Microcontroller Lab Mnual

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MICROCONTROLLER

LABORATORY MANUAL

V SEMESTER B.Tech (ECE & EIE)

AMRITA VISHWA VIDYAPEETHAM

UNIVERSITY

Prepared By,

Mr. Peeyush.K.P.

Assistant Professor

Department of Electronics & Communication Engineering

ASE Ettimadai

Department of Electronics & Communication Engineering

Amrita School of Engineering

Ettimadai



TABLE OF CONTENTS

1) Study of 8085 Simulator 1

2) Study of MPLAB IDE 7

3)

Study of Proteus 7 Professional 234) 8085 Architecture 49

5) 8085 Instruction Set Summary 50

6) 8085 Programs 54

a. Addition of two 8 bit numbers 54

b. Subtraction of two 8 bit numbers 55

c. Multiplication of two 8 bit numbers 56

d. Division of two 8 bit numbers 57

7) PIC16F877A Architecture 58

8) PIC16F877A Peripherals 59

9)

PIC16F877A Instruction Set Summary 60

10) MPLAB Programs 61

a. Addition of two 8 bits numbers 61

b. Addition of two 8 bit numbers with carry 62

c. Subtraction of two 8 bit numbers with borrow 63

d. Multiplication of two 8 bit numbers 64

e. Division of two 8 bit numbers 65

f. Addition of 5 numbers using Indirect Addressing Mode 67

g. Blinking 8 LEDs connected to a PORT 68

h.

Controlling an LED with a Switch 71i. Controlling an LED with a Switch using External Interrupt (INT0) 73

j. Controlling an LED with a Switch using PORTB Pin Change Interrupt 76

k. Generation of 5mS square wave using Timer0 79

l. Generation of 5mS square wave using Timer0 in Interrupt Mode 84

m. Generation of 5mS square wave using Timer1 in Interrupt Mode 87

n. Generation of 5mS square wave using Timer2 in Interrupt Mode 93

o. Continuous Transmission of a character using USART in Asynchronous

p. Mode of operation 98

q. Reception and Transmission of the same character using USART in

Asynchronous Mode of operation 105r. Analog to Digital Conversion 109

s. Analog to Digital Conversion in Interrupt Mode 113

t. Generation of PWM 116

u. EEPROM read and write 121

v. Compare mode of operation of CCP 125



Department of ECE, ASE Ettimadai Microcontroller Laboratory Manual

Page 1 of 129

8085 SIMULATOR

1) Click on 8085 Simulator icon from Desktop.

Starting address of the actual program is 4000h, but by default the starting address will be from

C000h.

It is shown in Memory Range text box in 8085 Simulator.

The default starting address should be changed from C000h to 4000h.

Register window

Assembler windowFlag Register window

Memory Editor window

Simulator window

Memory Range Text Box




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2) For this click on Settings Tab -> Set Memory Range.

3) Then the Memory Range Text Box can be edited with new value ie 4000h … 4FFFh. So enter

these values in Memory Range text box.

4) Type the Assembly Language Program in the Assembler window.

5) Click on Assemble button on bottom of Assembler window.

Memory Range Text Box

Assembler window

Assemble button




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The program will be assembled and the corresponding Opcodes along with its address will be

displayed below the Assembler window.

If the program is wrong, the simulator will display the error message at the bottom of the

Simulator along with the line number and the will be an’X’ mark on left of that particular

address where error is present.

This error should be corrected and click on Assemble again.

As the next step, the simulator should be given with the starting address of the program.

Program with

Opcode & Address

Error ie ‘X’ Mark

Error Messa e with Line No.




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By default, the starting address will be C000h. It should be changed to 4000h as this program is

starting from 4000h onwards.

6)

For this, change C000 to 4000 in the Start From text box in the Simulator window.

7) Click on Step By Step button in the Simulator window inorder to perform the execution of the

program step by step.

8)

Click on Forward button in the Simulator window, so first instruction will get executed.

Second instruction of the program will be highlighted which shows that first instruction has

been executed and the second instruction is going to be executed when the Forward button is

pressed again.

Start From text box

Step by Step button

Forward button

Highlight




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In the first instruction 01 is moved to A register, check whether 01 is present in A register or in

the Accumulator.

This can be seen checking the value of Accumulator in Register window.

9)

Click on Forward button until the whole program is executed. That means the last line of the

program will be highlighted in blue colour.

Next step is that the output should be checked.

Accumulator Value = 01

Last line Highlighted




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10) Select Show only loaded memory location radio button in Memory Editor window.

So the memory locations which are loaded with a value will be displayed

Show only loaded memory location radio button




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MPLAB IDE

Project Creation

1) Open MPLAB IDE 7.52 icon from the desktop.

2) Click on Project Tab from Menubar.

3) Click on Project Wizard.

Welcome screen will appear.

Toolbar

Menubar

Status bar




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4) Click on Next button in the welcome screen.

5) Select Device as PIC16F877A from Device drop down menu.

6)

Select the Active Toolsuite as Microchip MPASM Toolsuite. This is done because programs are

to be written in Assembly Language.

Device Drop down menu




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7) Click on Next button.

8) Select the folder in which New Project has to be stored. For this, Select Create New Project File

and then click on Browse button.

Browse button




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9) Open any Drive, say E Drive, create a folder directly in this Drive.

Folder should be created directly in the Drive specified because the path name for the project

should have only limited number of characters.

10)

Name the folder as MP_Lab.

11) Type the Project Name as PIC_Project.

12) Click on Save.

Project Name




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13) Verify that the Path for the Project is displayed properly as E:\MP_Lab\PIC_Project.

14) Click on Next.

15) Again Click on Next.

Project Path




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16) Click on Finish.

17)

Project Explorer window will be displayed.

Project Explorer Window




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18) Click on File -> New File or click on New File icon in the Toolbar.

19) Type the whole assembly language program.

20) Click on File -> Save As.

New File




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21) Open the Project Folder ie E:\MP_Lab in the Save In drop down menu. Otherwise the program

will not be assembled properly and the program files will be saved in some other location other

than Project Folder.

22) Type the file name as Add.asm. Don,t forget to type the extension of the file as .asm.

23)

Click on Save.

24)

After saving, the colour of the program will change into blue and red. If still the program is in black colour, that means the program is not saved with proper extension ie .asm.




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Adding Source File (Program File) into the New Project and Build the Project

1) Right click on Source Files in the Project Explorer window and click Add Files.

2) Open the Project Folder in E Drive ie MP_Lab in Look In drop down menu.

3) Select Add.asm. Click on Open.

Source Files




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Add.asm will be displayed under Source Files in the Project Explorer window.

4) Click on Project -> Build All or click on Build All icon in the Toolbar to assemble the project.

5) If there is no errors in the program, Build Succeeded message will be displayed in the output

window.

Add.asm

Build All

Build Succeeded




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If there are any errors, Build Failed message will be displayed in the Output Window along with

the errors in the program.

6)

Double click on the Error[108]: Message displayed in the output window.

7) The cursor will automatically go to the statement where the error is present.

Build Failed

Instruction with Error




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Debug and Run the Project

1) Click on Debugger -> Select Tool -> MPLAB SIM.

MPLAB Simulator Debug Toolbar will be displayed.

As the next step, output should be checked. To check the output, the output and input address

location should be monitored.

To monitor these address locations, Watch window is used.

2)

Click on View -> Watch.

Debug Toolbar




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Watch window will be displayed.

3) Select FIRSTNO symbol from the Symbol drop down menu.

4) Click on Add Symbol button.

FIRSTNO symbol is added to watch window, so that the value of FIRSTNO can be monitored.

Symbol Drop down menuAdd Symbol button




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5) The address location of FIRSTNO also can be identified from the Watch window.

6) Similarly add SECNO and SUM to Watch window.

As the next step add WREG to Watch Window.

7) Select WREG from SFR drop down menu.

8) Click on Add SFR button in Watch Window.

SFR Drop down menu




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9) WREG is also added to Watch window.

10)

To debug the program by executing step by step, click on Step Into icon in Debug Toolbar.

Green arrow will be displayed on the left side of the program. This shows the instruction to be

executed in the next click of Step Into icon.

Green arrow is in the second line of the program, which shows that first line has been executed

and the result is displayed in the Watch window with value of WREG as 0x01.

Green Arrow




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11) If there is any change in the value of a register, it will be shown in red colour in the Watch

window.

12) Similarly click on Step Into until the last line of the program ie Goto L1 is reached.

This shows that the whole program has been executed and debugged.

