1 Interfacing Stepper Motor to 8086 Using 8255

Contents

1 Interfacing Stepper Motor to 8086 using 8255 3

1.1 Using ULN2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2 Using the preassembled kit . . . . . . . . . . . . . . . . . . . . . . . . 7

2 Interfacing LED displays to 8086 11

2.1 Using 8255 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2 Using 8279 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3 Interfacing 8255 & 8253 to 8086 15

3.1 Using 8255 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2 Using 8253 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4 Interfacing ADC & DAC to 8086 21

4.1 ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.2 DAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

5 8051 Programming 25

5.1 Wave generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

5.2 Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6 Interfacing Hex Keyboard with 8086 30

7 Timers in Interrupt Mode 32

8 8051 timers: Stack Check Mode 35

9 8051 timers: Interrupt Mode 38

29thOctober, 2009

1

Introduction

Set Baud Rate

• Type BU and press enter

• Type 5 to set baud rate as 9600

Setup serial input

• Type SI and press enter

• Kit displays �SERIAL INPUT� and now kit is ready for serial input

Burning program onto 8086 kit

• Open command window

• Type the program, save, assemble and link the *.asm �le

• Then debug �lename.exe and press enter

� n filename.bin

� wcs:1000

� q

• Then type datacom and press enter

� set parameters and then transmit �lename.bin

� wait till transmission is complete

Execute the program

• Type GO 1000 and press enter

2

1 Interfacing Stepper Motor to 8086 using 8255

Experiment 1

6th August, 2009

1.1 Using ULN2003

1) A program to rotate a stepper motor continuously in the anticlockwise direction,for three di�erent speeds

CODE SEGMENT

ASSUME CS:CODE, DS:CODE

ORG 1000H

CR EQU 0C6H ;address of the control register

PB EQU 0C2H ;address of Port B

MOV AL, 80H ;control word for Port B as output

OUT CR, AL ;send it to the control register

MOV AL, 66H ;load sequence in AL

BACK:

OUT PB, AL ;send it to Port B

ROL AL, 1H ;rotate left once

CALL DELAY ;call a delay

JMP BACK ;repeat the sequence

DELAY PROC NEAR ;delay procedure

MOV CX, 0FFFFH

AGN:

LOOP AGN

RET

DELAY ENDP ;end of delay procedure

HLT

CODE ENDS

END

3

2) A program to �nd the step angle of the given stepper motor

CODE SEGMENT


ORG 1000H

CR EQU 0C6H ;address of control register



OUT CR, AL ;send it to control register

MOV CX, 200


BAC:


ROR AL, 1H ;rotate right once


LOOP BAC ;repeat until CX=0


BACK:

MOV DX, 3H

AGN:

MOV BX, 0FFFFH

DEC BX

JNZ AGN

DEC DX

JNZ BACK

RET


HLT

CODE ENDS

END

4

3) A program to rotate a stepper motor 90 degrees in the clockwise direction and 180degrees in the anticlockwise direction four times

CODE SEGMENT


ORG 1000H

CR EQU 0C6H ;address of control register


MOV DX, 4



ABC:

MOV CX, 50 ;CX=50


BACK:


ROR AL, 1H ;rotate right once


LOOP BACK ;repeat until CX=0

MOV CX, 100


BACK1:

OUT PB, AL

ROL AL, 1H ;rotate it once, to the left


LOOP BACK1 ;repeat until CX=0

DEC DX

JNZ ABC


MOV BX, 0FFFH

AGN:

DEC BX

JNZ AGN

RET


HLT

CODE ENDS

END

5

Procedure: ULN2003 driver IC circuit is setup on breadboard. The input is given using the 26pin �at cable from 8255 board. We are using Port B of 8255 to give input of the driver IC. Pin9, 10, 11, 12 of the 26 pin connector is found to be Port B using CRO. These pins are connectedto pin numbers 1, 2, 3 and 4 of ULN2003. Output is taken from 13, 14, 15 and 16 of ULN2003.Stepper motor have �ve input leads and a VCC lead. All 24 permututations are tried to get theanticlockwise rotation of the stepper motor.

