AUTOMATIC DRUNKEN DRIVE AVOIDING SYSTEM FOR AUTOMABILES

ABSTRACT

AIM:

The main aim of this project is to detect drunken driver

automatically to avoid accidents for automobiles.

DESCRIPTION:

In this project we have to detect that there are drunken driver

or is there any high temperature while driving in automobiles.

For this we are using LM35 (Temperature sensor), Alcohol

sensor, ADC 0808 (Analog to Digital Converter), LDR,

Break Indicator, Relay, LCD (Liquid Crystal Display).

LM35 is precision integrated circuit temperature sensor.

Its output voltage is linearly proportional to temperature (in Celsius).

The LM35 thus has an advantage over linear temperature sensors calibrated in° Kelvin, as the

user is not required to subtract a large constant voltage from its output to obtain convenient

Centigrade scaling. AD converters are used virtually everywhere where an analog signal has to

be processed, stored, or transported in digital form.

For example drunken driver driving the car, then

alcohol sensor detects it and passes the

information through ADC to Microcontroller.

Then Break Indicator stops the car and bulb will

OFF automatically and displays LCD.

These operations are controlled by

Microcontroller.

LDR

A photo resistor or light

dependent resistor (LDR)

or cadmium sulfide (CdS) cell is

resistor whose resistance decrease

s with increasing incident light

intensity. It can also be referred to

as a photoconductor

LDR

A photo resistor or light

dependent resistor (LDR)

or cadmium sulfide (CdS) cell is

resistor whose resistance decrease

s with increasing incident light

intensity. It can also be referred to

as a photoconductor

SENSOR

Sensor is the device which converts

any physical quantity to its

Equivalent electrical signal. There

are different types of sensor are

available there are: Temperature

sensor, Light sensor, Voltage sensor,

Smoke Sensor, Gas sensor, Fire

sensor, Alcohol Sensors, etc.

SENSOR

Sensor is the device which converts

any physical quantity to its

Equivalent electrical signal. There

are different types of sensor are

available there are: Temperature

sensor, Light sensor, Voltage sensor,

Smoke Sensor, Gas sensor, Fire

sensor, Alcohol Sensors, etc.

CHAPTER-1

EMBEDDED SYSTEMS

Introduction:

An embedded system is a system which is going to do a predefined specified task is the embedded system and is even defined as combination of both software and hardware. A general-purpose definition of embedded systems is that they are devices used to control, monitor or assist the operation of equipment, machinery or plant. "Embedded" reflects the fact that they are an integral part of the system. At the other extreme a general-purpose computer may be used to control the operation of a large complex processing plant, and its presence will be obvious.

All embedded systems are including computers or microprocessors. Some of these

computers are however very simple systems as compared with a personal computer.

The very simplest embedded systems are capable of performing only a single function or

set of functions to meet a single predetermined purpose. In more complex systems an application

program that enables the embedded system to be used for a particular purpose in a specific

application determines the functioning of the embedded system. The ability to have programs

means that the same embedded system can be used for a variety of different purposes. In some

cases a microprocessor may be designed in such a way that application software for a particular

purpose can be added to the basic software in a second process, after which it is not possible to

make further changes. The applications software on such processors is sometimes referred to as

firmware.

The simplest devices consist of a single microprocessor (often called a "chip”), which may itself be packaged with other chips in a hybrid system or Application Specific Integrated Circuit (ASIC). Its input comes from a detector or sensor and its output goes to a switch or activator which (for example) may start or stop the operation of a machine or, by operating a valve, may control the flow of fuel to an engine.

As the embedded system is the combination of both software and hardware

Figure: Block diagram of Embedded System

Software deals with the languages like ALP, C, and VB etc., and Hardware deals with Processors, Peripherals, and Memory.

Memory: It is used to store data or address.

Peripherals: These are the external devices connected

Processor: It is an IC which is used to perform some task

Applications of embedded systems

Manufacturing and process control

Construction industry

Transport

Buildings and premises

Domestic service

Communications

Office systems and mobile equipment

Banking, finance and commercial

Medical diagnostics, monitoring and life support

Embedded

System

Software Hardware

ALP

C

VB Etc.,

Processor

Peripherals

memory

Testing, monitoring and diagnostic systems

Processors are classified into four types like:

Micro Processor (µp)

Micro controller (µc)

Digital Signal Processor (DSP)

Application Specific Integrated Circuits (ASIC)

Micro Processor (µp):

A silicon chip that contains a CPU. In the world of personal computers, the terms microprocessor and CPU are used interchangeably. At the heart of all personal computers and most workstations sits a microprocessor. Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles.

Three basic characteristics differentiate microprocessors:

Instruction set : The set of instructions that the microprocessor can execute.

Bandwidth : The number of bits processed in a single instruction.

Clock speed : Given in megahertz (MHz), the clock speed determines how many instructions

per second the processor can execute.

In both cases, the higher the value, the more powerful the CPU. For example, a 32-bit microprocessor that runs at 50MHz is more powerful than a 16-bit microprocessor that runs at 25MHz. In addition to bandwidth and clock speed, microprocessors are classified as being either RISC (reduced instruction set computer) or CISC (complex instruction set computer).

A microprocessor has three basic elements, as shown above. The ALU performs all arithmetic computations, such as addition, subtraction and logic operations (AND, OR, etc). It is controlled by the Control Unit and receives its data from the Register Array.   The Register Array is a set of registers used for storing data. These registers can be accessed by the ALU very quickly. Some registers have specific functions - we will deal with these later.   The Control Unit controls the entire process. It provides the timing and a control signal for getting data into and out of the registers and the ALU and it synchronizes the execution of instructions (we will deal with instruction execution at a later date).  

Three Basic Elements of a Microprocessor

Micro Controller (µc):

A microcontroller is a small computer on a single integrated circuit containing a processor core,

memory, and programmable input/output peripherals. Program memory in the form of NOR

flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM.

Microcontrollers are designed for embedded applications, in contrast to the microprocessors

used in personal computers or other general purpose applications.

Figure: Block Diagram of Micro Controller (µc)

Timer, Counter, serial communication ROM, ADC, DAC, Timers, USART, Oscillators

Etc.,

ALU

CU

Memory

Digital Signal Processors (DSPs):

Digital Signal Processors is one which performs scientific and mathematical operation.

Digital Signal Processor chips - specialized microprocessors with architectures designed

specifically for the types of operations required in digital signal processing. Like a general-

purpose microprocessor, a DSP is a programmable device, with its own native instruction code.

DSP chips are capable of carrying out millions of floating point operations per second, and like

their better-known general-purpose cousins, faster and more powerful versions are continually

being introduced. DSPs can also be embedded within complex "system-on-chip" devices, often

containing both analog and digital circuitry.

Application Specific Integrated Circuit (ASIC)

ASIC is a combination of digital and analog circuits packed into an IC to achieve the desired control/computation function

ASIC typically contains

CPU cores for computation and control

Peripherals to control timing critical functions

Memories to store data and program

Analog circuits to provide clocks and interface to the real world which is analog in nature

I/Os to connect to external components like LEDs, memories, monitors etc.

Computer Instruction Set

There are two different types of computer instruction set there are:

1. RISC (Reduced Instruction Set Computer) and

2. CISC (Complex Instruction Set computer)

Reduced Instruction Set Computer (RISC)

A RISC (reduced instruction set computer) is a microprocessor that is designed to perform a smaller number of types of computer instruction so that it can operate at a higher speed (perform more million instructions per second, or millions of instructions per second). Since each instruction type that a computer must perform requires additional transistors and circuitry, a larger list or set of computer instructions tends to make the microprocessor more complicated and slower in operation.

Besides performance improvement, some advantages of RISC and related design improvements are:

A new microprocessor can be developed and tested more quickly if one of its aims is to be less

complicated.

Operating system and application programmers who use the microprocessor's instructions will

find it easier to develop code with a smaller instruction set.

The simplicity of RISC allows more freedom to choose how to use the space on a

microprocessor.

Higher-level language compilers produce more efficient code than formerly because they have always tended to use the smaller set of instructions to be found in a RISC computer.

RISC characteristics

Simple instruction set:

In a RISC machine, the instruction set contains simple, basic instructions, from which more

complex instructions can be composed.

Same length instructions.

Each instruction is the same length, so that it may be fetched in a single operation.

1 machine-cycle instructions.

Most instructions complete in one machine cycle, which allows the processor to handle several

instructions at the same time. This pipelining is a key technique used to speed up RISC

machines.

Complex Instruction Set Computer (CISC)

CISC, which stands for Complex Instruction Set Computer, is a philosophy for designing chips that are easy to program and which make efficient use of memory. Each instruction in a CISC instruction set might perform a series of operations inside the processor. This reduces the number of instructions required to implement a given program, and allows the programmer to learn a small but flexible set of instructions.

The advantages of CISCAt the time of their initial development, CISC machines used available technologies to optimize computer performance.

Microprogramming is as easy as assembly language to implement, and much less expensive than

hardwiring a control unit.

The ease of micro-coding new instructions allowed designers to make CISC machines upwardly

compatible: a new computer could run the same programs as earlier computers because the new

computer would contain a superset of the instructions of the earlier computers.

As each instruction became more capable, fewer instructions could be used to implement a given

task. This made more efficient use of the relatively slow main memory.