Red Colour




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PROTEUS 7 PROFESSIONAL

1) Click on Start -> Program Files -> Proteus 7 Professional -> ISIS 7 Professional.

ISIS 7 Professional




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ISIS screen will be displayed.

2)

Click on Component Mode icon in the Toolbar.

Works aceDevice List

Toolbar

ToolbarMenubar

Component Mode




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3) Click on Pick From Libraries button from Devices List.

Pick Devices window will be displayed.

Pick from Libraries

Pick Devices window




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Components required for the circuit should be added to the Device List.

4)

Type PIC16F877A in the Keywords text space in Pick Devices window so as to add PIC into

Device List.

5) Press Enter key.

PIC16F877A will be displayed in the Result Space.

PIC16F877A

Result Space

Keywords

Text Box




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6) Double click on PIC16F877A in the Result Space.

PIC16F877A will be added to the Devices List in Proteus.

Double Click Here

PIC16F877A

Device List




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7) To add the second component ie 330 R resistance, type MINRES330R in Keywords text space

in Pick Devices window.

8)

Press Enter key.

9) Double click on MINRES330R in the Result Space.

MINRES330R ie 330 R resistor will be added to Devices List in Proteus.

10) Similarly Type Led-Yellow in Keywords text space in Pick Devices window inorder to add Led

to Devices List.

Keywords

Text Box Double Click Here




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11) Press Enter key.

12) Double click on Led-Yellow in Result Space.

Then Led-Yellow will be added to the Devices List.




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Now all the devices required for drawing the circuits are added to the Devices List.

13) Click on OK button in Pick Devices window.

OK Button




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Proteus workspace will be displayed with all the Devices listed in the Device List.

As the next step, desired circuit should be drawn in the workspace. So the devices should be

taken to the workspace from the Device List.




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14) Click on PIC16F877A in the Device List, and then click in the Workspace. So a skeleton of PIC

will be displayed in the workspace with the help of which the position of PIC can be desired.

15) Inorder to fix the PIC in the desired position, click ones more in the workspace.

16) Click on Zoom button in the Toolbar.

Single Click Here

Single Click Here

Single Click Here




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PIC IC in the workspace has been moved out of the viewable area, so it should be taken back to

the viewable area.

17) Click on Green Square (shows the viewable area) on the left top side of Proteus and move the

Green Square over the Black Rectangle (PIC) which is placed near the Green Square.

18)

Click once more to fix the viewable area (Green Square).

Green Square (Viewable Area)

Black Square (PIC)

Viewable Area

Viewable Area




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After this step PIC has been brought back to the viewable area.




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19) Click on MINRES330R in the Device List.

20) Click twice in the Workspace. So the resistor will be added to the workspace.

21) Similarly add Led also to the workspace.

As the next step add Ground Terminal to the workspace.

Single Click HereDouble Click Here




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22) For this Click on Terminals Mode icon in the Toolbar.

23) Select Ground from Terminals List.

Terminals Mode

Ground




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24) Click twice in the workspace so that the Ground Terminal will be added to the workspace.

Make the connection between the components.

25) Move the cursor to the starting point from which the connection has to be made. A small red

square will be displayed at the starting point.

This shows the point where the connection has to be made.

Double Click Here

Red Square




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26) Click on this red square, move the cursor to the ending point.

27)

Click at the ending point.

28) So that a connection has been made between starting and ending point.

Ending Point

Single ClickStarting Point

Single Click




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Similarly make the connection between all the components including the Ground.

As the next step, program hex file should be loaded into the PIC and the Crystal Oscillator

Frequency should be specified for the operation of PIC.




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29) Right click on PIC IC in the workspace. Select Edit Properties of PIC.

Right Click

Edit Properties




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Edit Component window will be displayed.

30) Click on Browse button, inorder to add the Program hex file.

Browse




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31) Select File Name window will be displayed.

32) Select the Led.hex file from the Project folder E:\MP_Lab.

33) Click on Open button.

Led.hex

Open Button




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34) Verify that the path displayed in the Program File text box is correct ie E:\MP_Lab\Led.hex.

35) Enter the Crystal Oscillator Frequency as 4MHz in the Processor Clock Frequency text box.

Since for this circuit a 4MHz crystal is connected to the PIC for its clock generation.

All the steps required for the simulation of the Led Blinking Circuit is completed.

Path

4MHz




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36) Click on Play button located at the bottom left corner to start the simulation.

The Led connected to RB0 will start Blinking

Play Button




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Adding Virtual Instruments to Proteus Workspace

1) Click on Virtual Instruments Mode in Proteus Toolbar.

Virtual Instruments List will be displayed.

Virtual Instruments

Mode




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2) Click on Oscilloscope in Virtual Instruments List.

3) Add Oscilloscope to Workspace.

4) Click on Play button at the bottom of Proteus.

Oscilloscope




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Oscilloscope window will be displayed.

5) Click on Cursors button inorder to measure the Time Period of Waveform.

6) Move the mouse pointer to Oscilloscope screen, then cursor will be displayed

Cursors button

Cursor




Page 48 of 129

7) Click on starting and ending point of waveform, so two cursors will be displayed at

starting and ending point.

From these two cursor Time Period can be directly measured.

Cursor 1Cursor 2




Page 49 of 129

8085 ARCHITECTURE




Page 50 of 129

8085 Instruction Set

Data transfer (Copy)

Hex Mnemonic Hex Mnemonic Hex Mnemonic Hex Mnemonic

40 MOV B,B 58 MOV E,B 70 MOV M,B 1A LDAX D

41 MOV B,C 59 MOV E,C 71 MOV M,C 2A LHLD

42 MOV B,D 5A MOV E,D 72 MOV M,D 3A LDA

43 MOV B,E 5B MOV E,E 73 MOV M,E 02 STAX B

44 MOV B,H 5C MOV E,H 74 MOV M,H 12 STAX D

45 MOV B,L 5D MOV E,L 75 MOV M,L 22 SHLD

46 MOV B,M 5E MOV E,M 77 MOV M,A 32 STA

47 MOV B,A 5F MOV E,A 78 MOV A,B 01 LXI B

48 MOV C,B 60 MOV H,B 79 MOV A,C 11 LXI D

49 MOV C,C 61 MOV H,C 7A MOV A,D 21 LXI H

4A MOV C,D 62 MOV H,D 7B MOV A,E 31 LXI SP

4B MOV C,E 63 MOV H,E 7C MOV A,H F9 SPHL

4C MOV C,H 64 MOV H,H 7D MOV A,L E3 XTHL

4D MOV C,L 65 MOV H,L 7E MOV A,M EB XCHG

4E MOV C,M 66 MOV H,M 7F MOV A,A D3 OUT

4F MOV C,A 67 MOV H,A 06 MVI B DB IN

50 MOV D,B 68 MOV L,B 0E MVI C C5 PUSH B

51 MOV D,C 69 MOV L,C 16 MVI D D5 PUSH D

52 MOV D,D 6A MOV L,D 1E MVI E E5 PUSH H

53 MOV D,E 6B MOV L,E 26 MVI H F5 PUSH PSW




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54 MOV D,H 6C MOV L,H 2E MVI L C1 POP B