Result: Stepper motor was driven as per the requirement and step angle = 7.2o

6

1.2 Using the preassembled kit

1) A program to rotate a stepper motor continuously in the anticlockwise direction,for three di�erent speeds

CODE SEGMENT


PORT1 EQU 0C0H ;port address ORG 1000H

START:

MOV DI, OFFSET TABLE ;load address of table to DI

MOV CL, 04

LOOP1:

MOV AL, [DI]

OUT PORT1, AL ;output values

MOV DX, 1010H

DELAY: ;introduce delay

DEC DX

JNZ DELAY

INC DI

LOOP LOOP1

JMP START ;rotate motor continuously

TABLE:

DB 0AH, 6, 5, 9

HLT

CODE ENDS

END

7

2) A program to �nd the step angle of the given stepper motor

CODE SEGMENT


PORT1 EQU 0C0H ;port address

ORG 1000H

MOV BX, 50

START:

MOV DI, OFFSET TABLE ;load address of table to DI

MOV CL, 04 ;to get 200 steps

LOOP1:

MOV AL, [DI]

OUT PORT1, AL ;output values

MOV DX, 1010H

DELAY: ;introduce delay

DEC DX

JNZ DELAY

INC DI

LOOP LOOP1

DEC BX

JNZ START ;rotates motor till BX = 0

HLT

TABLE:

DB 9, 5, 6, 0AH

HLT

CODE ENDS

END

8

3) A program to rotate a stepper motor 90 degrees in the clockwise direction and 180degrees in the anticlockwise direction four times

CODE SEGMENT


PORT1 EQU 0C0H ;port address

ORG 1000H

MOV AH,4

START:

MOV BL, 12

FORWD:

MOV DI, OFFSET FORW

CALL ROTATE ;procedure for rotating values

DEC BL

JNZ FORWD ;loop for 48 steps

CALL DELAY ;delay

MOV BL, 25

REVER:

MOV DI, OFFSET REV

CALL ROTATE ;procedure for rotating values

DEC BL

JNZ REVER ;loop for 100 steps

CALL DELAY ;delay

DEC AH

JNZ START ;loop for repeating 4 times

ROTATE:

MOV CL, 4 ;procedure to output to port

REPT:

MOV AL, [DI]

OUT PORT1, AL

MOV DX, 1010H

LOOP1:

DEC DX ;delay after each step

JNZ LOOP1

INC DI

LOOP REPT

RET

MOV DX, 0FFFFH

DELAY:

DEC DX ;delay procedure

JNZ DELAY

RET

HLT

FORW:

DB 9, 5, 6, 0AH

REV:

DB 0AH, 6, 5, 9

CODE ENDS

END

9

Procedure: The 8255 board is given with power transistors already assembled. The output from8086 trainer kit is taken using a �at cable to 8255 board and output is given to motor.

Result: Stepper motor was driven as per the requirement and step angle = 7.2o

10

2 Interfacing LED displays to 8086

Experiment 2

13th August, 2009

2.1 Using 8255

1) A program to display an eight character word on the display

CODE SEGMENT


TABLE EQU 1200H

DATA EQU 00C8H

CON EQU 00C0H

ORG 1000H

CON:

MOV SI, TABLE ;display RAM pointer

MOV BL, 08H ;number of digits to scan

L1:

DEC BL

MOV AL, BL

OUT CONTL, AL ;select digit position

MOV AL, [SI]

OUT DATA, AL ;give display information

CALL DELAY ;delay of 2mS

INC SI ;data pointer incremented

CMP BL, 00H ;check if 8 digits are displayed

JNZ L1 ;if not, repeat

JMP CON ;repeat from first digit

DELAY:

MOV CL, 02H ;delay of 2mS

L2:

MOV AL, 0FFH

L3:

DEC AL

JNZ L3

DEC CL

JNZ L2

RET

ORG 1200H

DB 77H, 78H, 78H, 04H

DB 78H, 3EH, 5EH, 79H

CODE ENDS

END

11

2) A program to display a word rolling on the LED display

CODE SEGMENT


TABLE EQU 1200H

DATA EQU 00C8H

CONT EQU 00C0H

ORG 1000H

REP:

MOV CH, 0FH ;delay for rolling display

MOV DX, 0000H

COM:

MOV SI, TABLE

ADD SI, DX

MOV BL, 08H

LO1:

DEC BL

MOV AL, BL

OUT CONT, AL ;select digit position

MOV AL, [SI]

OUT DATA, AL ;give display information

CALL DELAY ;call delay procedure

INC SI ;increment data pointer

CMP BL, 00H

JNZ LO1

DEC CH

JNZ COM

SUB SI, 0007H

CMP SI, 120FH ;check for first 16 digits

JZ REP

INC DX

JMP COM

DELAY: ;delay procedure

MOV CL, 02

L1:

MOV AL, 0FFH

L2:

DEC AL

JNZ L2

DEC CL

JNZ L1

RET

ORG 1200H

DB 77H, 78H, 78H, 04H

DB 78H, 3EH, 5EH, 79H

DB 00H, 00H, 00H, 00H

DB 00H, 00H, 00H, 00H

DB 77H, 78H, 78H, 04H

DB 78H, 3EH, 5EH, 79H

CODE ENDS

END

12

2.2 Using 8279

1) A program to display a key pressed on a LED display

CODE SEGMENT


ORG 1000H

DATR EQU 0C0H

CNTR EQU 0C2H

TABLE

DB 0CH, 9FH, 4AH, 0BH, 99H, 29H, 28H, 8FH

DB 08H, 09H, 88H, 38H, 6CH, 1AH, 68H, 0E8H

LEA SI, TABLE ;pointer to the seven segment codes

MOV CX, 08 ;counter

MOV AL, 0 ;word for display RAM ,right entry

OUT CNTR, AL ;send it to control register

MOV AL, 3EH ;word to divide clock frequency by 30


MOV AL, 3EH ;word to divide clock frequency by 30


MOV AL, 0CCH ;word to clear display


MOV AL, 90H ;word to write display RAM


MOV AL, 0FFH ;data to blank out the display

AGN:

OUT DATR, AL ;send it to the data register

LOOP AGN ;repeat for 8 digits

GO:

LEA SI, TABLE

NEXT:

IN AL,CNTR ;read in the status register

TEST AL, 07 ;test if D0=1

JZ NEXT ;if not continue testing

MOV AL, 40H ;otherwise write CW to read FIFO


IN AL, DATR ;read in the FIFO

AND AL, 0FH ;mask upper nibble of key code

MOV BL, AL ;copy it to BL

MOV BH, 0

ADD SI, BX ;add BX to SI

MOV AL, [SI] ;take corresponding display code

OUT DATR, AL ;send it to data register

JMP GO ;continue for more keys

CODE ENDS

END

13

2) A program to display a word rolling on the LED display

CODE SEGMENT


ORG 1000H

START:

MOV SI, 1200H ;pointer to the seven segment codes

MOV CX, 0FH

MOV AL, 10H

OUT 0C2H, AL ;send it to control register

MOV AL, 0CCH ;word to clear display


MOV AL, 90H ;word to write display RAM


NEXT:

MOV AL, [SI] ;take corresponding display code

OUT 0C0H, AL ;send it to data register


INC SI

LOOP NEXT

JMP START

DELAY: ;delay procedure

MOV DX, 0A0FFH

LOOP1:

DEC DX

JNZ LOOP1

RET

ORG 1200H

DB 0FFH, 0FFH, 0FFH, 0FFH

DB 0FFH, 0FFH, 0FFH, 0FFH

DB 98H, 68H, 7CH, 0C8H

DB 0FFH, 1CH, 29H, 0FFH

CODE ENDS

END

Procedure: 8279 chip has two portions � one for providing scanned display interface for LEDand the other for interfacing with keyboards or an array of sensors. In the absence of this chip, theprocessor is fully involved in the detecting of key press and displaying of words. But with 8279,the processor has to just give the commands and the 8279 takes care of all the activities.

In case of a valid key press, the code of the key enters into the FIFO RAM. At the same time,the count in the status register increments. While programming, the key press is detected bychecking whether the count in the status register is incremented or not.

14

3 Interfacing 8255 & 8253 to 8086

Experiment 3

20th August, 2009

3.1 Using 8255

1) A program to generate a square wave of frequency at 6kHz at PB7

CODE SEGMENT


ORG 1000H

MOV AL,80H ;value to be passed to control register

OUT 0C6H,AL

BACK:

MOV AL, 00H

OUT 0C2H, AL ;set port B = 0H


MOV AL, 0FFH

OUT 0C2H, AL ;set port B = 0FFH


JMP BACK


MOV CX, 20

HERE:

NOP

LOOP HERE

RET

DELAY ENDP

HLT

CODE ENDS

END

Procedure: 6kHz square wave has a time period of 166.66µs. So a delay of 83µs is called foreach ON time and OFF time. For getting square wave at PB7, port B is made output port andoutput is taken from PB7. Others pins are don't cares.

