Microprocessor lab

MICROPROCESSOR & MICROCONTROLLER LAB MANUAL

8085 MICROPROCESSOR
PROGRAMS

C.SARAVANAKUMAR. M.E.,
LECTURER, DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
1


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 Halt the program.

OBSERVATION:

Input: 80 (4150)
80 (4251)
Output: 00 (4152)
01 (4153)

RESULT:

Thus the program to add two 8-bit numbers was executed.

2


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
9. location and terminate the program.

PROGRAM:

MVI C, 00 Initialize C to 00
LDA 4150 Load the value to Acc.
MOV B, A Move the content of Acc to B register.
LDA 4151 Load the value to Acc.
SUB B
JNC LOOP Jump on no carry.
CMA Complement Accumulator contents.
INR A Increment value in Accumulator.
INR C Increment value in register C
LOOP: STA 4152 Store the value of A-reg to memory address.
MOV A, C Move contents of register C to Accumulator.
STA 4153 Store the value of Accumulator memory address.
HLT Terminate the program.

3


OBSERVATION:

Input: 06 (4150)
02 (4251)
Output: 04 (4152)
01 (4153)

RESULT:

Thus the program to subtract two 8-bit numbers was executed.

4


MULTIPLICATION OF TWO 8 BIT NUMBERS

AIM:

To perform the 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).
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.

PROGRAM:

MVI D, 00 Initialize register D to 00
MVI A, 00 Initialize Accumulator content to 00
LXI H, 4150
MOV B, M Get the first number in B - reg
INX H
MOV C, M Get the second number in C- reg.
LOOP: ADD B Add content of A - reg 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 Memory
MOV A, D
STA 4153 Store the MSB of result in Memory

5


OBSERVATION:

Input: FF (4150)
FF (4151)
Output: 01 (4152)
FE (4153)

RESULT:

Thus the program to multiply two 8-bit numbers was executed.

6


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).
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.

PROGRAM:

LXI H, 4150
MOV B, M Get the dividend in B – reg.
MVI C, 00 Clear C – reg for qoutient
INX 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 NEXT
LOOP: STA 4152 Store the remainder in Memory
MOV A, C
STA 4153 Store the quotient in memory

7


OBSERVATION:

Input: FF (4150)
FF (4251)

Output: 01 (4152) ---- Remainder
FE (4153) ---- Quotient

RESULT:

Thus the program to divide two 8-bit numbers was executed.

8


LARGEST NUMBER IN AN ARRAY OF DATA

AIM:

To find the largest number in an array of data using 8085 instruction set.

ALGORITHM:

1) Load the address of the first element of the array in HL pair
2) Move the count to B – reg.
3) Increment the pointer
4) Get the first data in A – reg.
5) Decrement the count.
7) Compare the content of memory addressed by HL pair with that of A - reg.
8) If Carry = 0, go to step 10 or if Carry = 1 go to step 9
9) Move the content of memory addressed by HL to A – reg.
10) Decrement the count
11) Check for Zero of the count. If ZF = 0, go to step 6, or if ZF = 1 go to next step.
12) Store the largest data in memory.

PROGRAM:

LXI H,4200 Set pointer for array
MOV B,M Load the Count
INX H
MOV A,M Set 1st element as largest data
DCR B Decrement the count
LOOP: INX H
CMP M If A- reg > M go to AHEAD
JNC AHEAD
MOV A,M Set the new value as largest
AHEAD: DCR B
JNZ LOOP Repeat comparisons till count = 0
STA 4300 Store the largest value at 4300
HLT

9


OBSERVATION:

Input: 05 (4200) ----- Array Size
0A (4201)
F1 (4202)
1F (4203)
26 (4204)
FE (4205)

Output: FE (4300)

RESULT:

Thus the program to find the largest number in an array of data was executed

10


SMALLEST NUMBER IN AN ARRAY OF DATA

AIM:

To find the smallest number in an array of data using 8085 instruction set.

ALGORITHM:

1) Load the address of the first element of the array in HL pair
2) Move the count to B – reg.
4) Get the first data in A – reg.
5) Decrement the count.
7) Compare the content of memory addressed by HL pair with that of A - reg.
8) If carry = 1, go to step 10 or if Carry = 0 go to step 9
9) Move the content of memory addressed by HL to A – reg.
10) Decrement the count
11) Check for Zero of the count. If ZF = 0, go to step 6, or if ZF = 1 go to next step.
12) Store the smallest data in memory.