55 MOV D,L 6D MOV L,L 36 MVI M D1 POP D

56 MOV D,M 6E MOV L,M 3E MVI A E1 POP H

57 MOV D,A 6F MOV L,A 0A LDAX B F1 POP PSW

Arithmetic


80 ADD B C6 ADI 9E SBB M 3C INR A

81 ADD C CE ACI 9F SBB A 03 INX B

82 ADD D 90 SUB B D6 SU1 13 INX D

83 ADD E 91 SUB C DE SB1 23 INX H

84 ADD H 92 SUB D 09 DAD B 33 INX SP

85 ADD L 93 SUB E 19 DAD C 05 DCR B

86 ADD M 94 SUB H 29 DAD H 0D DCR C

87 ADD A 95 SUB L 39 DAD SP 15 DCR D

88 ADC B 96 SUB M 27 DAA 1D DCR E

89 ADC C 97 SUB A 04 INR B 25 DCR H

8A ADC D 98 SBB B 0C INR C 2D DCR L

8B ADC E 99 SBB C 14 INR D 35 DCR M

8C ADC H 9A SBB D 1C INR E 3D DCR A

8D ADC L 9B SBB E 24 INR H 0B DCX B

8E ADC M 9C SBB H 2C INR L 1B DCX D

8F ADC A 9D SBB L 34 INR M 2B DCX H

3B DCX SP




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Logical


37 STC A9 XRA C B3 ORA E BD CMP L

A0 ANA B AA XRA D B4 ORA H BE CMP M

A1 ANA C AB XRA E B5 ORA L BF CMP A

A2 ANA D AC XRA H B6 ORA M FE CPI

A3 ANA E AD XRA L B7 ORA A 07 RLC

A4 ANA H AE XRA M F6 ORI 0F RRC

A5 ANA L AF XRA A B8 CMP B 17 RAL

A6 ANA M EE XRI B9 CMP C 1F RAR

A7 ANA A B0 ORA B BA CMP D 2F CMA

E6 ANI B1 ORA C BB CMP E 3F CMC

A8 XRA B B2 ORA D BC CMP H

Branching & Control


C3 JMP D7 RST 2 EC CPE 00 NOP

C2 JNZ DF RST 3 F4 CP 76 HLT

CA JZ E7 RST 4 FC CM F3 DI

D2 JNC EF RST 5 C9 RET FB EI

DA JC F7 RST 6 C0 RNZ 20 RIM

E2 JPO FF RST 7 C8 RZ 30 SIM




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EA JPE CD CALL D0 RNC

F2 JP C4 CNZ D8 RC

FA JM CC CZ E0 RPO

E9 PCHL D4 CNC E8 RPE

C7 RST 0 DC CC F0 RP

CF RST 1 E4 CPO F8 RM




Page 54 of 129

8085 PROGRAMS

Addition of two 8 bit numbers

Aim

To perform addition of two 8 bit numbers using 8085.

Algorithm

1) Start the program by loading the first data into Accumulator.

2) Move the data to a register (B register).3) Get the second data and load into Accumulator.

4) Add the two register contents.5) Check for carry.

6) Store the value of sum and carry in memory location.

7)

Terminate the program.

Program

MVI C, 00 Initialize C register to 00

LDA 4150 Load the value to Accumulator.MOV B, A Move the content of Accumulator to B register.

LDA 4151 Load the value to Accumulator.ADD B Add the value of register B to A

JNC LOOP Jump on no carry.INR C Increment value of register C

LOOP:STA 4152 Store the value of Accumulator (SUM).

MOV A, C Move content of register C to Acc.STA 4153 Store the value of Accumulator (CARRY)

HLT

Output

Address Data

Input4150 FF

4151 FF

Output4152 FE4153 01




Page 55 of 129

Subtraction of two 8 bit numbers

Aim

To perform the subtraction of two 8 bit numbers using 8085.

Algorithm

1) Start the program by loading the first data into Accumulator.2) Move the data to a register (B register).

3) Get the second data and load into Accumulator.4) Subtract the two register contents.

5) Check for carry.6) If carry is present take 2’s complement of Accumulator.

7) Store the value of borrow in memory location.

8)

Store the difference value (present in Accumulator) to a memory location and terminatethe program.

Program

MVI C, 00 Initialize C register to 00LDA 4150 Load the value to Accumulator.

MOV B, A Move the content of Accumulator to B register.LDA 4151 Load the value to Accumulator.

SUB B Subtract the value of register B from AJNC LOOP Jump on no carry.

CMA Complement Accumulator contents.INR A Increment value of register A

INR C Increment value of register CLOOP:

STA 4152 Store the value of Accumulator (SUM).MOV A, C Move content of register C to Acc.

STA 4153 Store the value of Accumulator (CARRY)HLT

Output

Address Data

Input4150 05

4151 03

Output4152 02

4153 01




Page 56 of 129

Multiplication of two 8 bit numbers

Aim

To perform multiplication of two 8 bit numbers using 8085.

Algorithm

1) Start the program by loading HL register pair with address of memory location.

2) Move the data to a register (B register).3) Get the second data and load into Accumulator.

4) Add the two register contents.5) Check for carry.

6) Increment the value of carry.7) Check whether repeated addition is over and store the value of product and carry in

memory location.8) Terminate the program.

Program

MVI D, 00 Initialize register D to 00

MVI A,00 Initialize Accumulator content to 00LXI H,4150

MOV B,M Get the first number in B - regINX H

MOV C,M Get the second number in C- reg

LOOP:ADD B Add content of A to register B.JNC NEXT Jump on no carry to NEXT.

INR D Increment content of register D NEXT:

DCR C Decrement content of register C.JNZ LOOP Jump on no zero to address

STA 4152 Store the result in MemoryMOV A,D

STA 4153 Store the MSB of result in MemoryHLT

Output

Address Data

Input4150 FF

4151 02

Output4152 FE

4153 01




Page 57 of 129

Division of two 8 bit numbers

Aim

To perform the division of two 8 bit numbers using 8085.

Algorithm

1) Start the program by loading HL register pair with address of memory location.2) Move the data to a register (B register).

3) Get the second data and load into Accumulator.4) Compare the two numbers to check for carry.

5) Subtract the two numbers.6) Increment the value of carry.

7) Check whether repeated subtraction is over and store the value of product and carry in

memory location.8) Terminate the program

Program

LXI H,4150MOV B,M Get the dividend in B – reg.

MVI C,00 Clear C – reg for qoutientINX H

MOV A,M Get the divisor in A – reg. NEXT:

CMP B Compare A - reg with register B.JC LOOP Jump on carry to LOOP

SUB B Subtract A – reg from B- reg.INR C Increment content of register C.

JMP NEXT Jump to NEXTLOOP:

STA 4152 Store the remainder in MemoryMOV A,CSTA 4153 Store the quotient in memory

HLT

Output

Address Data

Input4150 02

4151 05

Output4152 01

4153 02




Page 58 of 129

PIC16F877A ARCHITECTURE




Page 59 of 129

PIC16F877A PERIPHERALS

Timer0: 8-bit timer/counter with 8-bit prescaler.

Timer1: 16-bit timer/counter with prescaler, can be incremented during SLEEP viaexternal crystal/clock.

Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler.

Two Capture, Compare, PWM modules.

o Capture is 16-bit, max. resolution is 12.5 ns.

o Compare is 16-bit, max. resolution is 200 ns.

o PWM max. resolution is 10-bit.

10-bit multi-channel Analog-to-Digital converter.

Synchronous Serial Port (SSP) with SPI (Master mode) and I2C (Master/Slave).

Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI) with 9-bit

address Detection.

Parallel Slave Port (PSP) 8-bits wide, with external RD, WR and CS controls (40/44-pin

only).

Brown-out detection circuitry for Brown-out Reset (BOR).




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INSTRUCTION SET SUMMARY




Page 61 of 129

MPLAB PROGRAMS

Addition of two 8 bits numbers

AimTo add two 8 bit numbers and store the result

Algorithm

1) Move first number to W Register.

2) Move content of W Register to 0x20 (FIRSTNO).3) Move second number to W Register.

4) Move content of W Register to 0x21 (SECNO).5) Add content of W Register (second No.) with content of 0x20 (first No.).

6)

Move the result to 0x22 (SUM).

Program

#INCLUDE<P16F877A.INC>FIRSTNO EQU 0X20

SECNO EQU 0X21SUM EQU 0X22

ORG 0X00MOVLW 0X01

MOVWF FIRSTNO

MOVLW 0X02MOVWF SECNOADDWF FIRSTNO,0

MOVWF SUML1

GOTO L1END

Output

Two 8 bit numbers will be added and the result will be stored in 0x22.




Page 62 of 129

Addition of two 8 bit numbers with carry

AimTo add two 8 bit numbers and store the result along with carry.

Algorithm

1)

Move first number to W Register.

2) Move content of W Register to 0x20 (NUMBER_1).3) Move second number to W Register.

4) Move content of W Register to 0x21 (NUMBER_2).5) Add content of W Register (second No.) with content of 0x20 (first No.).

6) Move the result to 0x22 (SUM).7) If Carry is there, Increment 0x23 (CARRY).

8) Else goto step 9.

9)

End

Program

#INCLUDE<P16F877A.INC>

NUMBER_1 EQU 0x20 ; Define a Symbol Name NUMBER_1 to an Address 0x30 NUMBER_2 EQU 0X21

SUM EQU 0X22CARRY EQU 0X23

ORG 0X00 ; Shows the Origin of the ProgramGOTO START

ORG 0X05 ; Bypassing Interrupt Vector AddressSTART

MOVLW 0XA2 ; Move First Number to W

MOVWF NUMBER_1 ; Move First Number NUMBER_1 (0x20)MOVLW 0X62

MOVWF NUMBER_2ADDWF NUMBER_1, 0 ; W = NUMBER_1 + W (Second No.)MOVWF SUM ; Move Result from W to SUM

BTFSC STATUS, C ; Check for Carry FlagINCF CARRY, 1 ; If Carry is there, increment Carry Register.

