Chapter2 2014

Chapter 3

PIC16F887A Instructions Set & Basic Concept of C Language

2

Introduction

Language that microcontroller and man use to communicate is called assembly language.

Programs written in assembly language must be translated into a "language of zeros and ones" in order for a microcontroller to understand it.

Assembly language is a set of rules used in writing a program for microcontroller.

Assembler is a program on the PC which translates assembly language of zeros and ones.

3

Introduction

The process of communication between a man and a microcontroller

PROGRAMMING LANGUAGES

4

The microcontroller executes the program loaded in its Flash memory. This is the so called executable code comprised of seemingly meaningless sequence of zeros and ones. It is organized in 12-, 14- or 16-bit wide words, depending on the microcontroller’s architecture..

All instructions that the microcontroller can recognize are together called the Instruction set. As for PIC microcontrollers the programming words of which are comprised of 14 bits, the instruction set has 35 different instructions in total.

ASSEMBLY LANGUAGE

As the process of writing executable code was endlessly tiring, the first ‘higher’ programming language called assembly language was created. The truth is that it made the process of programming more complicated, but on the other hand the process of writing program stopped being a nightmare. Instructions in assembly language are represented in the form of meaningful abbreviations, and the process of their compiling into executable code is left over to a special program on a PC called compiler. The main advantage of this programming language is its simplicity, i.e. each program instruction corresponds to one memory location in the microcontroller. It enables a complete control of what is going on within the chip, thus making this language commonly used today. 5

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PIC16F877A Instructions Set

PIC16F877A INSTRUCTION SET BY FUNCTIONAL GROUPS

F = Any file register (specified by number or label)

W = Working register, W L = Literal value (follows instruction)

12

Instruction ‘Move’

File register

Working register, W

Move data from F to WExample,

MOVF 0Dh,W

8 A1 2

5 F

0Ch

0Dh

0Eh

F FMOVE 0Dh,W

13


Working register, W

Move data from F to WExample,

MOVF 0Dh,W

8 A1 2

5 F

0Ch

0Dh

0Eh

8 AMOVE 0Dh,W

File register

14


Working register, W

Move data from W to FExample,

MOVWF 0Eh

8 A1 2

F F

0Ch

0Dh

0Eh

3 4MOVWF 0Eh

File register

15


Working register, W

Move data from W to FExample,

MOVWF 0Eh

8 A1 2

3 4

0Ch

0Dh

0Eh

3 4MOVWF 0Eh

File register

16

Instruction ‘Move’Move literal into WExample,

MOVLW 12

F FWorking register, W

1 2Working register, Wafter instruction MOVLW 12

17

Register OperationsClear W (reset all bits and value to 0) Example,

CLRW

3 4Working register, W

0 0Working register, Wafter instruction CLRW

18

Register OperationsClear F (reset all bits and value to 0) Example,

CLRF 0Dh

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

0 01 2

3 4

0Ch

0Dh

0Eh

File register after Instruction CLRF 0D

19

Register OperationsDecrement F (Reduce by 1) Example,

DECF 0Dh

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

8 91 2

3 4

0Ch

0Dh

0Eh

File register after Instruction DECF 0Dh

20

Register OperationsIncrement F (Increase by 1) Example,

INCF 0Dh

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

8 B1 2

3 4

0Ch

0Dh

0Eh

File register after Instruction INCF 0Dh

21

Register OperationsSwap the upper and lower four bits in F

Example,

SWAPF 0Dh

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

A 81 2

3 4

0Ch

0Dh

0Eh

File register after Instruction SWAPF 0Dh

22

Register OperationsComplement F value (invert all bits)

Example,

COMF 0Ch

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

8 AE D

3 4

0Ch

0Dh

0Eh

File register after Instruction COMF OCh

23

Register OperationsRotate bits left through Carry flag Example,

RLF 0Dh

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

1 41 2

3 4

0Ch

0Dh

0Eh

File register after Instruction RLF 0Dh

F registerC

C flag isset to ‘1’

