Acc. No. DC 89

7/27/2019 Acc. No. DC 89

1/78

DESIGN & DEVELOPMENT OF A PIC 16F877A BASED

FUZZY TEMPERATURE CONTROLLER

THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THEREQUIREMENTS FOR THE AWARD OF THE DEGREE OF

MASTER OF TECHNOLOGY

INVLSI DESIGN & MICROELECTRONICS TECHNOLOGY

BY

SEKHAR RANA

Under the Supervision of

Prof. M. K. NASKAR

Department of Electronics & Tele-Communication Engineering

Jadavpur UniversityKolkata-700032

West Bengal, IndiaMay 2010

7/27/2019 Acc. No. DC 89

2/78

Faculty of Engineering & Technology

Jadavpur University

This to certify that the thesis entitled DESIGN & DEVELOPMENT OF APIC 16F877A BASED FUZZY TEMPERATURECONTROLLER has been carriedout by Sekhar Rana (college Roll No. : 000710703016 of 2007-2008 andRegistration No. : 100871 of 2007-08 and Examination Roll no. : M6VLSI10-15)

under my guidance and supervision and be accepted in partial fulfillment ofthe requirement for the degree of Master of Technology in VLSI design &Microelectronics Technology.

_________________________Prof. M. K. Naskar

Professor (Dept. of ETCE)Jadavpur University

Kolkata-70032

West Bengal, India

________________________

Prof. Bhaskar GuptaH.O.D (Dept. of ETCE)

Jadavpur UniversityKolkata-70032

West Bengal, India

_____________________________Prof. N. Chakraborty

Dean, Faculty of Engg. & TechnologyJadavpur University

Kolkata-70032West Bengal, India

7/27/2019 Acc. No. DC 89

3/78

Faculty of Engineering & Technology

Jadavpur University

CERTIFICATE OF APPROVAL *

The forgoing thesis, entitled DESIGN & DEVELOPMENT OF A PIC 16F877A

BASED FUZZY TEMPERATURE CONTROLLER is hereby approved as a

creditable study of an engineering subject carried and presented in a manner

satisfactory to warrant its acceptance as prerequisite to the degree for which it has

been submitted. It is understood this by this approval the undersigned do not

necessarily endorse or accept every statement made, opinion expressed or conclusion

drawn therein but approve the thesis only for the purpose for which it has been

submitted.

Committee on final

Examination for

Evaluation of the thesis

..

(ADDITIONAL EXAMINER)

_________________________

(Prof. M. K. NASKAR)

(SUPERVISOR)

* Only in case the thesis is approved.

7/27/2019 Acc. No. DC 89

4/78

Acknowledgement

The satisfaction that accompanies the successful completion of any task would be

incomplete without the mention of the people who make it possible and whose

constant guidance and encouragement grown all the efforts with success. The

acknowledgement transcends the reality of formality when I would like to express

deep gratitude and respect to all those people behind the screen who guided, inspired

and helped me for the completion of my project work.

I would like to acknowledge my sincere appreciation to Prof. Mrinal Kanti Naskar,

Department of Electronics and Telecommunication Engineering, Jadavpur University

for this immense guidance, valuable advice & constructive suggestions in carrying out

this thesis work. He directed me very patiently but with great enthusiasm and concrete

interest towards the great efficiency of this work. I was fully allowed to have

necessary freedom to exercise thoughtful and scientific approach to the problem.

My sincere thanks to Prof. Bhaskar Gupta, Head of the Department, Electronics and

Telecommunication Engineering, Jadavpur University who was kind enough to

provide me with all the necessary facilities to carry out this project.

I would like to thank Sourav (Sourav Ghosh), Lecturer of CIEM and my other friends

for their immense help to develop the project.

I would like to thanks to my beloved parents & all of my family members for their

continual encouragement.

Dated: Regards

Place: ______________________

(Sekhar Rana)

7/27/2019 Acc. No. DC 89

5/78

ABSTRACT

Temperature deviation plays a negative impact on sophisticated

instruments in hardware industries as well as it shows its importance in

different types of commercial applications. An immense temperature

difference may cause various difficulties and can damage the various

components that use in the particular system, so it is very necessary to

take the desire step to solve this problem automatically. To control the

temperature automatically, here we make an autonomous system which

will measure the temperature of the particular system & shows the

deviation of temperature visually and take necessary step to solve the

problem. There are several ways to eradicate this problem, but here we

choose the particular one that will able to handle it quite easily and more

effectively. For this purpose, we introduce PIC (peripheral interface

controller) Microcontroller [16f877A] based temperature controller & to

control its operation use Fuzzy logic to make it more efficient. A fuzzylogic was used to perform the temperature control. The idea behind the

use of the fuzzy logic was from the fact that which can be applied forcontrol of complex systemswherein mathematical model is not available.

7/27/2019 Acc. No. DC 89

6/78

Contents

1. Introduction1.1. Background 2

1.2. Scope of the project 3

1.3. Introduction of PIC 16F877A 4

1.4. DC motor driver module 5

1.5. Voltage regulator (KA 7805) 7

1.6. Potentiometer Module 8

1.7. Fuzzy Logic module 10

1.8. Organization 18

2.System Overview2.1. Overview of the autonomous system 20

2.2 System description 21

2.3 Flow Chart of the System 23

3. Hardware design & Implementation3.1 Connection diagram of PIC 16F877A 25

3.2 Connection diagram of Sensor (LM 35) 26

3.3 Connection diagram of LCD Module 27

3.4 Connection diagram of DC motor 283.5 Short description of the components 29

7/27/2019 Acc. No. DC 89

7/78

4. Software Design & Implementation

4.1 Introduction to MikroC 36

4.2 How to Build a Project 36

4.3 MikroC Libraries 41

5. Results of Experiment 476. Conclusion and Future Scope 51

Bibliography 52

Appendix 54

7/27/2019 Acc. No. DC 89

8/78

1

CHAPTER 1iNTRODUCTiON

7/27/2019 Acc. No. DC 89

9/78

2

Chapter 1 Introduction

1.1 Background:

Since the down of civilization, Temperature change plays a pivotal role

on human beings. Now we are living on modern era, we never bothered to tolerate the

negative effects due to the deviation of temperature. It not only hampers the living style of

mankind but also shows huge negative impact the operation on different types of instruments,

it ruins the freshness of vegetables and it may causes different types diseases due to the

sudden change of temperature (e.g.-chicken pox). In some occasions it is very essential to

maintain the temperature up to some extent otherwise it may take life also (e.g. - In the case

of born of pre-mature/term baby, it is very essential to preserve the baby in particular

temperature). Today we are living in the generation where we are very much dependent on

different type of electronics gadgets; operation of the electronics circuitry, integrated chip is

very much effected due to the deviation of temperature. Due to the rise of temperature may

reduce the life span or it may damage the gadgets. Every sophisticated electronic instrument

can operate safely in a particular temperature range, after knowing the particular temperature

range; we have to maintain it.

7/27/2019 Acc. No. DC 89

10/78

3


1.2 Scope of the project:

Since this problem is related to the life and property of thehuman kind so it is very essential, to build a system to give a possible solution of this

threatening problem. Accurate identification of temperature, temperature deviation is very

important. Manually we can control it up to some extent, but always it is not possible. It is

quite tedious and error inductive. So it is very essential to build an autonomous system which

will maintain it automatically and reduce man power.

The system which we have built will measures the

temperature deviation (with respect to reference temperature) and take the necessary decision

automatically and keep the temperature in a particular level for satisfactory operation. This

detection of temperature change will be done automatically to provide more flexibility to that

done manually. The system has a temperature sensor which detects the actual and error value

of the temperature. The analog voltage value obtained from the sensor is then fed to a

controller whose job is to provide a unique digital value for each analog voltage value. After

fuzzification & defuzzification we get the desire value at the output. This particular

defuzzified value determines the rotation speed of the DC motor.