PROGRAM:

LXI H,4200 Set pointer for array
MOV B,M Load the Count
INX H
MOV A,M Set 1st element as largest data
DCR B Decrement the count
LOOP: INX H
CMP M If A- reg < M go to AHEAD
JC AHEAD
MOV A,M Set the new value as smallest
AHEAD: DCR B
JNZ LOOP Repeat comparisons till count = 0
STA 4300 Store the largest value at 4300
HLT

11


OBSERVATION:

Input: 05 (4200) ----- Array Size
0A (4201)
F1 (4202)
1F (4203)
26 (4204)
FE (4205)

Output: 0A (4300)

RESULT:

Thus the program to find the smallest number in an array of data was executed

12


ARRANGE AN ARRAY OF DATA IN ASCENDING ORDER

AIM:

To write a program to arrange an array of data in ascending order

ALGORITHM:

1. Initialize HL pair as memory pointer
2. Get the count at 4200 into C – register
3. Copy it in D – register (for bubble sort (N-1) times required)
4. Get the first value in A – register
5. Compare it with the value at next location.
6. If they are out of order, exchange the contents of A –register and Memory
7. Decrement D –register content by 1
8. Repeat steps 5 and 7 till the value in D- register become zero
9. Decrement C –register content by 1
10. Repeat steps 3 to 9 till the value in C – register becomes zero

PROGRAM:

LXI H,4200
MOV C,M
DCR C
REPEAT: MOV D,C
LXI H,4201
LOOP: MOV A,M
INX H
CMP M
JC SKIP
MOV B,M
MOV M,A
DCX H
MOV M,B
INX H
SKIP: DCR D
JNZ LOOP
DCR C
JNZ REPEAT
HLT

13


OBSERVATION:

Input: 4200 05 (Array Size)
4201 05
4202 04
4203 03
4204 02
4205 01

Output: 4200 05(Array Size)
4201 01
4202 02
4203 03
4204 04
4205 05

RESULT:

Thus the given array of data was arranged in ascending order.

14


ARRANGE AN ARRAY OF DATA IN DESCENDING ORDER

AIM:

To write a program to arrange an array of data in descending order

ALGORITHM:

1. Initialize HL pair as memory pointer
2. Get the count at 4200 into C – register
3. Copy it in D – register (for bubble sort (N-1) times required)
4. Get the first value in A – register
5. Compare it with the value at next location.
6. If they are out of order, exchange the contents of A –register and Memory
7. Decrement D –register content by 1
8. Repeat steps 5 and 7 till the value in D- register become zero
9. Decrement C –register content by 1
10. Repeat steps 3 to 9 till the value in C – register becomes zero

PROGRAM:

LXI H,4200
MOV C,M
DCR C
REPEAT: MOV D,C
LXI H,4201
LOOP: MOV A,M
INX H
CMP M
JNC SKIP
MOV B,M
MOV M,A
DCX H
MOV M,B
INX H
SKIP: DCR D
JNZ LOOP
DCR C
JNZ REPEAT
HLT

15


OBSERVATION:

Input: 4200 05 (Array Size)
4201 01
4202 02
4203 03
4204 04
4205 05

Output: 4200 05(Array Size)
4201 05
4202 04
4203 03
4204 02
4205 01

RESULT:

Thus the given array of data was arranged in descending order.

16


BCD TO HEX CONVERSION
AIM:

To convert two BCD numbers in memory to the equivalent HEX number using 8085
instruction set

ALGORITHM:

1) Initialize memory pointer to 4150 H
2) Get the Most Significant Digit (MSD)
3) Multiply the MSD by ten using repeated addition
4) Add the Least Significant Digit (LSD) to the result obtained in previous step
5) Store the HEX data in Memory

PROGRAM:

LXI H,4150
MOV A,M Initialize memory pointer
ADD A MSD X 2
MOV B,A Store MSD X 2
ADD A MSD X 4
ADD A MSD X 8
ADD B MSD X 10
INX H Point to LSD
ADD M Add to form HEX
INX H
MOV M,A Store the result
HLT

OBSERVATION:

Input: 4150 : 02 (MSD)
4151 : 09 (LSD)

Output: 4152 : 1D H

RESULT:

Thus the program to convert BCD data to HEX data was executed.

