Analog Sensor

8/8/2019 Analog Sensor

1/44

SUMMER TRAINING PROJECT REPORT

ON

INTERFACING OF ANALOG SENSORWITH AN 8051 MICROCONTROLLER

TO

NORTHERN INDIA ENGINEERING COLLEGE,

NEW DELHI

For the degree

OfBachelor in Technology

In

Electronics & Communication

NORTHERN INDIA ENGINEERING COLLEGE,

FC-26, SHASTRI PARK, NEW DELHI-53MAY 2010

SUBMITTED BY:

Ravinder Singh 0171562808 (ECE-S3)

Swati Varun 0001562808 (ECE-S3)

Gautam Panwar 0211562808 (ECE-S3)

Navendu Pratap Sagar - 0221562808(ECE-S3)

1


2/44

CERTIFICATE

This is to certify that Project Report titled INTERFACING OF ANALOGSENSOR WITH AN 8051 MICROCONTROLLER, which is submitted

by following students of Bachelors in Technology in Electronics and

Communication Engg. Of NORTHERN INDIA ENGINEERING

COLLEGE, NEW DELHI, under my supervision.

Projectee:

Ravinder Singh 0171562808

Swati Varun 0001562808

Gautam Panwar 0211562808

Navendu Pratap Sagar - 0221562808

Head of the department Supervisor/Guide

2


3/44

ACKNOWLEDGEMENT

We feel highly privileged to express our deep sense of gratitude to allthose who helped us during our project work. We would like to express

our grateful thanks for the help and advice given to us by

, HOD ECE Dept., for their valuable guidance in our project.

We express our gratitude and reverence to the preceptor and project

Guide.... for his advice, guidance and support which helped us in

completing our project.

We are also highly thankful to the management of NORTHERN INDIA

ENGINEERING COLLEGE, for providing necessary facilities and

infrastructure.

Date:

APPROVED BY:

3


4/44

CONTENTS

TABLE OF CONTENTS...................................................................4

OVERVIEW...5

CHAPTER1:INTRODUCTION.........................................................6

REQUIREMENTS...........................................................................7

CHAPTER 2: ANALOG SENSOR

2.1 Introduction.........................................................................8

2.2 Analog to digital converter .................................................8

2.3 Types of A/D converter102.4 Useful Analog sensors.......................................................12

CHAPTER 3: MICROCONTROLLER

3.1 Introduction...14

3.2 P89V51RD2FN Microcontroller............................................15

3.3 Pin Diagram..........................................................................16

3.4 Pin Descriptions...17

3.5 Data table..20

CHAPTER 4: ICs

4.1 MAX232.....27

4.2 ULN280330

4.3 PCF859133

CHAPTER 5: OVER ALL SYSTEM

5.1 Block Diagram.........................................................................36

5.2 Hardware..375.3 Programme..38

CONCLUSIONS.............................................................................43

TOOLS AND DEVELOPMENT......................................................44

REFERENCES...............................................................................44

4


5/44

OVERVIEW

In our project we have explained how to read value from an analog

sensor (Potentiometer used here) and send it to microcontroller via

analog to digital converter. The value read is further displayed by led

array in binary format. The circuit incorporates various IC along with

8051 microcontroller.

5


6/44

PART 1

INTRODUCTION

A sensor is a device which measures or detects a physical quantity. Whereas an

actuator is a device which converts a signal, usually electrical, into some action i.e.

mechanical.

Transducer is a device which can convert one form of energy to other.So,sensor as

well as actuator is a transducer.

Among the different types of energy which can be sensed are those classed as

radiant,mechanical,gravitational,electrical

, thermal and magnetic.All the value sensed are usually analog in nature. As these values involve

computational work, so these value must be converted into digital format as

computers cant accept analog signal.

Analog signals are those signals which can take any possible values between two

points whereas digital signals can take only certain discrete values between two

points.

6


7/44

REQUIREMENTS

Computer Interfacing.

Potentiometer(10kohm).

IC MAX232, ULN2803, PCF8591.

P89V51RD2FN microcontroller.

7


8/44

PART 2

ANALOG SENSOR

2.1 INTRODUCTION:

Analog sensors measure continuous information. An example of this kind of a

sensor is a light sensor which monitors the amount of light over time. Analog

sensors are often distinguished from digital sensors which use discrete

(discontinuous) values to represent information for input. Often though either

approach can be used to provide similar types of information. For example, film

cameras are analog devices, while Web cameras are digital devices.