7/27/2019 Acc. No. DC 89

11/78

4


1.3 Introduction of PIC 16F877A

Peripheral interface controller (PIC) is a family of microcontrollers by Microchip

Technology. PIC microcontrollers have attractive features and they are suitable for a wide

range of application. In this project report emphasis is on 8 bit PIC 16F877A. This is because

the Microchip PIC microcontroller are very easy to use and can be run perfectly well by

simply plugging them into a prototype board, adding the crystal Oscillator, along with two

capacitors. The choice of 16F877A for discussion in this chapter is just to make the reader

familiar with the minimum common features in PIC devices.

One of the major advantages of the PIC microcontroller is that they are parallel in their

architecture and the programming approach for the devices.

The PIC microcontroller was designed using Harvard Architecture, with separate address

spaces for data (SRAM), Program (FLASH or EPROM) and EEPROM memory. PIC

processor with few exception do not allow for direct access to their program memory space.

Fig. 1.1: Pin diagram of the PIC 16F877A

7/27/2019 Acc. No. DC 89

12/78

5


1.4 DC motor driver module

L293D is a dual H-bridge motor Driver, so with one IC we can interface two DC Motors

which can be controlled in both clockwise and counter clockwise direction and I have the

motor with fix direction of motion. I can make use of all the four I/Os to connect up to four

DC motors. L293D has output current of 600mA and peak output current of 1.2A per

channel. Moreover for protection of circuit from back E.M.F output diodes are included

within the IC. The output supply (VCC2) has a wide range from 4.5V to 36 V, which has

made L293d a best choice for DC motor driver.

Fig. 1.2: L293D Dual H-bridge Motor Driver

7/27/2019 Acc. No. DC 89

13/78

6


A simple schematic for interfacing a DC motor using L293D is shown below.

Fig. 1.3: schematic for interfacing a DC motor

Table 1.1: Truth Table of DC motor operation

A B Description0 0 Motor stops or Breaks.

0 1 Motor runs Anti-Clockwise

1 0 Motor runs Clockwise

1 1 Motor stops or Breaks

Three Pins are needed for interfacing a DC motor (A, B, Enable).Output to be enabled

completely then I can connect to VCC and only two pins needed from controller to make the

motor work. This truth table is same for both BJT and microcontroller.

7/27/2019 Acc. No. DC 89

14/78

7


1.5 Voltage regulator (KA7805)The KA78XX/KA78XXA series of three-terminal positive regulator are available in the

TO-220/D-PAK package and with several fixed output voltages, making them useful in a

wide range of applications. Each type employs internal current limiting, thermal shut down

and safe operating area. Protection, make it essentially indestructible. If adequate heat

sinking is provided, they can deliver over 1A output current. Although designed primarily as

fixed voltage regulators, these devices can be used to obtain adjustable voltages and currents.

Features

Output Current up to 1A.

Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V.

Thermal Overload Protection.

Short Circuit Protection.

Fig. 1.6: Voltage regulator (KA7805)

7/27/2019 Acc. No. DC 89

15/78

8


1.7 Potentiometer module

A potentiometer (colloquially known as a "pot") is a three-terminal resistor with a sliding

contact that forms an adjustable divider. If only two terminals are used (one side and the

wiper), it acts as a variable resistor or rheostat. Potentiometers are commonly used to control

electrical devices such as volume controls on audio equipment. Potentiometers operated by a

mechanism can be used as position transducers, for example, in a joystick. Potentiometers are

rarely used to directly control significant power (more than a watt). Instead they are used to

adjust the level of analog signals (e.g. volume controls on audio equipment), and as control

inputs for electronic circuits. For example, a light dimmer uses a potentiometer to control the

switching of a TRIAC and so indirectly control the brightness of lamps. A potentiometer is

constructed with a resistive element formed into an arc of a circle, and a sliding contact

(wiper) traveling over that arc. The resistive element, with a terminal at one or both ends, is

flat or angled, and is commonly made of graphite, although other materials may be used. The

zwiper is connected through another sliding contact to another terminal. On panel pots, the

wiper is usually the center terminal of three. For single-turn pots, this wiper typically travels

just under one revolution around the contact. "Multi-turn" potentiometers also exist, where

the resistor element may be helical and the wiper may move 10, 20, or more complete

revolutions, though multi-turn pots are usually constructed of a conventional resistive

element wiped via a worm gear. Besides graphite, materials used to make the resistive

element include resistance wire, carbon particles in plastic, and a ceramic/metal mixture

called cermets. In a linear slider pot, a sliding control is provided instead of a dial control.

The resistive element is a rectangular strip, not semi-circular as in a rotary potentiometer.Due to the large opening slot or the wiper, this type of pot has a greater potential for getting

contaminated.

Fig. 1.7: Potentiometer (Pot)

7/27/2019 Acc. No. DC 89

16/78

9


Fig. 1.8: Inside view of Potentiometer (Pot)

Potentiometers can be obtained with either linear or logarithmic relations between the slider

position and the resistance (potentiometer laws or "tapers"). A letter code ("A" taper, "B"

taper, etc.) may be used to identify which taper is intended, but the letter code definitions are

variable over time and between manufacturers.

Manufacturers of conductive track potentiometers use conductive polymer resistor pastes that

contain hard wearing resins and polymers, solvents, lubricant and carbon the constituent

that provides the conductive/resistive properties. The tracks are made by screen printing the

paste onto a paper based phenolic substrate and then curing it in an oven. The curing process

removes all solvents and allows the conductive polymer to polymerize and cross link. This

produces a durable track with stable electrical resistance throughout its working life.

Applications:

Potentiometers are widely used as user controls, and may control a very wide variety of

equipment functions. The widespread use of potentiometers in consumer electronics has

declined in the 1990s, with digital controls now more common. However they remain in

many applications, such as volume controls and as position sensors.

7/27/2019 Acc. No. DC 89

17/78

10


1.8 Fuzzy Logic Module

Introduction:

It is an advanced area of computation which can be applied for control the complex system

wherein mathematical model is not available. Fuzzy logic is a form of multi-valued

logic derived from fuzzy set theory to deal with reasoning that is approximate rather than

precise. The degree of truth of a statement can range between 0 and 1 and is not constrained

to the two truth-values of classic propositional logic. Fuzzy logic is widely used in machine

control. The term itself inspires a certain skepticism, sounding equivalent to "half-bakedlogic" or "bogus logic", but the "fuzzy" part does not refer to a lack of rigorous in the

method, rather to the fact that the logic involved can deal with fuzzy conceptsconcepts that

cannot be expressed as "true" or "false" but rather as "partially true". Although genetic

algorithms and neural networks can perform just as well as fuzzy logic in many cases, fuzzy

logic has the advantage that the solution to the problem can be cast in terms that human

operators can understand, so that their experience can be used in the design of the controller.

This makes it easier to mechanize tasks that are already successfully performed by humans.

Background and Evolution of Fuzzy Logic: - In the early 1900s,

Lukasiewicz came and proposed a systematic alternative to the bi-valued logic (bivalence) of

Aristotle. Knuth, a former student of Lukasiewicz proposed a three-valued logic apparently

missed by Lukasiewicz, which is used an integral range [-1, 0 +1] rather than [0, 1, 2].

Nonetheless, this alternative failed to gain acceptance.

Lotfi A. Zadeh, a professor of UC Berkeley in California, published his seminal work

"Fuzzy Sets" which described the mathematics of fuzzy set logic. This theory proposed

making the membership function (or the values False and True) operate over the range of real

numbers [0.0, 1.0].

For example, consider an antilock braking system, directed by a microcontroller chip. The

microcontroller has to make decisions based on brake temperature, speed, and other variables

in the system.

