL, RET, RETI, and whenever interrupts are provoked by the microcontroller.

Programming Tip: The SP SFR, on start-up, is initialized to 07h. This means the stack will

start at 08h and start expanding upward in internal RAM. Since alternate register banks 1, 2,

and 3 as well as the user bit variables occupy internal RAM from addresses 08h through 2Fh,

it is necessary to initialize SP in your program to some other value if you will be using the

alternate register banks and/or bit memory. It's not a bad idea to initialize SP to 2Fh as the

first instruction of every one of your programs unless you are 100% sure you will not be

using the register banks and bit variables.

DPL/DPH (Data Pointer Low/High, Addresses 82h/83h): The SFRs DPL and DPH work

together to represent a 16-bit value called the Data Pointer. The data pointer is used in

operations regarding external RAM and some instructions involving code memory. Since it is

an unsigned two-byte integer value, it can represent values from 0000h to FFFFh (0 through

65,535 decimal).

Programming Tip: DPTR is really DPH and DPL taken together as a 16-bit value. In reality,

you almost always have to deal with DPTR one byte at a time. For example, to push DPTR

onto the stack you must first push DPL and then DPH. You can't simply plush DPTR onto the

stack. Additionally, there is an instruction to "increment DPTR." When you execute this

instruction, the two bytes are operated upon as a 16-bit value. However, there is no


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instruction those decrements DPTR. If you wish to decrement the value of DPTR, you must

write your own code to do so.

DPL

DPH

DPTR

PC

PC (Program counter)

FIG 2.5: 16BIT REGISTERS


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PCON (Power Control, Addresses 87h): The Power Control SFR is used to control the

8051's power control modes. Certain operation modes of the 8051 allow the 8051 to go into a

type of "sleep" mode which requires much less power. These modes of operation are

controlled through PCON. Additionally, one of the bits in PCON is used to double the

effective baud rate of the 8051's serial port.

SMOD ------- -------- -------- GF1 GF0 PD IDL

FIG: 2.6.1. PCON REGISTER

TCON (Timer Control, Addresses 88h, Bit-Addressable): The Timer Control SFR is used

to configure and modify the way in which the 8051's two timers operate. This SFR controls

whether each of the two timers is running or stopped and contains a flag to indicate that each

timer has overflowed. Additionally, some non-timer related bits are located in the TCON

SFR. These bits are used to configure the way in which the external interrupts are activated

and also contain the external interrupt flags which are set when an external interrupt has

occurred.

Bit Addressable

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

FIG: 2.6.2. TCON REGISTER

The lower 4 bits

Are set aside for

Controlling the

Interrupts

Interrupt bits.

The upper four

Bits are used to

Store the TF and TR bits of both Timer 0 and 1.


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TF1 Timer1 overflow flag. Set by hardware when the Timer/Counter 1

overflows. Cleared by hardware as processor vectors to the interrupt service

routine.

TR1 Timer 1 run control bit. Set/cleared by software to turn Timer/Counter 1

ON/OFF.

TF0 Timer0 overflow flag. Set by hardware when the Timer/Counter 0

overflows. Cleared by hardware as processor vectors to the service routine

TR0 Timer 0 run control bit. Set/cleared by software to turn Timer/Counter 0

ON/OFF.

IE1 External Interrupt 1 edge flag. Set by hardware when External interrupt

edge is detected. Cleared by hardware when interrupt is processed.

IT1 Interrupt 1 type control bit. Set/cleared by software to specify falling

edge/low level triggered External Interrupt.

IE0 External Interrupt 0 edge flag. Set by hardware when External Interrupt

edge is detected. Cleared by hardware when interrupt is processed.

IT0 Interrupt 0-type control bit. Set/cleared by software to specify falling

edge/low level triggered External Interrupt.

TABLE: 2.2.1.TCON REGISTER


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TMOD (Timer Mode, Addresses 89h): The Timer Mode SFR is used to configure the mode

of operation of each of the two timers. Using this SFR your program may configure each

timer to be a 16-bit timer, an 8-bit auto-reload timer, a 13-bit timer, or two separate timers.

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

to count "events" that are indicated on an external pin.

Not Bit Addressable.

GATE C/T M1 M0 GATE C/T M1 M0

Timer 1 Timer 0

FIG: 2.6.3. TMOD REGISTER

GATE When TRx (in TCON) is set and GATE=1, Timer/Counter will run only while

INTx pin is high (hardware control). When GATE=0, Timer/Counter will run

only while TRx=1 (software control).

C/T Timer or Counter selector. Cleared for Timer operation (input from internal

system clock). Set for Counter operation (input from TX input pin).

M1 Mode selector bit.

M0 Mode selector bit.

TABLE: 2.2.2.TMOD REGISTER

M1 M0 Mode Operating Mode0 0 0 13-bit Timer

(8048 compatible) (TH1).

0 1 1 16-bit Timer/Counter.

1 0 2 8-bit Auto-Reload Timer/Counter (TL1).Reloaded from TH1 at

overflow.

1 1 3 timer 1 halted. Retains count.


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1 1 3 (Timer 1) Timer/Counter 1 stopped.

TL0/TH0 (Timer 0 Low/High, Addresses 8Ah/8Ch): These two SFRs, taken together,

represent timer 0. Their exact behaviour depends on how the timer is configured in the

TMOD SFR; however, these timers always count up. What is configurable is how and when

they increment in value.

TL1/TH1 (Timer 1 Low/High, Addresses 8Bh/8Dh): These two SFRs, taken together,

represent timer 1. Their exact behaviour depends on how the timer is configured in the

TMOD SFR; however, these timers always count up. What is configurable is how and when

they increment in value.