L1GOTO L1

END ; Physical end of the program

Output

Two 8 bit numbers are added and the result will be stored in 0x22 with Carry stored in0x23.




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Subtraction of two 8 bit numbers with borrow

Aim

To subtract two 8 bit numbers and store the result along with borrow.

Algorithm

1) Move first number to W Register.2) Move content of W Register to 0x20 (NUMBER_1).

3) Move second number to W Register.4) Move content of W Register to 0x21 (NUMBER_2).

5) Subtract content of 0x20 (first No.) with content of W Register (second No.).6) Move the result to 0x22 (DIFF).

7) If Borrow is there, Increment 0x23 (BORROW).8) Else goto step 9.

9)

End

Program


NUMBER_1 EQU 0X20 NUMBER_2 EQU 0X21

DIFF EQU 0X22BORROW EQU 0X23

ORG 0X00

GOTO MAIN

ORG 0X05MAIN

MOVLW 0X62MOVWF NUMBER_1

MOVLW 0XA2MOVWF NUMBER_2

SUBWF NUMBER_1, 0 ; WREG = NUMBER_1 - WREGMOVWF DIFF ; DIFF = WREG

BTFSS STATUS, C ; If borrow is not there, goto end.

CALL COMPLIMENT ; If Borrow present, goto 2’s COMPLIMENT function.GOTO L1

COMPLIMENTCOMF DIFF, 1 ; DIFF = one's compliment of DIFF

INCF DIFF, 1 ; DIFF = DIFF + 1INCF BORROW, 1 ; BORROW = BORROW + 1

RETURN




Page 64 of 129

L1GOTO L1

END

Output

Two 8 bit numbers are subtracted and the result will be stored in 0x22 with Borrowstored in 0x23.

Multiplication of two 8 bit numbers

Aim

To multiply two 8 bit numbers and store the result.

Algorithm

1)

Clear 0x23 (Product MSB) & 0x24 (Product LSB).2) Move first number to MULTIPLIER & COUNT.3) Move second number to MULTIPLICANT.

4) If Multiplier is zero, goto end.5) Else if Multiplicant is Zero, goto end.

6) Add Multiplicant (second number) with PRODUCT LSB (initially zero) and store theresult in PRODUCT LSB itself.

7) If Carry is there, increment PRODUCT MSB.8) Else Decrement COUNT by one.

9) If COUNT is not zero goto step 6.10) Else goto end.

Program


ORG 0X00GOTO START

COUNT EQU 0X20

MULTIPLIER EQU 0X21MULTIPLICANT EQU 0X22

PRODUCT_MSB EQU 0X23

PRODUCT_LSB EQU 0X24

ORG 0X05

START

CLRF PRODUCT_MSB ; Clear the PRODUCT_MSBCLRF PRODUCT_LSB ; Clear the PRODUCT_LSB




Page 65 of 129

MOVLW 0X03MOVWF COUNT ; COUNT = WREG

MOVWF MULTIPLIER ; MULTIPLIER = WREGMOVLW 0XFF ; WREG = 0XFF

MOVWF MULTIPLICANT ; MULTIPLICANT = WREG

MOVF MULTIPLIER,0 ; WREG = MULTIPLIERBTFSC STATUS,Z ; Check Multiplier is ZeroGOTO TERMINATE ; If Zero, TERMINATE

MOVF MULTIPLICANT,0 ; WREG = MULTIPLICANTBTFSC STATUS,Z ; Check MULTIPLICANT is Zero

GOTO TERMINATE ; If Zero, TERMINATE

L2ADDWF PRODUCT_LSB,1 ; PRODUCT_LSB = PRODUCT_LSB + WREG

BTFSC STATUS,C ; Check for CarryINCF PRODUCT_MSB,1 ; PRODUCT_MSB = PRODUCT_MSB + 1

DECFSZ COUNT,1 ; Decrement COUNT, check for ZeroGOTO L2 ; If not zero, GOTO L2

TERMINATE

GOTO TERMINATEEND

Output

Two 8 bit numbers are multiplied and the result will be stored in 0x23 (Product MSB)

and 0x24 (Product LSB).

Division of two 8 bit numbers

Aim

To perform divisionof two 8 bit numbers and store the result.

Algorithm

1) Clear 0x22 (Quotient) & 0x23 (Remainder).2) Move first number to DIVIDENT & REMAINDER.

3) Move second number to DIVISOR.

4)

If Divisor is zero (Division by Zero), set Quotient as 0xff and Remainder as 0x00.5) Subtract WREG content (second number ie Divisor) from REMAINDER (initiallyDivident) and store the result in REMAINDER itself.

6) If Borrow is there (Remainder < 0), add Divisor with Remainder and store it inREMAINDER itself, then goto end.

7) Else Increment QUOTIENT.8) Goto step 5.




Page 66 of 129

Program

#INCLUDE<P16F877A.INC>DIVIDENT EQU 0X20

DIVISOR EQU 0X21

QUOTIENT EQU 0X22REMINDER EQU 0X23

ORG 0X00GOTO START

ORG 0X05

START

CLRF QUOTIENT ; Clear QUOTIENTCLRF REMINDER ; Clear REMINDER

MOVLW 0X05 ; WREG = 0X05MOVWF DIVIDENT ; DIVIDENT = WREG

MOVWF REMINDER ; REMINDER = WREGMOVLW 0X07 ; WREG = 0X07

MOVWF DIVISOR ; DIVISOR = WREGMOVF DIVISOR,0 ; WREG = DIVISOR

BTFSC STATUS,Z ; Check Divisor is zero.GOTO L1 ; If zero, goto L1

L2:SUBWF REMINDER,1 ; REMINDER = REMINDER - WREG

BTFSS STATUS,C ; Check for borrow.GOTO L3 ; If Borrow is there (Remainder < 0), goto L3

INCF QUOTIENT,1 ; Increment QUOTIENTGOTO L2

L3:ADDWF REMINDER, 1 ; REMINDER = REMINDER + WREG

GOTO TERMINATEL1:

MOVLW 0XFF ; WREG = 0XFFMOVWF QUOTIENT ; QUOTIENT = WREG

MOVWF REMINDER ; REMINDER = WREG

TERMINATE:GOTO TERMINATE

END ; Physical end of program

Output

Two 8 bit numbers are divided and the result will be stored in 0x22 (Quotient) and 0x23(Remainder).




Page 67 of 129

Addition of 5 numbers using Indirect Addressing Mode

AimTo perform addition of 5 numbers using Indirect Addressing Mode and store the result.

Algorithm

1)

Store 5 numbers in consecutive locations starting from 0x20.

2) Move 0x04 to COUNT.3) Initialize FSR with address location 0x20.

4) Move the content of INDF to WREG.5) Increment FSR.

6) Add the content of INDF with content of WREG & store the result in WREG.7) If Carry is there, increment CARRY register.

8) Else Decrement COUNT & check if it is equal to zero.

9)

If COUNT is not equal to zero, goto step 5.10) Else store the result in SUM & terminate the program.

Program

#INCLUDE<P16F877A.INC>COUNT EQU 0X30

SUM EQU 0X31CARRY EQU 0X32

ORG 0X00GOTO START

ORG 0X05START

MOVLW 0XFFMOVWF 0X20

MOVLW 0XFFMOVWF 0X21

MOVLW 0XFFMOVWF 0X22MOVLW 0XFF

MOVWF 0X23MOVLW 0XFF

MOVWF 0X24

MOVLW 0X04MOVWF COUNT

MOVLW 0X20MOVWF FSR

MOVF INDF,0




Page 68 of 129

L1INCF FSR

ADDWF INDF,0BTFSC STATUS,C

INCF CARRY,1

DECFSZ COUNT,1GOTO L1MOVWF SUM

L2GOTO L2

END

Blinking 8 LEDs connected to a PORT

Aim

To Blink 8 LEDs connected to PORTB.

Circuit Diagram

Algorithm

1) Configure PORTB as output Port.

2) Make all LEDs ON.3) Delay.

4) Make all LEDs OFF.5) Delay.

6) Goto Step 2.