7/27/2019 Acc. No. DC 89

18/78

11


Fig. 1.9: Pictorial view of FUZZY controller

Fuzzy controllers are very simple conceptually. They consist of an input stage, a processing

stage, and an output stage. The input stage maps sensor or other inputs, such as switches,

thumbwheels, and so on, to the appropriate membership functions and truth values. The

processing stage invokes each appropriate rule and generates a result for each, then combines

the results of the rules. Finally, the output stage converts the combined result back into a

specific control output value.

As discussed earlier, the processing stage is based on a collection of logic rules in the form of

IF-THEN statements, where the IF part is called the "antecedent" and the THEN part is

called the "consequent". Typical fuzzy control systems have dozens of rules.

Consider a rule for a temperature control system:-

IF (temperature is "cold") THEN (heater is "high")

This rule uses the truth value of the "temperature" input, which is some truth value of "cold",

to generate a result in the fuzzy set for the "heater" output, which is some value of "high".

This result is used with the results of other rules to finally generate the crisp composite

output. Obviously, the greater the truth value of "cold", the higher the truth value of "high".

7/27/2019 Acc. No. DC 89

19/78

12


These operations may have precise definitions, though the definitions can vary considerably

between different implementations. "Very", for one example, squares membership functions;

since the membership values are always less than 1, this narrows the membership function.

"Extremely" cubes the values to give greater narrowing, while "somewhat" broadens the

function by taking the square root.There are several different ways to define the result of a

rule, but one of the most common and simplest is the "max-min" inference method, in which

the output membership function is given the truth value generated by the premise. Rules can

be solved in parallel in hardware, or sequentially in software. The results of all the rules that

have fired are "defuzzified" to a crisp value by one of several methods. There are dozens in

theory, each with various advantages and drawbacks. The "centroid" method is very popular,

in which the "center of mass" of the result provides the crisp value. Another approach is the

"height" method, which takes the value of the biggest contributor. The centroid method

favors the rule with the output of greatest area, while the height method obviously favors the

rule with the greatest output value. The example below demonstrates max-min inference and

centroid defuzzification for a system with input variables "x", "y", and "z" and an output

variable "n". Note that "mu" is standard fuzzy-logic nomenclature for "truth value":

Fig. 1.10: Centroid Defuzzification method

7/27/2019 Acc. No. DC 89

20/78

13


Notice how each rule provides a result as a truth value of a particular membership function

for the output variable. In centroid defuzzification the values are OR'ed, that is, the maximumvalue is used and values are not added, and the results are then combined using a centroid

calculation.

* Fuzzy control system design is based on empirical methods, basically a methodical

approach to trial-and-error. The general process is as follows:

Document the system's operational specifications and inputs and outputs.

Document the fuzzy sets for the inputs.

Document the rule set.

Determine the defuzzification method.

Run through test suite to validate system, adjust details as required.

Complete document and release to production.

As a general example, consider the design of a fuzzy controller for a steam turbine.

The block diagram of this control system appears as follows:

Fig. 1.11: Block diagram of FUZZY control system

There are two input variables, temperature and pressure, and a single output variable, the

turbine throttle setting. The turbine's operation can be reversed, so the throttle setting can be

positive or negative.

7/27/2019 Acc. No. DC 89

21/78

14

Fig. 1.12: FUZZY set mapping

The throttle settings are defined as follows:

N3: Large negative.

N2: Medium negative.

N1: Small negative.Z: Zero.

P1: Small positive.P2: Medium positive.

P3: Large positive.

The rule set includes such rules as:

Rule 1: IF temperature IS cool AND pressure IS weak,

THEN throttle is P3.

Rule 2: IF temperature IS cool AND pressure IS low,THEN throttle is P2.

Rule 3: IF temperature IS cool AND pressure IS ok,

THEN throttle is Z.

Rule 4: IF temperature IS cool AND pressure IS strong,

THEN throttle is N2.

7/27/2019 Acc. No. DC 89

22/78

15


In practice, the controller accepts the inputs and maps them into their membership functions

and truth values. These mappings are then fed into the rules. If the rule specifies an AND

relationship between the mappings of the two input variables, as the examples above do, the

minimum of the two is used as the combined truth value; if an OR is specified, the maximum

is used. The appropriate output state is selected and assigned a membership value at the truth

level of the premise. The truth values are then defuzzified.

Fig. 1.12: FUZZY evaluation Rule (2)

Fig.1.13: FUZZY evaluation Rule (3)

7/27/2019 Acc. No. DC 89

23/78

16


The two outputs are then combined:

Fig. 1.14: Centroid Defuzzification

The output value will adjust the throttle and then the control cycle will begin again to

generate the next value.

Characteristics of FUZZY Logic:

1. In fuzzy logic, exact reasoning is viewed as a limiting case of approximate reasoning.

2. In fuzzy logic everything is a matter of degree.

3. Any logical system can be fuzzified.

7/27/2019 Acc. No. DC 89

24/78

17


AdvantagesFL offers several unique features that make it a particularly good choice for many control

problems.

1) It is inherently robust since it does not require precise, noise-free inputs and can be

programmed to fail safely if a feedback sensor quits or is destroyed. The output control is a

smooth control function despite a wide range of input variations.

2) Since the FL controller processes user-defined rules governing the target control system, it

can be modified and tweaked easily to improve or drastically alter system performance.

3) FL is not limited to a few feedback inputs and one or two control outputs, nor is it

necessary to measure or compute rate-of-change parameters in order for it to be

implemented. Any sensor data that provides some indication of a system's actions and

reactions is sufficient.

4) FL can control nonlinear systems that would be difficult or impossible to model

mathematically. This opens doors for control systems that would normally be deemedunfeasible for automation.

5) Fuzzy logic controller is faster than the conventional PID controller.

6) Fuzzy Logic Controller is useful in reaching the set point faster.

7) Fuzzy Logic Controller much closer in spirit to human thinking and decision making.

8) Fuzzy Logic Controller can be designed even when the understanding of the system is

incomplete; when it is difficult to construct the mathematical model of the system.

9) Fuzzy Logic Controller is easier to prototype & implement for most system without anymodification.

7/27/2019 Acc. No. DC 89

25/78

18


1.9 Organization

This project work consists of seven chapters. The chapter 1 of this project presents an

introduction to the system. It includes PIC 16F877A Microcontroller, Voltage Regulator,

Potentiometer, Fuzzy Logic modules. The 2nd chapter discusses the system overview. It

describes the way in which the autonomous system is designed. It also shows the circuit

connection among them. Next chapter deals with Hardware design and Implementation. It

describes different hardware module that used to design the autonomous system. It deals with

connection between them and their short descriptions. Software also plays a vital role to

design the system, so it is in the immediate chapter (chapter 4). Next the obtained results and

a discussion are presented in chapter 5.The conclusion and future scope of the project is

shown in chapter 6.Appendix section is provided for further details of the topics.

7/27/2019 Acc. No. DC 89

26/78

19

CHAPTER 2SYSTEM OVERViEW

7/27/2019 Acc. No. DC 89

27/78

20

Chapter2- System overview

2.1 Overview of the autonomous system:

Fig. 2.1: Block diagram of the autonomous system

7/27/2019 Acc. No. DC 89

28/78

21


2.2 System description:

Figure 2.1, shows the block diagram of a PIC

16F877A based fuzzy temperature control system. It is an autonomous system, no need to

handle manually. The block diagram of the system shows different kinds of hardware

components, Such as-

Voltage regulator (KA 7805). It provides +5 Volt DC output power supply, which help to

operate the total circuitry. It plays a great role in this system because voltage fluctuation may

cause harmful to the system. See chapter 1 for the details of Voltage regulator (KA 7805).