Because micro program instruction sets can be written to match the constructs of high-level

languages, the compiler does not have to be as complicated.

The disadvantages of CISCStill, designers soon realized that the CISC philosophy had its own problems, including:

Earlier generations of a processor family generally were contained as a subset in every new

version --- so instruction set & chip hardware become more complex with each generation of

computers.

So that as many instructions as possible could be stored in memory with the least possible wasted

space, individual instructions could be of almost any length---this means that different

instructions will take different amounts of clock time to execute, slowing down the overall

performance of the machine.

Many specialized instructions aren't used frequently enough to justify their existence ---

approximately 20% of the available instructions are used in a typical program.

CISC instructions typically set the condition codes as a side effect of the instruction. Not only

does setting the condition codes take time, but programmers have to remember to examine the

condition code bits before a subsequent instruction changes them.

Memory Architecture

There two different type’s memory architectures there are:

Harvard Architecture

Von-Neumann Architecture

Harvard Architecture

Computers have separate memory areas for program instructions and data. There are two or more internal data buses, which allow simultaneous access to both instructions and data. The CPU fetches program instructions on the program memory bus.

The Harvard architecture is a computer architecture with physically separate storage and signal pathways for instructions and data. The term originated from the Harvard Mark I relay-based computer, which stored instructions on punched tape (24 bits wide) and data in electro-mechanical counters. These early machines had limited data storage, entirely contained within the central processing unit, and provided no access to the instruction storage as data. Programs needed to be loaded by an operator, the processor could not boot itself.

Figure: Harvard Architecture

Modern uses of the Harvard architecture

The principal advantage of the pure Harvard architecture - simultaneous access to more than one

memory system - has been reduced by modified Harvard processors using modern CPU cache

systems. Relatively pure Harvard architecture machines are used mostly in applications where

tradeoffs, such as the cost and power savings from omitting caches, outweigh the programming

penalties from having distinct code and data address spaces.

Digital signal processors (DSPs) generally execute small, highly-optimized audio or video

processing algorithms. They avoid caches because their behavior must be extremely

reproducible. The difficulties of coping with multiple address spaces are of secondary concern to

speed of execution. As a result, some DSPs have multiple data memories in distinct address

spaces to facilitate SIMD and VLIW processing. Texas Instruments TMS320 C55x processors,

as one example, have multiple parallel data busses (two write, three read) and one instruction

bus.

Microcontrollers are characterized by having small amounts of program (flash memory) and data

(SRAM) memory, with no cache, and take advantage of the Harvard architecture to speed

processing by concurrent instruction and data access. The separate storage means the program

and data memories can have different bit depths, for example using 16-bit wide instructions and

8-bit wide data. They also mean that instruction pre-fetch can be performed in parallel with other

activities. Examples include, the AVR by Atmel Corp, the PIC by Microchip Technology, Inc.

and the ARM Cortex-M3 processor (not all ARM chips have Harvard architecture).

Even in these cases, it is common to have special instructions to access program memory as data

for read-only tables, or for reprogramming.

Von-Neumann Architecture

A computer has a single, common memory space in which both program instructions and data are stored. There is a single internal data bus that fetches both instructions and data. They cannot be performed at the same time

The Von Neumann architecture is a design model for a stored-program digital computer that uses a central processing unit (CPU) and a single separate storage structure ("memory") to hold both instructions and data. It is named after the mathematician and early computer scientist John von Neumann. Such computers implement a universal Turing machine and have a sequential architecture.

A stored-program digital computer is one that keeps its programmed instructions, as well as its data, in read-write, random-access memory (RAM). Stored-program computers were advancement over the program-controlled computers of the 1940s, such as the Colossus and the ENIAC, which were programmed by setting switches and inserting patch leads to route data and to control signals between various functional units. In the vast majority of modern computers, the same memory is used for both data and program instructions. The mechanisms for transferring the data and instructions between the CPU and memory are, however, considerably more complex than the original von Neumann architecture.

The terms "von Neumann architecture" and "stored-program computer" are generally used interchangeably, and that usage is followed in this article.

Figure: Schematic of the Von-Neumann Architecture.

Basic Difference between Harvard and Von-Neumann Architecture

The primary difference between Harvard architecture and the Von Neumann architecture is in

the Von Neumann architecture data and programs are stored in the same memory and managed

by the same information handling system.

Whereas the Harvard architecture stores data and programs in separate memory devices and they

are handled by different subsystems.

In a computer using the Von-Neumann architecture without cache; the central processing unit

(CPU) can either be reading and instruction or writing/reading data to/from the memory. Both of

these operations cannot occur simultaneously as the data and instructions use the same system

bus.

In a computer using the Harvard architecture the CPU can both read an instruction and access

data memory at the same time without cache. This means that a computer with Harvard

architecture can potentially be faster for a given circuit complexity because data access and

instruction fetches do not contend for use of a single memory pathway.

Today, the vast majority of computers are designed and built using the Von Neumann

architecture template primarily because of the dynamic capabilities and efficiencies gained in

designing, implementing, operating one memory system as opposed to two. Von Neumann

architecture may be somewhat slower than the contrasting Harvard Architecture for certain

specific tasks, but it is much more flexible and allows for many concepts unavailable to Harvard

architecture such as self programming, word processing and so on.

Harvard architectures are typically only used in either specialized systems or for very specific

uses. It is used in specialized digital signal processing (DSP), typically for video and audio

processing products. It is also used in many small microcontrollers used in electronics

applications such as Advanced RISK Machine (ARM) based products for many vendors.

CHAPTER-2

Introduction to Project

There many different types of accidents are occurred in day to day life time system. In order to accidents we implement project. Accidents may cause due to many regions it may a break failed system; it may any regions most offen accidents are occurred due to over drunken person. Most of accidents are due to over drunken drivers. Due to that consumption of alcohol in order to avoid these accidents we implemented a one proto types project in these project we place an alcohol sensor. This sensor used to sense the drunken person from 200ppm onwards.

If the person is drunk, Initally we check the person weather person is dunked are not .This module inserted in cars or any vehicles. If the driver is dunked then sensor will sense the amount of alcohol consumed by the person and it will intimate by buzzing with the help of buzzer.

In these vehicle automations also consider whenever under night times we need to ON the your vehicle headlights instead of ONing headlight with the a key we placed a LDR in the module. On night times with the help of LDR headlight will be automatically we can ONed.Similary, we consider the one more parameter engine temperature here we controlling the engine, by placing the thermistor sensor we continuously monitoring the engine, whenever over heat is occurred we automatically the cooling section in this way we are controlling the engine from damages.

BLOCK DIAGRAM:

POWER SUPPLY:

Break

Indicator

Break

Indicator

Block Diagram Explanation

In this project we interface the alcohol sensors to ADC 0804.Output of LDR is in digital form so we can directly interface to microcontroller (AT 89S52) and we interface the LCD to microcontroller port pins here we operating the LCD in the 4-bit mode .We can operate the LCD in two modes it may be 8-bit mode and 4-bit mode.

Accidents may cause due to many regions it may a break failed system; it may any regions most offen accidents are occurred due to over drunken person. Most of accidents are due to over drunken drivers. Due to that consumption of alcohol in order to avoid these accidents we implemented a one proto types project in these project we place a alcohol sensor. This sensor used to sense the drunken person from 200ppm onwards.

We are taking inputs from sensor i.e., MQ3 this is one type of alcohol sensor is given to ADC whenever some amount is alcohol detected ADC will take that analog data and converted into its equivalent digital format, these data will given to microcontroller. If maximum amount alcohol is detected then it will give intimate by buzzer sound.

During in night condition we automatically controlling the headlight with the help of LDR. Similarly , we controlling and protecting the engine from over heat. If engine is over heated then we need to cool the engine in that case we providing a cooling section with the help of normal DC fan.

CHAPTER-3

Hardware Explanation

Block Diagram For Power Supply

Figure: Power Supply

Description

Transformer

A transformer is a device 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 mutual

induction.

Figure: Transformer Symbol

(or)

Transformer is a device that converts the one form energy to another form of energy like a

transducer.

Figure: Transformer

Basic Principle

A transformer makes use of Faraday's law and the ferromagnetic properties of an iron core to

efficiently raise or lower AC voltages. It of course cannot increase power so that if the voltage is

raised, the current is proportionally lowered and vice versa.

Figure: Basic Principle

Transformer Working

A transformer consists of two coils (often called 'windings') linked by an iron core, as shown in

figure below. There is no electrical connection between the coils; instead they are linked by a

magnetic field created in the core.

Figure: Basic Transformer

Transformers are used to convert electricity from one voltage to another with minimal loss of

power. They only work with AC (alternating current) because they require a changing magnetic

field to be created in their core. Transformers can increase voltage (step-up) as well as reduce

voltage (step-down).

Alternating current flowing in the primary (input) coil creates a continually changing magnetic

field in the iron core. This field also passes through the secondary (output) coil and the changing

strength of the magnetic field induces an alternating voltage in the secondary coil. If the

secondary coil is connected to a load the induced voltage will make an induced current flow. The

correct term for the induced voltage is 'induced electromotive force' which is usually abbreviated

to induced e.m.f.