Page 69 of 129

Registers associated with PORTB

Program

#INCLUDE<P16F877A.INC>ORG 0X00

GOTO STARTCOUNT EQU 0X20

COUNT1 EQU 0X21ORG 0X05

STARTBANKSEL TRISB

MOVLW 0X00MOVWF TRISB ; Configure PORTB Direction as Output

BANKSEL PORTBCLRF PORTB

LOOP

BANKSEL PORTBMOVLW 0XFFMOVWF PORTB ; 8 LEDs ON

CALL DELAYCALL DELAY

MOVLW 0X00MOVWF PORTB ; 8 LEDs OFF

CALL DELAYCALL DELAY

GOTO LOOPDELAY

MOVLW 0XFFMOVWF COUNT

L1MOVLW 0XFF

MOVWF COUNT1L2

DECFSZ COUNT1GOTO L2




Page 70 of 129

DECFSZ COUNTGOTO L1

RETURN

END

Output

LEDs connected to PORTB will start blinking.




Page 71 of 129

Controlling an LED with a Switch

Aim

To control an LED connected to RC2 with a Switch connected to RB1.1) When Switch is pressed LED should be ON.

2) When Switch is released LED should be OFF.

Circuit Diagram

Algorithm

1) Configure PORTC as Output.2) Configure RB1 as input

3) Configure Weak Internal Pull-ups for PORTB.4) If switch is pressed (RB1 = 0), make LED ON (RC2 = 1).

5) Else make LED OFF (RC2 = 0).6) Goto step 4.

Registers associated with PORTB




Page 72 of 129

Program


ORG 0X00GOTO START

START

BSF STATUS,RP0BCF STATUS,RP1

CLRF TRISC

BSF TRISB,1BCF OPTION_REG,NOT_RBPU ; Enable weak Internal Pull Ups for PORTBBCF STATUS,RP0

CLRF PORTCLOOP

BTFSS PORTB,1 ; Check whether switch is PressedGOTO L2

GOTO L3

L2

BSF PORTC,2 ; LED ONGOTO LOOP

L3

BCF PORTC,2 ; LED OFFGOTO LOOP

END




Page 73 of 129

Output

On pressing the switch, LED will be ON, on releasing the switch, LED will be OFF.

Controlling an LED with a Switch using External Interrupt (INT0)

Aim

To control an LED connected to RC0 with a Switch connected to INT0 pin (RB0).

1) When Switch is pressed LED should be ON.2) When Switch is released LED should be OFF.

Circuit




Page 74 of 129

Algorithm

Main

1) Configure RB0/INT0 as input.

2)

Configure PORTC as output.3)

Configure Weak Internal Pull-ups for PORTB.4) Configure Interrupt on Falling Edge.

5) Enable INT0.6) Enable Global Interrupt Enable.

7) If switch is pressed (RB0 = 0), goto step 7.8) Else make LED OFF (RC0 = 0).

ISR

1) Disable GIE.

2)

If INT0 Interrupt Flag Bit is set (INTF),a.

Clear INTF.

b. Make LED ON (RC0 = 1).3) Else return to main program.

Register description of INTCON Register

Program


ORG 0X00GOTO START

ORG 0X04GOTO ISR




Page 75 of 129

STARTBANKSEL TRISB

BSF TRISB,0CLRF TRISC

BCF OPTION_REG,NOT_RBPU

BCF OPTION_REG,INTEDG ; Configure Interrupt Edge as Falling EdgeBANKSEL PORTBCLRF PORTC

BANKSEL TRISBBSF INTCON,INTE ; Enable INT0 Interrupt

BSF INTCON,GIE ; Enable Global InterruptBCF INTCON,INTF

L1BANKSEL PORTB

BTFSC PORTB,0BCF PORTC,0

GOTO L1ISR

BANKSEL INTCONBCF INTCON,GIE

BTFSS INTCON,INTF ; Check INT0 Interrupt FlagRETFIE

BCF INTCON,INTFBANKSEL PORTB

BSF PORTC,0RETFIE ; Return from ISR with Interrupt Enable (GIE = 1).

END

Output





Page 76 of 129

Controlling an LED with a Switch using PORTB Pin Change Interrupt

Aim

To control an LED connected to RC0 with a Switch connected to RB4 pin.1) When Switch is pressed LED should be ON.

2) When Switch is released LED should be OFF.

Circuit

Algorithm

Main

1) Configure RB4 as input.

2) Configure PORTC as output.3) Configure Weak Internal Pull-ups for PORTB.

4) Enable PORTB Pin Change Interrupt.5) Enable Global Interrupt Enable (GIE).

6) If switch is pressed (RB4 = 0), goto step 7.7) Else make LED OFF (RC0 = 0).

ISR

1) Disable GIE.

2) If PORTB Pin Change Interrupt Flag Bit is set (RBIF),Clear RBIF.3) Else return to main program.

4) If switch is pressed (RB4 = 0), Make LED ON (RC0 = 1).5)

Else return to main program.




Page 77 of 129


Program


ORG 0X00GOTO START

ORG 0X04

GOTO ISRSTART

BANKSEL TRISB

BSF TRISB,4CLRF TRISC

BANKSEL OPTION_REGBCF OPTION_REG,NOT_RBPU

BANKSEL PORTCCLRF PORTC

BANKSEL INTCONBSF INTCON,RBIE ; Enable PORTB Pin Change Interrupt

BSF INTCON,GIEBCF INTCON,RBIF

L1BANKSEL PORTB

BTFSC PORTB,4BCF PORTC,0

GOTO L1




Page 78 of 129

ISRBANKSEL INTCON

BSF INTCON,GIEBTFSS INTCON,RBIF ; Check PORTB Pin Change Interrupt Flag

RETFIE

BCF INTCON,RBIFBTFSS PORTB,4 ; Check whether switch is pressedBSF PORTC,0

RETFIEEND

Output





Page 79 of 129

Generation of 5mS square wave using Timer0

Aim

To generate a square wave of 5mS On & Off time in PORTC using Timer0.

Circuit

Algorithm

1) Configure PORTC as output.

2) Configure Timer0 in Timer Mode.3) Assign Prescalar to Timer0.

4) Configure Prescalar as 32.5) Initialize Timer0 register with 0x63.

6) Wait until Timer0 Interrupt Flag (T0IF) is set.7) Clear T0IF.

8) Compliment PORTC.9) Re-initialize Timer0 register with 0x63.

10)

Goto step 6.




Page 80 of 129

Registers associated with Timer0

Register Description of OPTION_REG Register




Page 81 of 129


Description of TMR0 Register

TMR0 is the 8 bit Timer Register of Tmer0. Since it is an 8 bit Register, it can have

values from 0x00 to 0xFF ie 256 values. Since TMR0 is the Timer Register, it will be

incremented from initial value (0x00 default value) to final value (0xFF) in every clock cycle. If4MHz is used as the Crystal Oscillator, each instruction will take 1 usec for its execution. So

TMR0 will take 256 usec in total to reach 0xFF from 0x00. Since there is a prescalar (1:256

max) in addition to TMR0 Register, Timer0 can generate upto maximum of 65 mS delay ie (256

* 256 usec) when using 1:256 as Prescalar.

Inorder to generate a delay lesser than 65 mS, the initial value that has to be loaded into

TMR0 register has to be changed.

Eg: Generate a delay of 5mS with Timer0 with 4MHz Crystal Oscillator.

Since Timer0 is used,

255 * 1 usec * Prescalar = 5000 usec

Prescalar = 5000/(255 * 1)

= 19 = 32 (Next higher Prescalar for Timer0)

Calculation of value that has to be loaded into TMR0 Register,

TMR0=255− ()

= 255 – (5000/32)= 99 = 0x63




Page 82 of 129

Program


GOTO START

STARTBSF STATUS,RP0BCF STATUS,RP1

CLRF TRISCBCF STATUS,RP0

CLRF PORTC

BSF STATUS,RP0BCF OPTION_REG,T0CS ; Select Timer Mode of operation for Timer0

BCF OPTION_REG,PSA ; Assign Prescalar to Timer0BSF OPTION_REG,PS2 ; Set Prescalar as 1:32

BCF OPTION_REG,PS1BCF OPTION_REG,PS0

BCF STATUS,RP0

MOVLW 0X63MOVWF TMR0 ; Initialize TMR0 to generate 5mS delay with Timer0

L1

BTFSS INTCON,T0IF ; Check Timer0 Interrupt FlagGOTO L1

BCF INTCON,T0IF

COMF PORTC,1 ; Complement PORTC

MOVLW 0X63 ; Re-initialize TMR0

MOVWF TMR0

GOTO L1

END




Page 83 of 129

Output

Square wave on 5mS ON & OFF Time will be generated in PORTC which can beverified from the Oscilloscope output.