Now,the question arises, how these analog signals are converted into digital

signals.There are several ic available in market which performs the function of a to

d conversion.

We have used PCF8591 IC as a/d converter..

2.2 Analog to Digital Converter:

Microcontrollers almost always deal with discrete values. An important part of

using an Analog Signal is being able to convert it to a Discrete Signal such as a 8-

bit digital value. This allows the Microcontroller to do things like compute values

and perform comparisons. Fortunately, most modern controllers have a resource

called an Analog to Digital converter (A/D converter).

8


9/44

The function of the A/D converter is to convert an Analog signal into a digital

value. It does this with a mapping function that assigns discrete values to the entire

range of voltages. It is typical for the range of an A/D converter to be 0 to +5 volts.

The A/D converter will divide the range of values by the number of discrete

combinations. For example, the table on the right shows 5 samples of an Analog

Signal that have been converted into digital values.

The Chart on the bottom shows the results of the A/D conversions for 14 samples.

The sample numbers are shown along the X axis at the bottom. The left hand Y axis

indicates the voltage of the Analog sample that was fed into the A/D converter. On

the right hand side, the 8-bit value assigned to the conversion is show.

As you can see from the blue line, this was an analog function just like the originalAnalog Signal graph shown above. The A/D converter has mapped a set of discrete

values onto this graph.

9


10/44

Now these digital signals are send to microcontrooler for processing. Afterthat, microcontroller sends value in binary to led array.

2.3 Types of a/d converters:

1. Ladder comparison2. Successive approximation

3. Flash comparison

These three are important converters. Beside these, several other

converters are also available.

1. Ladder comparison

2. Successive approximation10


11/44

3. Flash comparison

If N is the number of bits in the output word,

Then 2^N comparators will be required.

2.4 Useful Analog Sensors:11


12/44

All of the circuits shown in this section are intended to be connected to an A/D

converter port.

CdS cells:

Cadmium sulphide is a unique compound with a property that itsresistance varies with intensity of light. Higher the intensity, lower the

resistance. In the diagram shown in right, p1 is CdS cell whereas r1 is

10k resistance. Using voltage divider equation, we can calculate the

voltage at avg light and accordingly choose our a/d converter.

Potentiometers:

12


13/44

Potentiometer is one of the most extensively used analog sensor.It is

widely used in robotic arm to sense the angle in a range of 0 to 270

degree.it is basically a resistive sensor.its schematic is similar to the

schematic of CdS cell sensor mentioned above.Value read by a/d

converter changes with contact position on r2.As the contact positionchanges ,different values of voltage occurs at i/p of a to d converter

according to voltage divider rule.

PART 3

MICROCONTROLLER13


14/44

3.1 INTRODUCTION:Microcontrollers are "special purpose computers." Microcontrollers do one thing

well. There are a number of other common characteristics that define

microcontrollers. If a computer matches a majority of these characteristics, then you

can call it a "microcontroller":

Microcontrollers are "embedded" inside some other device (often a

consumer product) so that they can control the features or actions of the product.

Another name for a microcontroller, therefore, is "embedded controller."

Microcontrollers are dedicated to one task and run one specific program.

The program is stored in (read-only memory) and generally does not change.Microcontrollers are often low-power devices. A desktop computer is

almost always plugged into a wall socket and might consume 50 watts of

electricity. A battery-operated microcontroller might consume 50 milliwatts.

A microcontroller has a dedicated input device and often (but not always)

has a small LED or LCD display for output. A microcontroller also takes input

from the device it is controlling and controls the device by sending signals to

different components in the device.

In our project we are using P89C51RD2 MICROCONTROLLER.

3.2 P89V51RD2FN MICROCONTROLLER

The P89C51RD2 is a low-power, high-performance CMOS 8-bit

microcontroller with 8K bytes of Flash programmable and erasable read only

memory (PEROM). The device is manufactured using Philips high-density

14


15/44

nonvolatile memory technology and is compatible with the industry-standard MCS-

51 instruction set and pinout. 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 Flash on a monolithic chip, the Philips

P89V51RD2FN is a powerful microcomputer which provides a highly-flexible andcost-effective solution to many embedded control applications.