The iron core is laminated to prevent 'eddy currents' flowing in the core. These are currents

produced by the alternating magnetic field inducing a small voltage in the core, just like that

induced in the secondary coil. Eddy currents waste power by needlessly heating up the core but

they are reduced to a negligible amount by laminating the iron because this increases the

electrical resistance of the core without affecting its magnetic properties.

Transformers have two great advantages over other methods of changing voltage:

1. They provide total electrical isolation between the input and output, so they can be safely

used to reduce the high voltage of the mains supply.

2. Almost no power is wasted in a transformer. They have a high efficiency (power out /

power in) of 95% or more.

Classification of Transformer

Step-Up Transformer

Step-Down Transformer

Step-Down Transformer

Step down transformers are designed to reduce electrical voltage. Their primary voltage is

greater than their secondary voltage. This kind of transformer "steps down" the voltage applied

to it. For instance, a step down transformer is needed to use a 110v product in a country with a

220v supply.

Step down transformers convert electrical voltage from one level or phase configuration usually

down to a lower level. They can include features for electrical isolation, power distribution, and

control and instrumentation applications. Step down transformers typically rely on the principle

of magnetic induction between coils to convert voltage and/or current levels.

Step down transformers are made from two or more coils of insulated wire wound around a core

made of iron. When voltage is applied to one coil (frequently called the primary or input) it

magnetizes the iron core, which induces a voltage in the other coil, (frequently called the

secondary or output). The turn’s ratio of the two sets of windings determines the amount of

voltage transformation.

Figure: Step-Down Transformer

An example of this would be: 100 turns on the primary and 50 turns on the secondary, a ratio of 2 to 1.

Step down transformers can be considered nothing more than a voltage ratio device.

With step down transformers the voltage ratio between primary and secondary will mirror the

"turn’s ratio" (except for single phase smaller than 1 kva which have compensated secondary). A

practical application of this 2 to 1 turn’s ratio would be a 480 to 240 voltage step down. Note that

if the input were 440 volts then the output would be 220 volts. The ratio between input and

output voltage will stay constant. Transformers should not be operated at voltages higher than

the nameplate rating, but may be operated at lower voltages than rated. Because of this it is

possible to do some non-standard applications using standard transformers.

Single phase step down transformers 1 kva and larger may also be reverse connected to step-

down or step-up voltages. (Note: single phase step up or step down transformers sized less than 1

KVA should not be reverse connected because the secondary windings have additional turns to

overcome a voltage drop when the load is applied. If reverse connected, the output voltage will

be less than desired.)

Step-Up Transformer

A step up transformer has more turns of wire on the secondary coil, which makes a larger

induced voltage in the secondary coil. It is called a step up transformer because the voltage

output is larger than the voltage input.

Step-up transformer 110v 220v design is one whose secondary voltage is greater than its primary

voltage. This kind of transformer "steps up" the voltage applied to it. For instance, a step up

transformer is needed to use a 220v product in a country with a 110v supply.

A step up transformer 110v 220v converts alternating current (AC) from one voltage to another

voltage. It has no moving parts and works on a magnetic induction principle; it can be designed

to "step-up" or "step-down" voltage. So a step up transformer increases the voltage and a step

down transformer decreases the voltage.

The primary components for voltage transformation are the step up transformer core and coil.

The insulation is placed between the turns of wire to prevent shorting to one another or to

ground. This is typically comprised of Mylar, nomex, Kraft paper, varnish, or other materials. As

a transformer has no moving parts, it will typically have a life expectancy between 20 and 25

years.

Figure: Step-Up Transformer

Applications

Generally these Step-Up Transformers are used in industries applications only.

Types of Transformer

Mains Transformers

Mains transformers are the most common type.  They are designed to reduce the AC mains

supply voltage (230-240V in the UK or 115-120V in some countries) to a safer low voltage.

The standard mains supply voltages are officially 115V and 230V, but 120V and 240V are the

values usually quoted and the difference is of no significance in most cases.

Figure: Main Transformer

To allow for the two supply voltages mains transformers usually have two separate primary coils

(windings) labeled 0-120V and 0-120V. The two coils are connected in series for 240V (figure

2a) and in parallel for 120V (figure 2b). They must be wired the correct way round as shown in

the diagrams because the coils must be connected in the correct sense (direction):

   

Most mains transformers have two separate secondary coils (e.g. labeled 0-9V, 0-9V) which may

be used separately to give two independent supplies, or connected in series to create a centre-

tapped coil (see below) or one coil with double the voltage.

Some mains transformers have a centre-tap halfway through the secondary coil and they are

labeled 9-0-9V for example. They can be used to produce full-wave rectified DC with just two

diodes, unlike a standard secondary coil which requires four diodes to produce full-wave

rectified DC.

A mains transformer is specified by:

1. Its secondary (output) voltages Vs.

2. Its maximum power, Pmax, which the transformer can pass, quoted in VA (volt-amp). This

determines the maximum output (secondary) current, Imax...

...where Vs is the secondary voltage.  If there are two secondary coils the maximum

power should be halved to give the maximum for each coil.

3. Its construction - it may be PCB-mounting, chassis mounting (with solder tag

connections) or toroidal (a high quality design).

Audio Transformers

Audio transformers are used to convert the moderate voltage, low current output of an audio

amplifier to the low voltage, high current required by a loudspeaker.  This use is called

'impedance matching' because it is matching the high impedance output of the amplifier to the

low impedance of the loudspeaker.

Figure: Audio transformer

Radio Transformers

Radio transformers are used in tuning circuits. They are smaller than mains and audio

transformers and they have adjustable ferrite cores made of iron dust. The ferrite cores can be

adjusted with a non-magnetic plastic tool like a small screwdriver. The whole transformer is

enclosed in an aluminum can which acts as a shield, preventing the transformer radiating too

much electrical noise to other parts of the circuit.

Figure: Radio Transformer

Turns Ratio and Voltage

The ratio of the number of turns on the primary and secondary coils determines the ratio of the

voltages...

...where Vp is the primary (input) voltage, Vs is the secondary (output) voltage, Np is the number

of turns on the primary coil, and Ns is the number of turns on the secondary coil.

Diodes

Diodes allow electricity to flow in only one direction.  The arrow of the circuit symbol shows the

direction in which the current can flow.  Diodes are the electrical version of a valve and early

diodes were actually called valves.

Figure: Diode Symbol

A diode is a device which only allows current to flow through it in one direction.  In this

direction, the diode is said to be 'forward-biased' and the only effect on the signal is that there

will be a voltage loss of around 0.7V.  In the opposite direction, the diode is said to be 'reverse-

biased' and no current will flow through it.

Rectifier

The purpose of a rectifier is to convert an AC waveform into a DC waveform (OR) Rectifier

converts AC current or voltages into DC current or voltage.  There are two different rectification

circuits, known as 'half-wave' and 'full-wave' rectifiers.  Both use components called diodes to

convert AC into DC.

The Half-wave Rectifier

The half-wave rectifier is the simplest type of rectifier since it only uses one diode, as shown in

figure.

Figure: Half Wave Rectifier

Figure 2 shows the AC input waveform to this circuit and the resulting output.  As you can see,

when the AC input is positive, the diode is forward-biased and lets the current through.  When

the AC input is negative, the diode is reverse-biased and the diode does not let any current

through, meaning the output is 0V.  Because there is a 0.7V voltage loss across the diode, the

peak output voltage will be 0.7V less than Vs.

Figure: Half-Wave Rectification

While the output of the half-wave rectifier is DC (it is all positive), it would not be suitable as a

power supply for a circuit.  Firstly, the output voltage continually varies between 0V and Vs-

0.7V, and secondly, for half the time there is no output at all. 

The Full-wave Rectifier

The circuit in figure 3 addresses the second of these problems since at no time is the output

voltage 0V.  This time four diodes are arranged so that both the positive and negative parts of the

AC waveform are converted to DC.  The resulting waveform is shown in figure 4.

Figure: Full-Wave Rectifier

Figure: Full-Wave Rectification

When the AC input is positive, diodes A and B are forward-biased, while diodes C and D are

reverse-biased.  When the AC input is negative, the opposite is true - diodes C and D are

forward-biased, while diodes A and B are reverse-biased.

While the full-wave rectifier is an improvement on the half-wave rectifier, its output still isn't

suitable as a power supply for most circuits since the output voltage still varies between 0V and

Vs-1.4V.  So, if you put 12V AC in, you will 10.6V DC out.

Capacitor Filter

The capacitor-input filter, also called "Pi" filter due to its shape that looks like the Greek letter

pi, is a type of electronic filter. Filter circuits are used to remove unwanted or undesired

frequencies from a signal.

Figure: Capacitor Filter

A typical capacitor input filter consists of a filter capacitor C1, connected across the rectifier

output, an inductor L, in series and another filter capacitor connected across the load.

1. The capacitor C1 offers low reactance to the AC component of the rectifier output while

it offers infinite reactance to the DC component. As a result the capacitor shunts an

appreciable amount of the AC component while the DC component continues its journey

to the inductor L

2. The inductor L offers high reactance to the AC component but it offers almost zero

reactance to the DC component. As a result the DC component flows through the

inductor while the AC component is blocked.

3. The capacitor C2 bypasses the AC component which the inductor had failed to block. As

a result only the DC component appears across the load RL.