Page 84 of 129

Generation of 5mS square wave using Timer0 in Interrupt Mode

Aim

To generate a square wave of 5mS On & Off time in PORTC using Timer0 in InterruptMode of operation.

Circuit

Algorithm

Main1) Configure PORTC as output.

2) Configure Timer0 in Timer Mode.3) Assign Prescalar to Timer0.

4) Configure Prescalar as 32.5) Enable Timer0 Interrupt Enable.

6) Enable GIE.7) Initialize Timer0 register with 0x63.

8) Goto step 8.

ISR

1) Disable GIE.2) If Timer0 Interrupt Flag Bit is set (T0IF),

a. Clear T0IF. b. Compliment PORTC.

c. Re-initialize Timer0 register with 0x63.3) Else return to main program.




Page 85 of 129


Program


ORG 0X00GOTO START

ORG 0X04GOTO ISR

STARTBANKSEL TRISC

CLRF TRISCBANKSEL PORTC

CLRF PORTC

BANKSEL OPTION_REGBCF OPTION_REG,T0CSBCF OPTION_REG,PSA

BSF OPTION_REG,PS2BCF OPTION_REG,PS1

BCF OPTION_REG,PS0

BANKSEL INTCONBSF INTCON,T0IE ; Enable Timer0 Interrupt

BSF INTCON,GIE

BANKSEL TMR0MOVLW 0X63MOVWF TMR0

L1

GOTO L1ISR

BCF INTCON,GIE




Page 86 of 129

BTFSS INTCON,T0IF ; Check Timer0 Interrupt FlagRETFIE

BCF INTCON,T0IFBANKSEL PORTC

COMF PORTC,1

BANKSEL TMR0MOVLW 0X63MOVWF TMR0

RETFIEEND

Output

Square wave on 5mS ON & OFF Time will be generated in PORTC which can be

verified from the Oscilloscope output.




Page 87 of 129


Aim


Circuit

Algorithm


2) Configure Timer1 in Timer Mode.3) Configure Prescalar as 1:1.

4) Initialize TMR1L with 0x77.5) Initialize TMRIH with 0xEC.

6) Enable Timer1 Interrupt Enable.7) Enable Peripheral Interrupt Enable (PEIE).

8) Enable GIE.9) Switch on Timer1.

10)

Goto step 10.

ISR1) Disable GIE.

2) If Timer1 Interrupt Flag Bit is set (TMR1IF),a. Clear TMR1IF.

b. Compliment PORTC.c. Re-initialize TMR1L with 0x77.




Page 88 of 129

d. Re-initialize TMRIH with 0xEC.3) Else return to main program.


Register description of T1CON Register




Page 89 of 129

Register description of PIE1 Register

Register description of PIR1 Register


Description of TMR1H & TMR1L Registers

Timer1 is a 16 bit Timer. TMR1H is the 8 bit Timer Register which holds the 8 bit MSB

and TMR1L is an 8 bit Timer Register which holds the remaining 8 bit LSB of Timer1. Since it

is a 16 bit Timer, it can have values from 0x00 to 0xFFFF ie 65536 values. Since TMR1H &




Page 90 of 129

TMR1L is the 16 bit Timer Register, it will be incremented from initial value (0x00 default

value) to final value (0xFFFF) in every clock cycle. If 4MHz is used as the Crystal Oscillator,

each instruction will take 1 usec for its execution. So TMR1H & TMR1L together will take

65536 usec in total to reach 0xFFFF from 0x00. Since there is a prescalar (1:8 max) in addition

to TMR1H & TMR1L Register, Timer1 can generate upto maximum of 524 mS delay ie (65536

* 8 usec) when using 1:8 as Prescalar.

Inorder to generate a delay lesser than 524 mS, the initial value that has to be loaded into

TMR1H & TMR1L registers has to be changed.



65535 * 1 usec * Prescalar = 5000 usec

Prescalar = 5000/(65535 * 1)

= 0.08 = 1 (Next higher Prescalar for Timer1)

Calculation of value that has to be loaded into TMR1H & TMR1L Register,

TMR1H:TMR1L = 65535− ()

= 65535 – (5000/1)

= 60535 = 0 x EC 77

TMR1H = 0xEC TMR1L = 0x77

Program


ORG 0X00GOTO START

ORG 0X04GOTO ISR

ORG 0X05START

BANKSEL TRISCCLRF TRISC

BANKSEL T1CONBCF T1CON,TMR1CS ; Select Timer Mode of Operation for Timer1

BCF T1CON,T1CKPS1 ; Set Timer1 Prescalar as 1:1BCF T1CON,T1CKPS0




Page 91 of 129

BANKSEL TMR1LMOVLW 0X77

MOVWF TMR1L ; Initialize TMR1L with 0x77BANKSEL TMR1H

MOVLW 0XEC

MOVWF TMR1H ; Initialize TMR1H with 0xECBANKSEL PIE1BSF PIE1,TMR1IE ; Enable Timer1 Interrupt

BSF INTCON,PEIE ; Enable Peripheral InterruptsBSF INTCON,GIE

BANKSEL T1CONBSF T1CON,TMR1ON ; Switch on Timer1

L1GOTO L1

ISRBCF INTCON,GIE

BANKSEL PIR1BTFSS PIR1,TMR1IF ; Check Timer1 Interrupt Flag

RETFIEBCF PIR1,TMR1IF

BANKSEL PORTCCOMF PORTC,1

BANKSEL TMR1LMOVLW 0X77

MOVWF TMR1LBANKSEL TMR1H

MOVLW 0XECMOVWF TMR1H

RETFIE

END




Page 92 of 129

Output





Page 93 of 129


Aim


Circuit

Algorithm


2) Configure Prescalar as 1:16.3) Configure Postscalar as 1:2.

4) Initialize PR2 with 0x9C.5) Initialize Timer2 register with 0x00.

6) Enable Timer2 Interrupt Enable.7) Enable PEIE.

8) Enable GIE.9) Switch on Timer2.

10)

Goto step 10.ISR

1) Disable GIE.2) If Timer2 Interrupt Flag Bit is set (TMR2IF),

a. Clear TMR2IF. b. Compliment PORTC.

c. Re-initialize Timer2 register with 0x00.3) Else return to main program.




Page 94 of 129


Register description of T2CON Register





Page 95 of 129


Description of TMR2 Register

TMR2 is the 8 bit Timer Register of Tmer2. Since it is an 8 bit Register, it can have

values from 0x00 to 0xFF ie 256 values. Since TMR2 is the Timer Register, it will be

incremented from initial value (0x00) to final value (0xFF default value) in every clock cycle. If

4MHz is used as the Crystal Oscillator, each instruction will take 1 usec for its execution. So

TMR2 will take 256 usec in total to reach 0xFF from 0x00. Since there is a prescalar (1:16 max)

and postscalar (1:16 max) in addition to TMR2 Register, Timer2 can generate upto maximum of

65 mS delay ie (256 * 16 * 16 usec) when using 1:16 as Prescalar & 1:16 as Postscalar.

Inorder to generate a delay lesser than 65 mS, the final value has to be changed. Final

value till which the Timer2 register (TMR2) has to be incremented is specified in PR2 Register.

So that Timer2 can increment from 0x00 to final value that is specified in PR2 Register.



255 * 1 usec * Prescalar * Postscalar = 5000 usec

Prescalar * Postscalar = 5000/(255 * 1)

= 19 = 32

Therefore,

Prescalar = 16 & Postscalar = 2




Page 96 of 129

Calculation of value that has to be loaded into PR2 Register,

PR2= ()

∗

= (5000/(16 * 2))

= 156 = 0x9C

Program


GOTO STARTORG 0X04

GOTO ISRORG 0X05

START

BANKSEL TRISCCLRF TRISCBANKSEL T2CON

BSF T2CON,T2CKPS1 ; Set Prescalar as 1:16BSF T2CON,T2CKPS0

BCF T2CON,TOUTPS3 ; Set Postscalar as 1:2BCF T2CON,TOUTPS2

BCF T2CON,TOUTPS1BSF T2CON,TOUTPS0

BANKSEL PR2MOVLW 0X9C

MOVWF PR2 ; Set final value of Timer2 with 0x9CBANKSEL TMR2

CLRF TMR2BANKSEL PIE1

BSF PIE1,TMR2IE ; Enable Timer2 InterruptBSF INTCON,PEIE

BSF INTCON,GIEBANKSEL T2CON

BSF T2CON,TMR2ON ; Switch ON Timer2L1

GOTO L1

ISRBCF INTCON,GIEBANKSEL PIR1

BTFSS PIR1,TMR2IF ; Check Timer2 Interrupt FlagRETFIE

BCF PIR1,TMR2IFBANKSEL PORTC

COMF PORTC,1




Page 97 of 129

BANKSEL TMR2CLRF TMR2

RETFIE

END

Output





Page 98 of 129

Continuous Transmission of a character using USART in Asynchronous

Mode of operation

Aim

To transmit a character ‘A’ continuously from PIC using USART in Asynchronous Modeof Operation at 9600bps.

