microprosessor principles

∙  1ECH                                492                      111101100

∙  FA98                             64152                      1111101010011000

6. Convert the decimal number 1625 to: Hexadecimal, Octal and Binary.

              Hexadecimal          Octal                      Binary

               659                        3131                           11001011001

7. What is the purpose of an Assembler?

The assembler checks the typographical errors and validity of the instructions used in the assembler program.It does not check the logical error of the program.

8. What is the purpose of a debugger?

The debugger proves that a program is working correctly or not.

9. What are the steps in Developing a program?

Given  a task         Analyze  the task        Develop a flowchart        Code  program         

        Edit to enable the program         Compile/Assemble to translate into machine code

        Use the  debugger to test the step to the program         Document

10. A microprocessor / Microcontroller instructions are classified as one, two or three

cycles instructions, explain what this mean?

Every instruction takes a certain time to execute the number of cycles ,represent the time it takes for the instruction to execute completely.

11. Use the instruction set provided for the Intel 8051 series of microcontrollers,

perform a hand assembly of the following program:

START: MOV A,#05H                               74,05

MOV B, #04H                                             75,04

MOV R0, B                                                  A8

LOOP: ADD A, B                                        25

DJNZ R0, LOOP                                         D8

END

Develop a flowchart for the above program, and explain what the program does.

Initially we store 5H in A and 4H in B  then the program add the contents of A,B until R0 reaches the value of 0.

Flowchart for the above program

The result is 15H OR 21.

Task 2

Part i:

Development of Some Simple Assembly Language Programs

Write a program to determine the factorial of a given number stored in register A.

The result is 18H OR 24.

Question 1:

What is maximum integer number that the above program provides a satisfactory

result?

For N=4     Answer =4*3*2*1=24

       N=5     Answer=5*4*3*2*1=120

       N=6     Answer=6*5*4*3*2*1=720

When N=6 ,the result is expected in above 255 which in the maximum decimal number that can be placed in an 8 bit register so N=5  is the maximum.

Question 2:

How is it possible to modify the program to increase the range of numbers?

The program needs to be modified to handle 16 bit multiplication rather than using the “MUL” they can only handle A*B.

RevisionsQuestions and Tutorials

1. What are the purpose(s) of addressing Modes in microcontrollers?

   The addressing modes enable the program to read and write from into memory location.

    For example to move data from one place and place it in another.

2. List some of the addressing modes of the Intel 8051 processors and give an

example.

Direct Addressing:        MOV A,20H

Indirect Addressing:     MOV R0,#20H

                                      MOV A,@R0

Immediate Addressing:MOV A,#05

        

3. What is the purpose of the program counter?

The  program counter holds the address( lines number) of the next instruction that the process must execute at start ,program counter (PC) is loaded with 0000H (it is 16 bit register) therefore the processor executes the instruction in address 0000H.

4. Explain what the Intel 8051 processor performs when it is first switched ON or

reset.

When the processor is first switched ON, the program counter as well as the rest of registers become  cleared to Zero.Therefore the processor then looks at the program counter(0000H) and begins to execute the instructions in this address.  

5. Draw a block diagram representation of a simple 8051-based Microcontroller

based system.

        

Part II: Assembly Language Program Development

Part II - Problem 1: Fibonacci Numbers

The first 10 Fibonocci numbers as illustrated below when the first two numbers are 1

and 1.

1, 1, 2, 3, 5, 8, 13, 21, …

the next numbers are generated by adding the last two numbers together.

So the next number in the above series is 13+21=34 and so on.

For example if we initially placenumber 2 in location 20H and number 4 in location 21H then the program should

generate:2, 4, 6, 10, 16, 26,42

The program to generate the series: :2, 4, 6, 10, 16, 26,42

(These are 2H, 4H, 6H, 0AH, 10H, 1AH, 2AH respectively in hexadecimal)

Develop a program to generate the next 6 Fibonocci numbers given that the first two

numbers are stored in locations 30H and 31H. For example if we initially place

number 15H in location 30H and number 22Hin location 31H then the program should

generate:15H,22H,37H,59H,90H,E9

The program to generate the series: 15H,22H,37H,59H,90H,E9

(These are 21,34,55,89,144 and 233 respectively in decimal)

Question

Modify the program so that it will automatically check if the number is small

enough to store in a memory location

When we consider this program the next number be

Should be 120H (288) but this is higher than FFH(255)

Therefore the carry sets to 1.

Part II - Problem 2: Filling and Copying Memory Blocks

Filling Memory Blocks

This program fills the memory location from 20H to

2FH.

It fills  the numbers from 0FH-1H.

 Copying Memory Blocks

Initially  we have to fill  with random numbers from location 20H to 2FH

This program copies the contents of memory location

20H-2FH into locations 40H-4FH.

Part II - Problem 3: Sorting Numeric Data

Write a program to sort numbers stored in memory locations 20H to 2FH in

Descending order ,if locations 20H to 2FH contains:

5,7,8,1,2,9,11,12,34,15,65,23,31,3,6,4

Then the program should rearrange the numbers to give:

65,34,31,23,15,12,11,9,8,7,6,5,4,3,2,1

Initially  we have to fill  with random numbers from location 20H to 2FH

        

        

        

Question

Modify the program so that it will sort the numbers in ascending order (i.e. Increasing

order).

If locations 20H to 2FH contains:

5,7,8,1,2,9,11,12,34,15,65,23,31,3,6,4

Then the program should rearrange the numbers to give:

1,2,3,4,5,6,7,8,9,11,12,15,23,31,34,65

Initially  we have to fill  with random numbers from location 20H to 2FH

Part III - Problem 4: Simulation of a 24-Hour Alarm

Clock

The  task is here is to write an assembly language program that simulates the function

of a 24-hour Alarm Clock.

        

        

The  program starts by incrementing (adding 1) to the Seconds (i.e. memory location

22H) until it reaches 60H, at which point  it  should reset seconds to 00 and add a ‘1’

to the minutes (i.e. memory location 21H). If minutes reach 60H, it should reset

minutes to 00 and add a ‘1’ to hours (i.e. memory location 20H). Once hours reach to

24, it  should reset it to 00 and start the process over and over again.