Figure: Centered Tapped Full-Wave Rectifier with a Capacitor Filter

Voltage Regulator

A voltage regulator is an electrical regulator designed to automatically maintain a constant

voltage level. It may use an electromechanical mechanism, or passive or active electronic

components. Depending on the design, it may be used to regulate one or more AC or DC

voltages. There are two types of regulator are they.

Positive Voltage Series (78xx) and

Negative Voltage Series (79xx)

78xx:

’78’ indicate the positive series and ‘xx’indicates the voltage rating. Suppose 7805 produces

the maximum 5V.’05’indicates the regulator output is 5V.

79xx:

’78’ indicate the negative series and ‘xx’indicates the voltage rating. Suppose 7905

produces the maximum -5V.’05’indicates the regulator output is -5V.

These regulators consists the three pins there are

Pin1: It is used for input pin.

Pin2: This is ground pin for regulator

Pin3: It is used for output pin. Through this pin we get the output.

Figure: Regulator

CHAPTER-4

Microcontroller (AT89S52):

Description of Microcontroller 89S52:

The AT89S52 is a low-power, high-performance CMOS 8-bit micro controller with 8Kbytes of in-system programmable flash memory. The device is manufactured Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 micro controller. 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 one monolithic http; the Atmel AT89S52 is a powerful micro controller, which provides a highly flexible and cost effective solution to any cost effective solution to any embedded control applications to any 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, full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt Or hardware reset.

Architecture of 8052µC:

Figure: Microcontroller Architecture

Features:

• Compatible with MCS-51 Products

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

– Endurance: 1000 Write/Erase Cycles

• 4.0V to 5.5V Operating Range

• Fully Static Operation: 0 Hz to 33 MHz

• Three-level Program Memory Lock

• 256K Internal RAM

• 32 Programmable I/O Lines

• 3 16-bit Timer/Counters

• Eight Interrupt Sources

• Full Duplex UART Serial Channel

• Low-power Idle and Power-down Modes

• Interrupt Recovery from Power-down Mode

• Watchdog Timer

• Dual Data Pointer

• Power-off Flag

Pin Diagram:

Pin Description:

VCC 40

Supply voltage.

GND 20

Ground.

Port 0 (32-39):

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

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

inputs. Port 0 can also be configured to be the multiplexed low order address/data bus during

accesses to external 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 (1-8):

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. 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.

Port 2 (21-28):

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 emits the high-order address byte during

fetches from external program memory and during accesses to external data memory that uses

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 2emits 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 (10-17):

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 writ 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Port 3 also serves the functions of various special features of the AT89S52, as shown in the following table.

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

RST

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

ALE/PROG

Address Latch Enable (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 of1/6 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 micro controller 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. A should be

strapped to VCC for internal program executions. This pin also receives the 12-voltProgramming

enables 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.

Oscillator Characteristics:

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

can be configured for use as an on-chip oscillator, as shown in Figure 1. 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.

Oscillator Connections

Special Function Register (SFR) Memory:

Special Function Registers (SFR s) are areas of memory that control specific functionality of the 8051 processor. For example, four SFRs permit access to the 8051’s 32 input/output lines. Another SFR allows the user to set the serial baud rate, control and access timers, and configure the 8051’s interrupt system.

Accumulator: The Accumulator, as its name suggests is used as a general register to accumulate the results of a large number of instructions. It can hold 8-bit (1-byte) value and is the most versatile register.

The “R” registers: The “R” registers are a set of eight registers that are named R0, R1. Etc. up to R7. These registers are used as auxiliary registers in many operations.

The “B” registers: The “B” register is very similar to the accumulator in the sense that it may hold an 8-bit (1-byte) value. Two only uses the “B” register 8051 instructions: MUL AB and DIV AB.

Data Pointer:

The Data pointer (DPTR) is the 8051’s only user accessible 16-bit (2Bytes) register. The accumulator, “R” registers are all 1-Byte values. DPTR, as the name suggests, is used to point to data. It is used by a number of commands, which allow the 8051 to access external memory.

Programs counter & Stack pointer:

The program counter (PC) is a 2-byte address, which tells the 8051 where the next instruction to execute is found in memory. The stack pointer like all registers except DPTR and PC may hold an 8-bit (1-Byte) value.

Memory:

Special Function Registers (SFRs) are areas of memory that control specific functionality of the 8051 processor. For example, four SFRs permit access to the 8051’s 32 input/output lines. Another SFR allows the user to set the serial baud rate, control and access timers, and configure the 8051’s interrupt system.

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.

Timer 0:

Timer 0 functions as either a timer or event counter in four modes of operation . Timer 0 is controlled by the four lower bits of the TMOD register and bits 0, 1, 4 and 5 of the TCON register. Mode 0 ( 13-bit Timer) Mode 0 configures timer 0 as a 13-bit timer which is set up as an 8-bit timer (TH0 register) with a modulo 32 pre-scale

implemented with the lower five bits of the TL0 register . The upper three bits of TL0 register are indeterminate and should be ignored. Pre-scale overflow increments the TH0 register. Mode 1 ( 16-bit Timer )Mode 1 is the same as Mode 0, except that the Timer register is being run with all 16 bits .

Mode 1 configures timer 0 as a 16-bit timer with the TH0 and TL0 registers connected in cascade. The selected input increments the TL0 register. Mode 2 (8-bit Timer with Auto-Reload)Mode 2 configures timer 0 as an 8-bit timer ( TL0 register ) that automatically reloads from the TH0 register . TL0 overflow sets TF0 flag in the TCON register and reloads TL0 with the contents of TH0, which is preset by software. Mode 3 ( Two 8-bit Timers )Mode 3 configures timer 0 so that registers TL0 and TH0 operate as separate 8-bit timers. This mode is provided for applications requiring an additional 8-bit timer or counter.

Timer 1:

Timer 1 is identical to timer 0, except for mode 3, which is a hold-count mode. Mode 3 (Halt) Placing Timer 1 in mode 3 causes it to halt and hold its count. This can be used to halt Timer 1 when TR1 run control bit is not available i.e., when Timer 0 is in mode 3.

Baud Rates:

The baud rate in Mode 0 is fixed. The baud rate in Mode 2 depends on the value of bit SMOD in Special Function Register PCON. If SMOD = 0 (which is its value on reset), the baud rate is 1/64 the oscillator frequency. If SMOD = 1, the baud rate is 1/32 the oscillator frequency. In the 89S52, the baud rates in Modes 1 and 3 are determined by the Timer 1 overflow rate. In case of Timer 2 , these baud rates can be determined by Timer 1 , or by Timer 2 , or by both (one for transmit and the other for receive ).

TCON REGISTER: Timer/counter Control Register

7 6 5 4 3 2 1 0

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

Bit

Number

Bit

Mnemonics

Description

7 TF1 Timer 1 overflow flag

Cleared by hardware when processor vectors to interrupt routien.

Set by hardware on timer/counter overflow, when the imer 1 register overflows.

6 TR1 Timer 1 run control bit

Clear to turn off timer/counter 1.

Set to turn on timer/counter 1.

5 TF0 Timer 1 overflow flag

Cleared by hardware when processor vectors to interrupt routien.

Set by hardware on timer/counter overflow, when the timer0 register overflows.

4 TR0 Timer 1 run control bit

Clear to turn off timer/counter 0.

Set to turn on timer/counter 0.

3 IE1 Interrupt 1 Edge flag

Cleared by hardware when interrupt is processed if edge-triggered (IT1)

Set by hardware when external interrupt is detected on INT1 pin.

2 IT1 Interrupt 1 type control bit

Clear to select low level active (level triggered) for external interrupt 1.

Set to select falling edge active (edge triggered) for external interrupt 1.

1 IE0 Interrupt 0 Edge flag

Cleared by hardware when interrupt is processed if edge-triggered (IT0)

Set by hardware when external interrupt is detected on INT0 pin.

0 IT0 Interrupt 0 type control bit

Clear to select low level active (level triggered) for external interrupt 0.

Set to select falling edge active (edge triggered) for external interrupt 0.

TMOD REGISTER: Timer/Counter 0 and 1 Modes

7 6 5 4 3 2 1

0

GATE1 C/T 1 M11 M01 GATE0 C/T 0 M10 M00

Bit

Number

Bit Mnemonics Description

7 GATE1 Timer 1 Gate Control Bit

Clear to enable timer 1 whenever the TR1 bit is set.

Set to enable timer 1 only while the INT1 pin is high & TR1 bit is set.

6 C/T 1 Timer1 counter/timer select bit

Clear for timer operation: timer1 counts the divided down system

clock.

Set for counter operation: timer1 counts negative transition on external

pin T1.

5 M11 Timer 1 mode select bits

M11 M01 operating mode

0 0 Mode0: 8 bit timer/counter (TH1) with 5 bit

prescaler (TL1).

0 1 Mode1: 16 bit timer/counter.

1 0 Mode2: 8 bit auto reload timer/counter (TL1).

1 1 Mode3: timer 1 halted. Retains count.

4 M01

3 GATE 0 Timer 0 Gate Control Bit

Clear to enable timer 0 whenever the TR0 bit is set.

Set to enable timer 0 only while the INT0 pin is high & TR0 bit is set.

2 C/T 0 Timer0 counter/timer select bit

Clear for timer operation: timer0 counts the divided down system

clock.