Circuit

Algorithm

1) Configure High Speed Transmission (Set BRGH).2) Configure Baud Rate as 9600 (Move 25 to SPBRG).

3)

Configure Asynchronous Mode of Transmission.4) Enable Transmission.

5) Configure RC6 & RC7 as TX & RX pin of USART (Set SPEN =1).6) Wait until Transmission Interrupt Flag is set (TXIF).

7) Move ‘A’ to Transmit Register.8) Goto step 6.




Page 99 of 129

Register associated with Asynchronous Transmitter

Register description of TXSTA Register




Page 100 of 129

Register description of RCSTA Register






Page 101 of 129

Description of SPBRG Register

SPBRG Register is the register used for setting the Baud Rate (Bits Per Second) at which

Transmission or Reception has to be taken place.

For setting a Baud Rate as say 9600bps, a particular 8 bit Value has to be moved to SPBRG.

For finding this value there are separate equations when BRGH = 1 & BRGH = 0,

By substituting the value of Fosc (Crystal Oscillator Frequency) and the Desired Baud Rate, the

value of ‘X’ can be found out. This value has to be moved to SPBRG inorder to set the Desired

Baud Rate.

Eg: Fosc = 4MHz & Baud Rate = 9600bps whwn BRGH = 1,

9600bps = 4MHz/(16(X+1))

Therefore,

X = 25 = 0x19.

So SPBRG = 0x19 will generate Baud Rate of 9600bps when using 4MHz Crsytal Oscillator.

Usually instead performing this calculations, the SPBRG values corresponding to popular Baud

Rates are given in the form of a Table in the Data sheet.

There are Tables corresponding to BRGH = 1 & BRGH = 0.




Page 102 of 129




Page 103 of 129

Program


GOTO START

ORG 0X05STARTBANKSEL TXSTA

BSF TXSTA,BRGH ; Set High Speed TransmissionBANKSEL SPBRG

MOVLW .25MOVWF SPBRG ; Set Baud Rate as 9600bps

BANKSEL TXSTABCF TXSTA,SYNC ; Set Asynchronous Transmission

BSF TXSTA,TXEN ; Enable TransmissionBANKSEL RCSTA

BSF RCSTA,SPEN ; Configure RC6 & RC7 as USART PinsLOOP

BANKSEL PIR1BTFSS PIR1,TXIF ; Check Transmission Interrupt Flag

GOTO LOOPBANKSEL TXREG

MOVLW 'A'MOVWF TXREG ; Transmit ‘A’

GOTO LOOPEND

Output

The character ‘A’ will be continuously transmitted from PIC to PC which can be seen on

Virtual Terminal window of Proteus.




Page 104 of 129

Note: For adding Virtual Terminal to Workspace click on Virtual Instruments Mode in

Proteus Toolbar. Then Select Virtual Instruments from Virtual Instruments List.




Page 105 of 129

Reception and Transmission of the same character using USART in

Asynchronous Mode of operation

Aim

To receive a character that is transmitted from PC and transmit this same character backto the PC using USART in Asynchronous Mode of Operation at 9600bps.

Circuit

Algorithm

Main

1) Configure High Speed Transmission (Set BRGH).2) Configure Baud Rate as 9600 (Move 25 to SPBRG).

3) Configure Asynchronous Mode of Transmission.4) Enable Transmission.

5) Enable Continuous Receive.6)

Configure RC6 & RC7 as TX & RX pin of USART (Set SPEN =1).

7) Wait until Receive Interrupt Flag is set (RCIF).

8)

Read Receive Register to W register.9) Wait until Transmit Interrupt Flag is set (TXIF).10) Move read character from W register to Transmit Register.

11) Goto step 7




Page 106 of 129

Register associated with Asynchronous Transmitter

Register description of RCSTA Register




Page 107 of 129



Program

PROCESSOR P16F877#INCLUDE<P16F877.INC>ORG 0X00

GOTO STARTORG 0X05

STARTBANKSEL TXSTA

BSF TXSTA,BRGH




Page 108 of 129

BANKSEL SPBRGMOVLW .25

MOVWF SPBRGBANKSEL TXSTA

BCF TXSTA,SYNC

BSF TXSTA,TXENBANKSEL RCSTABSF RCSTA,CREN ; Enable Continous Receive

BSF RCSTA,SPENLOOP

BANKSEL PIR1BTFSS PIR1,RCIF ; Check Receive Interrupt Flag

GOTO LOOPBANKSEL RCREG

MOVF RCREG,0 ; Move received character to WREGBANKSEL PIR1

LOOP1BTFSS PIR1,TXIF ; Check Transmit Interrupt Flag

GOTO LOOP1BANKSEL TXREG

MOVWF TXREG ; Transmit received character to PCGOTO LOOP

END

Output

The characters which have been entered through the PC’s keyboard, will be received byPIC and then it will be retransmitted back to the PC.

So whatever characters that are typed in the Virtual Terminal will be echoed back in VirtualTerminal window.




Page 109 of 129

Analog to Digital Conversion

Aim

To convert the analog signal that is given by a Potentiometer connected to Channel 0(RA0) and display the digital data on 8 LEDs connected to PORTB.

Circuit

Algorithm

1) Configure RA0 as input.2) Configure PORTB as output.

3) Configure PORTA & PORTE as Analog Input Pins.4) Configure ADC Clock Source as FOSC/32.

5) Select Analog Input Channel 0 (RA0) as ADC input Channel.6) Select Left Justification for ADC Result Format.

7) Switch ON ADC.8) Start ADC Conversion.

9) Wait until ADC Conversion is completed.

10)

Move ADC Result from ADRESH to W register.11) Move ADC Result from W register to PORTB.12) Goto step 8.




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Registers associated with ADC

Register description for ADCON0 Register




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Register description for ADCON1 Register

Program

PROCESSOR P16F877#INCLUDE<P16F877.INC>

ORG 0X00MOVLW 0X00

MOVWF PCLATHCLRF STATUS

GOTO STARTSTART

BANKSEL TRISABSF TRISA,0 ; Configure RA0 as input

BANKSEL TRISB




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CLRF TRISBBANKSEL PORTB

CLRF PORTBBANKSEL ADCON1

CLRF ADCON1

BANKSEL ADCON0BSF ADCON0,ADCS1 ; Configure ADC Clock as Fosc/32BCF ADCON0,ADCS0

BCF ADCON0,CHS2 ; Select ADC input channel as Channel 0BCF ADCON0,CHS1

BCF ADCON0,CHS0BANKSEL ADCON1

BCF ADCON1,ADFM ; Select ADC Result Format as Left JustifiedBANKSEL ADCON0

BSF ADCON0,ADON ; Switch ON ADCBSF ADCON0,GO_DONE ; Start ADC Conversion

LOOP BANKSEL ADCON0

BSF ADCON0,GO_DONEL1 BTFSC ADCON0,GO_DONE ; Check for End of Conversion of ADC

GOTO L1BANKSEL ADRESH

MOVF ADRESH,0 ; Move MSB 8 bit of ADC Result to WREGMOVWF PORTB ; Move ADC Result to PORTB

GOTO LOOPEND

Output

On varying the potentiometer, the corresponding digital value will be displayed on the

LEDs.




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Analog to Digital Conversion in Interrupt Mode

Aim

To convert the analog signal that is given by a Potentiometer connected to Channel 0(RA0) and display the digital data on 8 LEDs connected to PORTB in Interrupt Mode.