Another very important component is Sensor (LM 35) .It may call input of the system. It

sense temperature of the environment and fed to the PIC 16F877A microcontroller. For the

details of LM 35, see chapter 3.

Most important component of this autonomous system is PIC 16F877A microcontroller. It is

called the heart of this system. It almost controls the entire component those use in this

system. Firstly it collects analog data from the sensor, then by using its ADC module it

converts its equivalent digital data to the respective output port. According to program it

transfers data to different system components. For the details of PIC 16F877A

microcontroller module see the APPENDIX A.

Another key component of this system is LCD display device. It shows visually the current

temperature of the environment. Here we use 16x2 LCD modules, by which we display four

data string. For the details of the LCD display see chapter3 and APPENDIX A.

7/27/2019 Acc. No. DC 89

29/78

22


This system also includes another important hardware component which is known as DC

motor driver (L293D). If we connect the DC motor directly to the PIC microcontroller then

back e.m.f may damage the microcontroller, so it is very essential. For details see chapter1.

Final component or Output component that use in this system is DC motor. Applying desire

PWM duty cycle provided by the microcontroller and controlled by the fuzzy logic is applied

to the DC motor. So it rotates according to the defuzzification value of the fuzzy controller

which controls the rising temperature of the system. For further details see chapter1.

7/27/2019 Acc. No. DC 89

30/78

23


2.3 Flow chart of the system:

Fig. 2.2: Flow chart of the system

ENTERConstants

E (t) =0E (t-1) =0

y = 0?

CALL DELAY

PORT A = INPUTRA2 = ANALOG I/PPORT B = OUTPUT

BEGIN

GET ADC

Result of A/D Conversion = y

e (t) e (t-1) = CHANGE OF ERROR

WRITE ZERO TO PORT B

FUZZY CONTROL PROCESS

WRITE Y TO PORT B

IntroducePIC16F877XT, OSC,WDT OFF

7/27/2019 Acc. No. DC 89

31/78

24

CHAPTER 3HARDWARE DESiGN &

iMPLEMENTATiON

7/27/2019 Acc. No. DC 89

32/78

25

Chapter 3- Hardware design & Implementation

3.1 Connection diagram and description of PIC 16F877A

Fig. 3.1: PIC 16F877A Fig. 3.2: Connection of PIC with other components

Fig 3.2 shows the connection of PIC 16F877A with other circuit components. Pin no (2) of LM35

is connected with the pin no (4) of the PIC 16F877A microcontroller, which is known as RA2

through 1K resistor. (+5) volt DC is connected to the master clear (MCLR) through 10K resistor

for the initiation purpose. An 8 MHZ crystal oscillator is also connected with PIC microcontroller

by pin no (13) and (14). It also interfaces with DC motor driver. Pin no (17), of the PIC

microcontroller which is known as RC2 is connected with the pin no (2) of the DC motor driver

(L293D). Connection of PIC 16F877A microcontroller with LCD display as shown in table-

Table 3.1: connection of PIC 16F877A with LCD display

Pin no of PIC 16F877A Pin no of LCD display

35(RB2) 4

36(RB3) 6

37(RB4) 11

38(RB5) 12

39(RB6) 13

40(RB7) 14

7/27/2019 Acc. No. DC 89

33/78

26


3.2 Connection diagram and description of 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.

Fig. 3.3: Picture of LM35 Fig. 3.4: Connection of sensor with other components

From the above picture it is clearly shows that 3-terminal LM35 device is connected with the

PIC 16F877A microcontroller. First terminal (pin 1) of the LM35 is connected with the +5

volt power supply which is nothing but the terminal 3 of the voltage regulator (KA

7805).second terminal (pin 2) of the sensor is connected with the pin no (4) of the

microcontroller, named as RA2 via 1K resistor and terminal 3 of the sensor (LM35) is

grounded.

For details see Appendix A.

7/27/2019 Acc. No. DC 89

34/78

27


3.3 Connection diagram and description of LCD ModuleLCD display (HD44780U) has two display lines. Each line can display 20 characters at a

time. A single HD440U can display up to one 8 character line or two 8 character lines. In this

project it interfaced to PIC 16F877A to show temperature readings.

Fig. 3.5: Connection of LCD display (2x16) with PIC 16F877A

From the above figure, it is clear that some output port (B) pins of the PIC 16F877A is

connected with the LCD display. These pin configuration is shown as-----

Table 3.3: Pin connection

Pin no of PIC 16F877A Pin no of LCD display35(RB2) 3

36(RB3) 4

37(RB3) 6

38(RB4) 12

39(RB5) 13

40(RB6) 14

For details see Appendix A.

7/27/2019 Acc. No. DC 89

35/78

28


3.4 Connection diagram of DC motor

Fig. 3.6: Connection of DC motor with DC motor driver (L293D)

From the above picture we can clearly see that DC motor is connected with DC motor driver

with particular fashion. Pin (6) of the DC motor driver connected with the negative terminal

off the DC motor. On the other hand Pin (3) of the DC motor driver connected with the

positive terminal off the DC motor. If we connect the DC motor directly to the PIC

microcontroller then back e.m.f may damage the microcontroller, so it is very essential.

7/27/2019 Acc. No. DC 89

36/78

29


3.4 Short description of the componentsa)PIC 16F877A:-

Microcontroller is a highly integrated chip that contains all the components comprising a

controller. Typically it includes a CPU, RAM, ROM, I/O ports, timers and UARTs.Unlike a

general-purpose computer, which also includes all of these components. Typically

Microcontroller is called a dedicated processor that is designed for a very specific task-to

control a particular system. As a result the parts can be simplified and reduced, which cuts

down on production costs.

In our project we use the PIC 16F877A microcontroller. It provides several advantages over

other microcontrollers. Different series of PIC microcontroller are popular because of high

performance, low cost, low power consumption and small in size. It uses high performance

RISC architecture, PIC 16F877A uses 35 single word instructions, having 20MHZ operating

frequency. The additional flexibility in PIC 16F877A microcontroller is that it has 8K x 14

words of FLASH Program Memory, 368 x 8 bytes of Data Memory (RAM) and 256 x 8

bytes of EEPROM data memory. It also has 8 channel 10 bit ADC, two PWM module, 14

interrupt source, Eight level deep hardware stack, Direct, indirect and relative addressing

modes, Power-on Reset (POR), Power-up Timer (PWRT) and Oscillator Start-up Timer

(OST), Watchdog Timer (WDT) with its own on-chip RC, oscillator for reliable operation,

Programmable code-protection, Power saving SLEEP mode Selectable oscillator options,

Low-power, high-speed CMOS FLASH/EEPROM technology.

Fig. 3.7: PIC 16F877A

7/27/2019 Acc. No. DC 89

37/78

30


The key features of PIC 16F877A are shown in tabular form-

Table 3.4: Key Features of PIC 16F877A

Serial No Key Features PIC 16F877A

1 Operating Frequency DC -20 MHZ

2 FLASH Program Memory 8K

3 Data memory (bytes) 368 Bytes

4 EEPROM Data Memory 15

5 Interrupts 14

6 I/O Ports PORTS(A,B,C,D,E)

7 Timers 3

8 PWM modules 2

9 Serial Communications MSSP,USART

10 Parallel Communications PSP

11 10-bit A/D Module 8 INPUT CHANNELS

12 Instruction Set 35

For our project purpose some of the features of PIC 16F877A are very important, like Flash

program memory, I/O ports, PWM modules and 10-bit ADC module.

i) Program (.HEX code) downloaded into the flash memory should be less than 8K.

ii) We need to define which port is used as the input port and which port is used as

output port.iii) PWM module mainly used to drive the motor. So it determine the PWM duty

cycle, which is mainly use to rotate the motor.

iv) The conversion of an analog input signal results in a corresponding 10-bit digital

number.