Set for counter operation: timer0 counts negative transition on external

pin T0.

1 M10 Timer 0 mode select bits

M10 M00 operating mode

1 0 Mode0: 8 bit timer/counter (TH1) with 5 bit

pre-scaler (TL1).

0 1 Mode1: 16 bit timer/counter.

1 0 Mode2: 8 bit auto reload timer/counter (TL1).

1 1 Mode3: timer 1 halted. Retains count.

TH0 is an 8 bit timer using timer1’s TR0 & TF0 bits.

CHAPTER-5

Sensor

Definition:

A sensor is a device that measures a physical quantity and converts it into a signal which can be

read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts

the measured temperature into expansion and contraction of a liquid which can be read on a

calibrated glass tube. A thermocouple converts temperature to an output voltage which can be

read by a voltmeter. For accuracy, all sensors need to be calibrated against known standards

(OR)

Sensor is the device which converts any physical quantity to its equivalent electrical

signal. There are different types of sensor are available there are: Temperature sensor, Light

sensor, Voltage sensor, Smoke Sensor, Gas sensor, Fire sensor, Magnetic Sensors, etc.

Classification of measurement errors

A good sensor obeys the following rules:

Is sensitive to the measured property Is insensitive to any other property likely to be encountered in its application

Does not influence the measured property

Ideal sensors are designed to be linear or linear to some simple mathematical function of the

measurement, typically logarithmic. The output signal of such a sensor is linearly proportional to

the value or simple function of the measured property. The sensitivity is then defined as the ratio

between output signal and measured property. For example, if a sensor measures temperature

and has a voltage output, the sensitivity is a constant with the unit [V/K]; this sensor is linear

because the ratio is constant at all points of measurement

Sensor deviations

If the sensor is not ideal, several types of deviations can be observed:

The sensitivity may in practice differ from the value specified. This is called a sensitivity

error, but the sensor is still linear.

Since the range of the output signal is always limited, the output signal will eventually

reach a minimum or maximum when the measured property exceeds the limits. The full

scale range defines the maximum and minimum values of the measured property.

If the output signal is not zero when the measured property is zero, the sensor has an

offset or bias. This is defined as the output of the sensor at zero input.

If the sensitivity is not constant over the range of the sensor, this is called nonlinearity.

Usually this is defined by the amount the output differs from ideal behavior over the full

range of the sensor, often noted as a percentage of the full range.

If the deviation is caused by a rapid change of the measured property over time, there is a

dynamic error. Often, this behavior is described with a bode plot showing sensitivity

error and phase shift as function of the frequency of a periodic input signal.

If the output signal slowly changes independent of the measured property, this is defined

as drift (telecommunication).

Long term drift usually indicates a slow degradation of sensor properties over a long

period of time.

Noise is a random deviation of the signal that varies in time.

Hysteresis is an error caused by when the measured property reverses direction, but there

is some finite lag in time for the sensor to respond, creating a different offset error in one

direction than in the other.

If the sensor has a digital output, the output is essentially an approximation of the

measured property. The approximation error is also called digitization error.

If the signal is monitored digitally, limitation of the sampling frequency also can cause a

dynamic error, or if the variable or added noise noise changes periodically at a frequency

near a multiple of the sampling rate may induce aliasing errors.

The sensor may to some extent be sensitive to properties other than the property being

measured. For example, most sensors are influenced by the temperature of their

environment.

All these deviations can be classified as systematic errors or random errors. Systematic errors

can sometimes be compensated for by means of some kind of calibration strategy. Noise is a

random error that can be reduced by signal processing, such as filtering, usually at the expense of

the dynamic behavior of the sensor.

Resolution

The resolution of a sensor is the smallest change it can detect in the quantity that it is measuring.

Often in a digital display, the least significant digit will fluctuate, indicating that changes of that

magnitude are only just resolved. The resolution is related to the precision with which the

measurement is made. For example, a scanning tunneling probe (a fine tip near a surface collects

an electron tunneling current) can resolve atoms and molecules.

Different Types Sensor:

1] Acoustic, sound, vibration

Geophone

Hydrophone

Lace Sensor a guitar pickup

Microphone

Seismometer

Accelerometer

2] Automotive, transportation

Air-fuel ratio meter

Crank sensor

Curb feeler , used to warn driver of curbs

Defect detector , used on railroads to detect axle and signal problems in passing trains

Engine coolant temperature sensor , or ECT sensor, used to measure the engine

temperature

Hall effect sensor , used to time the speed of wheels and shafts

MAP sensor , Manifold Absolute Pressure, used in regulating fuel metering.

Mass flow sensor , or mass airflow (MAF) sensor, used to tell the ECU the mass of air

entering the engine

Oxygen sensor , used to monitor the amount of oxygen in the exhaust

Parking sensors , used to alert the driver of unseen obstacles during parking manoeuvres

Radar gun , used to detect the speed of other objects

Speedometer , used measure the instantaneous speed of a land vehicle

Speed sensor , used to detect the speed of an object

Throttle position sensor , used to monitor the position of the throttle in an internal

combustion engine

Tire-pressure monitoring sensor , used to monitor the air pressure inside the tires

Transmission fluid temperature sensor , used to measure the temperature of the

transmission fluid

Turbine speed sensor (TSS), or input speed sensor (ISS), used to measure the rotational

speed of the input shaft or torque converter

Variable reluctance sensor , used to measure position and speed of moving metal

components

Vehicle speed sensor (VSS), used to measure the speed of the vehicle

Water sensor or water-in-fuel sensor, used to indicate the presence of water in fuel

Wheel speed sensor , used for reading the speed of a vehicle's wheel rotation

3] Chemical

Breathalyzer and Alcohol Sensor

Carbon dioxide sensor

Carbon monoxide detector

Catalytic bead sensor

Chemical field-effect transistor

Electrochemical gas sensor

Electronic nose

Electrolyte–insulator–semiconductor sensor

Hydrogen sensor

Hydrogen sulfide sensor

Infrared point sensor

Ion-selective electrode

Nondispersive infrared sensor

Microwave chemistry sensor

Nitrogen oxide sensor

Olfactometer

Optode

Oxygen sensor

Pellistor

pH glass electrode

Potentiometric sensor

Redox electrode

Smoke detector

Zinc oxide nanorod sensor

4] Electric current, electric potential, magnetic, radio

Ammeter

Current sensor

Galvanometer

Hall effect sensor

Hall probe

Leaf electroscope

Magnetic anomaly detector

Magnetometer

Metal detector

Multi-meter

Ohmmeter

Radio direction finder

Telescope

Voltmeter

Voltage detector

Watt-hour meter

5] Environment, weather, moisture, humidity

Bedwetting alarm

Dew warning

Fish counter

Gas detector

Hook gauge evaporimeter

Hygrometer

Leaf sensor

Pyranometer

Pyrgeometer

Psychrometer

Rain gauge

Rain sensor

Seismometers

Snow gauge

Soil moisture sensor

Stream gauge

Tide gauge

6] Flow, fluid velocity

Air flow meter

Anemometer

Flow sensor

Gas meter

Mass flow sensor

Water meter

7] Ionizing radiation, subatomic particles

Bubble chamber

Cloud chamber

Geiger counter

Neutron detection

Particle detector

Scintillation counter

Scintillator

Wire chamber

8] Navigation instruments

Air speed indicator

Altimeter

Attitude indicator

Depth gauge

Fluxgate compass

Gyroscope

Inertial reference unit

Magnetic compass

MHD sensor

Ring laser gyroscope

Turn coordinator

Variometer

Vibrating structure gyroscope

Yaw rate sensor

9] Position, angle, displacement, distance, speed, acceleration

Accelerometer

Capacitive displacement sensor

Free fall sensor

Gravimeter

Inclinometer

Laser rangefinder

Linear encoder

Linear variable differential transformer (LVDT)

Liquid capacitive inclinometers

Odometer

Piezoelectric accelerometer

Position sensor

Rotary encoder

Rotary variable differential transformer

Selsyn

Sudden Motion Sensor

Tilt sensor

Tachometer

Ultrasonic thickness gauge

10] Optical, light, imaging

Charge-coupled device

Colorimeter

Contact image sensor

Electro-optical sensor

Flame detector

Infra-red sensor

LED as light sensor

Nichols radiometer

Fiber optic sensors

Photodetector

Photodiode

Photomultiplier tubes

Phototransistor

Photoelectric sensor

Photoionization detector

Photomultiplier

Photoresistor

Photoswitch

Phototube

Proximity sensor

Scintillometer

Shack-Hartmann

Wavefront sensor

11] Pressure

Barograph

Barometer

Boost gauge

Bourdon gauge

Hot filament ionization gauge

Ionization gauge

McLeod gauge

Oscillating U-tube

Permanent Downhole Gauge

Pirani gauge

Pressure sensor

Pressure gauge

Tactile sensor

Time pressure gauge

12] Force, density, level

Bhangmeter

Hydrometer

Force gauge

Level sensor

Load cell

Magnetic level gauge

Nuclear density gauge

Piezoelectric sensor

Strain gauge

Torque sensor

Viscometer

13] Thermal, heat, temperature

Bolometer

Calorimeter

Exhaust gas temperature gauge

Gardon gauge

Heat flux sensor

Infrared thermometer

Microbolometer

Microwave radiometer

Net radiometer

Resistance temperature detector

Resistance thermometer

Silicon bandgap temperature sensor

Temperature gauge

Thermistor

Thermocouple

Thermometer

14] Proximity, presence

Alarm sensor

Motion detector

Occupancy sensor

Passive infrared sensor

Reed switch

Stud finder

Triangulation sensor

Touch switch

Wired glove

Doppler radar

Alcohol Sensor (MQ 3)

Features

High sensitivity to alcohol and small sensitivity to Benzene.