Circuit





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Program

PROCESSOR P16F877#INCLUDE<P16F877.INC>

ORG 0X00GOTO START

ORG 0X04GOTO ISR

STARTBANKSEL TRISA

BSF TRISA,0BANKSEL TRISB

CLRF TRISBBANKSEL PORTB

CLRF PORTBBANKSEL ADCON1

CLRF ADCON1BANKSEL ADCON0

BSF ADCON0,ADCS1BSF ADCON0,ADCS0

BCF ADCON0,CHS2BCF ADCON0,CHS1

BCF ADCON0,CHS0BANKSEL ADCON1

BCF ADCON1,ADFM

BANKSEL PIE1BSF PIE1,ADIE ; Enable ADC Interrupt

BANKSEL INTCONBSF INTCON,PEIE

BSF INTCON,GIEBANKSEL ADCON0

BSF ADCON0,ADONBSF ADCON0,GO_DONE




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L1 NOP

NOP NOP

BSF ADCON0,GO_DONE

GOTO L1

ISRBSF INTCON,GIE

BANKSEL PIR1BTFSS PIR1,ADIF ; Check for ADC Interrupt Flag

RETFIEBCF PIR1,ADIF

BANKSEL ADRESH

MOVF ADRESH,0MOVWF PORTB

RETFIEEND

Output

On varying the potentiometer, the corresponding digital value will be displayed on the

LEDs.




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Generation of PWM

Aim

To generate a PWM signal of 5kHz frequency and 80% duty cycle using 20MHz as theCrystal Oscillator Frequency in CCP1 pin (RC2).

Circuit

Registers associated with PWM Operation




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Register description for CCPxCON Register





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Description of PR2 Register

PR2 register is used for setting the Period of PWM. It is an 8 bit register.Period of PWM signal can be set by moving an 8 bit value to PR2 register. For finding out this

value, there is an equation,

PR2= -1

Description of CCPRxL Register and CCPxX & CCPxY Bits

In PIC16F877A, PWM Module with 8 bit PWM Period (PR2 Register) and 10 bit On

Time is present. 8 bits of On Time can be given in CCPRxL Register and the remaining 2 bits

can be given in CCPxX & CCPxY bits of CCPxCON Register ie 4 th and 5 th bits.

CCPRxL:CCPxCON<5:4> = Duty Cycle∗ Period Tosc∗ TMR2 Prescalar




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Eg: Generate a PWM of 5kHz frequency and 80% duty cycle using 20MHz as the Crystal

Oscillator Frequency.

Calculation of Period value that has to be written to PR2 Register,

Tpclk (Time for 1 instr) = 1/(20MHz/4) = 0.2 usec. Since, 1Pclk = 20MHz/4

PWM Period = 1/5kHz = 200 usec.

Tosc = 1/20MHz = 0.05 usec.


255*0.2 usec*Prescalar = 200 usec

Prescalar = 200/(255*0.2) = 3.92 = 4

PR2 = ( ( PWM Period) / ( Tosc x 4 x Prescaler ) ) - 1

= ( ( 200 usec ) / ( 0.05 usec x 4 x 4 )) - 1

= 250 – 1

= 249 = 0xF9

Calculation of On Time that has to be written to CCPRxL:CCPxCON<5:4> Registers,

(CCPRxL:CCPxCON<5:4>) = (Duty Cycle*Period)/(Tosc*(Prescalar))

= (0.8x(1/5,000))/((1/20,000,000)*4)

= (0.8x200 usec)/(0.05 usec*4)

= 800 = 0x320

= 11001000 00 (binary)

CCPRxL = 11001000 = 0xC8 CCPxCON<5:4> ie CCPxX = 0 CCPxY = 0

Program


GOTO STARTORG 0X05

STARTBANKSEL TRISC

BCF TRISC,2

On Time




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BANKSEL T2CONCLRF T2CON

BCF T2CON,T2CKPS1 ; Set Prescalar as 1:4BSF T2CON,T2CKPS0

BANKSEL PR2

MOVLW 0XF9MOVWF PR2 ; Initialize PWM Period as 0xF9BANKSEL CCPR1L

MOVLW 0XC8MOVWF CCPR1L ; Initialize 8 bits of On Time as 0xC8

BANKSEL CCP1CONBCF CCP1CON,CCP1X ; Initialize 2 bit LSBs of On Time as 00

BCF CCP1CON,CCP1YMOVLW 0X0F

MOVWF CCP1CONBANKSEL T2CON

BSF T2CON,TMR2ON ; Switch ON Timer2L1

GOTO L1END

Output

PWM with 5kHz frequency and 80% duty cycle will be generated in CCP1 (RC2)pin.

Note:

Crystal Oscillator frequency should be set as 20MHz in Proteus.




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EEPROM Read and Write

Aim

1)

To write data (0x06) to address 0x01 of EEPROM.2) Read the data back from the same address and display it on 8 LEDs connected to

PORTB.

Circuit

Registers associated with EEPROM




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Register description for EECON1 Register






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Programs

#INCLUDE<P16F877A.INC>ORG 0X00GOTO START

ORG 0X05STARTBANKSEL TRISBCLRF TRISBBANKSEL PORTBCLRF PORTBBANKSEL EECON1BTFSC EECON1, WR ; Wait for write to finishGOTO $-1BANKSEL EEADRMOVLW 0X01MOVWF EEADR ; Write Address (0x01) to EEADR RegisterBANKSEL EEDATAMOVLW 0X06MOVWF EEDATA ; Write Data (0x06) to EEDATA RegisterBANKSEL EECON1BCF EECON1, EEPGD ; Set EEPROM as Data memoryBSF EECON1, WREN ; Enable Write to EEPROMBCF INTCON, GIEBANKSEL EECON2MOVLW 0x55 ; Write control word 55h to EECON2MOVWF EECON2MOVLW 0xAA ; Write control word AAh to EECON2MOVWF EECON2BANKSEL EECON1BSF EECON1, WR ; Start write operationBSF INTCON, GIE ;BCF EECON1, WREN ; Disable Write operation to EEPROM

BANKSEL EEADR




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MOVLW 0X01MOVWF EEADR

BANKSEL EECON1BCF EECON1, EEPGD

BSF EECON1, RD

BANKSEL EEDATAMOVF EEDATA, W ; Move the contents of EEPROM to WREGMOVWF PORTB ; Move EEPROM contents to PORTB

L1GOTO L1

END

Output

EEPROM data (0x06) will be displayed in 8 LEDs.




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Compare Mode of Operation of CCP

Aim

To perform the compare operation,1) Set CCP1 pin as High.

2) Complement PORTB after each Compare event.

Circuit

Registers associated with Compare Mode of Operation




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Register description for CCPxCON Register





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Program


ORG 0X00GOTO START

ORG 0X04GOTO ISR

ORG 0X05START

BANKSEL TRISBBCF TRISC,2

CLRF TRISBBANKSEL PORTC

CLRF PORTBBANKSEL T1CON

BSF T1CON,T1CKPS1 ; Set Prescalar as 1:8BSF T1CON,T1CKPS0

BCF T1CON,TMR1CS ; Set Timer Mode of operation for Timer1

BANKSEL TMR1LMOVLW 0X00MOVWF TMR1L

BANKSEL TMR1HMOVLW 0X00

MOVWF TMR1H

BANKSEL CCP1CON




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CLRF CCP1CONMOVLW 0X08 ; Set Compare Mode of operation for CCP1,

MOVWF CCP1CON ; set CCP1 (RC2) pin on Compare eventBANKSEL PIR1

BCF PIR1,CCP1IF

BANKSEL CCPR1HMOVLW 0XF1

MOVWF CCPR1HBANKSEL CCPR1L

MOVLW 0XFFMOVWF CCPR1L

BANKSEL PIE1BSF PIE1,TMR1IE

BSF PIE1,CCP1IE ; Enable CCP1 InterruptBSF INTCON,PEIE

BSF INTCON,GIEBANKSEL T1CON

BSF T1CON,TMR1ON

L1

GOTO L1ISR

BCF INTCON,GIEBANKSEL PIR1

BTFSS PIR1,CCP1IF ; Check CCP1 Interrupt FlagGOTO TMR_ISR

BCF PIR1,CCP1IFBANKSEL CCPR1H

BANKSEL PORTBCOMF PORTB,1

RETFIETMR_ISR

BCF INTCON,GIEBANKSEL PIR1

BTFSS PIR1,TMR1IF ; Check Timer1 Interrupt FlagRETFIE

BCF PIR1,TMR1IFBANKSEL TMR1L

MOVLW 0X00MOVWF TMR1L

BANKSEL TMR1HMOVLW 0X00




MOVWF TMR1HRETFIE

END

Output

PORTB will get complemented after each Compare event. CCP1 (RC2) pin will be set

after the first Compare operation.

Microcontroller Lab Mnual

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