Waveform: Observed frequency = 4.23 kHz; Ton = 118µS; Toff = 118µS

15

2) A program to generate a asymmetrical wave of 20% duty cycle at PC7 using BSRmode of 8255

CODE SEGMENT


ORG 1000H

MOV AL, 90H ;value to be passed to control register

OUT 0C6, AL

MOV AL, 90H

OUT 0C6H, AL

BACK:

MOV AL, 0FH

OUT 0C6H, AL ;set port C = 0FFH


MOV AL, 0EH

OUT 0C6H, AL ;set port C = 0H


CALL DELAY

CALL DELAY

CALL DELAY

JMP BACK


MOV CX, 20H

HERE:

NOP

LOOP HERE

RET

DELAY ENDP

HLT

CODE ENDS

END

Procedure: A square wave of 20% duty cycle means the square wave is ON for 15

thof the timeperiod. A delay of some value is created. The delay is called once when the output port is ONand the delay is called four times when the port is OFF. PC7 is set/reset using the BSR mode.

Waveform: Observed frequency = 4.23 kHz; Ton = 47µS; Toff = 188µS

16

3.2 Using 8253

1) A program to generate three simultaneous square waveforms of frequencies 13kHz,60kHz and 1kHz at OUT1, OUT2 & OUT3 respectively using same clock frequencyof 1.5MHz.

DATA SEGMENT

CR EQU 0CEH ;address of the control register

CNT0 EQU 0C8H ;address of counter 0

CNT1 EQU 0CAH ;address of counter 1

CNT2 EQU 0CCH ;address of counter 2

DATA ENDS

CODE SEGMENT

ASSUME CS:CODE, DS:DATA

ORG 1000H

MOV AL, 36H ;select counter 0 in mode 3

OUT CR, AL ;value to be passed to control register

MOV AX, 180 ;load count = 115 in AX

OUT CNT0, AL ;send lower byte of count to counter 0

MOV AL, AH ;move higher byte of count to AL

OUT CNT0, AL ;send higher byte of count to counter 0

MOV AL, 76H ;select counter 1 in mode 3






MOV AL, 0B6H ;select counter 2 in mode 3






HLT

CODE ENDS

END

Procedure: For 8253, a delay procedure is not required. It produces hardware delay which ismade use to create the waveforms. Mode 3 of counters 0, 1 & 2 is made use in this program.Counter 0 divides input frequency by 115 to produce a square wave of 13kHz. Similarly, counter 1and counter 2 divides the input frequency by 25 and 1500 to produce 60kHz and 1kHz respectively.

Waveforms: Observed frequency = 17.8 kHz; Ton = 28µS; Toff = 28µS

17

Observed frequency = 92.5 kHz; Ton = 5.4µS; Toff = 5.4µS

Observed frequency = 1.5 kHz; Ton = 333µS; Toff = 333µS

18

2) A program to generate an asymmetric square wave at the output of counter 2using any two modes of the 8253 chip. Use the modes which do not require an L toH transition at the gate.

Using Mode 2

DAT SEGMENT

CR EQU 0CEH ;address of control register


DAT ENDS

COD SEGMENT

ASSUME CS: COD, DS: DAT

ORG 1000H

MOV AL, 0B4H ;control word for counter 2 in mode 2



OUT CNT2, AL ;lower byte of count to counter 2



HLT

COD ENDS

END

Using Mode 4

DAT SEGMENT

CR EQU 0CEH ;address of control register


DAT ENDS

COD SEGMENT

ASSUME CS: COD, DS: DAT

ORG 1000H

AGA:

MOV AL, 0B8H ;control word for counter 2 in mode 4






JUMP AGA

HLT

COD ENDS

END

Procedure: The control word is selected such as to set counter 2 in mode 2 or mode 4. In mode2, the counter reloads after one cycle. In mode 4, the counter has to be reloaded by the user. Thepulse will be high for N cycles and low for one cycle where N = count.

19

Waveforms:Ton = 5τ ; Toff = τ

. 5τ τ

Ton = 7τ ; Toff = τ

. 7τ τ

20

4 Interfacing ADC & DAC to 8086

Experiment 4

10th September, 2009

4.1 ADC

1) A program to measure the DC voltage at ADC pin and get digital readout.