Fast response and High sensitivity.

Stable and long life.

Simple drive circuit.

Application They are suitable for alcohol checker, Breathalyzer.

Basic Operation

Structure and configuration of MQ-3 gas sensor is shown as Fig. 1 (Configuration A or B),

sensor composed by micro AL2O3 ceramic tube, Tin Dioxide (SnO2) sensitive layer, measuring

electrode and heater are fixed into a crust made by plastic and stainless steel net. The heater

provides necessary work conditions for work of sensitive components. The enveloped MQ-3

have 6 pin, 4 of them are used to fetch signals, and other 2 are used for providing heating current.

Electric parameter measurement circuit is shown as Fig.2

E. Sensitivity characteristic curve

Sensitivity Adjustment

Resistance value of MQ-3 is difference to various kinds and various concentration gases. So,

when using these components, sensitivity adjustment is very necessary. we recommend that you

calibrate the detector for 0.4mg/L ( approximately 200ppm ) of Alcohol concentration in air and

use value of Load resistance that( RL) about 200 KΩ(100KΩ to 470 KΩ).When accurately

measuring, the proper alarm point for the gas detector should be determined after considering the

temperature and humidity influence.

Temperature Sensor (LM 35):

The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is

linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage

over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a

large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does

not require any external calibration or trimming to provide typical accuracies of ±1⁄4°C

at room temperature and ±3⁄4°C over a full −55 to +150°C temperature range. Low cost is

assured by trimming and calibration at the wafer level. The LM35’s low output impedance,

linear output, and precise inherent calibration make interfacing to readout or control circuitry

especially easy. It can be used with single power supplies, or with plus and minus supplies. As it

draws only 60 μA from its supply, it has very low self-heating, less than 0.1°C in still air. The

LM35 is rated to operate over a −55° to +150°C temperature range,while the LM35C is rated for

a −40° to +110°C range (−10° with improved accuracy). The LM35 series is available packaged

in hermetic TO-46 transistor packages, while the LM35C, LM35CA, and LM35D are also

available in the plastic TO-92 transistor package. The LM35D is also available in an 8-lead

surface mount small outline package and a plastic TO-220 package.

Features Calibrated directly in ° Celsius (Centigrade)

Linear + 10.0 mV/°C scale factor

0.5°C accuracy guaranteeable (at +25°C)

Rated for full −55° to +150°C range

Suitable for remote applications

Low cost due to wafer-level trimming

Operates from 4 to 30 volts

Less than 60 μA current drain

Low self-heating, 0.08°C in still air

Nonlinearity only ±1⁄4°C typical

Low impedance output, 0.1 W for 1 mA load

Typical Application

LM35 interface with the ADC 0804:

Thermistor

A thermistor is a type of resistor whose resistance varies significantly with temperature, more

so than in standard resistors. The word is a portmanteau of thermal and resistor. Thermistors are

widely used as inrush current limiters, temperature sensors, self-resetting over current protectors,

and self-regulating heating elements.

Thermistors differ from resistance temperature detectors (RTD) in that the material used in a

thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature

response is also different; RTDs are useful over larger temperature ranges, while thermistors

typically achieve a higher precision within a limited temperature range [usually −90 °C to

130 °C].

Thermistor symbol

Assuming, as a first-order approximation, that the relationship between resistance and temperature is linear, then:

where

ΔR = change in resistance

ΔT = change in temperature

k = first-order temperature coefficient of resistance

Thermistors can be classified into two types, depending on the sign of k. If k is positive, the

resistance increases with increasing temperature, and the device is called a positive temperature

coefficient (PTC) thermistor, or posistor. If k is negative, the resistance decreases with

increasing temperature, and the device is called a negative temperature coefficient (NTC)

thermistor. Resistors that are not thermistors are designed to have a k as close to zero as possible

(smallest possible k), so that their resistance remains nearly constant over a wide temperature

range.

Instead of the temperature coefficient k, sometimes the temperature coefficient of resistance α

(alpha) or αT is used. It is defined as.

For example, for the common PT100 sensor, α = 0.00385 or 0.385 %/°C. This αT coefficient

should not be confused with the α parameter below.

Thermistor, a word formed by combining thermal with resistor, refers to a device whose

electrical resistance, or ability to conduct electricity, is controlled by temperature. Thermistors

come in two varieties; NTC, negative thermal coefficient, and PTC, positive thermal coefficient,

sometimes called posisitors.

The resistance of NTC thermistors decreases proportionally with increases in temperature. They

are most commonly made from the oxides of metals such as manganese, cobalt, nickel and

copper. The metals are oxidized through a chemical reaction, ground to a fine powder, then

compressed and subject to very high heat. Some NTC thermistors are crystallized from

semiconducting material such as silicon and germanium.

NTC thermistors

The RS range of NTC thermistors includes standard tolerance negative temperature coefficient

thermistors, a range of small close tolerance R/T curve matched thermistors and a range of DO-

35 package devices.

Standard tolerance thermistors

A range of 13 negative temperature coefficient bead thermistors and 4 disc thermistors

constructed from a compound of nickel magnetite. Of the 13 bead thermistors, ten types are

sealed in glass and three are incorporated into stainless steel probe assemblies. This range was

designed primarily for temperature

measurement and control, flow measurement and liquid level detection. The four NTC disc

thermistors are intended for use in temperature compensation, measurement and control

applications. Disc diameter in all cases is 10mm with a lead pitch of 5mm (nominal).

The range of DO-35 packaged NTC thermistors is designed for temperature measurement and

control in applications which demand cost effective reliability. Typical applications include

domestic appliances, automotive systems, data processing equipment and heating/ventilating/air

conditioning control. The hermetically-sealed construction combines the advantages of high

temperature operation and high reliability of glass bead types with the closer tolerances

associated with chip devices. The glass encapsulation offers the additional benefit of high

voltage insulation.

Basic formulae

The temperature coefficient µ at any temperature within the operating range may be obtained

from the

Formula:

To determine the resistance at any temperature within the operating range may be obtained from

the formula:

B = characteristic temperature constant (°K)

T = bead temperature in (°K)

R1 = resistance of thermistor at temperature t1 (½)

R2 = resistance of thermistor at temperature t2 (½)

e = 2.7183

(Temperature in °K = temperature in °C +273).Application notes

Typical applications include temperature control of ovens, deep freezers, rooms and for process

control, etc. Can also be used to drive high and low temperature alarms. In the basic circuit

below, calibration should be carried out by comparison with a known standard (e.g. a

thermometer or thermocouple). In the case of 0°C, a mixture of ice and water can be used and for

+100°C, use boiling water.

Note: That non-linearity should be expected at extended temperatures.

Light Dependent Resistor (LDR)

A photo-resistor or light dependent resistor or cadmium sulfide (CdS) cell is

a resistor whose resistance decreases with increasing incident light intensity. It can also be

referred to as a photoconductor.

A photo resistor is made of a high resistance semiconductor. If light falling on the device is of

high enough frequency, photons absorbed by the semiconductor give bound electrons enough

energy to jump into the conduction band. The resulting free electron (and its hole partner)

conduct electricity, there by lowering resistance.

A photoelectric device can be either intrinsic or extrinsic. An intrinsic semiconductor has its

own charge carriers and is not an efficient semiconductor, e.g. silicon. In intrinsic devices the

only available electrons are in the valence band, and hence the photon must have enough energy

to excite the electron across the entire bandgap. Extrinsic devices have impurities, also

called dopants, added whose ground state energy is closer to the conduction band; since the

electrons do not have as far to jump, lower energy photons (i.e., longer wavelengths and lower

frequencies) are sufficient to trigger the device. If a sample of silicon has some of its atoms

replaced by phosphorus atoms (impurities), there will be extra electrons available for conduction.

This is an example of an extrinsic semiconductor.

The symbol for a photo-resistor

Applications:

Photo-resistors come in many different types. Inexpensive cadmium sulfide cells can be found in

many consumer items such as camera light meters, street lights, clock radios, alarms, and

outdoor clocks.

They are also used in some dynamic compressors together with a small incandescent

lamp or light emitting diode to control gain reduction.Lead sulfide (PbS) and indium

antimonide (InSb) LDRs (light dependent resistor) are used for the mid infrared spectral

region. Ge:Cu photoconductors are among the best far-infrared detectors available, and are used

for infrared astronomy and infrared spectroscopy.Transducers are used for changing energy

types.