P1 (Port 1, Address 90h, and Bit-Addressable): This is input/output port 1. Each bit of this

SFR corresponds to one of the pins on the microcontroller. For example, bit 0 of port 1 is pin

P1.0, bit 7 is pin P1.7. Writing a value of 1 to a bit of this SFR will send a high level on the


SCON (Serial Control, Addresses 98h, Bit-Addressable):

The Serial Control SFR is used to configure the behaviour of the 8051's on-board serial port.

This SFR controls the baud rate of the serial port, whether the serial port is activated to

receive data, and also contains flags that are set when a byte is successfully sent or received.

Programming Tip:

To use the 8051's on-board serial port, it is generally necessary to initialize the following

SFRs: SCON, TCON, and TMOD. This is because SCON controls the serial port. However,

in most cases the program will wish to use one of the timers to establish the serial port's baud

rate. In this case, it is necessary to configure timer 1 by initializing TCON and TMOD.

SM0 SM1 SM2 REN TB8 RB8 TI RI


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FIG: 2.6.4.SCON REGISTER

Bit Name Bit Address Explanation of function

7 SM0 9FH Serial port mode bit 0.

6 SM1 9EH Serial port mode bit 1.

5 SM2 9DH Multiprocessor communications Enable (explained later).

4 REN9CH

Receiver Enable. This bit must be set in order to receive

characters.

3 TB8 9BH Transmit bit 8. The 9th bit to transmit in mode 2 and 3.

2 RB8 9AH Receive bit 8. The 9th bit received in mode 2 and 3.

1 TI 99H Transmit flag. Set when a byte has been completelytransmitted.

0 RI 98H Receive flag. Set when a byte has been completely received.

TABLE 2.2.3: SCON REGISTER

Mode0: transmitted/received (LSB first). The baud rate is fixed at 1/12 the oscillator

frequency.

Mode 1: 10 bits are transmitted (through TxD) or received (through RxD): a start bit (0), 8

data bits (LSB first), and a stop bit (1). On receive; the stop bit goes into RB8 in Special

Function Register SCON. The baud rate is variable.

Mode 2: 11 bits are transmitted (through TxD) or received (through RxD): start bit (0), 8 data

bits (LSB first), a programmable 9th data bit, and a stop bit (1). On Transmit, the 9th data bit

(TB8 in SCON) can be assigned the value of 0 or 1. Or, for example, the parity bit (P, in the

PSW) could be moved into TB8. On receive; the 9th data bit goes into RB8 in Special

Function Register SCON, while the stop bit is ignored. The baud rate is programmable to

either 1/32 or 1/64 the oscillator frequency.

Mode 3: 11 bits are transmitted (through TxD) or received (through RxD): a start bit (0), 8

data bits (LSB first), a programmable 9th data bit, and a stop bit (1). In fact, Mode 3 is the

same as Mode 2 in all respects except baud rate. The baud rate in Mode 3 is variable. In all

four modes, transmission is initiated by any instruction that uses SBUF as a destination


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register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. Reception is

initiated in the other modes by the incoming start bit if REN = 1.

SM2:

Enables the multiprocessor communication feature in Modes 2 and 3. In Mode 2 or 3, if SM2

is set to 1, then Rl will not be activated if the received 9th data bit (RB8) is 0. In Mode 1, if

SM2=1 then RI will not be activated if a valid stop bit was not received. In Mode 0, SM2

should be 0.

REN: Enables serial reception. Set by software to enable reception. Clear by software to

disable reception.

TB8: The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as

desired.

RB8: In Modes 2 and 3, is the 9th data bit that was received. In Mode 1, it SM2=0, RB8 is

the stop bit that was received. In Mode 0, RB8 is not used.

TI (Transmit Interrupt): This is an extremely important flag bit in the SCON register.

When the 8051 finishes the transfer of the 8-bit character it raises the TI flag to indicate that

it is ready to transfer another byte. The TI bit is raised at the beginning of the stop bit.

RI (Receive Interrupt): This is an extremely important flag bit in the SCON register. When

the 8051 receives data serially via RxD, it gets rid of the start and stop bits and places the

byte in the SBUF register. Then it raises the RI flag bit to indicate that a byte has been

received and could be picked up before it is lost.

SBUF (Serial Control, Addresses 99h): The Serial Buffer SFR is used to send and receive

data via the on-board serial port. Any value written to SBUF will be sent out the serial port's

TXD pin. Likewise, any value which the 8051 receives via the serial port's RXD pin will be

delivered to the user program via SBUF. In other words, SBUF serves as the output port

when written to and as an input port when read from.

P2 (Port 2, Address A0h, Bit-Addressable): This is input/output port 2. Each bit of this





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Programming Tip: While the 8051 has four I/O port (P0, P1, P2, and P3), if your hardware

uses external RAM or external code memory (i.e., your program is stored in an external ROM

or EPROM chip or if you are using external RAM chips) you may not use P0 or P2. This is

because the 8051 uses ports P0 and P2 to address the external memory. Thus if you are using

external RAM or code memory you may only use ports P1 and P3 for your own use.

IE (Interrupt Enable, Addresses A8h): The Interrupt Enable SFR is used to enable and

disable specific interrupts. The low 7 bits of the SFR are used to enable/disable the specific

interrupts, where as the highest bit is used to enable or disable ALL interrupts. Thus, if the

high bit of IE is 0 all interrupts are disabled regardless of whether an individual interrupt is

enabled by setting a lower bit.

EA ---------- ET2 ES ET1 EX1 ET0 EX0

FIG: 2.6.5.IE REGISTER

P3 (Port 3, Address B0h, Bit-Addressable): This is input/output port 3. Each bit of this




IP (Interrupt Priority, Addresses B8h, Bit-Addressable): The Interrupt Priority SFR is

used to specify the relative priority of each interrupt. On the 8051, an interrupt may either be

of low (0) priority or high (1) priority. An interrupt may only interrupt interrupts of lower

priority. For example, if we configure the 8051 so that all interrupts are of low priority except

the serial interrupt, the serial interrupt will always be able to interrupt the system, even if

another interrupt is currently executing. However, if a serial interrupt is executing no other

interrupt will be able to interrupt the serial interrupt routine since the serial interrupt routine

has the highest priority.