The P89V51RD2FN provides the following standard features: 64 kB flash

microcontroller with 1024 byte RAM; Clock type: 12-clk (6-clk opt.) ; External

interrupt: 2; I/O pins: 32 ; Memory type: FLASH ; Number of pins: 40 ; Operating

frequency: 0~20/40 (6clk/12clk) MHz; Operating temperature: -40~85 Cel; Power

supply: 4.5~5.5V ; Program security: yes; Serial interface: UART ; Series: 80C51

family

3.3 PIN DIAGRAM

15


16/44

3.4 PIN DESCRIPTION

VCC:

16


17/44

Supply voltage.

GND:

Ground.

Port 0:

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

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

high impedance inputs.

Port 0 may also be configured to be the multiplexed low order address/data bus

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

pull ups.

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

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

verification.

Port 1:

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

pulled high by the internal pull-ups when 1s are written to them and can be used

as inputs in this state. As inputs, Port 1 pins that are externally pulled LOW will

source current (IIL) because of the internal pull-ups. P1.5, P1.6, P1.7 have high

current drive of 16 mA. Port 1 also receives the low-order address bytes during the

external host mode programming and verification.

Port 2:

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

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

pulled high by the internal pull ups and can be used as inputs. As inputs, Port 2 pins

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

pull ups. Port 2 emits the high-order address byte during fetches from external

program memory and during accesses to external data memory that use 16-bit

addresses. In this application, it uses strong internal pull ups when emitting 1s.

During accesses to external data memory that use 8-bit addresses (MOVX @ RI),

Port 2 emits the contents of the P2 Special Function Register. Port 2 also receivesthe high-order address bits and some control signals during Flash programming and

verification.

Port 3:

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

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

17


18/44

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

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

ups. Port 3 also serves the functions of various special features of the AT89C51 as

listed below:

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

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 output pulse for latching the low byte of the address duringaccesses to external memory. This pin is also the program pulse input (PROG)

during Flash programming. In normal operation ALE is emitted at a constant rate of

1/6 the oscillator frequency, and may be used for external timing or clocking

purposes. Note, however, that one ALE pulse is skipped during each access to

external Data Memory.

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

With the bit set, ALE is active only during a MOVX or MOVC instruction.

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

if the microcontroller is in external execution mode.

PSEN:

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

microcontroller 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:18


19/44

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

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

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

latched on reset.

EA should be strapped to VCC for internal program executions. This pin alsoreceives the 12-volt programming enable voltage(VPP) during Flash programming,

for parts that require12-volt VPP.

XTAL1:

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

circuit.

XTAL2:

Output from the inverting oscillator amplifier.

DATA TABLE:

BLOCK DIAGRAM OF IC:

19


20/44

RECOMMENDED OPERATING CONDITIONS:

OPERATING RANGE:

20


21/44

RELIABILITY CHARACTERISTICS:

POWER-UP TIMING:

21


22/44

PIN IMPEDANCE:

STATIC CHARACTERISTICS:

22


23/44

SPECIAL FUNCTION REGISTERS:

23


24/44

24


25/44

25


26/44

26


27/44

PART 4

ICs

4.1 MAX 232

INTRODUCTION:

The MAX232 is a dual driver/receiver that includes a capacitive voltage generator

to supply TIA/EIA-232-F

Voltage levels from a single 5-V supply. Each receiver converts TIA/EIA-232-Finputs to 5-V TTL/CMOS levels.

These receivers have a typical threshold of 1.3 V, a typical hysteresis of 0.5 V, and

can accept 30-V inputs.

Each driver converts TTL/CMOS input levels into TIA/EIA-232-F levels.

They are

supplied in 16 pin plastic DIP

packages with a

copper lead

frame to reduce

thermal

resistance.

PIN CONNECTION:

27


28/44

FUNCTION TABLE:

28


29/44

4.2 ULN 2803

29


30/44

INTRODUCTION:

The ULN2803APG / AFWG Series are high voltage, high current Darlington

drivers comprised of eight NPN Darlington pairs.All units feature integral clamp diodes for switching inductive loads.

Applications include relay, hammer, lamp and display (LED) drivers.

FEATURES:

Output current (single output) 500 mA (Max.)

High sustaining voltage output 50 V (Min.)

Output clamp diodes

Inputs compatible with various types of logic.