A Light Dependent Resistor

ADC

The ADC0808 data acquisition component is a monolithic CMOS device with an 8-bit analog-

to-digital converter, 8-channel multiplexer and microprocessor compatible control logic. The 8-

bit A/D converter uses successive approximation as the conversion technique. The converter

features a high impedance chopper stabilized comparator, a 256R voltage divider with analog

switch tree and a successive approximation register. The 8-channel multiplexer can directly

access any of 8-single-ended analog signals. The device eliminates the need for external zero

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

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

ADC0808 has been optimized by incorporating the most desirable aspects of several A/D

conversion techniques. The ADC0808 offers high speed, high accuracy, minimal temperature

dependence, excellent long-term accuracy and repeatability, and consumes minimal power.

These features make this device ideally suited to applications from process and machine control

to consumer and automotive applications.

Features:

1. Easy interface to all microprocessors.

2. Operates ratio metrically or with 5 VDC or analog span adjusted voltage reference.

3. No zero or full-scale adjust required.

4. 8-channel multiplexer with address logic.

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

6. Outputs meet TTL voltage level specifications.

7. Standard hermetic or molded 28-pin DIP package.

8. 28-pin molded chip carrier package.

9. ADC0808 equivalent to MM74C949.

Key Specifications:

1. Resolution 8 Bits

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

3. Single Supply 5 VDC

4. Low Power 15 mW

5. Conversion Time 100 µs

Pin diagram:

Types of ADC:

Digital-Ramp ADC.

Successive Approximation ADC.

Flash ADC.

Digital-Ramp ADC:

Conversion from analog to digital form inherently involves comparator action where the value of

the analog voltage at some point in time is compared with some standard. A common way to do

that is to apply the analog voltage to one terminal of a comparator and trigger a binary counter

which drives a DAC. The output of the DAC is applied to the other terminal of the comparator.

Since the output of the DAC is increasing with the counter, it will trigger the comparator at some

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

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

Successive Approximation ADC:

The successive approximation ADC is much faster than the digital ramp ADC because it uses

digital logic to converge on the value closest to the input voltage. A comparator and a DAC are

used in the process. A flowchart explaining the working is shown in the figure below.

Flash ADC:

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

comparators provide an input to the combinational logic circuit, so the conversion time is just the

propagation delay through the network - it is not limited by the clock rate or some convergence

sequence. It is the fastest type of ADC available, but requires a comparator for each value of

output (63 for 6-bit, 255 for 8-bit, etc.) Such ADCs are available in IC form up to 8-bit and 10-

bit flash ADCs (1023 comparators) are planned. The encoder logic executes a truth table to

convert the ladder of inputs to the binary number output.

Applications:

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

or transported in digital form. Fast video ADCs are used, for example, in TV tuner cards. Slow

on-chip 8, 10, 12, or 16 bit ADCs are common in microcontrollers. Very fast ADCs are needed

in digital oscilloscopes, and are crucial for new applications like software defined radio and in

music recording. ADC's dynamic range is also important.

Relays

A relay is used to isolate one electrical circuit from another. It allows a low current control

circuit to make or break an electrically isolated high current circuit path. The basic relay consists

of a coil and a set of contacts. The most common relay coil is a length of magnet wire wrapped

around a metal core. When voltage is applied to the coil, current passes through the wire and

creates a magnetic field. This magnetic field pulls the contacts together and holds them there

until the current flow in the coil has stopped. The diagram below shows the parts of a simple

relay.

Figure: Relay

Operation:

When a current flows through the coil, the resulting magnetic field attracts an armature that is

mechanically linked to a moving contact. The movement either makes or breaks a connection

with a fixed contact. When the current is switched off, the armature is usually returned by a

spring to its resting position shown in figure 6.6(b). Latching relays exist that require operation

of a second coil to reset the contact position.

By analogy with the functions of the original electromagnetic device, a solid-state relay operates

a thyristor or other solid-state switching device with a transformer or light-emitting diode to

trigger it.

Pole and throw

SPST

SPST relay stands for Single Pole Single Throw relay. Current will only flow through the

contacts when the relay coil is energized.

Figure: SPST Relay

SPDT Relay

SPDT Relay stands for Single Pole Double Throw relay. Current will flow between the movable

contact and one fixed contact when the coil is De-energized and between the movable contact

and the alternate fixed contact when the relay coil is energized. The most commonly used relay

in car audio, the Bosch relay, is a SPDT relay.

Figure: SPDT Relay

DPST Relay

DPST relay stands for Double Pole Single Throw relay. When the relay coil is energized, two

separate and electrically isolated sets of contacts are pulled down to make contact with their

stationary counterparts. There is no complete circuit path when the relay is De-energized.

Figure: DPST Relay

DPDT Relay

DPDT relay stands for Double Pole Double Throw relay. It operates like the SPDT relay but has

twice as many contacts. There are two completely isolated sets of contacts.

Figure: DPDT Relay

This is a 4 Pole Double Throw relay. It operates like the SPDT relay but it has 4 sets of isolated

contacts.

Figure: 4 Pole Double Throw relay

Types of relay:

1. Latching Relay

2. Reed Relay

3. Mercury Wetted Relay

4. Machine Tool Relay

5. Solid State Relay (SSR)

Latching relay

Latching relay, dust cover removed, showing pawl and ratchet mechanism. The ratchet operates

a cam, which raises and lowers the moving contact arm, seen edge-on just below it. The moving

and fixed contacts are visible at the left side of the image.

A latching relay has two relaxed states (bi-stable). These are also called "impulse", "keep", or

"stay" relays. When the current is switched off, the relay remains in its last state. This is achieved

with a solenoid operating a ratchet and cam mechanism, or by having two opposing coils with an

over-center spring or permanent magnet to hold the armature and contacts in position while the

coil is relaxed, or with a remanent core. In the ratchet and cam example, the first pulse to the coil

turns the relay on and the second pulse turns it off. In the two coil example, a pulse to one coil

turns the relay on and a pulse to the opposite coil turns the relay off. This type of relay has the

advantage that it consumes power only for an instant, while it is being switched, and it retains its

last setting across a power outage. A remanent core latching relay requires a current pulse of

opposite polarity to make it change state.

Figure: Latching relay

Reed relay

A reed relay has a set of contacts inside a vacuum or inert gas filled glass tube, which protects

the contacts against atmospheric corrosion. The contacts are closed by a magnetic field generated

when current passes through a coil around the glass tube. Reed relays are capable of faster

switching speeds than larger types of relays, but have low switch current and voltage ratings.

Mercury-wetted Relay

A mercury-wetted reed relay is a form of reed relay in which the contacts are wetted with

mercury. Such relays are used to switch low-voltage signals (one volt or less) because of their

low contact resistance, or for high-speed counting and timing applications where the mercury

eliminates contact bounce. Mercury wetted relays are position-sensitive and must be mounted

vertically to work properly. Because of the toxicity and expense of liquid mercury, these relays

are rarely specified for new equipment. See also mercury switch.

Machine tool relay

A machine tool relay is a type standardized for industrial control of machine tools, transfer

machines, and other sequential control. They are characterized by a large number of contacts

(sometimes extendable in the field) which are easily converted from normally-open to normally-

closed status, easily replaceable coils, and a form factor that allows compactly installing many

relays in a control panel. Although such relays once were the backbone of automation in such

industries as automobile assembly, the programmable logic controller (PLC) mostly displaced

the machine tool relay from sequential control applications.

Solid-state relay

A solid state relay (SSR) is a solid state electronic component that provides a similar function to

an electromechanical relay but does not have any moving components, increasing long-term

reliability. With early SSR's, the tradeoff came from the fact that every transistor has a small

voltage drop across it. This voltage drop limited the amount of current a given SSR could handle.

As transistors improved, higher current SSR's, able to handle 100 to 1,200 Amperes, have

become commercially available. Compared to electromagnetic relays, they may be falsely

triggered by transients.

Figure: Solid relay, which has no moving parts

Specification

Number and type of contacts – normally open, normally closed, (double-throw)

Contact sequence – "Make before Break" or "Break before Make". For example, the old

style telephone exchanges required Make-before-break so that the connection didn't get

dropped while dialing the number.

Rating of contacts – small relays switch a few amperes, large contactors are rated for up

to 3000 amperes, alternating or direct current

Voltage rating of contacts – typical control relays rated 300 VAC or 600 VAC,

automotive types to 50 VDC, special high-voltage relays to about 15 000 V

Coil voltage – machine-tool relays usually 24 VAC, 120 or 250 VAC, relays for

switchgear may have 125 V or 250 VDC coils, "sensitive" relays operate on a few milli-

amperes

Applications:

Relays are used:

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

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

automobile,

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

circuit breakers (protection relays),

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

potentials, for example when controlling a mains-powered device from a low-voltage

switch. The latter is often applied to control office lighting as the low voltage wires are

easily installed in partitions, which may be often moved as needs change. They may also

be controlled by room occupancy detectors in an effort to conserve energy,

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

connecting relay contacts in series, the OR function by connecting contacts in parallel.

Due to the failure modes of a relay compared with a semiconductor, they are widely used

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

machinery.

As oscillators, also called vibrators. The coil is wired in series with the normally closed

contacts. When a current is passed through the relay coil, the relay operates and opens the

contacts that carry the supply current. This stops the current and causes the contacts to

close again. The cycle repeats continuously, causing the relay to open and close rapidly.

Vibrators are used to generate pulsed current.

To generate sound. A vibrator, described above, creates a buzzing sound because of the

rapid oscillation of the armature. This is the basis of the electric bell, which consists of a

vibrator with a hammer attached to the armature so it can repeatedly strike a bell.