24

Register OperationsRotate bits right through Carry flag Example,

RRF 0Dh

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

4 51 2

3 4

0Ch

0Dh

0Eh

File register after Instruction RRF 0Dh

F registerC

C flag is clear to ‘0’

25

Register OperationsClear (reset to zero) the bit specified Example,

BCF 0Dh,03

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

8 21 2

3 4

0Ch

0Dh

0Eh

File register after Instruction BCF 0Dh,03

26

Register OperationsSet (to 1) the bit specified Example,

BSF 0Eh,03

8 A1 2

3 4

0Ch

0Dh

0Eh

File register

8 A1 2

3 C

0Ch

0Dh

0Eh

File register after Instruction BSF 0Eh,03

27

Arithmetic Operations

File register

Working register, W

Add F to WExample,

ADDWF 0Ch,W

8 A1 2

5 F

0Ch

0Dh

0Eh

3 4

28


File register

Working register, Wafter ADDWF 0C,W

Add F to WExample,

ADDWF 0C,W

8 A1 2

5 F

0Ch

0Dh

0Eh

4 6

29


File register

Working register, W

Add W to FExample,

ADDWF 0C

8 A1 2

5 F

0Ch

0Dh

0Eh

3 4

30


File registerafter ADDWF 0C

Working register, W

Add W to FExample,

ADDWF 0C

8 A4 6

5 F

0Ch

0Dh

0Eh

3 4

31

Arithmetic OperationsAdd L to WExample,

ADDLW 15


2 7Working register, Wafter instruction ADDLW 15

32


File register

Working register, W

Subtract W from FExample,

SUBWF 0Dh

8 A1 2

5 F

0Ch

0Dh

0Eh

3 4

33


File registerafter SUBWF 0Dh

Working register, W

Subtract W from FExample,

SUBWF 0Dh

5 61 2

5 F

0Ch

0Dh

0Eh

3 4

34


File register

Working register, W

Subtract W from F, placing result in WExample,

SUBWF 0Dh,W

8 A1 2

5 F

0Ch

0Dh

0Eh

3 4

35


File register

Working register, Wafter SUBWF 0D,W

Subtract W from F, placing result in WExample,

SUBWF 0Dh,W

8 A1 2

5 F

0Ch

0Dh

0Eh

5 6

If result 0 , C = 1If result < 0 , C = 0

36

Arithmetic OperationsSubtract W from L, placing result in WExample,

SUBLW 13


0 1Working register, Wafter instruction SUBLW 15

If result 0 , C = 1If result < 0 , C = 0

37

Logic Operations

File register

Working register, W

AND the bits of W and F, result in FExample,

ANDWF 0Ch

8 A1 2

5 F

0Ch

0Dh

0Eh

3 4

38

Logic Operations

File registerafter ANDWF 0C

Working register, W

AND the bits of W and F, result in FExample,

ANDWF 0Ch

8 A1 0

5 F

0Ch

0Dh

0Eh

3 4

39

Logic Operations

File register

Working register, W

AND the bits of W and F, result in WExample,

ANDWF 0Ch,W

8 A1 2

5 F

0Ch

0Dh

0Eh

3 4

40

Logic Operations

File register

Working register, Wafter ANDWF 0C,W

AND the bits of W and F, result in WExample,

ANDWF 0Ch,W

8 A1 2

5 F

0Ch

0Dh

0Eh

1 0

41

Logic OperationsAND the bits of L and W, result in WExample,

ANDLW AA

B CWorking register, W

A 8Working register, Wafter instruction ANDLW AA

42

Logic Operations

File register

Working register, W

OR the bits of W and F, result in FExample,

IORWF 0Ch

8 A1 2

5 F

0Ch

0Dh

0Eh

3 4

43

Logic Operations

File registerafter IORWF 0C

Working register, W

OR the bits of W and F, result in FExample,

IORWF 0Ch

1 2

5 F

0Ch

0Dh

0Eh

3 48 A3 6

5 F

0Ch

0Dh

0Eh

44

Logic Operations

File register

Working register, W

OR the bits of W and F, result in WExample,

IORWF 0Ch,W

8 A1 2

5 F

0Ch

0Dh

0Eh

3 4

45

Logic Operations

File register

Working register, Wafter IORWF 0C,W

OR the bits of W and F, result in WExample,

IORWF 0Ch,W

3 68 A1 2

5 F

0Ch

0Dh

0Eh

46

Logic OperationsOR the bits of L and W, result in WExample,

IORLW AB


B FWorking register, W after IORLW AB

47