7/27/2019 Acc. No. DC 89

38/78

31


b)LCD Module:-

LCD display (HD44780U) has two display lines. Each line can display 20 characters at a

time. A single HD440U can display up to one 8 character line or two 8 character lines. In this

project it interfaced to PIC 16F877A to show temperature readings. Since all the functions

such as display RAM, Character generator and Liquid crystal driver required for driving a

dot-matrix liquid crystal display are internally provided on one chip, a minimal system can

be interfaced with this controller or driver.

Fig. 3.8: LCD module

Key function of the LCD display device (HD44780U) are shown as-

i) 5x 8 and 5x 10 dot matrix possible.

ii) It support low power operation (2.7 to 5.5 V).

iii) Wide range of Liquid crystal display driver power range (3.0 to 11 V).

iv) Liquid crystal drive waveform: A (One line frequency AC waveform).

v) It comprises high speed MPU bus interface.

vi) 4 bit or 8 bit MPU interface enabled.

vii) 80x 8 bit displays RAM (80 characters MAX.).

viii) Bit character generator ROM for a total of 240 character fonts.

ix) 64x 8 bit character generator RAM.

x) It also provides 16 common x 40 segment liquid crystal display driver.

(For details see Appendix A)

7/27/2019 Acc. No. DC 89

39/78

32


c)Sensor (LM35) Module:-

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

14C at room temperature and 34C over a full 55 to +150C temperature range. Low

cost is assured by trimming and calibration at the wafer level. The LM35s 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 A from its supply, it has very low self-heating, less than

0.1C in still air. The LM35 is rated to operate over a 55 to +150C temperature range,

while the LM35C is rated for a 40 to +110C range (10with 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.

0.5C accuracy guarantee able (at +25C).

Rated for full 55 to +150C range.

Suitable for remote applications.

Low cost due to wafer-level trimming.

Operates from 4 to 30 volts.

Less than 60 A current drain.

Low self-heating, 0.08C in still air.

7/27/2019 Acc. No. DC 89

40/78

33

Fig. 3.9: Sensor (LM35) module

7/27/2019 Acc. No. DC 89

41/78

34


d)DC MotorMotors come in many sizes and types, but their basic function is the same. Motors of all

types serve to convert electrical energy into mechanical energy.

They can be found in VCR's, elevators, CD players, toys, robots, watches, automobiles,

subway trains, fans, space ships, air conditioners, refrigerators, and many other places. D.C.

motors are motors that run onDirect Currentfrom a battery or D.C. power supply. Direct

Current is the term used to describe electricity at a constant voltage. A.C. motors run

onAlternating Current, which oscillates with a fixed cycle between a positive and negative

value. Electrical outlets provide A.C. power. When a battery or D.C. power supply is

connected between a D.C. motor's electrical leads, the motor converts electrical energy to

mechanical work as the output shaft turns. The electric motor is the most convenient of all

sources of motive power. It is clean and silent, starts instantly, and can be built large enough

to drive the world's fastest trains or small enough to work a watch.

Fig. 3.10: DC Motor

7/27/2019 Acc. No. DC 89

42/78

35

CHAPTER 4SOFTWARE DESiGN &

iMPLEMENTATiON

7/27/2019 Acc. No. DC 89

43/78

36

Chapter 4 Software Design & Implementation

4.1 Introduction to MikroC

MikroC is a powerful, feature rich development tool for PICmicros. It is designed to provide

easiest possible solution for developing applications for embedded systems, without

compromising performance or control. PIC and C fit together well: PIC is the most popular

8-bit chip in the world, used in a wide variety of applications, and C, prized for its efficiency,

is the natural choice for developing embedded systems. MikroC provides a successful match

featuring highly advanced IDE, ANSI compliant compiler, broad set of hardware libraries,

comprehensive documentation, and plenty of ready to run examples.

4.2 How to build a project

Step 1: The software MikroC pro for PIC 2009 is opened and the c code for the program

is then written on the writing window. After writing the code we go to the topmost toolbar

Project > Build or press Ctrl+ F9 to build the code as shown in the figure... The following

pictures show the above process:

Fig. 4.1: How to build a project

7/27/2019 Acc. No. DC 89

44/78

37


Step 2:After building the code the compiler starts to compile the program.After checking

the initial errors and rectifying them the entire code was Built by the software to generate

the corresponding HEX code of the c program the functions used in the above program are

linked together into a subroutine which generates the HEX code from the raw c code.

Fig. 4.2: Compilation of the project

Step 3:After creation of subroutine the compiler generates the HEX code and tells the user

how much space it occupies and how much RAM it has to be used. After the HEX code has

been created the code gets ready to be downloaded. After completion it looks like the

following figure:-

7/27/2019 Acc. No. DC 89

45/78

38


Fig. 4.3: Messages of Compilation

Step 4: The fourth step is to save the created code into the respective destination. The

leftmost toolbar exhibits a Create New Project option. This project is named as temp

indicator and saved in the D: / drive. The device name has been given as PIC16F877A and

the clock speed is input as 8 MHz.

7/27/2019 Acc. No. DC 89

46/78

39


Fig. 4.4: Project setting

After final generation of the HEX code it looks like the following.

Fig. 4.5: Generated HEX code

7/27/2019 Acc. No. DC 89

47/78

40


Step 5: The next software that is used is C which comes along the Universal Debugger

and is used for downloading the code into the debugger. Before loading the previously

created HEX code into the microcontroller, it is first erased with the help of this software to

remove any previously loaded programs. For this we click on the ERASE option available

on the middle of the toolbar as shown in the figure.

Fig. 4.6: HEX code download software

Step 6:The final step is to write the hex code program into the microcontroller. For this

the debugger is interfaced with the computer via RS 232 cable. After successful interfacing

the code is downloaded into the chip via the C software. After successful downloading it

looks like the following.

Fig. 4.6: HEX code placed in C software

7/27/2019 Acc. No. DC 89

48/78

41


5.3 MikroC pro for PIC Libraries

There are so many PIC library function provided by the MikroC pro. But among those huge

library functions, we find some of are very important for our project purpose. These are as

follows-

1. ADC library: - ADC (Analog to Digital Converter) module is available with a

number of PIC micros. Library function ADC_Read is included to provide you

comfortable work with the module in single-ended mode.

a)ADC_Read

Table 4.1: ADC read

Prototype unsigned ADC_Read(unsigned short channel);

Returns 10 or 12-bit unsigned value read from the specified channel

(MCU dependent).

Description

Initializes PICs internal ADC module to work with RC clock.

Clock determines the time period necessary for performing AD

conversion (min 12TAD).Parameter channel represents the

channel from which the analog value is to be acquired. Refer to

the appropriate datasheet for channel-to-pin mapping.

Note: This function doesn't work with the external voltage

reference source, only with the internal voltage reference.

Requires Nothing.

Example

unsigned temp;

...

temp = ADC_Read(2); // Read analog value from channel 2

7/27/2019 Acc. No. DC 89

49/78

42


2) LCD library: -The MikroC PRO for PIC provides a library for communication

with Lcds (with HD44780 compliant controllers) through the 4-bit interface.