17


HEX TO BCD CONVERSION
AIM:

To convert given Hexa decimal number into its equivalent BCD number using 8085
instruction set

ALGORITHM:

1) Initialize memory pointer to 4150 H
2) Get the Hexa decimal number in C - register
3) Perform repeated addition for C number of times
4) Adjust for BCD in each step
5) Store the BCD data in Memory

PROGRAM:

LXI H,4150 Initialize memory pointer
MVI D,00 Clear D- reg for Most significant Byte
XRA A Clear Accumulator
MOV C,M Get HEX data
LOOP2: ADI 01 Count the number one by one
DAA Adjust for BCD count
JNC LOOP1
INR D
LOOP1: DCR C
JNZ LOOP2
STA 4151 Store the Least Significant Byte
MOV A,D
STA 4152 Store the Most Significant Byte
HLT

OBSERVATION:

Input: 4150 : FF

Output: 4151 : 55 (LSB)
4152 : 02 (MSB)

RESULT:

Thus the program to convert HEX data to BCD data was executed.

18


HEX TO ASCII CONVERSION
AIM:

To convert given Hexa decimal number into its equivalent ASCII number using
8085 instruction set.

ALGORITHM:

1. Load the given data in A- register and move to B – register
2. Mask the upper nibble of the Hexa decimal number in A – register
3. Call subroutine to get ASCII of lower nibble
4. Store it in memory
5. Move B –register to A – register and mask the lower nibble
6. Rotate the upper nibble to lower nibble position
7. Call subroutine to get ASCII of upper nibble
8. Store it in memory
9. Terminate the program.

PROGRAM:

LDA 4200 Get Hexa Data
MOV B,A
ANI 0F Mask Upper Nibble
CALL SUB1 Get ASCII code for upper nibble
STA 4201
MOV A,B
ANI F0 Mask Lower Nibble
RLC
RLC
RLC
RLC
CALL SUB1 Get ASCII code for lower nibble
STA 4202
HLT

SUB1: CPI 0A
JC SKIP
ADI 07
SKIP: ADI 30
RET

19


OBSERVATION:

Input: 4200 E4(Hexa data)

Output: 4201 34(ASCII Code for 4)
4202 45(ASCII Code for E)

RESULT:

Thus the given Hexa decimal number was converted into its equivalent ASCII Code.

20


ASCII TO HEX CONVERSION
AIM:

To convert given ASCII Character into its equivalent Hexa Decimal number using
8085 instruction set.

ALGORITHM:

1. Load the given data in A- register
2. Subtract 30 H from A – register
3. Compare the content of A – register with 0A H
4. If A < 0A H, jump to step6. Else proceed to next step.
5. Subtract 07 H from A – register
6. Store the result
7. Terminate the program

PROGRAM:

LDA 4500
SUI 30
CPI 0A
JC SKIP
SUI 07
SKIP: STA 4501
HLT

OBSERVATION:

Input: 4500 31

Output: 4501 0B

RESULT:

Thus the given ASCII character was converted into its equivalent Hexa Value.

21


SQUARE OF A NUMBER USING LOOK UP TABLE
AIM:

To find the square of the number from 0 to 9 using a Table of Square.

ALGORITHM:

1. Initialize HL pair to point Look up table
2. Get the data .
3. Check whether the given input is less than 9.
4. If yes go to next step else halt the program
5. Add the desired address with the accumulator content
6. Store the result

PROGRAM:

LXI H,4125 Initialsie Look up table address
LDA 4150 Get the data
CPI 0A Check input > 9
JC AFTER if yes error
MVI A,FF Error Indication
STA 4151
HLT
AFTER: MOV C,A Add the desired Address
MVI B,00
DAD B
MOV A,M
STA 4151 Store the result
HLT Terminate the program

LOOKUP TABLE:

4125 01
4126 04
4127 09
4128 16
4129 25
4130 36
4131 49
4132 64
4133 81

22


OBSERVATION:

Input: 4150: 05

Output: 4151 25 (Square)

Input : 4150: 11

Output: 4151: FF (Error Indication)

RESULT:

Thus the program to find the square of the number from 0 to 9 using a Look up table
was executed.

23


INTERFACING WITH 8085

24


INTERFACING 8251 (USART) WITH 8085 PROCESSOR

AIM:

To write a program to initiate 8251 and to check the transmission and reception of
character

THEORY:

The 8251 is used as a peripheral device for serial communication and is programmed
by the CPU to operate using virtually any serial data transmission technique. The USART
accepts data characters from the CPU in parallel format and then converts them into a
continuous serial data stream for transmission. Simultaneously, it can receive serial data
streams and convert them into parallel data characters for the CPU. The CPU can read the
status of USART ant any time. These include data transmission errors and control signals.

Prior to starting data transmission or reception, the 8251 must be loaded with a set
of control words generated by the CPU. These control signals define the complete
functional definition of the 8251 and must immediately follow a RESET operation. Control
words should be written into the control register of 8251. These control words are split into
two formats:

1. MODE INSTRUCTION WORD
2. COMMAND INSTRUCTION WORD

1. MODE INSTRUCTION WORD

This format defines the Baud rate, Character length, Parity and Stop bits required to
work with asynchronous data communication. By selecting the appropriate baud factor sync
mode, the 8251 can be operated in Synchronous mode.