CODE SEGMENT

ASSUME CS:CODE,DS:CODE

ORG 1000H

MOV AL, 10H ;make ALE low

OUT 0C8H, AL

MOV AL, 18H ;enable ALE

OUT 0C8H, AL

MOV AL, 01 ;make SC high

OUT 0D0H, AL

MOV AL, 00 ;create delay

MOV AL, 00

MOV AL, 00

MOV AL, 00

OUT 0D0H ;make ALE & SC low

LOOP:

IN AL, 0D8H ;check for EOC

AND AL, 01

CMP AL, 01

JNZ LOOP ;if EOC port is low, jump

IN AL, 0C0H

MOV BX, 1100H

MOV [BX], AL ;move data to the memory location

HLT

CODE ENDS

END

Procedure: ADC creates a digital output depending on the analog input given. Analog signalis given to the ADC through one of the inut pins. Then ALE and SC are enabled to latch addressand to start conversion. After giving a delay ALE and SC are lowered. EOC port is monitored. Ifit is low then data is taken in and send to memory.

21

4.2 DAC

1) A program to generate a triangular waveform of T = 10ms.

CODE SEGMENT

ASSUME CS:CODE,DS:DAT

ORG 1000H MOV AL, 0 ;AL=0

REPEA:

OUT 0C8H, AL ;send AL to port A

CALL DELAY ;call delay

INC AL

CMP AL, 45 ;compare AL with 45H

JNZ REPEA ;if not equal, repeat

AGN:

OUT 0C8H, AL ;if AL=45H, decrement loop


DEC AL

CMP AL, 0 ;comapare AL with 0

JNZ AGN ;if not 0, continue decrementing

JMP REPEA ;if AL=0, increment


MOV CX, 26 ;value of N for a small delay

HERE:

LOOP HERE

RET

DELAY ENDP

HLT

CODE ENDS

END

Procedure: DAC converts digital signals into analog form. Depending on the digital input given,a current is generated which is converted into voltage by the DAC. To create a triangular waveform�rst the count is incremented by giving a delay after each increment. After a particular value thecount is decremented in a similar manner. Time period is calculated depending on the clock.

Waveform: T = 9.8ms

22

2) A program to generate a ramp waveform of T = 1ms.

CODE SEGMENT

ASSUME CS:CODE,DS:DAT

ORG 1000H

AGN:

MOV AL,0 ;AL=0

REPEA:

OUT 0C8H,AL ;send AL to port A


INC AL

CMP AL,24 ;compare AL with 24H

JNZ REPEA ;if not equal, repeat

JMP AGN ;if AL=0, increment


MOV CX,10 ;value of N for a small delay

HERE:

LOOP HERE

RET

DELAY ENDP

HLT

CODE ENDS

END

Procedure: DAC converts digital signals into analog form. Depending on the digital input given,a current is generated which is converted into voltage by the DAC. To create a ramp waveform thecount is incremented by giving a delay after each increment. Then this is repeated. Time periodis calculated depending on the clock.

Waveform: T = 1.1ms

23

3) A program to generate a staircase waveform with each step 1ms delay.

CODE SEGMENT

ASSUME CS:CODE, DS:DAT

ORG 1000H

STRT:

MOV AL, 0 ;AL=0

OUT 0C8H, AL ;send AL to Port A


REPEA:

ADD AL, 31 ;add 31 to AL

OUT 0C8H, AL ;send AL to Port A


CMP AL, 248 ;check whether AL=248

JNZ REPEA ;if not, repeat addition

JMP STRT ;if AL=248, go to START


MOV CX, 240 ;value of N for Delay

AGN:

LOOP AGN

RET

DELAY ENDP

HLT

CODE ENDS

END

Procedure: DAC converts digital signals into analog form. Depending on the digital input given,a current is generated which is converted into voltage by the DAC. To create 8 steps total countis divided by 8. So count is to be incremented by 32 after the delay to get a staircase waveform.

Waveform: T = 8.2ms ⇒ each step of approx. 1ms

24

5 8051 Programming

Experiment 5

17th September, 2009

5.1 Wave generation

1) A Program to generate a square wave of 10 kHz frequency at any output pin.

ORG 0000H

MAIN:

HERE:

CPL P1.3 ;complement

ACALL DELAY ;call delay procedure

SJMP HERE ;infinite loop for square wave generation

DELAY:

MOV R2,#45 ;delay loop for 0.1msec

AGAIN:

DJNZ R2,AGAIN

RET

END

25

2) A program to generate a asymmetric wave with ON time 1 ms and OFF time 0.3 ms.