Logic Operations

File register

Working register, W

Exclusive OR the bits of W and F, result in FExample,

XORWF 0Ch

3 68 A1 2

5 F

0Ch

0Dh

0Eh

48

Logic Operations

File registerafter XORWF 0C

Working register, W

Exclusive OR the bits of W and F, result in FExample,

XORWF 0Ch

3 62 4

5 F

0Ch

0Dh

0Eh

8 A

49

Logic Operations

File register

Exclusive OR the bits of W and F, result in WExample,

XORWF 0Ch,W

8 A1 2

5 F

0Ch

0Dh

0EhWorking register, W

3 6

50

Logic Operations

File register

Working register, Wafter XORWF 0C,W

Exclusive OR the bits of W and F, result in WExample,

XORWF 0Ch,W

2 48 A1 2

5 F

0Ch

0Dh

0Eh

51

Logic OperationsExclusive OR the bits of L and W, result in WExample,

XORLW AB


1 7Working register, W after EORLW AB

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Test and Skip Test a bit in F and Skip next instruction if it is Clear (= 0) BTFSC 0Ch,3

Test a bit in F and Skip next instruction if it is Set (= 1) BTFSS 0Ch,3

Decrement F and Skip next instruction if it is now Zero DECFSZ 0Ch

Increment F and Skip next instruction if it is now Zero INCFSZ 0Ch

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PIC16F877A Assembly Language

Representing a number in assemblerIn assembly language MPLAB, numbers can be represented in decimal, hexadecimal or binary form. For Example, number 240 can be represent as:

.240 or d’240’ - Decimal

0xF0, h’F0’ - Hexadecimal

b’11110000’ - Binary

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PIC16F877A Assembly Language(Mnemonic form)

; Start main loop;...............................................................

reset CLRF 06 ;Clear Port B Data

start BTFSS 05,0 ;Test RA0 input buttonGOTO reset ;and reset port B if pressedBTFSC 05,01 ;Test RA1 input buttonGOTO start ;and run count if pressed

INCF 06 ;increment count at Port BMOVLW 0FF ;Delay count literalCALL delay ;Jump to subroutine 'delay'

GOTO start ;Repeat main oop alwaysEND ;Terminate source code

Label

Command Operand

Comment

C PROGRAMMING

However, programmers have always needed a programming language close to the language being used in everyday life. As a result, the higher programming languages have been created. One of them is C. The main advantage of these languages is simplicity of program writing. It is no longer possible to know exactly how each command executes, but it is no longer of interest anyway. In case it is, a sequence written in assembly language can always be inserted in the program, thus enabling it.

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COMPILER

a specialized program in a PC called compiler is in charge of compiling

program into machine language. Figures above give a rough illustration of what is going on during the process

of compiling the program from higher to lower programming language.

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Here is an example of a simple program written in C language:

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ADVANTAGES OF HIGHER PROGRAMMING LANGUAGES

Support a high level of abstraction: both operations and data Greater portability for a program. As long as there is a translator for

the language on a particular computer architecture, the program can be used on that architecture.

Data representation is hidden. Programmer avoids dealing with details that are not part of his/her problem.

Generally easier to read than machine or assembly language. Programs are generally easier to maintain and modify.