Initializing 8251 using the mode instruction to the following conditions

8 Bit data
No Parity
Baud rate Factor (16X)
1 Stop Bit

gives a mode command word of 01001110 = 4E (HEX)

25


MODE INSTRUCTION - SYNCHRONOUS MODE

S2 S1 EP PEN L2 L1 B2 B1

BAUD RATE FACTOR
0 1 0 1
0 0 1 1
SYNC MODE (1X) (16X) (64X)

CHARACTR LENGTH
0 1 0 1
0 0 1 1
6 7
5 BITS BITS BITS 8 BITS

PARITY ENABLE
1= ENABLE 0 = DISABLE

EVEN PARITY GEN/CHECK
0 =ODD 1 = EVEN

NUMBER OF STOP BITS
0 1 0 1
0 0 1 1
1.5
INVALID 1 BIT BIT 2 BIT

26


MODE INSTRUCTION - ASYNCHRONOUS MODE

S2 S1 EP PEN L2 L1 B2 B1

CHARACTER LENGTH
0 1 0 1
0 0 1 1
5 BITS 6 BITS 7 BITS 8 BITS

PARITY ENABLE
1= ENABLE 0 = DISABLE

EVEN PARITY GEN/CHECK
0 =ODD 1 = EVEN

EXTERNAL SYNC DETECTS
1 = SYSDET IS AN INPUT
0 = SYSDET IS AN IOUTPUT

SINGLE CHARACTER SYNC
1 = SINGLE SYNC CHARACTER
0 = DOUBLE SYNC CHARACTER

2. COMMAND INSTRUCTION WORD

This format defines a status word that is used to control the actual operation of
8251. All control words written into 8251 after the mode instruction will load the command
instruction.

The command instructions can be written into 8251 at any time in the data block
during the operation of the 8251. to return to the mode instruction format, the master reset
bit in the command instruction word can be set to initiate an internal reset operation which
automatically places the 8251 back into the mode instruction format. Command instructions
must follow the mode instructions or sync characters.

Thus the control word 37 (HEX) enables the transmit enable and receive enable bits,
forces DTR output to zero, resets the error flags, and forces RTS output to zero.
27


EH IR RTS ER SBRK RXE DTR TXEN

TRANSMIT ENABLE
1=Enable 0 = Disable

DATA TERMINAL READY
HIGH will force DTR
Output to Zero

RECEIVE ENABLE
1=Enable 0 = Disable

SEND BREAK CHARACTER
1 = Forces TXD LOW
0 = Normal Operation

ERROR RESET
1=Reset Error Flags
PE,OE,FE

REQUEST TO SEND
HIGH will force RTS
Output to Zero

INTERNAL RESET
HIGH Returns 8251 to
Mode Instruction Format

ENTER HUNT MODE
1= Enable a Search for
Sync Characters( Has
No Effect in Async mode)

COMMAND INSTRUCTION FORMAT

28


ALGORITHM:

1. Initialise timer (8253) IC
2. Move the mode command word (4E H) to A -reg
3. Output it to port address C2
4. Move the command instruction word (37 H) to A -reg
6. Move the the data to be transferred to A -reg
8. Reset the system
9. Get the data through input port address C0
10. Store the value in memory
11. Reset the system

PROGRAM:
MVI A,36H
OUT CEH
MVI A,0AH
OUT C8H
MVI A,00
OUT C8H
LXI H,4200
MVI A,4E
OUT C2
MVI A,37
OUT C2
MVI A,41
OUT C0
RST 1

ORG 4200
IN C0
STA 4500
RST 1

OBSERVATION:

Output: 4500 41

RESULT:

Thus the 8251 was initiated and the transmission and reception of character was
done successfully.

29


INTERFACING ADC WITH 8085 PROCESSOR

AIM:

To write a program to initiate ADC and to store the digital data in memory

PROGRAM:

MVI A,10
OUT C8
MVI A,18
OUT C8
MVI A,10
OUT D0
XRA A
XRA A
XRA A
MVI A,00
OUT D0
LOOP: IN D8
ANI 01
CPI 01
JNZ LOOP
IN C0
STA 4150
HLT

OBSERVATION:

Compare the data displayed at the LEDs with that stored at location 4150

RESULT:

Thus the ADC was initiated and the digital data was stored at desired location

30


INTERFACING DAC WITH 8085
AIM:

To interface DAC with 8085 to demonstrate the generation of square, saw tooth and
triangular wave.