ORG 0000H

MAIN:

HERE:

SETB P1.3 ;make P1.3 = 1

ACALL DELAY ;call delay



CLR P1.3 ;make P1.3 = 0


SJMP HERE ;infinite loop

DELAY:

MOV R2,#2 ;delay loop for 0.3 msec

THERE:

MOV R3,#153

AGAIN:

DJNZ R3,AGAIN

DJNZ R2,THERE

RET

END

26

5.2 Miscellaneous

1) A program to add two 64 bit numbers which are in consecutive locations in RAMand store it in RAM.

ORG 0000H

MAIN:

MOV R0,#31H

MOV R1,#8H

MOV DPTR,#40H

REPEAT1:

CLR A ;loop for moving the 1st number into RAM

MOVC A,@A+DPTR

MOV @R0,A

INC DPTR

INC R0

DJNZ R1,REPEAT1

MOV R0,#51H

MOV R1,#8H

MOV DPTR,#60H

REPEAT2:

CLR A ;loop for moving the 2nd number into RAM

MOVC A,@A+DPTR

MOV @R0,A

INC DPTR

INC R0

DJNZ R1,REPEAT2

CLR C

MOV R2,#08

MOV R0,#31H

MOV R1,#51H

SETB PSW.3 ;select register bank 1

MOV R0,#61H

CLR PSW.3 ;select register bank 0

AGAIN:

MOV A,@R0

ADDC A,@R1 ;adding the 2 numbers

INC R0

INC R1

SETB PSW.3

MOV @R0,A ;sum is moved into RAM and stored

INC R0

CLR PSW.3

DJNZ R2,AGAIN

ORG 40H

DATA1:

DB 24H,0AEH,32H,38H,0C0H,32H,0DEH,32H

ORG 60H

DATA2:

DB 54H,0EH,0FCH,81H,2AH,93H,93H,88H

END

27

2) A program to store a word ÌNDIAN' in ROM. Read it from ROM and display itat Port 0. Display one character at a time with a delay between successive displays.

ORG 0000H

MAIN:

MOV DPTR,#500H

MOV R2,#06

BACK:

CLR A ;loop for moving each character to P0

MOVC A,@A+DPTR ;DPTR points to the character being displayed

MOV P0,A

ACALL DELAY

INC DPTR

DJNZ R2,BACK

HERE:

SJMP HERE

DELAY:

MOV R2,#45 ;delay procedure

AGAIN:

DJNZ R2,AGAIN

RET

ORG 50H

DAT:

DB Ì',`N',`D',Ì',À',`N'

END

28

3) Write a look up table in ROM for the cubes of decimal numbers. In another ROMlocation, store the squares. Depending on the status of pin P0.0, get the squares/cubesdisplayed at Port 1 LEDs.

ORG 0000H

MAIN:

START:

SETB P0.0 ;setting P0.0 as input port

JNB P0.0,Square ;if P0.0=0 jump to square

JB P0.0,Cube ;if P0.0=1 jump to cube

SQUARE:

MOV DPTR,#500H

MOV R2,#10

BACK11:

CLR A ;loop for displaying the contents of DAT1

MOVC A,@A+DPTR

MOV P1,A

ACALL DELAY

INC DPTR

DJNZ R2,BACK11

SJMP START

CUBE:

MOV DPTR,#700H

MOV R2,#08

BACK:

CLR A ;loop for displaying the contents of DAT2

MOVC A,@A+DPTR

MOV P1,A

ACALL DELAY

INC DPTR

DJNZ R2,BACK

SJMP START

DELAY: ;procedure for delay

MOV R2,#60

THERE:

MOV R3,#255

AGAIN:

MOV R4,#255

HERE:

DJNZ R4,HERE

DJNZ R3,AGAIN

DJNZ R2,THERE

RET

END

ORG 500H

DAT1:

DB 0,1,4,9,16,25,36,49,64,81

ORG 700H

DAT2:

DB 0,1,8,27,64,125,216,243

29

6 Interfacing Hex Keyboard with 8086

Experiment 6

27thSeptember, 2009

A program to identify a key pressed on hex keyboard interfaced through 8255 to 8086.

