AU Solved Paper 41004 - set 14

AU Solved Paper 41004

May - 2018

Microprocessors & Microcontrollers

Semester-V (EEE) - Regulation 2013

 

[Maximum Marks: 100

Time: Three Hours]

 

Answer ALL Questions

PART A - (10 x 2 = 20 Marks)

 

Q.1 List the features of accumulator. (Refer Two marks Q.2 of Chapter - 1).

Q.2 Write the difference between standard I/O and memory mapped 1/0. (Refer section 7.2.4.1)

Q.3 List the classification of instruction based on its size.

Ans. : Based on instruction size 8085 instructions are classified as 1 byte, 2 byte and 3 byte instructions.

 

Q.4 Define stack. (Refer Two marks Q.25 of Chapter - 1)

Q.5 Compare microprocessor and microcontroller. (Refer section 14.1)

 

Q.6 How the microcontrollers respond to any interrupt request?

Ans.:  In response to the interrupt, the microcontroller goes through following steps:

1. It completes the execution of current instruction and save the address of the next instruction, i.e. the contents of PC on the stack.

2. It also saves the current status of all the interrupts internally i.e. not on the stack.

3. It then transfers the program control to a fixed location in memory called the interrupt vector table (IVT). IVT holds the address of the interrupt service routine.

4. The microcontroller gets the address of the interrupt service routine (ISR) from IVT and transfers program control to the ISR. It executes instructions within the interrupt service routine in sequence till it reaches the RETI (Return from the interrupt) instruction.

5. Upon executing the RETI instruction, it gets the program counter (PC) address from the stack and restores the interrupt logic. Since PC is loaded with the address of the next instruction from where the interrupt was initiated, it starts to execute from that address.

 

Q.7 How the DMA operations perform in microprocessor? (Not in new syllabus)

Q.8 Write the modes of operation in 8254. (Refer Two Marks Q.1 of Chapter - 10)

Q.9 What is use of data pointer register? (Refer Two Marks Q.16 of Chapter - 14)

 

Q.10 What is the advantage of closed loop control system for interfacing?

Ans. :

1.  Closed loop control systems are more accurate even in the presence of non-linearities.

2. The sensitivity of the system may be made small to make the system more stable.

3. The closed loop systems are less affected by noise.

 

PART B - (5 × 13 = 65 Marks)

Q.11 a) Draw and explain the building blocks and its signal of 8085 processor. (Refer sections 1.2 and 1.3) [13]

OR

b) i) Describe the interrupts of 8085 and its types with service routine. (Refer section 4.2) [7]

ii) Draw the timing diagram of MOV A, M instruction and explain each machine cycle. [6]

Ans. : Fig.1 shows the timing diagram of MOV A, M instruction. This instruction copies the contents from memory location pointed by HL register pair into the register specified within the instruction. This instruction requires two machine cycles.

1) Opcode fetch : Program counter places address on low order and high order address bus. The opcode at this memory location (e.g. 7EH of MOV A, M) is read into the microprocessor and is decoded. 4 T-states are required for this machine cycle. Program counter is incremented by one.

2) Memory read : HL register pair gives address on low order and high order address bus. The data at this addressed memory location is read into the specified register of the microprocessor. Program counter is incremented by one.

 

Q.12 a) i) Explain the types of addressing modes in 8085 with suitable example. (Refer section 2.3) [7]

ii) Write an 8085 program to find the greatest number among 10 numbers. (Refer Lab experiment 3.1.6) [6]

OR

b) i) Explain the types of instruction in 8085 with example. (Refer Two marks Q.4 of Chapter 2 and section 2.2) [7]

ii) Write an 8085 program to find the average of 10 numbers and find the execution time of program. [6]

Ans. :

; Initialization 1

MVI C, 0AH  ; Load counter  [7]

LXI H, 2200H ; Initialize memory pointer  [10]

LX1 D, 0000H ; SUM = 0 [10]

MVI A, 00H ; clear A [7]

; Loop 1

BACK : ADD M ; A = A + Number [7]

JNC SKIP ; [10/7]

INR D ; Add carry to MSB of SUM  [4]

SKIP : INX H ; Increment memory pointer [6]

DCR C ; Decrement count [4]

JNZ BACK ; Check if counter ≠ 0 repeat [10/7]

; Store and Initialization 2

MOV E, A ; Store lower byte of SUM [4]

XCHG ; Load 16-bit sum in HL[4]

MVI E, 00 ; Quotient = 0 [7]

MVI A, 0AH ; Load divisor [7]

MOV B, A ; Store divisor [4]

MVI C, 08 ; Count = 8 [7]

; Loop 2

NEXT : DAD H ; Dividend = Dividend × 2 [10]

MOV A, E  ;  [4]

RLC  ;  [4]

MOVE, A ; Quotient = Quotient × 2 [4]

MOV A, H ; [4]

SUB B ; Is most significant by of dividend divisor [4]

JC SKIP1 ; No, go to next step [10/7]

MOV H, A ; Yes subtract divisor [4]

INR E ; and Quotient = Quotient + 1 [4]

SKIP1: DCR C ; Count = Count - 1 [4]

JNZ NEXT ; is count≠  0 repeat [10/7]

; Store 2

MOV A, E ; [4]

STA 2201 H ; Store quotient (Average) [13]

MOV A, H ; [4]

STA 2202 H ; Store remainder  [13]

T states

For initialization 1 : 34

For Loop 1 : 38 × 10 = 380.

For store and initialization 2 : 33

For Loop 2 : 54 × 8 = 432

For store 2 : 34

Total T-states ≈ 913

Considering crystal frequency = 5 MHz

We have, operating frequency = 2.5 MHz and

Time 1 T-state  1 / 2.5 MHz = 0.4 μsec

ஃ Time for program ≈ 0.4 μsec × 913 = 0.3654 msec

 

Q.13 a) Draw and explain the architecture of 8051 microcontroller.

(Refer section 14.3) [13]

OR

b) Briefly discuss the ports of 8051, internal circuits and its functions in detail. (Refer section 16.1) [13]

Q.14 a) Draw the functional diagram of 8255 and explain its control word, modes of operation. (Refer sections 8.3, 8.4 and 8.5) [13]

OR

b) Draw the functional diagram of 8251 and explain its block in detail. (Refer section 11.4) [13]

Q.15 a) Illustrate the keyboard and display interface with 8051 and write the program to get the input 45H from the external keyboard and display it on the external display device. (Refer sections 17.1 and 17.2) [13]

OR

b) Interface the stepper motor with 8051 and explain its operation of stepper motor with neat diagram and program to rotate in clockwise direction. (Refer section 17.4) [13]

 

PART C - (1 × 15 = 15 Marks)

Q.16 a) Design an 8085 based system with 512B RAM, 4KB ROM, external keyboard and seven segment display device. (Refer sections 6.4.1, 12.1 and 12.2) [15]

OR

b) Design a microcontrolled based system to control the water level in the tank. (Not in new syllabus) [15]