Package TypeAPG : DIP18pin

Package TypeAFWG : SOL18pin

PIN CONNECTION:

30


31/44

31


32/44

4.3 PCF8591

32


33/44

INTRODUCTION

The PCF8591 is a single-chip, single-supply low power 8-bit CMOS data

acquisition device with four analog inputs, one analog output and a serial I2C-businterface. Three address pins A0, A1 and A2 are used for programming the

hardware address, allowing the use of up to eight devices connected to the I2C-bus

without additional hardware. Address, control and data to and from

the device are transferred serially via the two-line bidirectional I2C-bus.

The functions of the device include analog input multiplexing, on-chip track and

hold function, 8-bit analog-to-digital conversion and an 8-bit digital-to-analog

conversion. The maximum conversion rate is given by the maximum speed of the

I2C-bus

FEATURES

Single power supply

Operating supply voltage 2.5 V to 6 V

Low standby current

Serial input/output via I2C-bus

Address by 3 hardware address pins

Sampling rate given by I2C-bus speed

4 analog inputs programmable as single-ended or differential inputs Auto-incremented channel selection

Analog voltage range from VSS to VDD

On-chip track and hold circuit

8-bit successive approximation A/D conversion

Multiplying DAC with one analog output

APPLICATIONS

Closed loop control systems

33


34/44

Low power converter for remote data acquisition

Battery operated equipment

Acquisition of analog values in automotive, audio and TV applications.

PIN CONNECTION:

Block Diagram:

34


35/44

PART 5

35


36/44

OVER ALL SYSTEM

5 .1 BLOCK DIAGRAM

5.2 HARDWARE

36


37/44

Interfacing

Interfacing is an important task to be accomplished in almost all

automation applications. The digital signals are to be generated to make the

hardware run as per the instructions of program.In the present application, the programming is done in .C. programming

language. .C. is chosen for its simplicity and ruggedness. It offers simple methods

to interact with the serial port through which the interfacing is done.

PROGRAMME

37


38/44

#ifndef __I2C_H

#define __I2C_H

#include

#include

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

#define NOP _nop_()

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

void I2C_START();

void I2C_STOP();

void I2C_SEND(unsigned char );unsigned char I2C_REC(void);

void I2C_ACK();

void I2C_NACK();

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

sbit SCL=P1^6;

sbit SDA=P1^7;

bit FLAG;

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

#endif

void I2C_START()

{

SDA=1;

SCL=1;NOP;

SDA=0;

NOP;

SCL=0;

}

38


39/44

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

void I2C_STOP()

{

SDA=0;SCL=1;

NOP;

SDA=1;

NOP;

SCL=0;

}

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

void I2C_SEND(unsigned char VALUE){

unsigned char i;

for(i=0;i


40/44

unsigned char I2C_REC(void)

{

unsigned char i,VALUE;

VALUE=0;SDA=1;

for(i=0;i


41/44

NOP;

NOP;

SCL=0;

}

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

void I2C_NACK()

{

SDA=1;

SCL=1;

NOP;

NOP;

SCL=0;

}unsigned char read_adc(unsigned char channel)

{

unsigned char value;

I2C_START();

I2C_SEND(0X90);

I2C_SEND(channel);

I2C_START();

I2C_SEND(0X91);

value=I2C_REC();I2C_ACK();

value=I2C_REC();

I2C_NACK();

I2C_STOP();

return value;

}

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

void init_uart()

{

SCON=0X50;TMOD=0X20;

TH1=TL1=0XFD;

TR1=1;

}

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

void tx(unsigned char value)

41


42/44

{

SBUF=value;

while(!TI);

TI=0;

}//--------------------------

main()

{

while(1)

{

P0=read_adc(0);

}

}

CONCLUSION

42


43/44

The project was successfully completed after a lot of efforts and work hours. This

project underwent compiling, debugging, removing errors, make it bug free, adding

more facilities & interactivity, make it more reliable and user friendly.

Guidance was taken from faculty; help from the friend were accepted at the variousproject development phases. Many books related to controlling of microcontroller were

referred to get the desired results.

TOOLS AND DEVELOPMENT

43


44/44

Hardware:The hardware used to develop our project includes:

1. pot ( potentiometer, 10kohm)

2. IC MAX232, ULN2803, PCF8591

3. A P89V51RD2FN microcontroller.

Software: C language, KEIL Compiler, flash magic

REFERENCES

SITES:

http://www.google.com

http://www.wikipedia.com

BOOKS:

The 8051 microcontroller & Embedded system-Muhammad Ali Mazidi
http://www.google.com/http://www.wikipedia.com/http://www.google.com/http://www.wikipedia.com/

Documents

Analog Sensor