APPARATUS REQUIRED:

• 8085 Trainer Kit
• DAC Interface Board

THEORY:

DAC 0800 is an 8 – bit DAC and the output voltage variation is between – 5V and +
5V.The output voltage varies in steps of 10/256 = 0.04 (appx.). The digital data input and
the corresponding output voltages are presented in the Table1.

Input Output
Data in Voltage
HEX
00 - 5.00
01 - 4.96
02 - 4.92
… …
7F 0.00
… …
FD 4.92
FE 4.96
FF 5.00

Referring to Table1, with 00 H as input to DAC, the analog output is – 5V. Similarly,
with FF H as input, the output is +5V. Outputting digital data 00 and FF at regular intervals,
to DAC, results in different wave forms namely square, triangular, etc,. The port address of
DAC is 08 H.

31


ALGORITHM:

(a) Square Wave Generation

1. Load the initial value (00) to Accumulator and move it to DAC
2. Call the delay program
3. Load the final value(FF) to accumulator and move it to DAC
4. Call the delay program.
5. Repeat Steps 2 to 5

(b) Saw tooth Wave Generation

1. Load the initial value (00) to Accumulator
2. Move the accumulator content to DAC
3. Increment the accumulator content by 1.
4. Repeat Steps 3 and 4.

(c) Triangular Wave Generation

5. If accumulator content is zero proceed to next step. Else go to step 3.
6. Load value (FF) to Accumulator
8. Decrement the accumulator content by 1.
9. If accumulator content is zero go to step2. Else go to step 7.

32


PROGRAM:


START: MVI A,00
OUT Port address of DAC
CALL DELAY
MVI A,FF
CALL DELAY
JMP START

DELAY: MVI B,05
L1: MVI C,FF
L2: DCR C
JNZ L2
DCR B
JNZ L1
RET


START: MVI A,00
L1: OUT Port address of DAC
INR A
JNZ L1
JMP START

33



START: MVI L,00
L1: MOV A,L
INR L
JNZ L1
MVI L,FF
L2: MOV A,L
DCR L
JNZ L2
JMP START

RESULT:

Thus the square, triangular and saw tooth wave form were generated by interfacing
DAC with 8085 trainer kit.

34


INTERFACING 8253 (TIMER IC) WITH 8085 PROCESSOR

AIM:

To interface 8253 Programmable Interval Timer to 8085 and verify the operation
of 8253 in six different modes.

APPARATUS REQUIRED:

1) 8085 Microprocessor toolkit.
2) 8253 Interface board.
3) VXT parallel bus.
4) Regulated D.C power supply.
5) CRO.

MODE 0-Interrupt On Terminal Count:-

The output will be initially low after mode set operation. After loading the counter, the
output will remain low while counting and on terminal count, the output will become high
until reloaded again.

Let us see the channel in mode0. Connect the CLK 0 to the debounce circuit and
execute the following program.

PROGRAM:
MVI A, 30H ;Channel 0 in mode 0.
OUT CEH
MVI A, 05H ;LSB of count.
OUT C8H
MVI A, 00H ;MSB of count.
OUT C8H
HLT

It is observed in CRO that the output of channel 0 is initially low. After giving ‘x’ clock
pulses, we may notice that the output goes high.

MODE 1-Programmable One Shot:-

After loading the count, the output will remain low following the rising edge of the
gate input. The output will go high on the terminal count. It is retriggerable; hence the
output will remain low for the full count after any rising edge of the gate input.

35


The following program initializes channel 0 of 8253 in Mode 1 and also initializes triggering
of gate. OUT 0 goes low as clock pulses and after triggering It goes back to high level after
five clock pulses. Execute the program and give clock pulses through the debounce logic and
verify using CRO.

PROGRAM:
OUT CEH ;
MVI A, 05H ;LSB of count.
OUT C8H
OUT C8H
OUT DOH ;Trigger Gate 0.
HLT

MODE 2-Rate Generator:

It is a simple divide by N counter. The output will be low for one period of the input
clock. The period from one output pulse to next equals the number of input count in the
count register. If the count register is reloaded between output pulses, the present period will
not be affected, but the subsequent period will reflect a new value.

MODE 3-Square Generator:

It is similar to mode 2 except that the output will remain high until one half of the
count and goes low for the other half provided the count is an even number. If the count is
odd the output will be high for (count +1)/2 counts. This mode is used for generating baud
rate of 8251.

