micro-controller experiment

Experiment 1

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Deboleena Roy 09EC3203 Shruti Khatri 09EC1057

Experiment 1: Familiarization with 8051 kit

Objective:Study about the kit components and its interface with the PC. Write the following programs in the assembly language of 8051.

1. Find the second largest of an array of 100 numbers stored in external memory from location 9000H onwards. The number be stored at location 9500H. Show the contents of memory locations before and after running the program to establish correctness of it

2. Compute the LCM of two numbers. Assume the numbers to be stored at location 9000H and 9001H. Store the result at 9002H.

3. Check whether a NULL-terminated string stored from location 9000H is a palindrome or not. If the string is a palindrome, store 1 at location 9500H, else clear the location.

Apparatus and Software1. ESA51E 8051 Trainer Board2. Compiler – Kiel µVision43. Driver – Win51E

Design (Hardware)ESA51E is trainer kit that is interfaced with PC through RS-232-C serial port connection. It is provided external power supply of +5V. The compiler converts the assembly code into a .hex file which is then loaded on the code space of 8051 using driver Win51E

Design (Software)

Part 1: Obtain second largest number from an array of 100 numbers

Design1. For the first number, read it and store it in R1.2. Now, input the next number in R3.3. Copy content of R1 at some random location, say 60H.4. If R3 = value at 60H, R2= R3.5. If R3 > value at 60H, R1 = R3; R2 = value at 60h.6. If R3 < value at 60H, and R3 > R2; R2 = R3.7. Loop8. End

Experiment 1

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Software Code

ORG 8100HMOV DPTR,#9000HMOV R0,#99

MOVX A,@DPTRMOV R1,A

INC DPTRMOVX A,@DPTR

MOV 60H,R1CJNE A,60H,NEXTMOV R2,ASJMP LOOP

NEXT: JNC SHIFTMOV R2,ASJMP LOOP

SHIFT: MOV R3,AMOV A,R1

MOV R2,AMOV A,R3

MOV R1,A

LOOP: DJNZ R0,MAINSJMP FINISH

MAIN: INC DPTRMOVX A,@DPTRMOV 60H,R1CJNE A,60H,NEXT2MOV R2,ASJMP LOOP

NEXT2: JNC SHIFTMOV 60H,R2CJNE A,60H,NEXT3SJMP LOOP

NEXT3: JNC MOVR2ASJMP LOOP

MOVR2A: MOV R2,ASJMP LOOP

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FINISH: MOV DPTR,#9500HMOV A,R2MOVX @DPTR,A

HERE: SJMP HEREEND

Part 2: Find the LCM of 2 given numbers

Design1. Input the numbers in R1 and R2.2. If R1 < R2, interchange the values.3. Store A = R1, B = R2.4. Perform the following until B = 0 is satisfied.

a. Store B at some location say 60hb. Divide A by B.c. Store B’s value in A, and store the remainder in B.d. Loop

5. GCD = value at 60H.

6. Obtain LCM by using the formula, LCM=R1×R2GCD

.

7. END

Software Code

ORG 8100H

MOV DPTR,#9000H MOVX A,@DPTRMOV R1,A INC DPTRMOVX A,@DPTRMOV R2,A MOV 60H,R1CJNE A,60H, NEXT1 SJMP LEAVE

NEXT1: JNC SWITCH MOV A,R1MOV B,R2 SJMP LOOP

SWITCH: MOV A,R1

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MOV R3,A MOV A,R2MOV R1,AMOV A,R3MOV R2,A MOV A,R1MOV B,R2

LOOP: MOV R4,BDIV ABMOV A,BJZ GCDOUTMOV A,R4 SJMP LOOP

GCDOUT: MOV A,R1 MOV B,R4DIV AB MOV B,R2MUL AB

LEAVE: INC DPTRMOVX @DPTR,AINC DPTRMOV A,BMOVX @DPTR,A

HERE: SJMP HEREEND

Part 3: Find out whether a given string is a palindrome

Design1. Obtain the string length by reading till NULL is obtained, and running a counter alongside.2. Start reading character by character.3. Store 1st character at location 70H and corresponding mirror image in A. Compare and if

same, continue to next character. If not, exit loop. Go to step 54. If the entire string is scanned (R1=0), then exit loop. Move #1 to 9500H.5. END

Experiment 1

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Software Code

ORG 8100HMOV R2,#0HMOV DPTR,#8FFFH ;1 less than starting value

STRING:INC R2INC DPTRMOVX A,@DPTRCJNE A,#0H,STRINGDEC DPLMOV R0,DPL

MOV A,R2MOV B,#2HDIV ABMOV R2,A

MOV DPTR,#9000H

LOOP:MOVX A,@DPTRMOV R4,DPLMOV 70H,AMOV DPL,R0MOVX A,@DPTRCJNE A,70H,LEAVEDEC DPLMOV R0,DPLMOV DPL,R4INC DPTRDJNZ R2,LOOP

MOV DPTR,#9500HMOV A,#01HMOVX @DPTR,ALJMP NEXT

LEAVE: MOV DPTR,#9500HMOV A,#0HMOVX @DPTR,A

NEXT: SJMP NEXTEND

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ObservationTo work with user given data, and to verify the functionality of the code, we can use the software package to view and edit the registers of the microcontroller. Next, by running the program over the inserted values we can validate the code.

Part 1:

User InputAddress Value9000H 00H9001H 50H9002H 60H9003H 70H9004H 00H … . … . … .9063H 00H

OutputAddress Value9500H 60H

Part 2:

User InputAddress Value9000H 06H (6)9001H 0AH (10)

OutputAddress Value9002H 1EH (30)

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Part 3:

Case 1

User InputAddress Value9000H 03H9001H 02H9002H 01H9003H 02H9004H 03H9005H 00H

OutputAddress Value9500H 01H (it is a palindrome)

Case 2

User InputAddress Value9000H 03H9001H 02H9002H 00H9003H 02H9004H 03H9005H 00H

OutputAddress Value9500H 00H (it is not palindrome)

The program reads the string up to 9001H as it encounters the null character at 9002H. So it sees the string as ‘03’ ‘02’ which is not a palindrome

Experiment 1

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Discussion

Deboleena Roy 09EC32031. The program is written in assembly language. Usual conditional constructs like if … else, for,

do … while are replaced by intuitive register transfers and jumps.2. Mathematical operations, transfer of values with external RAM (MOVX), comparisons are

restricted to Register Accumulator (A)3. Each program is executed by first setting the program counter to start of the location of the

code in code space. In our case it is 8100H4. Each program terminates with an infinite loop of the type

NEXT: JUMP NEXTso that the PC remains stuck there and no further instructions in other parts of the code space gets executed.

5. CJNE function was abundantly used in all 3 parts. The syntax is CJNE value#1, value#2. Value#1 must always be A (accumulator). Carry bit is set to 1 if A < value#2 else it is set to zero.

Shruti Khatri 09EC10571. In this experiment, we wrote and burned basic programs on the 8051 micro-controller.2. Syntax used in assembly language is not very intuitive. Most operations don't work on

registers and the accumulator has to be used during the operation and the result needs to be copied in the register. Same is the case with operations like compare which doesn't work on registers.

3. When writing the program we should always make sure that the program ends with an infinite loop otherwise on running the code some instructions that are already present at memory locations that we haven't re-written might be executed. We should press break to stop the execution of the infinite loop and see the results.

4. When performing compare operation the value of carry varies depending on whether greater than or less than is true and this can be used in the program.

5. The program counter should be set in the WIN51E environment at the location from which we want the program to execute.

Documents

micro-controller experiment