--------- -------- PT2 PS PT1 PX1 PT0 PX0


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FIG: 2.6.6.IP REGISTER

ACC (Accumulator, Addresses E0h, Bit-Addressable): The Accumulator is one of the

most-used SFRs on the 8051 since it is involved in so many instructions. The Accumulator

resides as an SFR at E0h, which means the instruction MOV A,#20h is really the same as

MOV E0h,#20h. However, it is a good idea to use the first method since it only requires two

bytes whereas the second option requires three bytes.

B (B Register, Addresses F0h, Bit-Addressable): The "B" register is used in two

instructions: the multiply and divide operations. The B register is also commonly used by

programmers as an auxiliary register to temporarily store values.

PSW (Program Status Word, Addresses D0h, Bit-Addressable): The Program Status

Word is used to store a number of important bits that are set and cleared by 8051 instructions.

The PSW SFR contains the carry flag, the auxiliary carry flag, the overflow flag, and the

parity flag. Additionally, the PSW register contains the register bank select flags which are

used to select which of the "R" register banks are currently selected.

Programming Tip: If you write an interrupt handler routine, it is a very good idea to always

save the PSW SFR on the stack and restore it when your interrupt is complete. Many 8051

instructions modify the bits of PSW. If your interrupt routine does not guarantee that PSW is

the same upon exit as it was upon entry, your program is bound to behave rather erradically

and unpredictably--and it will be tricky to debug since the behavior will tend not to make any

sense

PSW register, also referred to as the flag register, is an 8 bit register Only 6 bits are used

These four are CY (carry), AC (auxiliary carry), P (parity), and OV (overflow)

They are called conditional flags, meaning that they indicate some conditions that resultedafter an instruction was executed. The PSW3 and PSW4 are designed as RS0 and RS1, and

are used to change the bank. The two unused bits are user-definable

CY AC F0 RS1 RS0 OV -- P


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CY PSW.7 Carry flag

AC PSW.6 Auxiliary carry flag.

F0 PSW.5 Available to the user for general purpose.

RS1 PSW.4 Register bank selector bit1.

RS0 PSW.3 Register bank selector bit0.

OV PSW.2 Overflow flag.

-- PSW.1 User definable bit.

P PSW.0 Parity flag. Set/cleared by hardware each instruction

Cycle to indicate an odd/even number of 1 bit in the

accumulator.

2.5. CONCLUSION:

A highly integrated chip that contains all the components comprising a controller. Typically

this includes a CPU, RAM, some form of ROM, I/O ports, and timers.

Unlike a general-purpose computer, which also includes all of these components, a microcontroller is

designed for a very specific task -- to control a particular system.

As a result, the parts can be simplified and reduced, which cuts down on production costs.

Microcontrollers are sometimes called embedded microcontrollers, which just mean that they are part

of an embedded system -- that is, one part of a larger device or system.

The 8051 is a flexible microcontroller with a relatively large number of modes of operations. Yourprogram may inspect and/or change the operating mode of the 8051 by manipulating the values of the

8051's Special Function Registers (SFRs).

SFRs are accessed as if they were normal Internal RAM. The only difference is that Internal RAM is

from address 00h through 7Fh whereas SFR registers exist in the address range of 80h through FFh.


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LCD a type of display used indigitalwatches and manyportable computers. LCD

displays utilize two sheets of polarizing material with a liquid crystal solution between them.

An electric current passed through the liquid causes the crystals to align so that light cannot

pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass

through or blocking the light. Monochrome LCD images usually appear as blue or dark gray

images on top of a grayish-white background. Color LCD displays use two basic techniques

for producing

color: Passive matrix is the less expensive of the two technologies.

The other technology, called thin film transistor(TFT) or active-matrix, produces

color images that are as sharp as traditional CRT displays, but the technology is expensive.

Recent passive-matrix displays using new CSTN and DSTN technologies produce

sharp colors rivaling active-matrix displays. Most LCD screens used innotebook

computersare backlit, or transmissive, to make them easier to read. In our project we 16*2

character type of LCD.

3.1. SPECIFICATION OF LCD:

Important factors to consider when evaluating an LCD:

Resolution versus range: Fundamentally resolution is the granularity (or number of levels)

with which a performance feature of the display is divided. Resolution is often confused with

range or the total end-to-end output of the display. Each of the major features of a display has

both a resolution and a range that are tied to each other but very different. Frequently the

range is an inherent limitation of the display while the resolution is a function of theelectronics that make the display work.

Spatial performance: LCDs come in only one size for a variety of applications and a variety

of resolutions within each of those applications. LCD spatial performance is also sometimes

described in terms of a "dot pitch". The size (or spatial range) of an LCD is always described

in terms of the diagonal distance from one corner to its opposite. This is an historical remnant

from the early days of CRT television when CRT screens were manufactured on the bottoms

of glass bottles, a direct extension of cathode ray tubes used in oscilloscopes. The diameter of

the bottle determined the size of the screen. Later, when televisions went to a squarer format,

the square screens were measured diagonally to compare with the older round screens.
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Temporal/timing performance: Contrary to spatial performance, temporal performance is a

feature where smaller is better. Specifically, the range is the pixel response time of an LCD,

or how quickly you can change a sub-pixel's brightness from one level to another. For LCD

monitors, this is measured in btb (black to black) or gtg (gray to gray). These different types

of measurements make comparison difficult. Further, this number is almost never published

in sales advertising.

Color performance: There are many terms to describe color performance of an LCD. They

includecolor gamutwhich is the range of colors that can be displayed and color depth which

is the color resolution or the resolution or fineness with which the color range is divided.