CODE SEGMENT


ORG 1000H

ROW_0 DB 0,1,2,3

ROW_1 DB 4,5,6,7

ROW_2 DB 8,9,0AH,0BH

ROW_3 DB 0CH,0DH,0EH,0FH

CR EQU 0C6H ;address of the control register

PA EQU 0C0H ;address of Port A


MOV AL, 82H ;8255 control word

OUT CR, AL ;send to control register

MOV AL, 0

OUT PA, AL ;send zeros to all the rows

KEYP:

IN AL, PB ;read in the columns

AND AL, 0FH ;mask the upper nibble

CMP AL, 0FH ;compare with 0FH

JZ KEYP ;if equal, no key pressed

CALL DELAY ;if key press ,wait for debounce time

;after the delay, confirm the key press




JZ KEYP ;if equal, no key pressed

ROW0:

MOV AL, 0FEH ;send `0' to Row0 alone

OUT PA, AL




JZ ROW1 ;no key press in Row0, so check Row1

LEA SI, ROW_0 ;not equal, SI to point to Row0 data

JMP COL_ID ;go to finding the column

ROW1:

MOV AL, 0FDH ;send `0' to Row1 alone and repeat steps

OUT PA, AL

IN AL, PB

AND AL, 0FH

CMP AL, 0FH

JZ ROW2

LEA SI, ROW_1

30

JMP COL_ID

ROW2:

MOV AL, 0FBH ;send `0' to Row2 alone and repeat steps

OUT PA, AL

IN AL, PB

AND AL, 0FH

CMP AL, 0FH

JZ ROW3

LEA SI, ROW_2

JMP COL_ID

ROW3:

MOV AL, 0F7H ;send `0' to Row3 alone and repeat steps

OUT PA, AL

IN AL, PB

AND AL, 0FH

CMP AL, 0FH

JZ KEYP

LEA SI, ROW_3

COL_ID:

SHR AL, 1 ;to identify the column ,shift right

JNC FOUND ;if no carry, column is found

INC SI ;otherwise point SI to next data of row

JMP COL_ID ;go back to finding the column

FOUND:

MOV BX, 1500H

MOV AL, [SI] ;get the data pointed by SI into AL

MOV [BX], AL ;this is the pressed key, store in KEY

DELAY PROC NEAR

MOV CX, 6000 ;delay for key debounce

AGN:

LOOP AGN

RET

DELAY ENDP

CODE ENDS

END

Procedure: The rows and columns are connected to lower four bits of Port A and Port Brespectively. The key press is detected by �rst sending zero to all rows and the columns areread. If no key is pressed we get 1111 from PB3 to PB0 else we get a zero corresponding to thecolumn which contains the key pressed. Now to recongnise the row containing the key, the rowsare grounded one by one. The columns are read. When the value read is less than 1111, then therow grounded gives the required row. To ensure the a key press detected is valid, key debouncetime is given and checked again. If even then the key press is detected the key press is a valid one.

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7 Timers in Interrupt Mode

Experiment 7

1stOctober, 2009

1) A program to generate two square waves of frequency 5kHz and 13kHz simultane-ously using timers in interrupt mode.

ORG 0000H

MAIN:

LJMP NEXT

ORG 000BH ;interrupt vector for timer 0

CPL P1.3 ;toggle P1.3

RETI

ORG 001BH ;interrupt vector for timer 1


RETI

ORG 0030H

NEXT:

MOV TMOD,#22H ;set both the timers in mode 2

MOV IE,#8AH ;enable timer0 and timer1 overflow interrupt

MOV TH0,#048H ;load TH0 value

MOV TH1,#0B9H ;load TH1 value

SETB TCON.4 ;start timer 0


WAIT:

SJMP WAIT

END

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2) A program to generate the half the input frequency using timers.

ORG 0000H

LJMP MAIN

ORG 0003H ;interrupt vector for interrupt 0


RETI

ORG 0030H

MAIN:

SETB TCON.0 ;make INT0 an edge-triggered interrupt

MOV IE,#81H ;enable external interrupt 0

HERE:

SJMP HERE

END

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3) A program to �nd the frequency of the input square wave.

ORG 0000H

MAIN:

RPT:

MOV TMOD,#15H ;timer1 as timer and timer0 as counter

SETB P3.4 ;set P3.4 as input port

MOV TL0,#00H ;clear TL0

MOV TH0,#00H ;clear TH0

SETB TCON.4 ;start counter 0

MOV R0,#28 ;to time 1 sec

AGAIN:

MOV TL1,#00H ;load count value in TL1

MOV TH1,#00H ;load count value in TH1


BACK:

JNB TCON.7,BACK ;test timer 1 flag

CLR TCON.7 ;clear timer 1 flag

CLR TCON.6 ;stop timer 1

DJNZ R0,AGAIN ;repeat the loop until R0=0

MOV A,TL0

MOV P2,A ;move the count value to port2

MOV A,TH0

MOV P1,A ;move the count value to port1

SJMP RPT

END

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8 8051 timers: Stack Check Mode

Experiment 8

15th October, 2009

1) A program to generate a symmetric square wave of 11 kHz on any port pin usingtimer 0 in mode 1.

