AU Solved Paper - 9

AU Solved Paper

December-2015

Microprocessors & Microcontrollers

Semester-V (EEE) - 2013 Course

 

Time: Three Hours]

[Maximum Marks: 100

 

Answer ALL Questions

PART - A (10 × 2 = 20 Marks)

 

Q.1 What is the use of stack pointer ? (Refer Two Marks Q.25 of Chapter - 1)

Q.2 Mention the use of ALE. (Refer Two Marks Q.10 of Chapter - 1)

Q.3 How is time delay generated using subroutines ? (Refer Lab Experiment 3.2.2)

Q.4 Explain the functioning of CMP instruction. (Refer section 2.2.3)

Q.5 List the interrupts of 8051 microcontroller. (Refer Two Marks Q.6 of Chapter - 16)

Q.6 Write the function of TMOD register in 8051 microcontroller. (Refer section 16.3.1)

Q.7 Write the control word value for 8255 PPI when PORT A and PORT B are inputs in simple I/O mode.

Ans. :

X = Don't care Assuming don't cares as zeros we have control word = 92 H

 

Q.8 What are the working modes of 8254 timer? (Refer Two Marks Q.1 of Chapter - 10)

Q.9 What is meant by PSW? (Refer section 15.3.5)

 

Q.10 List out the difference between MOV and MOVX instructions.

Ans. :

 

PART B (5 × 16 = 80 Marks)

Q.11 a) Explain with a neat block diagram, the architecture of 8085 microprocessor. (Refer section 1.2) [16]

OR

b) i) Explain the interrupt structure of 8085 microprocessor. (Refer section 4.2) [8]

ii) Draw the timing diagram of Opcode Fetch machine cycle. (Refer section 5.4.1) [8]

 

Q.12 a) i) Explain the addressing modes of 8085 microprocessor with example for each. (Refer section 2.3) [8]

ii) Write a 8085 assembly language program to divide a 8 bit number by another 8 bit number and store the remainder and quotient in memory locations 4252 and 4253 respectively. [8]

Ans. :

MVI A, Dividend

MVI B, Divisor

MVI C, 00H ; quotient = 0

BACK: CMP B ; Check whether dividend < divisor

JC    LAST ; if yes goto LAST

SUB B ; dividend = dividend - divisor

INR C ; increment quotient

JMP BACK

LAST: STA 4252H ; Store remainder

MOV A, B ; Get quotient

STA 4253H ; Store quotient

OR

b) Write an 8085 assembly language program to solve the following equation:

Z = 2X+Y where X and Y are stored in memory locations 4200 and 4201 respectively. The value of Y should be stored in 4202(Lower byte) and 4203(higher byte). [16]

Ans. :

MVI B, 00H ; Reset higher byte

LDA 4200H ; Get value of X

STC ; Set carry

CMC ; Complement carry

RAL ; Multiply by 2

JNC NEXT

INR B ; Save carry in Higher byte

NEXT: MOV A, C ; Save 2X

LDA 4201H ; Get value of Y

ADD C ; Add Y

JNC NEXT1

INR B ; Add carry in higher byte

NEXT1 : STA 4202H ; Store lower byte

MOV A, B ; get higher byte

STA 4203H ; Store higher byte

 

Q.13 a) Explain the Timers of 8051 microcontroller with appropriate diagrams. (Refer section 16.4) [16]

OR

b) Explain the I/O ports and their functions of 8051 microcontroller. (Refer section 16.1) [16]

Q.14 a) Explain the block diagram, architecture and registers of the 8279 keyboard / display controller. (Refer section 12.5) [16]

OR

b) i) Explain the block diagram and modes of the 8254 timer. (Refer sections 10.2 and 10.4) [8]

ii) Explain the architecture, functions and registers of the 8255 PPI. (Refer section 8.3) [8]

Q.15 a) Explain the working of a washing machine and how it is controlled by the 8051 microcontroller. (Not in new syllabus) [16]

OR

b) Explain how to control a stepper motor using 8051 microcontroller with a neat interfacing diagram and assembly program. (Refer section 17.4) [16]