Although color gamut can be expressed as three pairs of numbers, the XY coordinates

withincolor spaceof the reddest red, greenest green, and bluest blue, it is usually expressedas a ratio of the total area within color space that a display can show relative to some standard

such as saying that a display was "120% of NTSC". NTSC is the National Television

Standards Committee, the old standard definition TV specification. Color gamut is a

relatively straight forward feature. However with clever optical techniques that are based on

the way humans see color, termed color stretch, colors can be shown that are outside of the

nominal range of the display. In any case, color range is rarely discussed as a feature of the

display as LCDs are designed to match the color ranges of the content that they are intended

to show. Having a color range that exceeds the content is a useless feature.

Color depth or color support is sometimes expressed in bits, either as the number of bits per

sub-pixel or the number of bits per pixel. This can be ambiguous as an 8-bit color LCD can

be 8 total bits spread between red, green, and blue or 8 bits each for each color in a different

display. Further, LCDs sometimes use a technique calledditheringwhich is time averaging

colors to get intermediate colors such as alternating between two different colors to get a

color in between. This doubles the number of colors that can be displayed; however this is

done at the expense of the temporal performance of the display. Dithering is commonly used

on computer displays where the images are mostly static and the temporal performance is

unimportant.

Brightness and contrast ratio:Contrast ratiois the ratio of the brightness of a full-on pixel

to a full-off pixel and, as such, would be directly tied to brightness if not for the invention of

the blinking backlight (orburst dimming). The LCD itself is only a light valve, it does not

generate light; the light comes from a backlight that is either a florescent tube or a set

ofLEDs. The blinking backlight was developed to improve the motion performance of LCDs

by turning the backlight off while the liquid crystals were in transition from one image to

another. However, a side benefit of the blinking backlight was infinite contrast. The contrast

reported on most LCDs is what the LCD is qualified at, not its actual performance. In anycase, there are two large caveats to contrast ratio as a measure of LCD performance.
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3.1.1.16 x 2 Alphanumeric LCD Module Features:

Intelligent, with built-in Hitachi HD44780 compatible LCD controller and RAM providing

simple interfacing.

61 x 15.8 mm viewing area.

5 x 7 dot matrix format for 2.96 x 5.56 mm characters, plus cursor line.

Can display 224 different symbols.

Low power consumption (1 mA typical).

Powerful command set and user-produced characters.

TTL and CMOS compatible.

Connector for standard 0.1-pitch pin headers.

3.2 TYPES OF LCD DISPLAY:

There are three LCD display types: segment (or alphanumeric), dot matrix (or character) and

graphic LCD.

Segment LCD (or Alphanumeric LCD): Segment LCD can display Arabic numbersrepresented by 7 segments or Arabic numbers and Roman letters represented by 14 segments.

Symbols, such as plus/minus signs, measurement units and any custom icons, can also be

displayed. Each symbol is treated as one segment. Segment LCD is widely used on the

displays of scientific instruments. It is easy to control and most cost-effective to develop.

Segment LCD is limited to displaying numbers, Roman letters and fixed symbols. If you need

to display anything else, you have to use either the dot matrix display or graphic display.

Dot Matrix LCD (or Character LCD): Dot matrix LCD is used to display a number of lines

of characters. The most commonly used dot matrix LCD displays 1 to 4 lines of 16 to 40

characters. Each character is represented by 5x7 dots plus cursor (actually 5x8 dots including

the cursor). Each character block is addressed separately and can form numbers, Roman

letters, character in other languages and a limited number of symbols. Dot matrix LCD is

used when you need to display more characters than those in English alphabet. It is relatively

simple to control and also inexpensive than graphic models.

Graphic LCD: Graphic LCD provides users with a greater degree of flexibility. They are

composed of pixels arranged in rows and columns. Each pixel can be addressed individually

for text, graphics or any combination of the two. Graphic LCD is used in applications when

the use needs to have total control of the whole viewing area. However, flexibility also comes


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with the difficulty in designing the control circuitry. Fortunately there are special controller

chips available for this purpose.

3.3. INTERFACING LCD TO 8051MICROCONTROLLER:

To send any of the commands from given table to the LCD,make pin RS=0.For data,makeRS=1,then send a high to low pulse to the E pin to enable the internal latch of the LCD.As

shown in figure for LCD connections

P0.7

P0.6

P0.5

8051 MICRO CONTROLLER P0.4

(AT89C51ED2) P0.3

P0.2

P0.1

P0.0

P2.2

P2.1

P2.0

D7

D6

D5

D4

D3

D2

D1

D0

E

R/W

RS

HELLO WORLD


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FIG 3.1: INTERFACING LCD TO 8051MICROCONTROLLER

Pin

Number

Symbol Level I/O Function

1 Vss - - Power supply(GND)

2 Vcc - - Power supply(+5v)

3 Vee - - Contrast adjust

4 RS I/O I 0=Instruction input

1=Data input

5 R/W 0/1 I 0=write to LCD module

1=Read from LCD module

6 E 1,1->0 I Enable signal

7 DB0 0/1 I/O Data bus line 0(LSB)

8 DB1 0/1 I/O Data bus line 1







TABLE 3.1: PIN DESCRIPTION


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3.4. SCHEMATIC DIAGRAM OF LCD DISPLAY:

1 2

3

7 8 9 10 11 12 13 14 4 5 6

7 8 9 10 11 12 13 14 4 5 6

1

G +5V -5V

11

D0 D1

D2 D3 D4 D5 D6 D7 RS R\W EN


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FIG:3.2 SCHEMATIC DIAGRAM OF LCD DISPLAY:

BIT RS R/W D7 D6 D5 D4 D3 D2 D0 Function

0 0 0 0 0 0 0 0 0 1 Clear LCD and memory, home cursor

0 0 0 0 0 0 0 0 1 0 Clear and home cursor only

0 0 0 0 0 0 0 1 1/0 S Screen action as display character written

S=1/0: Shift screen/cursor

I/O=1/0: cursor R/L, screen L/R

0 0 0 0 0 0 1 D C B D=1/0: Screen on/off

C=1/0: Cursor on/off

B=1/0: Cursor blink/no blink

0 0 0 0 0 1 S/C R/L 0 0 S/C: 1/0: Screen/Cursor

R/L: Shift one space R/L

0 0 0 0 1 DL N F 0 0 DL=1/0:8/4 Bits per Character

N=1/0; 2/1 Rows of Characters

F=1/0; 5*10/5*7Dots/Character

0 0 0 1

Character address Write to character RAM address after

this

0 0 1 Display data address Write to display RAM address after this


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0 1 BF Current address BF=1/0: busy/Notbusy

1 0 Character type Write byte to last RAM chosen

1 1 Character type Read byte from last RAM chosen

FIG3.3.2X16 CHARACTER LCD WITH BACKLIGHTING.

FIG3 FIG:

3.4.TYPICAL PINOUT ON A DISPLAY WITH 1X16 PIN CONNECTOR


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3.5. CIRCUIT DESCRIPTION:

FIG 3.5: CIRCUIT DIAGRAM OF LCD

It is very important to keep a track of the working of almost all the automated andsemi-automated devices, be it a washing machine, an autonomous robot or anything else.This is achieved by displaying their status on a small display module.LCD (Liquid CrystalDisplay) screen is such a display module and a 16x2 LCD module is very commonly used.These modules are replacingseven segmentsand other multi segment LEDs for thesepurposes. The reasons being: LCDs are economical, easily programmable, have no limitationof displaying special & evencustom characters(unlike in seven segments),animationsand soon. LCD can be easily interfaced with a microcontroller to display a message or status of adevice.
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4.1.INTRODUCTION:

Each day, our lives become more dependent on 'embedded systems', digital

information technology that is embedded in our environment. More than 98% of processors

applied today are in embedded systems, and are no longer visible to the customer as

'computers' in the ordinary sense. An Embedded System is a special-purpose system in which

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

Unlike a general-purpose computer, such as a personal computer, an embedded system

performs one or a few pre-defined tasks, usually with very specific requirements. Since the

system is dedicated to specific tasks, design engineers can optimize it, reducing the size and

cost of the product. Embedded systems are often mass-produced, benefiting from economies

of scale. The increasing use of PC hardware is one of the most important developments in

high-end embedded systems in recent years. Hardware costs of high-end systems have

dropped dramatically as a result of this trend, making feasible some projects which

previously would not have been done because of the high cost of non-PC-based embedded

hardware. But software choices for the embedded PC platform are not nearly as attractive as

the hardware.

Typically, an embedded system is housed on a single microprocessor board with the

programs stored in ROM. Virtually all appliances that have a digital interface -- watches,

microwaves, VCRs, cars -- utilize embedded systems. Some embedded systems include an

operating system, but many are so specialized that the entire logic can be implemented as a

single program.

Physically, Embedded Systems range from portable devices such as digital watches

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

systems controlling nuclear power plants.

In terms of complexity embedded systems can range from very simple with a single

microcontroller chip, to very complex with multiple units, peripherals and networks mounted

inside a large chassis or enclosure.

4.1.1 Definition of an Embedded System: An Embedded system is defined

as, for a particular/specific application implementing the software code to interact directly

with that particular hardware what we built. Software is used for providing features and


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flexibility, Hardware = {Processors, ASICs, Memory...} is used for Performance (&

sometimes security).

(Or)

An embedded system is a special-purpose computer system designed to perform oneor a few dedicated functions, often with real-time computing constraints. It is usually

embedded as part of a complete device including hardware and mechanical parts. In contrast,

a general-purpose computer, such as a personal computer, can do many different tasks

depending on programming.

(Or)

An embedded system is a single-purpose computer built into a larger system for the

purposes of controlling and monitoring the system. A specialized computer system that is part

of a larger system or machine.

4.1.2 Features of an Embedded System:

The versatility of the embedded computer system lends itself to utility in all kinds of

enterprises, from the simplification of deliverable products to a reduction in costs in their

development and manufacture. Complex systems with rich functionality employ special

operating systems that take into account major characteristics of embedded systems.

Embedded operating systems have minimized footprint and may follow real-time operating

system specifics.

The special computers system is usually less powerful than general-purpose systems,

although some expectations do exist where embedded systems are very powerful and

complicated. Usually a low power consumption CPU with a limited amount of memory is

used in embedded systems. Many embedded systems use very small operating systems; most

of these provide very limited operating system capabilities.

Since the embedded system is dedicated to specific tasks, design engineers can

optimize it, reducing the size and cost of the product, or increasing the reliability and

performance. Some embedded systems are mass-produced, benefiting from economies of

scale.

Some embedded systems have to operate in extreme environment conditions such as

very high temperature & humidity.

For high volume systems such as portable music players or mobile phones,

minimizing cost is usually the primary design consideration. Engineers typically select

hardware that is just good enough to implement the necessary functions.


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For low volume or prototype embedded systems, general purpose computers may be

adapted by limiting the programs or by replacing the operating system with a real-time

operating system.

4.1.3 Characteristics of an Embedded System:

An Embedded computing systems generally exhibit rich functionality complex

functionality is usually the reason for introducing CPUs into the design. However, they also

exhibit many non-functional requirements that make the task especially challenging:

Real-time deadlines that will cause system failure if not met;

Multi-rate operation;

In many cases, low power consumption;

Low manufacturing cost, which often means limited code size.

Workstation programmers often concentrate on functionality. They may consider the

performance characteristics of a few computational kernels of their software, but rarely

analyze the total application. They almost never consider power consumption and

manufacturing cost. The need to juggle all these requirements makes embedded systemprogramming very challenging and is the reason why embedded system designers need to

understand computer architecture.