PROGRAM:

OUT CEH ;
MVI A, 0AH ;LSB of count.
OUT C8H
OUT C8H
HLT

We utilize mode 3 to generate a square wave of frequency 150 kHz at Channel 0.Set the
jumper so that the clock of 8253 is given a square wave of Frequency 1.5 MHz. This
program divides the program clock by 10 and thus the Output at channel 0 is 150 KHz.
36


MODE 4-Software Triggered Strobe:

The output is high after the mode is set and also during counting. On Terminal
count, the output will go low for one clock period and becomes high again. This mode can
be used for interrupt generation.

MODE 5-Hardware Triggered Strobe:

Counter starts counting after rising edge of trigger input and the output goes low for
one clock period. When the terminal count is reached, the counter is retrigerrable. On
terminal count, the output will go low for one clock period and becomes high again. This
mode can be used for interrupt generation.

RESULT:

Thus the 8253 PIT was interfaced to 8085 and the operations for mode 0, Mode 1
and mode 3 was verified.

37


INTERFACING 8279 KEYBOARD/DISPLAY CONTROLLER
WITH 8085 MICROPROCESSOR
AIM:

To interface 8279 Programmable Keyboard Display Controller to 8085
Microprocessor.

APPARATUS REQUIRED:

1) 8085 Microprocessor toolkit.
2) 8279 Interface board.
3) VXT parallel bus.
4) Regulated D.C power supply.

PROGRAM:

START: LXI H,4130H
MVI D,0FH ;Initialize counter.
MVI A,10H
OUT C2H ;Set Mode and Display.
MVI A,CCH ;Clear display.
OUT C2H
MVI A,90H ;Write Display
OUT C2H
LOOP: MOV A,M
OUT C0H
CALL DELAY
INX H
DCR D
JNZ LOOP
JMP START

DELAY: MVI B, A0H
LOOP2: MVI C, FFH
LOOP1: DCR C
JNZ LOOP1
DCR B
JNZ LOOP2
RET

38


Pointer equal to 4130 .FF repeated eight times.

4130 - FF
4131 –FF
4132 –FF
4133 –FF
4134 –FF
4135 –FF
4136 –FF
4137 –FF
4138 –98
4139 –68
413A -7C
413B -C8
413C -1C
413D -29
413E -FF
413F -FF

RESULT:

Thus 8279 controller was interfaced with 8085 and program for rolling display was
executed successfully.

39


8051 MICROCONTROLLER
PROGRAMS

40


ADDITION OF TWO 8 – BIT NUMBERS

AIM:

To perform addition of two 8 – bit numbers using 8051 instruction set.

ALGORITHM:

1. Clear C – register for Carry
2. Get the data immediately .
3. Add the two data
4. Store the result in memory pointed by DPTR

PROGRAM:

ORG 4100
CLR C
MOV A,#data1
ADD A,#data2
MOV DPTR,#4500
MOVX @DPTR,A
HERE: SJMP HERE

OBSERVATION:

Input: 66
23

Output: 89 (4500)

RESULT:

Thus the program to perform addition of two 8 – bit numbers using 8051 instruction set
was executed.

41


SUBTRACTION OF TWO 8 – BIT NUMBERS

AIM:

To perform Subtraction of two 8 – bit numbers using 8051 instruction set.

ALGORITHM:

1. Clear C – register for Carry
2. Get the data immediately .
3. Subtract the two data
4. Store the result in memory pointed by DPTR

PROGRAM:

ORG 4100
CLR C
MOV A,#data1
SUBB A,#data2
MOV DPTR,#4500
MOVX @DPTR,A
HERE: SJMP HERE

OBSERVATION:

Input: 66
23

Output: 43 (4500)

RESULT:

Thus the program to perform subtraction of two 8 – bit numbers using 8051 instruction
set was executed.

42


MULTIPLICATION OF TWO 8 – BIT NUMBERS

AIM:

To perform multiplication of two 8 – bit numbers using 8051 instruction set.

ALGORITHM:

1. Get the data in A – reg.
2. Get the value to be multiplied in B – reg.
3. Multiply the two data
4. The higher order of the result is in B – reg.
5. The lower order of the result is in A – reg.
6. Store the results.

PROGRAM:

ORG 4100
CLR C
MOV A,#data1
MOV B,#data2
MUL AB
MOV DPTR,#4500
MOVX @DPTR,A
INC DPTR
MOV A,B
MOVX @DPTR,A
HERE: SJMP HERE

43


OBSERVATION:

Input: 80
80

Output: 00 (4500)
19 (4501)

RESULT:

Thus the program to perform multiplication of two 8 – bit numbers using 8051
instruction set was executed.

44


DIVISION OF TWO 8 – BIT NUMBERS

AIM:

To perform division of two 8 – bit numbers using 8051 instruction set.