ORG 0000H

MAIN:

MOV TMOD,#01H ;timer 0 in mode 1

HERE:

MOV TH0,#0FFH

MOV TL0,#0ADH

CPL P1.3

ACALL DELAY

SJMP HERE

DELAY:


AGAIN:

JNB TCON.5,AGAIN ;set when rolling over from 0FFFFH to 0000H


CLR TCON.5

RET

END

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2) A program to generate an asymmetrical square wave with ON time 15 ms and OFFtime of 3 ms on pin P0.5 using timer 1 in mode 2.

ORG 0000H

MAIN:

MOV TMOD,#20H

MOV TH1,#00H ;timer 1 mode 2

REP:

SETB P0.5

MOV R2,#5

HERE:

ACALL DELAY

DJNZ R2,HERE

CLR P0.5

ACALL DELAY

SJMP REP

DELAY:

MOV R0,#22

AGAIN:


BAK:

JNB TCON.7,BAK

CLR TCON.6

CLR TCON.7

DJNZ R0,AGAIN

RET

END

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3) A program to a square wave whose one cycle consists of one square wave of period30 ms followed by three square waves of 10 ms each.

ORG 0000H

MAIN:

MOV TMOD,#01H ;timer 0 mode 1

HERE:

SETB P0.2

ACALL DELAY

ACALL DELAY

ACALL DELAY

CLR P0.2

ACALL DELAY

ACALL DELAY

ACALL DELAY

MOV R0,#3

BACK:

SETB P0.2

ACALL DELAY

CLR P0.2

ACALL DELAY

DJNZ R0,BACK

SJMP HERE

DELAY:

MOV TH0,#0DCH

MOV TL0,#03AH


AGAIN:

JNB TCON.5,AGAIN ;set when rolling over from 0FFFFH to 0000H


CLR TCON.5

RET

END

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9 8051 timers: Interrupt Mode

Experiment 9

22nd October, 2009

1) A program to generate a symmetric square wave of 25 KHz at any port pin usingtimer 1 in mode 1.

ORG 0000H

MAIN:

LJMP START ;goto label START

ORG 001BH ;ISR corresponding to timer 1

CPL P1.0 ;compliment P0.0

MOV TH1,#0FFH ;load timer

MOV TL1,#0E3H

RETI

ORG 0030H

START:

MOV TMOD,#10H ;timer 1 in mod 1

MOV IE,#88H ;enable timer 1 interrupt

MOV TH1,#0FFH ;load the timer

MOV TL1,#0E3H

SETB TCON.6 ;start timer

HERE:

SJMP HERE ;wait for interrupt

END

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2) A program to generate a square wave with ON time of 2 ms and OFF time of 0.5ms using timer 0 in mode 1.

ORG 0000H

MAIN:

LJMP START


JB P1.7,ONE ;jump if P1.7 = 1

SETB P1.7 ;set P1.7

CLR P1.0 ;clear P1.0

MOV TH0,#0F1H ;delay for 2 ms

MOV TL0,#0ACH

RETI

ONE:


SETB P1.0 ;set P1.0

MOV TH0,#0FCH ;delay for 0.5 ms

MOV TL0,#06AH

RETI

ORG 0050H

START:


MOV TMOD,#01H ;timer 0 in mod 1


MOV TH0,#0FCH ;load timer

MOV TL0,#6AH


HERE:


END

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3) A program to blink LEDs of port 1 with a delay of 1s.

ORG 0000H

MAIN:

LJMP START


DJNZ R0,SKIP ;if R0!=0 go to label SKIP

MOV R0,10 ;reload R0

MOV A,#0FFH

XRL P1,A ;compliment the bits of P1

MOV TH1,#00H ;load timer

MOV TL1,#00H

SKIP:

RETI

ORG 0030H

START:

MOV TMOD,#10H ;timer 1, mod 1


MOV R0,#28 ;R0= 28

MOV TL1,#00H ;load timer

MOV TH1,#00H


HERE:


END

40

1 Interfacing Stepper Motor to 8086 Using 8255

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Transcript of 1 Interfacing Stepper Motor to 8086 Using 8255