4.1.4 Overview of an Embedded System Architecture:

Every Embedded system consists of a custom-built hardware built around a central

processing unit. This hardware also contains memory chips onto which the software is

loaded.

The operating system runs above the hardware and the application software runs

above the operating system. The same architecture is applicable to any computer including

desktop computer. However these are significant differences. It is not compulsory to have an

operating system in every embedded system. For small applications such as remote control

units, air conditioners, toys etc.


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4.1.5 Applications of Embedded Systems:

Some of the most common embedded systems used in everyday life are

Small embedded controllers: 8-bit CPUs dominate, simple or no operating system

(e.g., thermostats)

Control systems: Often use DSP chip for control computations

(e.g., automotive engine control)

Distributed embedded control: Mixture of large and small nodes on a real-time

Embedded networks

(e.g., cars, elevators, factory automation)

System on chip: ASIC design tailored to application area

(e.g., consumer electronics, set-top boxes)

Network equipment: Emphasis on data movement/packet flow

(e.g., network switches; telephone switches)

Critical systems: Safety and mission critical computing

(e.g., pacemakers, automatic trains)

Signal processing: Often use DSP chips for vision, audio, or other signal

Processing (e.g., face recognition)

Robotics: Uses various types of embedded computing (especially

Vision and control) (e.g., autonomous vehicles)

Computer peripherals: Disk drives, keyboards, laser printers, etc.

Wireless systems: Wireless network-connected sensor networks and

Motes to gather and report information

Embedded PCs: Palmtop and small form factor PCs embedded into

Equipment

Command and control: Often huge military systems and systems of systems

(e.g., a fleet of warships with interconnected


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Computers)

Home Appliances, intercom, telephones, security systems, garage door openers, answering

machines, fax machines, home computers, TVs, cable TV tuner, VCR, camcorder, remote

controls, video games, cellular phones, musical instruments, sewing machines, lightingcontrol, paging, camera, pinballmachines, toys, exercise equipment

Office Telephones, computers, security systems, fax machines, microwave, copier, laser

printer, colorprinter, paging

Auto Trip computer, engine control, air bag, ABS, instrumentation, security system,

transmissioncontrol, entertainment, climate control, cellularphone, keyless entry.

4.2. TYPES OF EMBEDDED SYSTEMS:

Based on functionality and performance embedded systems categorized as 4 types

1. Stand alone embedded systems

2. Real time embedded systems

3. Networked information appliances

4. Mobile devices

4.2.1 Stand alone embedded systems:As the name implies, stand alone systems work in stand alone mode. They take i/p,

process them and produce the desire o/p. The i/p can be an electrical signal from transducer

or temperature signal or commands from human being. The o/p can be electrical signal to

drive another system an led or LCD display

Ex digital camera, microwave oven, CD player, Air conditioner etc

4.2.2 Real time embedded systems:In this type of an embedded system a specific work has to be complete in a particular

period of time.

Hard Real time systems: - embedded real time used in missiles

Soft Real time systems: - DVD players

4.2.3 Networked information appliances: Embedded systems that are

provided with n/w interfaces and accessed by n/w such as local area n/w or internet are called

Network Information Appliances.


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Ex: A web camera is connected to the internet. Camera can send pictures in real time to any

computers connected to the internet

4.2.4 Mobile devices: Actually it is a combination of both VLSI and Embedded

System. Mobile devices such as Mobile phone, Personal digital assistants, smart phones etc

are special category of embedded systems

4.3PROGRAMMING LANGUAGE USED:

BASIC FORM OF ASSEMBLY LANGUAGE PROGRAM

Now that the basic form of an assembly language program has been given, the next question

is: how it is created, assembled and made ready to run? The steps to create an executable

assembly language program are outlined as follows.

IMPLEMENTATION


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FIG4.2 BASIC FORM OF ALP

First we use an editor to type in a program similar to program. Many excellent editorsor word processors are available that can be used to create and/or edit the program. A

widely used editor is the MS-DOS EDIT program .which comes with all Microsoft

operating systems. Notice that the editor must be able to produce an ASCII file. For

many assemblers, the file names follow the usual DOS conventions, but the source

file has the extension "ASM "or "SRC ", depending on which assembler you are

using. Check your assembler for the convention. The "asm ", extension for the

source file is used by an assembler in the next step.

The "ASM "source file containing the program code is created in step 1 is fed to an8051 assembler. The assembler converts the instructions into machine code. The

assembler will produce an object file and a list file. The extension for the object file

is "OBJ "by the extension for the list file is "1ST ".


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Assemblers require a third step calling linking. The link program takes one or moreobjects files and produces an absolute object file with the extension "ABS". 8051

trainers that have a monitor program use this ABS file.

next the "ABS "file is fed into a program called "OH "(Object to Hex Converter)which creates a file with extension "HEX "that these ready to burn into ROM. This

program comes with all 8051 assemblers. Recent Windows-based assemblers

combine steps 2 through 4 into one step.

5.1.SCHEMATIC BLOCK DIAGRAM:

fig:5.1.SCHEMATIC BLOCK DIAGRAM


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5.2 DTMF(DUAL TONE MULTIPLE FREQUENCY):

5.2.1.Introduction:Dual-tone multi-frequency (DTMF) signaling is used for

telecommunication signaling over analog telephone lines in the voice-frequency band

between telephone handsets and other communications devices and the switching center.

Telephone Keypad: The contemporary keypad is laid out in a 34grid, although the original

DTMF keypad had an additional column for four now-defunct menu selector keys. When

used to dial a telephone number, pressing a single key will produce a pitch consisting of two

simultaneous pure tone sinusoidal frequencies. The row in which the key appears determines

the low frequency, and the column determines the high frequency. For example, pressing the

'1' key will result in a sound composed of both a 697 and a 1209 hertz (Hz) tone. The original

keypads had levers inside, so each button activated two contacts. The multiple tones

are the reason for calling the system multifrequency. These tones are then decoded by the

switching center to determine which key was pressed.