ALGORITHM:

1. Get the data in A – reg.
2. Get the value to be divided in B – reg.
3. Divide the two data
4. The quotient is in A – reg.
5. The remainder is in B – reg.
6. Store the results.

PROGRAM:

ORG 4100
CLR C
MOV A,#data1
MOV B,#data2
DIV AB
MOV DPTR,#4500
MOVX @DPTR,A
INC DPTR
MOV A,B
MOVX @DPTR,A
HERE: SJMP HERE

45


OBSERVATION:

Input: 05
03

Output: 01 (4500)
02 (4501)

RESULT:

Thus the program to perform multiplication of two 8 – bit numbers using 8051
instruction set was executed.

46


RAM ADDRESSING

AIM:

To exhibit the RAM direct addressing and bit addressing schemes of 8051
microcontroller.

ALGORITHM:

1. For Bit addressing, Select Bank 1 of RAM by setting 3rd bit of PSW
2. Using Register 0 of Bank 1 and accumulator perform addition
3. For direct addressing provide the address directly (30 in this case)
4. Use the address and Accumulator to perform addition
5. Verify the results

PROGRAM:

Bit Addressing:

SETB PSW.3
MOV R0,#data1
MOV A,#data2
ADD A,R0
MOV DPTR,#4500
MOVX @DPTR,A
HERE: SJMP HERE

Direct Addressing:

MOV 30,#data1
MOV A,#data2
ADD A,30
MOV DPTR,#4500
MOVX @DPTR,A
HERE: SJMP HERE

47


OBSERVATION:

Bit addressing:

Input: 54
25

Output: 79 (4500)

Direct addressing:

Input: 54
25

Output: 79 (4500)

RESULT:

Thus the program to exhibit the different RAM addressing schemes of 8051 was
executed.

48


INTERFACING STEPPER MOTOR WITH 8051

AIM:

To interface stepper motor with 8051 parallel port and to vary speed of motor, direction of
motor.

APPARATUS REQUIRED:

• Stepper Motor Interface Board

THEORY:

A motor in which the rotor is able to assume only discrete stationary angular position is a
stepper motor. The rotor motion occurs in a stepwise manner from one equilibrium
position to next.

The motor under our consideration uses 2 – phase scheme of operation. In this scheme,
any two adjacent stator windings are energized. The switching condition for the above said
scheme is shown in Table.

Clockwise Anti - Clockwise
A1 B1 A2 B2 A1 B1 A2 B2
1 0 0 1 1 0 1 0
0 1 0 0 0 1 0 1
0 1 0 1 0 1 0 0
1 0 1 0 1 0 0 1

In order to vary the speed of the motor, the values stored in the registers R1, R2, R3 can
be changed appropriately.

49


ALGORITHM:

1. Store the look up table address in DPTR
2. Move the count value (04) to one of the register (R0)
3. Load the control word for motor rotation in accumulator
4. Push the address in DPTR into stack
5. Load FFC0 in to DPTR.
7. Send the control word for motor rotation to the external device.
8. Pop up the values in stack and increment it.
9. Decrement the count in R0. If zero go to next step else proceed to step 3.
10. Perform steps 1 to 9 repeatedly.

PROGRAM:

ORG 4100
START: MOV DPTR,#4500H
MOV R0,#04
AGAIN: MOVX A,@DPTR
PUSH DPH
PUSH PDL
MOV DPTR,#FFC0H
MOV R2, 04H
MOV R1,#FFH
DLY1: MOV R3, #FFH
DLY: DJNZ R3,DLY
DJNZ R1,DLY1
DJNZ R2,DLY1
MOVX @DPTR,A
POP DPL
POP DPH
INC DPTR
DJNZ R0,AGAIN
SJMP START

50


DATA:

4500: 09, 05, 06, 0A

RESULT:

Thus the speed and direction of motor were controlled using 8051 trainer kit.

51


INTERFACING DAC WITH 8051

AIM:

To interface DAC with 8051 parallel port to demonstrate the generation of square,
saw tooth and triangular wave.

APPARATUS REQUIRED:

• DAC Interface Board

THEORY:

DAC 0800 is an 8 – bit DAC and the output voltage variation is between – 5V and +
5V.The output voltage varies in steps of 10/256 = 0.04 (appx.). The digital data input and
the corresponding output voltages are presented in the Table below
.

Input Data in HEX Output Voltage
00 - 5.00
01 - 4.96
02 - 4.92
… …
7F 0.00
… …
FD 4.92
FE 4.96
FF 5.00

Referring to Table1, with 00 H as input to DAC, the analog output is – 5V. Similarly,
with FF H as input, the output is +5V. Outputting digital data 00 and FF at regular intervals,
to DAC, results in different wave forms namely square, triangular, etc,.