Table 4.2: External dependencies of LCD Library

The following variables

must be defined in all

projects using Lcd Library:

Description : Example :

extern sfr sbit LCD_RS: Register Select line. sbit LCD_RS at RB4_bit;

extern sfr sbit LCD_EN: Enable line. sbit LCD_EN at RB5_bit;

extern sfr sbit LCD_D7; Data 7 line. sbit LCD_D7 at RB3_bit;




extern sfr sbitLCD_RS_Direction;

Register Select direction

pin.sbit LCD_RS_Direction at

TRISB4_bit;

extern sfr sbitLCD_EN_Direction; Enable direction pin.

sbit LCD_EN_Direction atTRISB5_bit;

extern sfr sbitLCD_D7_Direction; Data 7 direction pin.

sbit LCD_D7_Direction at

TRISB3_bit;


sbit LCD_D6_Direction atTRISB2_bit;


sbit LCD_D5_Direction atTRISB1_bit;

extern sfr sbit

LCD_D4_Direction;Data 4 direction pin.

sbit LCD_D4_Direction at

TRISB0_bit;

Library Routines

Lcd_Init

Lcd_Out

Lcd_Out_Cp

Lcd_Chr

Lcd_Chr_Cp

Lcd_Cmd

7/27/2019 Acc. No. DC 89

50/78

43


3) PWM Library: - CCP module is available with a number of PIC MCUs.

MikroC PRO for PIC provides library which simplifies using PWM HW Module.

Note: Some MCUs have multiple CCP modules. In order to use the desired CCP

library routine, simply change the number 1 in the prototype with the appropriate

module number, i.e. PWM2_Start ();

Library Routines:-

PWM1_Init

PWM1_Set_Duty

PWM1_Start

PWM1_Stop

Table 4.3: PWM Initialization

Prototype void PWM1_Init(constlongfreq);

Returns Nothing.

Description Initializes the PWM module with duty ratio 0. Parameterfreq is a desired PWM frequency in Hz (refer to devicedata sheet for correct values in respect with Fosc).Thisroutine needs to be called before using other functionsfrom PWM Library.

Requires MCU must have CCP module.

Note: Calculation of the PWM frequency value is carriedout by the compiler, as it would produce a relativelylarge code if performed on the library level.Therefore, compiler needs to know the value of theparameter in the compile time. That is why thisparameter needs to be a constant, and not a variable.

Example Initialize PWM module at 5KHz:

PWM1_Init(5000);

7/27/2019 Acc. No. DC 89

51/78

44


Table 4.3: PWM1 Duty set

Prototype void PWM1_Set_Duty(unsigned short duty_ ratio);

Returns Nothing.

Description Sets PWM duty ratio. Parameter duty takes values from 0 to

255, where 0 is 0%, 127 is 50%, and 255 is 100% duty ratio.

Other specific values for duty ratio can be calculated as

(Percent*255)/100.

Requires MCU must have CCP module. PWM1_Init must be called

before using this routine.

Example Set duty ratio to 75%:

PWM1_Set_Duty(192);

Table 4.4: PWM1 Start

Prototype void PWM1_Start(void);

Returns Nothing.

Description Starts PWM.

Requires MCU must have CCP module. PWM1_Init must be called

before using this routine.

Example PWM1_Start();

7/27/2019 Acc. No. DC 89

52/78

45


Table 4.5: PWM1 stop

Prototype void PWM1_Stop(void);

Returns Nothing.

Description Stops PWM.

Requires MCU must have CCP module. PWM1_Init must be called beforeusing this routine. PWM1_Start should be called before using this

routine; otherwise it will have no effect as the PWM module is notrunning.

Example PWM1_Stop();

7/27/2019 Acc. No. DC 89

53/78

46

CHAPTER 5RESULTS OF EXPERiMENT

7/27/2019 Acc. No. DC 89

54/78

47

Chapter 5 Results of Experiment

The heat of the system is sensed by a sensor and compared with the set value. The error

between the actual and set value is called to be set offset. This offset determines the main

fuzzy rules of the system. They are as follows:

If the offset is large, then cool the system, more

If the offset is very small, then dont change the cooler, much

Fuzzy logic processing runs under these rules and the rules related to the rate of change of

the set/actual offset. This allows us very smooth adjustment of cooling rate. Input data of theoffset is calculated by means of taking relative heat difference of actual heat to the set value

as shown below:-

Error (E) = (Actual Heat of the System)-(Set Value)

Input data for rate of change of error (CE) is the difference between the last value of E, (En)

and the previous value of E, (En-1):-

Rate of change of error (CE) = ((En) - (En-1))

The figures shown below represent condition and conclusion membership functions.

Condition membership functions represent offset (E).

Fig. 5.1: Membership function for E

7/27/2019 Acc. No. DC 89

55/78

48


Fig. 5.2: Membership function for CE

Table 5.1: Fuzzy Rule Base table

Error

Change of error ZR

(28C)

PS

(28C-34C)

PM

(34C-40C)

PB

( 40C-46C)

NB(-6C) ZERO ZERO SLOW MEDIUM

NS(-3C) ZERO SLOW MEDIUM MEDIUM

ZR(0C) ZERO SLOW MEDIUM FAST

PS(+3C) SLOW SLOW MEDIUM FAST

PB(+6C) SLOW MEDIUM FAST FAST

ZR = ZEROPS = POSITIVE SMALL

PM = POSETIVE MEDIUM

PB = POSITIVE BIGNB = NEGETIVE BIG

NS = NEGETIVE SMALL

LM35 produces 10mV per C. Therefore 35 C is represented by 350 mV. So for28C it become 280mV.Now-

Equivalent Analog Value stored in 10-bit A/D converter (X) =

VIN *(2^n -1)

__________________VFS

7/27/2019 Acc. No. DC 89

56/78

49


So for 28C, X = 286.44

34C, X = 347.82

40C, X = 409.2046C, X = 470.58

Changes of PWM duty ratio, Parameter duty takes values from 0 to 255, where 0 is0%, 127 is 50%, and 255 is 100% duty ratio. Other specific values for duty ratio canbe calculated as (Percent*255)/100.

For (0%) duty ratio Duty ratio is (0).For (33%) duty ratio Duty ratio is (84.15).

For (0%) duty ratio Duty ratio is (168.30).For (0%) duty ratio Duty ratio is (255).

After Building the desire program by using MikroC pro, we get different file of differentextension. Such as ------------

Fig. 5.3: Contents of HEX data

Among those files, we choose .HEX file and downloaded its contents into theMicrocontroller (PIC 16F877A). HEX file is look like-------------

040000008A15002835

:100006000F3083120313FC004730FD00FD0B092857:0A001600FC0B0928000000000800A0:0E002000213083120313FD00FD0B142808008D:0E002E00F201F101F001F801F30100300800C9:06003C00000000000800B6:100042007B15FB1F2B280130F300F201F101F001B7:08005200FA0DF20CFF3008006A:08005A00FA1FF2130030080048:10006200FB14FB1F3B28FF30F300F200F100F0000D:08007200FA0DF20CFF3008004A:10007A00A0017208031D52287108F2007008F100ED:10008A00F001A0157208031D52287108F200F1014F:10009A00A01120167208031960282008F302031D14

:1000AA00031C64280310F21B6828F00DF10DF20DF1:1000BA00F30B582864280130FC0017206B28023003 ..so on

7/27/2019 Acc. No. DC 89

57/78

50

CHAPTER 6CONCLUSiON & FUTURE SCOPE

7/27/2019 Acc. No. DC 89

58/78

51

Chapter 6 Conclusion and Future Scope

Conclusion and Future Scope

The PIC 16F877A based embedded temperature sensor system for an automatic Temperature

control system is found to perform as expected. The change of temperature is detected by the

temperature sensor (LM 35) and data is displayed on the LCD device continuously. The

change of temperature corresponding to the sensors output it is evaluated by the use of

FUZZY logic. According to the fuzzy rule base table, the analog data is fuzzified. After

Defuzzification, which is processed by the microcontroller (PIC 16F877A) send it to A/D

converter, for digital output. The DC motor collected output data from the Output port of the

microcontroller (PIC 16F877A). The rotation speed depends on the digital data supplied to it.

The entire system is automated and requires no manual intervention. As temperature change

almost all the time so it is obvious that control the temperature manually is quite difficult.

We can use this autonomous system to increase the longevity of the sophisticated instruments

and may use for other purpose.