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Example

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Programming in C Language Fundamental type of variable

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61

Using C for programming

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#include <stdio.h>void main(){}

#include <stdio.h>

void main(){

int number = 10; float weight; weight = 60.00;

printf(“Enter the value of number :”); scanf(“%d”,&number);

number = 50.00;}


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SELECTION STATEMENTS

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ITERATION STATEMENTS



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Port Initialization To set Port A as an input;

void main (void){

TRISA = 0b11111111;}

To set Port A as an output;void main (void){

TRISA = 0b00000000;PORTA = 0b00000000; //clear PORTA

}

REGISTER TRISA

1 1 1 1 1 1 1

REGISTER TRISA

0 0 0 0 0 0 0

REGISTER PORTA

0 0 0 0 0 0 0

Delay in Mikro C Delay in milisecond

Delay_ms(1000); //1000ms = 1s Delay in microsecond

Delay_us(1000) ; //1000us = 1ms Delay in 1 minute

void 1minutedelay(void) //function for 1 minute delay

{

unsigned int i;

for (i = 1; i <= 60; i ++) {

Delay_ms(1000);

}

} 67

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Flowchart

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A Simple PIC Application (Program1)

PIC

Inputport A

Outputport B

RCclock

+5V

OutputLEDs

Input push buttons(active low)

Clear

Count

CLKIN

MCLR

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A Simple PIC Application (Program1)

Clockcircuit

10kClear

Count

2n

10k 10k

2200V

+5V

PIC

144

18

17

16

5 6

7

8

9

10

11

12

13

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Flow Chart for subroutine output

Program 1

Initialize Port

Clear output port

Increment output

again


void main(void)

{

TRISB = 0x00; //Port B is set as output

while (1)

{

PORTB = PORTB + 1; //increment PORTB

}

}

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Flowchart for Program 1Program 1

Initialize Port

Clear output port

Increment output

start

Reset?

Run?

reset

Yes

No

Yes

No

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Flowchart for subroutine Delay

Delay

Timer = FF

Decrement Timer

Timer= 0 ?

End

down

Yes

No

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Flowchart for Program 1 (with Delay) Program 1

Initialize Port

Clear output port

Increment output

start

Reset?

Run?

reset

Yes

No

Yes

No

Delay

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HEX file of Program 1

:020000040000FA:100000000030660007288C008C0B0428080086014D:10001000051C072885180828860A103003200828A0:00000001FF

View listing file

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Flowchart of PIC Program Development process

PIC Program

Convert specification into algorithm/flowchart

Edit/write source code

Assemble program

Syntax error?

Test hex code in simulator

LogicalError?

A

A

Download hex code to chip

Test in target hardware

FunctionalError?

Done

YesYes

Yes

No

No

No

MICRO C #define BUTTON PORTA.F4 //Button at PORTA bit 4 #define LED PORTB.F0 //LED at PORTB bit 0 void main() { TRISB = 0b00000000; //All bit at PORTB is output PORTB = 0b00000000; //Clear (give 0V) at all PORTB output ADCON1 = 0b00000110; // Set PORTA as digital input TRISA = 0b00010000; // Set direction of bit 4 PORTA as input while(1) //endless loop { if (BUTTON == 0) //if button is press { LED = 1 //LED at PORTB bit 0 switch ON } else { LED = 0; //LED at PORTB bit 0 switch OFF } }//end of while }//end of main()

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ADCON1 Register

LITAR SKEMATIK

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EXAMPLE #define BUTTON PORTA.F4 //Button at PORTA bit 4 #define LED PORTB.F0 //LED at PORTB bit 0 void main() { TRISB = 0b00000000; //All bit at PORTB is output PORTB = 0b00000000; //Clear (give 0V) at all PORTB output ADCON1 = 0b00000110; //Set PORTA as digital input while(1) //endless loop { if (BUTTON == 0) //if button is press { LED = 1 //LED at PORTB bit 0 switch to ON } else { LED = 0; } }//end of while }//end of main()

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Engineering

Chapter2 2014