52


ALGORITHM:


1. Move the port address of DAC to DPTR
2. Load the initial value (00) to Accumulator and move it to DAC
4. Load the final value(FF) to accumulator and move it to DAC
5. Call the delay program.
6. Repeat Steps 2 to 5


5. Repeat Steps 3 and 4.


5. If accumulator content is zero proceed to next step. Else go to step 3.
6. Load value (FF) to Accumulator
8. Decrement the accumulator content by 1.
9. If accumulator content is zero go to step2. Else go to step 7.

53


PROGRAM:


ORG 4100
MOV DPTR,PORT ADDRESS OF DAC
START: MOV A,#00
MOVX @DPTR,A
LCALL DELAY
MOV A,#FF
MOVX @DPTR,A
LCALL DELAY
LJUMP START

DELAY: MOV R1,#05
LOOP: MOV R2,#FF
HERE: DJNZ R2,HERE
DJNZ R1,LOOP
RET
SJMP START


ORG 4100
MOV A,#00
LOOP: MOVX @DPTR,A
INC A
SJMP LOOP

54



ORG 4100
START: MOV A,#00
LOOP1: MOVX @DPTR,A
INC A
JNZ LOOP1
MOV A,#FF
LOOP2: MOVX @DPTR,A
DEC A
JNZ LOOP2
LJMP START

RESULT:

Thus the square, triangular and saw tooth wave form were generated by interfacing
DAC with 8051 trainer kit.

55


PROGRAMMING 8051 USING KEIL SOFTWARE

AIM:

To perform arithmetic operations in 8051 using keil software.

PROCEDURE:

1. Click Keil Vision2 icon in the desktop
2. From Project Menu open New project
3. Select the target device as ATMEL 89C51
4. From File Menu open New File
5. Type the program in Text Editor
6. Save the file with extension “.asm”
7. In project window click the tree showing TARGET
8. A source group will open.
9. Right Click the Source group and click “Add files to Source group”
10. A new window will open. Select our file with extension “.asm”
11. Click Add.
12. Go to project window and right click Source group again
13. Click Build Target (F7).
14. Errors if any will be displayed.
15. From Debug menu, select START/STOP Debug option.
16. In project window the status of all the registers will be displayed.
17. Click Go from Debug Menu.
18. The results stored in registers will be displayed in Project window.
19. Stop the Debug process before closing the application.

PROGRAM:

ORG 4100
CLR C
MOV A,#05H
MOV B,#02H
DIV AB

56


OBSERVATION:

A: 02
B: 01
SP:07

Note that Stack pointer is initiated to 07H

RESULT:

Thus the arithmetic operation for 8051 was done using Keil Software.

57


SYSTEM DESIGN USING MICROCONTROLLER

AIM:

To Design a microcontroller based system for simple applications like security
systems combination lock etc.

PROCEDURE:

1. Read number of bytes in the password
2. Initialize the password
3. Initialize the Keyboard Display IC (8279) to get key and Display
4. Blank the display
5. Read the key from user
6. Compare with the initialized password
7. If it is not equal, Display ‘E’ to indicate Error.
8. Repeat the steps 6 and 7 to read next key
9. If entered password equal to initialized password, Display ‘O’ to indicate open.

PROGRAM:

MOV 51H,#
MOV 52H,#
MOV 53H,#
MOV 54H,#
MOV R1,#51
MOV R0,#50
MOV R3,#04
MOV R2,#08
MOV DPTR,#FFC2
MOV A,#00

58


MOVX @DPTR,A
MOV A,#CC
MOVX @DPTR,A
MOV A,#90
MOVX @DPTR,A
MOV A,#FF
MOV DPTR,#FFCO
LOOP: MOVX @DPTR,A
DJNZ R2,LOOP
AGAIN: MOV DPTR,#FFC2
WAIT: MOVX A,@DPTR
ANL A,#07
JZ WAIT
MOV A,#40
MOVX @DPTR,A
MOV DPTR,#FFCO
MOVX A,@DPTR
MOV @R0,A
MOV A,@R1
CJNE A,50H,NEQ
INC R1
DJNZ R3,AGAIN
MOV DPTR,#FFCO
MOV A,#OC
MOVX @DPTR,A
XX: SJMP XX

NEQ: MOV DPTR,#FFCO
MOV A,#68
MOVX @DPTR,A
YY: SJMP YY

RESULT:

Thus the program for security lock system was executed

59

Microprocessor lab

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