Fig:5.2


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General Description:

The HT9170B/D are Dual Tone Multi Frequency (DTMF) receivers integrated withdigital decoder and band split filter functions as well as power-down mode and inhibit modeoperations. Such devices use digital counting techniques to detect and decode all the 16DTMF tone pairs into a 4-bit code output.

Highly accurate switched capacitor filters are implemented to divide tone signals intolow and high group signals. A built-in dial tone rejection circuit is provided to eliminate theneed for pre-filtering.

DTMF (dual-tone multi-frequency) signals

1209 Hz 1336 Hz 1477 Hz 1633 Hz

697 Hz 1 2 3 A

770 Hz 4 5 6 B

852 Hz 7 8 9 C

941 Hz * 0 # D

5.2.2.HT9170D\B Features:

Operating voltage: 2.5V~5.5V Minimal external components No external filter is required Low standby current (on power down mode) Excellent performance Tristate data output for MCU interface 3.58MHz crystal or ceramic resonator 1633Hz can be inhibited by the INH pin HT9170B: 18-pin DIP package T9170D: 18-pin SOP package


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5.2.3.Pin Description:

HT9170B HT9170D

DIP-A SOP-A

Pin Name I/O Internal

Connection

Description

VP I OperationalAmplifier

Operational amplifier non-inverting input

VN I Operational amplifier inverting inputGS O Operational amplifier output terminal

VREEF O VREF Reference voltage output, normally VDD/2

X1 I Oscillator The system oscillator consists of an inverter, a bias resistorand the necessary load capacitor on chip.

X2 O A standard 3.579545MHz crystal connected to X1 and X2terminals implements

The oscillator function.

PWDN I CMOS IN

Pull-low

Active high. This enables the device to go into power downmode and inhibits the oscillator. This pin input is internallypulled down.

INH I CMOS IN

Pull-low

Logic high. This inhibits the detection of tones representingcharacters A, B, C and D. This pin input is internally pulleddown.

VSS _ _ Negative power supply,

OE I CMOS IN D0~D3 output enable, high


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Pull-High

D0-D3 O CMOS OUT Receiving data output terminalsOE=_H_: Output enableOE=_L_: High impedance

DV O CMOS OUT Data valid outputWhen the chip receives a valid tone (DTMF) signal, the DVgoes high; otherwiseit remains low.

EST O CMOS OUT Early steering output (see Functional Description)

RT/GT I/O CMOS

IN/OUT

Tone acquisition time and release time can be set throughconnection with external resistor and capacitor.

VDD _ Positive power supply, 2.5V~5.5V for normal

TABLE: 5.1.PIN DESCRIPTION OF HT9170D\B

5.2.4. Circuit Diagram:

FIG: 5.3.Circuit diagram

The important components of this robot are a DTMF decoder, microcontroller and motor

driver. A CM8870 series DTMF decoder is used here. All types of theCM8870 series use

digital counting techniques to detect and decode all the 16 DTMF tone pairs into a 4-bit code

output. The built-in dial tone rejection circuit eliminates the need of pre-filtering. When the


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input signals are given at pins 1(IN+)& 2(IN-) , a differential input configuration is

recognized to be effective, the correct 4-bit decode signal of the DTMF tone is transferred to

(pin11) through (pin14) outputs. The pin11 topin14 of DTMF decoder are connected to the

pins of microcontroller (P1.4 to P1.7).The 89V51RD2 is a 8-bit 80C51, 5V low power64 kB

Flash microcontroller with 1 kB RAM. it provides the following features: 64 kB of on-chipFlash program memory with ISP (In-System Programming) and IAP (In-Application

Programming), Four 8-bit I/O ports with three high-current Port 1 pins (16 mA each),Three

16-bit timers/counters.

Outputs from port pins P0.0 through P0.3 andP0.7 of the microcontroller are fed to the inputsIN1 throughIN4 and enable pins (EN1 and EN2) of motor driver L293D IC, respectively todrive two geared dc motors. Switch S1 is used for manual reset. The microcontroller output isnot sufficient to drive the dc motors, so current drivers are required for motor rotation. TheL293D is a quad, high-current, half-h driver designed to provide bidirectional drive currentsof up to600mA at voltages from 4.5V to 36V. It makes it easier to drive the dc motors. The

L293D consists of four drivers. Pins IN1through IN4 and OUT1 through OUT4 are the inputand output pins, respectively of driver 1 through driver 4. Drivers 1 and 2, and driver 3 and 4are enabled by enable pin 1(EN1) and pin 9(EN2), respectively. When enable input EN1(pin1) is high, drivers 1 and 2 are enabled and the outputs corresponding to their inputs areactive. Similarly, enable input EN2 (pin9)enables drivers 3 and 4.The motors are rotatedaccording to the status of IN1 to IN4 pins of L293D which in turn are depending on outputpins of microcontroller, viz., P0.0 - P0.3.

5.3.MOTOR DRIVER(L293D):

5.3.1.Introduction:

L293D is a dualH-bridgemotor driver integrated circuit (IC). Motor drivers act as current

amplifiers since they take a low-current control signal and provide a higher-current signal.

This higher current signal is used to drive the motors.