To perform time delay functions. Relays can be used to act as an mechanical time delay

device by controlling the release time by using the effect of residual magnetism by means

of a inserting copper disk between the armature and moving blade assembly.

LCD(Liqiud Crystal Display )

One of the most common devices attached to an controller is an LCD display. Some of the most

common LCDs connected to the controllers are 16X1, 16x2 and 20x2 displays. This means 16

characters per line by 1 line 16 characters per line by 2 lines and 20 characters per line by 2 lines,

respectively. But in this project we are interfacing the 16*2 LCD it consists a 16 pins.

Schematic Diagram:

Figure: Schematic Diagram

Pin Description

LCD consist

the three control

line (RS,

R/W,&En), eight data lines (D0-D7), Supply Voltage (Vcc), Contrast control (Vee) and ground

(Vss).

Control Pins Description

EN (Enable)

Line is called "Enable." This control line is used to tell the LCD that you are sending it data. To

send data to the LCD, your program should make sure this line is low (0) and then set the other

two control lines and/or put data on the data bus. When the other lines are completely ready,

PinSymbol Level Function

1 VSS - Power, GND

2 VDD - Power, 5V

3 Vo - Power, for LCD Drive

4 RS H/L

Register Select Signal

H: Data Input

L: Instruction Input

5 R/W H/LH: Data Read (LCD->MPU)

L: Data Write (MPU->LCD)

6 E H,H->L Enable

7-14 DB0-DB7 H/L Data Bus; Software selectable 4- or 8-bit mode

15 NC - NOT CONNECTED

16 NC - NOT CONNECTED

bring EN high (1) and wait for the minimum amount of time required by the LCD datasheet (this

varies from LCD to LCD), and end by bringing it low (0) again.

RS (Register Select)

Line is the "Register Select" line. When RS is low (0), the data is to be treated as a command or

special instruction (such as clear screen, position cursor, etc.). When RS is high (1), the data

being sent is text data which should be displayed on the screen. For example, to display the letter

"T" on the screen you would set RS high.

R/W (Read write)

Line is the "Read/Write" control line. When RW is low (0), the information on the data bus is

being written to the LCD. When RW is high (1), the program is effectively querying (or reading)

the LCD. Only one instruction ("Get LCD status") is a read command. All others are write

commands, so RW will almost always be low.

Finally, the data bus consists of 4 or 8 lines (depending on the mode of operation selected by the

user). In the case of an 8-bit data bus, the lines are referred to as DB0, DB1, DB2, DB3, DB4,

DB5, DB6, and DB7.

Logic status on control lines:

• E - 0 Access to LCD disabled

- 1 Access to LCD enabled

• R/W - 0 Writing data to LCD

- 1 Reading data from LCD

• RS - 0 Instructions

- 1 Character

Writing data to the LCD:

1) Set R/W bit to low

2) Set RS bit to logic 0 or 1 (instruction or character)

3) Set data to data lines (if it is writing)

4) Set E line to high

5) Set E line to low

Read data from data lines (if it is reading) on LCD:

1) Set R/W bit to high

2) Set RS bit to logic 0 or 1 (instruction or character)

3) Set data to data lines (if it is writing)

4) Set E line to high

5) Set E line to low

CHAPTER-6

Software Components:

ABOUT SOFTWARE

Software’s used are:

Keil software for c programming

Express PCB for lay out design

Express SCH for schematic design.

What's New in µVision3?

µVision3 adds many new features to the Editor like Text Templates, Quick Function Navigation,

and Syntax Coloring with brace high lighting Configuration Wizard for dialog based startup and

debugger setup. µVision3 is fully compatible to µVision2 and can be used in parallel with

µVision2.

What is µVision3?

µVision3 is an IDE (Integrated Development Environment) that helps you write, compile, and

debug embedded programs. It encapsulates the following components:

A project manager.

A make facility.

Tool configuration.

Editor.

A powerful debugger.

To help you get started, several example programs (located in the \C51\Examples, \C251\

Examples, \C166\Examples, and \ARM\...\Examples) are provided.

HELLO is a simple program that prints the string "Hello World" using the Serial

Interface.

MEASURE is a data acquisition system for analog and digital systems.

TRAFFIC is a traffic light controller with the RTX Tiny operating system.

SIEVE is the SIEVE Benchmark.

DHRY is the Dhrystone Benchmark.

WHET is the Single-Precision Whetstone Benchmark.

Additional example programs not listed here are provided for each device architecture.

Building an Application in µVision2

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

1. Select Project -(forexample,166\EXAMPLES\HELLO\HELLO.UV2).

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

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

Creating Your Own Application in µVision2

To create a new project in µVision2, you must:

1. Select Project - New Project.

2. Select a directory and enter the name of the project file.

3. Select Project - Select Device and select an 8051, 251, or C16x/ST10 device from the

Device Database™.

4. Create source files to add to the project.

5. Select Project - Targets, Groups, Files. Add/Files, select Source Group1, and add the

source files to the project.

6. Select Project - Options and set the tool options. Note when you select the target device

from the Device Database™ all special options are set automatically. You typically only

need to configure the memory map of your target hardware. Default memory model

settings are optimal for most applications.

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

Debugging an Application in µVision2

To debug an application created using µVision2, you must:

1. Select Debug - Start/Stop Debug Session.

2. Use the Step toolbar buttons to single-step through your program. You may enter G,

main in the Output Window to execute to the main C function.

3. Open the Serial Window using the Serial #1 button on the toolbar.

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

Starting µVision2 and creating a Project

µVision2 is a standard Windows application and started by clicking on the program icon. To

create a new project file select from the µVision2 menu.

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

for the new project file name.

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

New Folder in this dialog to get a new empty folder. Then select this folder and enter the file

name for the new project, i.e. Project1. µVision2 creates a new project file with the name

PROJECT1.UV2 which contains a default target and file group name. You can see these names

in the Project.

Window – Files.

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

The Select Device dialog box shows the µVision2 device database. Just select the micro

controller you use. We are using for our examples the Philips 80C51RD+ CPU. This selection

sets necessary tool options for the 80C51RD+ device and simplifies in this way the tool

Configuration.

Building Projects and Creating a HEX Files

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

may translate all source files and line the application with a click on the Build Target toolbar

icon. When you build an application with syntax errors, µVision2 will display errors and

warning messages in the Output Window – Build page. A double click on a message line opens

the source file on the correct location in a µVision2 editor window. Once you have successfully

generated your application you can start debugging.

After you have tested your application, it is required to create an Intel HEX file to download the

software into an EPROM programmer or simulator. µVision2 creates HEX files with each build

process when Create HEX files under Options for Target – Output is enabled. You may start

your PROM programming utility after the make process when you specify the program under the

option Run User Program #1.

CPU Simulation

µVision2 simulates up to 16 Mbytes of memory from which areas can be mapped for read, write,

or code execution access. The µVision2 simulator traps and reports illegal memory accesses.

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

peripherals of the various 8051 derivatives. The on-chip peripherals of the CPU you have

selected are configured from the Device.

Database selection

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

about selecting a device. You may select and display the on-chip peripheral components using

the Debug menu. You can also change the aspects of each peripheral using the controls in the

dialog boxes.

Start Debugging

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

Depending on the Options for Target – Debug Configuration, µVision2 will load the application

program and run the startup code µVision2 saves the editor screen layout and restores the screen

layout of the last debug session. If the program execution stops, µVision2 opens an editor

window with the source text or shows CPU instructions in the disassembly window. The next

executable statement is marked with a yellow arrow. During debugging, most editor features are

still available.

For example, you can use the find command or correct program errors. Program source text of

your application is shown in the same windows. The µVision2 debug mode differs from the edit

mode in the following aspects:

_ The “Debug Menu and Debug Commands” described on page 28 are Available. The additional

debug windows are discussed in the following.

_ The project structure or tool parameters cannot be modified. All build Commands are disabled.

Disassembly Window

The Disassembly window shows your target program as mixed source and assembly program or

just assembly code. A trace history of previously executed instructions may be displayed with

Debug – View Trace Records. To enable the trace history, set Debug – Enable/Disable Trace

Recording.

If you select the Disassembly Window as the active window all program step commands work

on CPU instruction level rather than program source lines. You can select a text line and set or

modify code breakpoints using toolbar buttons or the context menu commands.

You may use the dialog Debug – Inline Assembly… to modify the CPU instructions. That allows

you to correct mistakes or to make temporary changes to the target program you are debugging.

Steps for executing the Keil programs:

1. Click on the Keil uVision Icon on Desktop

2. The following fig will appear

3. Click on the Project menu from the title bar

4. Then Click on New Project

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

6. Then Click on save button above.

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

8. Click on the + Symbol beside of Atmel

9. Select AT89C51 as shown below

10. Then Click on “OK”

11. The Following fig will appear

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

13. Now your project is ready to USE

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

shown in next page.

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

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

clicking on its blue boarder.

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

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

based program save it with extension “ .C”

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

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

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

22. Click only one time on option “ADD”

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

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

25. The new window is as follows

26. Then Click “OK”

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

in fig below

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

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

30. You are running your program successfully

SCHEMATIC DIAGRAM

Schematic Explanation