Design modifications

The sensor design must be modified. The resolution of the sensor

is not sufficient. It cant measures the small change of temperature, so further we need to use

high-resolution temperature sensor. Here we use fuzzy logic to get quicker response, but here

we use temperature range, which is not so long. So it is essential to increase the operation

range further. The software (MikroC pro version3.2), which we use, is unable to produce

.HEX file if the source file size is more than 12KB. In this autonomous system we set a

particular temperature (say 280C) and we assume that temperature only increase further but it

may not happen. If temperature falls, then we need another component (say Heater) to

compensate the temperature.

7/27/2019 Acc. No. DC 89

59/78

52

Bibliography

1. Design with PIC Microcontroller by John B. Peatman.http:// WWW.amazon.com

2. Interfacing PIC Microcontrollers: Embedded Design by InteractiveSimulation by Martin P. Bates.

3. Fuzzy Fundamentals" by Earl Cox, IEEE SPECTRUM, October 1992, 58:61.Notes from this article constitute the core of this tutorial.

4. Gerla G., Fuzzy Logic Programming and fuzzy control, Studia Logica, 79(2005) 231-254.

5. Fuzzy Logic Temperature Controller by Yunseop Kim.

6. Ying, H., and B.-G. Hu: "Introduction to Fuzzy Control," International Journalof Fuzzy Systems, Vol 5, (2003) 87-88.

7. "Designing with Fuzzy Logic" by Kevin Self, IEEE SPECTRUM, November1990, 42:44,105.

8. mikroc_pic_pro_manual_v100.

9. http:// www.microchip.com

10. http:// www.mikroe.com

7/27/2019 Acc. No. DC 89

60/78

53

APPENDIX

7/27/2019 Acc. No. DC 89

61/78

54

Appendix

/* Project name

PIC 16F877A BASED FUZZY TEMPERATURE CONTROLLER

* Copyright:

Mikroelectronika, 2009.

* Test Configuration:

MCU: PIC 16F877A

Oscillator: HS, 08.0000 MHZExt. Module LCD (16x2)

Software MikroC pro v3.2

// Program begin

sbit LCD_RS at RB4_bit;

sbit LCD_EN at RB5_bit;

sbit LCD_D4 at RB0_bit;




sbit LCD_RS_Direction at TRISB4_bit;

sbit LCD_EN_Direction at TRISB5_bit;

sbit LCD_D4_Direction at TRISB0_bit;




void main()

{

float tempres;

7/27/2019 Acc. No. DC 89

62/78

55

Appendix

// For LCD variablefloat c,e;

unsigned d,g;

unsigned x1,x2;

char c1,c2,c3;

// For PWM variable

float error;

float t=0; // For storing previous temp

float cherror; //Change of error rate

ADCON1=0x80; // Config A/D converter

TRISA=0xFF; // Set portA as input port

PORTC = 0xFF;

TRISC = 0; // Set PORTC as Output

PORTB = 0xFF;

TRISB=0; // Set PORTB as Output port

PWM1_Init(5000); // initialize PWM at 5 KHZ

7/27/2019 Acc. No. DC 89

63/78

56

Appendix

while(1)

{

delay_ms(400);

tempres=Adc_Read(2); // Reading of sensor from pin4 (RA2)

tempres=tempres*5; ; //Scaling for sensor(0-1V) and ADC(0-5V) adjustment

error=tempres-286.44; //28C = 286.44, X=(Vin/Vfs)*(2^10-1)

cherror=(error-t)/0.5; // (present temp-past temp/delay)

// see FUZZY table

if((error==0)&& (cherror==0))

Pwm_Change_Duty(0);

if((error==0)&& (cherror

7/27/2019 Acc. No. DC 89

64/78

57

Appendix

if((error

7/27/2019 Acc. No. DC 89

65/78

58

Appendix

if((122.76

7/27/2019 Acc. No. DC 89

66/78

59

Appendix

Lcd_Out(2,1,"SET TEMP=28");

Lcd_Chr_Cp('.');

Lcd_Chr_Cp(223);

Lcd_Out(1,1,"REAL TEMP=");

Lcd_Chr_Cp(c1);

Lcd_Chr_Cp(c2);

Lcd_Chr_Cp('.');

Lcd_Chr_Cp(c3);

Lcd_Chr_Cp(223);

Lcd_Out_Cp("C");

}

}

7/27/2019 Acc. No. DC 89

67/78

60

Appendix

Architecture of PIC 16F877A Microcontroller

PIC 16F877A microcontroller has Harvard architecture. The program memory and data

memory uses separate buses. Instructions pipelining allows instruction to get executed in

single cycle of the next instruction. The architecture of PIC 16F877A microcontroller is

shown as-------

Architecture of PIC Microcontroller

7/27/2019 Acc. No. DC 89

68/78

61

Appendix

Pin Function of PIC 16F877A

Pin No Pin Name Function of Pin1 MCLR/VPP/THV Master clear (reset) input or programming voltage input

or high voltage test mode control.

2 RA0/AN0 RA0 can also be analog input0.

3 RA1/AN1 RA1 can also be analog input1.

4 RA2/AN2/VREF- RA2 can also be analog input2 or negative analog ref.

voltage.

5 RA3/AN3/VREF+ RA3 can also be analog input3 or positive analog ref.

voltage.

6 RA4/T0CKI RA4 can also be the clock input to the Timer0

timer/counter.

7 RA5/SS/AN4 RA5 can also be analog input4 or the slave select for the

synchronous serial port.

8 RE0/RD/AN5 RE0 can also be read control for the parallel slave port,

or analog input5.

9 RE1/WR/AN6 RE1 can also be write control for the parallel slave port,

or analog input6.

10 RE2/CS/AN7 RE2 can also be select control for the parallel slave port,

or analog input7.

11 VDD Positive supply for logic and I/O pins.

12 VSS Ground reference for logic and I/O pins.

13 OSC1/CLKIN Oscillator crystal input/external clock source input.

14 OSC2/CLKOUT Oscillator crystal output. In RC mode, OSC2 pin outputs

CLKOUT which has 1/4 the frequency of OSC1

15 RC0/T1OSO/T1CKI RC0 can also be the Timer1 oscillator output or a

Timer1 clock input.

16 RC1/T1OSI/CCP2 RC1 can also be the Timer1 oscillator input or Capture2

input/Compare2 output/PWM2 output.

7/27/2019 Acc. No. DC 89

69/78

62

17 RC2/CCP1 RC2 can also be the Capture1 input/Compare1

output/PWM1 output.

18 RC3/SCK/SCL RC3 can also be the synchronous serial clock input/

output for both SPI and I2C modes.

19 RD0/PSP0

PORTD is a bi-directional I/O port or parallel slave port

when interfacing to a microprocessor bus.

20 RD1/PSP1

21 RD2/PSP2

22 RD3/PSP3

23 RC4/SDI/SDA RC4 can also be the SPI Data In (SPI mode).

24 RC5/SDO RC5 can also be the SPI Data Out (SPI mode).

25 RC6/TX/CK RC6 can also be the USART Synchronous Clock.

26 RC7/RX/DT RC7 can also be the USART Synchronous Data.

27 RD4/PSP4 Same as Pin No- 19,20,21,22,28,29,30.

PORTD is a bi-directional I/O port or parallel slave port

when interfacing to a microprocessor bus.

28 RD5/PSP5

29 RD6/PSP6

30 RD7/PSP7

31 VSS Ground reference for logic and I/O pins

32 VDD Positive supply for logic and I/O pins.

33 RB0/INT RB0 can also be the external interrupt pin.

34 RB1 RB1 can also be the external interrupt pin.

35 RB2 RB2 can also be the external interrupt pin.

36 RB3/PGM RB3 can also be the low voltage programming input.

37 RB4 Interrupt-on-change pin.

38 RB5 Interrupt-on-change pin.

39 RB6/PGC Interrupt-on-change pin or In-Circuit Debugger pin.

Serial programming clock.