L293D contains two inbuilt H-bridge driver circuits. In its common mode of operation, two

DC motors can be driven simultaneously, both in forward and reverse direction. The motor

operations of two motors can be controlled by input logic at pins 2 & 7 and 10 & 15. Input

logic 00 or 11 will stop the corresponding motor. Logic 01 and 10 will rotate it in clockwise

and anticlockwise directions, respectively.Enable pins 1 and 9 (corresponding to the two

motors) must be high for motors to start operating. When an enable input is high, the

associated driver gets enabled. As a result, the outputs become active and work in phase with

their inputs. Similarly, when the enable input is low, that driver is disabled, and their outputs

are off and in the high-impedance state.
http://www.engineersgarage.com/electronic-circuits/h-bridge-motor-controlhttp://www.engineersgarage.com/electronic-circuits/h-bridge-motor-controlhttp://www.engineersgarage.com/electronic-circuits/h-bridge-motor-controlhttp://www.engineersgarage.com/electronic-circuits/h-bridge-motor-control


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5.3.2.pindescription:

FIG:5.4

Pin No Function Name

1 Enable pin for Motor 1; active high Enable 1,22 Input 1 for Motor 1 Input 13 Output 1 for Motor 1 Output 14 Ground (0V) Ground5 Ground (0V) Ground6 Output 2 for Motor 1 Output 27 Input 2 for Motor 1 Input 28 Supply voltage for Motors; 9-12V (up to 36V) Vcc 29 Enable pin for Motor 2; active high Enable 3,410 Input 1 for Motor 1 Input 311 Output 1 for Motor 1 Output 312 Ground (0V) Ground13 Ground (0V) Ground

14 Output 2 for Motor 1 Output 415 Input2 for Motor 1 Input 416 Supply voltage; 5V (up to 36V) Vcc 1

TABLE: 5.2.PIN DESCRIPTION

Based on which key is pressed, the robot will be able to interpret the tone and activate relays

and such to turn on motors and move about.

The 16-lane output will drive a set of trabsustirs, which will in turn drive a set of

much larger automotive relays, to switch a pair of drill motors, as well as motors that will

rotate the camera-equipped head left and right.Speed will be controlled in steps using a few high-load resistors taken from the drills.


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Three speed settings should be plenty.

Fig: 5.5.Robot directions

5.3.3.Circuit Description:

Fig: 5.6


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5.4.DC MOTOR:

By far the vast majority of robots use electric motors, of which there are several

kinds. DC motors, which are familiar to many people, spin rapidly when electric current is

passed through them. They will spin backwards if the current is made to flow in the opposite

direction.

Fig: 5.7

100RPM 12V DC geared motors for robotics applications. Very easy to use andavailable

In standard size. Nut and threads on shaft to easily connect and internal threaded shaft for

Easily connecting it to wheel.

5.4.1.DC motor Features:

100RPM 12V DC motors with Gearbox 3000RPM base motor 6mm shaft diameter with internal hole 125gm weight Same size motor available in various rpm 1.2kgcm torque No-load current = 60 mA(Max), Load current = 300 mA(Max)


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6.REGULATED POWER SUPPLY:

6.1.INTRODUCTION:

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

low voltage supply for electronic circuits and other devices. A RPS (Regulated Power

Supply) is the Power Supply with Rectification, Filtering and Regulation being done on the

AC mains to get a Regulated power supply for Microcontroller and for the other devices

being interfaced to it.

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

function. A d.c power supply which maintains the output voltage constant irrespective of a.c mainsfluctuations or load variations is known as Regulated D.C Power Supply

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

FIGURE 6.1: CIRCUIT DIAGRAM OF POWER SUPPLY


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6.1.1Transformer:

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

Electrical circuit to another without change in frequency.

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

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

Step-up transformers increase in output voltage, step-down transformers decrease in output

voltage. Most power supplies use a step-down transformer to reduce the dangerously high

mains voltage to a safer low voltage. The input coil is called the primary and the output coil

is called the secondary. There is no electrical connection between the two coils; instead they

are linked by an alternating magnetic field created in the soft-iron core of the transformer.

The two lines in the middle of the circuit symbol represent the core. Transformers waste

very little power so the power out is (almost) equal to the power in. Note that as voltage is

stepped down current is stepped up. The ratio of the number of turns on each coil, called the

turns ratio, determines the ratio of the voltages. A step-down transformer has a large number

of turns on its primary (input) coil which is connected to the high voltage mains supply, and a

small number of turns on its secondary (output) coil to give a low output voltage.

FIGURE: 6.2. ELECTRICAL TRANSFORMER


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Operation of bridge rectifier:

During positive half cycle of secondary, the diodes D2 and D3 are in forward biased while

D1 and D4 are in reverse biased as shown in the fig 2.12. The current flow direction is shown

in the fig (2.12) with dotted arrows.

FIGURE: 6.4. POSITIVE HALF CYCLE OPERATION

During negative half cycle of secondary voltage, the diodes D1 and D4 are in forward biased

while D2 and D3 are in reverse biased as shown in the fig(2.13). The current flow direction is

shown in the fig (2.13) with dotted arrows.

FIGURE: 6.5NEGATIVE HALF CYCLE OPERATION

6.2.3: Filter:

A Filter is a device which removes the a.c component of rectifier output but allows the d.c

component to reach the load


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6.2.4: Regulator:

Voltage regulator ICs is available with fixed (typically 5, 12 and 15V) or variable output

voltages. The maximum current they can pass also rates them. Negative voltage regulators

are available, mainly for use in dual supplies. Most regulators include some automaticprotection from excessive current ('overload protection') and overheating ('thermal

protection'). Many of the fixed voltage regulators ICs have 3 leads and look like power

transistors, such as the 7805 +5V 1A regulator shown on the right. The LM7805 is simple to

use. You simply connect the positive lead of your unregulated DC power supply (anything

from 9VDC to 24VDC) to the Input pin, connect the negative lead to the Common pin and

then when you turn on the power, you get a 5 volt supply from the output pin.

FIGURE : 6.6.A THREE TERMINAL VOLTAGE REGULATOR

78XX:

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

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

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

usually results in an effective o

Cellphone Operated Robotcv_2v

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