40 RB7/PGD Interrupt-on-change pin or In-Circuit Debugger pin.

Serial programming data.

7/27/2019 Acc. No. DC 89

70/78

63

Appendix

Memory Organization

There are three memory blocks in each of the PIC16F87X MCUs. The Program Memory andData Memory have separate buses so that concurrent access can occur. The PIC16F87X

devices have a 13-bit program counter capable of addressing an 8K x 14 program memory

space. The PIC16F877/876 devices have 8K x 14 words of FLASH program memory, and

the PIC16F873/874 devices have 4K x 14. Accessing a location above the physically

implemented address will cause a wraparound. The RESET vector is at 0000h and the

interrupt vector is at 0004h.

PIC16F877 PROGRAM MEMORY MAP AND STACK

7/27/2019 Acc. No. DC 89

71/78

64

Appendix

Analog to Digital Conversion Module

Introduction

PIC 16F877A has an in built analog to digital converter module. The analog to digital

converter (A/D converter) module has eight inputs for the 40/44 pin devices. The conversion

of an analog input signal results in a corresponding 10-bit digital number. The A/D module

has high and low voltage reference input that is software selectable to some combination of

VDD, VSS, RA2, or RA3. The A/D converter has a unique feature of being able to operate

while the device is in SLEEP mode. To operate in SLEEP, the A/D clock must be derived

from the A/Ds internal RC oscillator.

Registers of the ADC module

The A/D module has four registers. These registers are:-

1. A/D Result High Register (ADRESH)

2. A/D Result Low Register (ADRESL)

3. A/D Control Register0 (ADCON0)

4. A/D Control Register1 (ADCON1)

Configuration of the ADC module

These steps should be followed for doing an A/D Conversion:

1. Configure the A/D module:

Configure analog pins/voltage reference and digital I/O (ADCON1)

Select A/D input channel (ADCON0)

Select A/D conversion clock (ADCON0)

Turn on A/D module (ADCON0)

7/27/2019 Acc. No. DC 89

72/78

65

Appendix

2. Configure A/D interrupt (if desired):

Clear ADIF bit

Set ADIE bit

Set PEIE bit

Set GIE bit

3. Wait the required acquisition time.

4. Start conversion:

Set GO/DONE bit (ADCON0)

5. Wait for A/D conversion to complete, by either:

Polling for the GO/DONE bit to be cleared (with interrupts enabled); OR

Waiting for the A/D interrupt.

6. Read A/D result registers pair :-( ADRESH: ADRESL), clear bit ADIF if required.

7. For the next conversion, go to step 1 or step 2, as required. The A/D conversion time

per bit is defined as TAD. A minimum wait of 2TAD is

required before the next acquisition starts.

7/27/2019 Acc. No. DC 89

73/78

66

Appendix

A/D Block Diagram

7/27/2019 Acc. No. DC 89

74/78

67

Appendix

LCD display Pins: -There are in total of 14 pins marked with numbers (16 if

there is a backlight). Their function is described in the table bellow:-

Function Pin

Number

ame Logic

State

Description

GROUND 1 VSS - 0V

POWER

SUPPLY

2 VDD - +5V

CONTRAST 3 VEE - 0 Vdd

CONTROL

OF

OPERATING

4 RS 0

1

D0 D7 are interpreted as

commands D0-D7 are interpreted as

data

5 RW 0

1

Write data (from controller to LCD)

read data (from LCD to controller)

6

E

0

1

From 1 to 0

Access to LCD disabled

Normal operating Data/commands

are transferred to LCD

DATA/

COMMAND

S

7 D0 0/1 Bit 0 LSB

8 D1 0/1 Bit 1

9 D2 0/1 Bit 2

10 D3 0/1 Bit 3

11 D4 0/1 Bit 4

12 D5 0/1 Bit 5

13 D6 0/1 Bit 6

14 D7 0/1 Bit 7 MSB

7/27/2019 Acc. No. DC 89

75/78

68

Appendix

Instruction Description of LCD Module

Clear display: - Clear Display writes space codes 20H (character pattern for

character code 20H must be a blank pattern) into all DDRAM addresses. It then sets

DDRAM address 0 into the address counter and return the display to its original

status if it was shifted. In other words, the display disappears and the cursor or

blinking goes to the left edge of the display (in the first line if 2 lines are displayed).

It also sets I/D to 1 (Increment mode) in entry mode.

Clear Display

Return Home: - Return home sets DDRAM address 0 into the address counter,

and returns the display to its original status if it was shifted. The DDRAM contents do

not change. The cursor or blinking goes to the left edge of the display (in the first line

if two lines are displayed).

Return Home

Entry Mode Set:-

i) I/D: -Increments (I/D = 1) or decrements (I/D = 0) the DDRAM address by 1

when a character code is written into or read from DDRAM. The cursor or

blinking moves to the right when incremented by 1 and to the left when

decremented by 1. The same applies to writing and reading of CGRAM.

RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0

0 0 0 0 0 0 0 0 1 0


0 0 0 0 0 0 0 0 1 -

7/27/2019 Acc. No. DC 89

76/78

69

Appendix

ii) S: -Shifts the entire display either to the right (I/D = 0) or to the left (I/D = 1)when S= 1. The display does not shift if S is 0. If S=1, it will seem as if the

cursor does not move but the display does. The display does not shift when

reading from DDRAM.

Entry Mode Set

Display On/Off Control:-

i) D: - The display is on when D = 1 and off when D = 0. When off, the display data

remains in DDRAM, but can be displayed instantly by setting D = 1.

ii) C: - The Cursor is displayed when C = 1 and not displayed when C is equal

to zero. Even if the cursor disappears, the function of I/D or other specificationswill not change during display data write.

iii) B: - The character indicated by the cursor blinks when B = 1. The

blinking is displayed as switching between all blank dots and displayed

characters at a speed of 409.6 ms intervals when fcp or fosc is 250 KHZ. The

cursor and blinking can be set to display simultaneously (The blinking

frequency changes according to fosc or the reciprocal of fcp).

Display On/Off Control

Appendix


0 0 0 0 0 0 0 1 I/D S


0 0 0 0 0 0 1 D C B

7/27/2019 Acc. No. DC 89

77/78

70

Cursor or Display Shift: - Cursor or display shift shifts the cursor position

or display to the right or left without writing or reading display data. This function is

used to correct or search the display. In a two line display the cursor moves to the

second line when it passes the 40th digit of the first line. Note that the first and second

line displays will shift at the same time.

Cursor or Display Shift

Function Set:-

i) DL: - Sets the interface data length. Data is send or received in 8 bit lengths

(DB7 to DB0) when DL is equal to one and in 4 bit lengths (DB7 to DB4) when

DL is equal to zero. When 4 bit length is selected, data must be sent or received

twice.

ii) N: - Sets the number of display lines.

iii) F: - Sets the character font.

Note: - Perform the function at the head of the program before executing

any instructions (except for the read busy flag and address instruction).

From this point, the function set instruction can not be executed unless the

interface data length is changed.

Function Set

Appendix


0 0 0 0 0 1 S/C R/L - -


0 0 0 0 1 DL N F - -

7/27/2019 Acc. No. DC 89

78/78

Set CGRAM Address: - Set CGRAM address the CGRAM address

binary AAAAAA into the address counter. Data is then written to or readfrom the MPU for CGRAM.

Set CGRAM address


0 0 0 1 A A A A A A

Date post:	02-Apr-2018
Category:	Documents
Upload:	uma-mageshwari
View:	215 times
Download:	0 times

Acc. No. DC 89

Documents