AU Solved Paper 20459 - set 15

AU Solved Paper 20459

December - 2018

Microprocessors & Microcontrollers

Semester - V/VI (EEE) - Regulation 2013

 

Time: Three Hours]

[Maximum Marks: 100

 

Answer ALL Questions

PART A (10 × 2 = 20 Marks)

Q.1 List the registers of 8085 processor. (Refer section 1.2.1)

Q.2 State any four pins of 8085 processor which are used to generate control and status signals. (Refer section 1.3.3)

Q.3 State any four data transfer instructions and their function. (Refer section 2.2.1)

Q.4 Define subroutine. (Refer page 2-25)

Q.5 State any four inbuilt features of 8051 microcontroller. (Refer section 14.2)

 

 Q.6 How multiplication is performed in 8085 and 8051 ?

Ans. :  In 8085, since multiplication instruction is not available multiplication can be performed by repeatative addition or by using shift, and add method. In 8051, multiplication is performed using MUL AB instruction.

 

Q.7 Find the control word of 8255 if port A is configured as input and port B is configured as output in mode 0.

Ans. :

X = don't care Assuming don't cares as zeroes we have control word = 90H

 

Q.8 State the application of 8251 and 8279 ICs.

Ans. : The 8251 is an universal synchronous and asynchronous communication controller and it is used for serial communication. The 8279 is used to interface keyboard and display to the microprocessor.

 

Q.9 Specify the difference between MOV and MOVX instructions.

Ans. : MOV instruction of 8051 is used to access data within the internal memory. On the other hand, MOVX instruction of 8051 is used to access external data memory.

 

Q.10 State any four applications of microcontroller.

Ans. :

1. Washing machine

2. Micro-oven

3. Refrigerator

4. Critical application, flight control system.

5. Various embedded systems.

6. Various portable devices.

 

PART B - (5 × 13 = 65 Marks)

Q.11 a) With neat block diagram, explain the various functional building blocks of 8085 processor. (Refer section 1.2)

OR

b) Define vector address. List the various interrupts of 8085 processor and elucidate the use of interrupt service routine. (Refer section 4.2.2.1)

Q.12 a) Define addressing mode. Identify the addressing mode of the following instructions and explain them.

i) STA 6350H - Direct addressing mode (Refer section 2.2.1)

ii) CMA - Implied addressing mode  (Refer section 2.2.3)

iii) MOV A, M - Indirect addressing mode (Refer section 2.2.1)

iv) MOV D, E - Register addressing mode (Refer section 2.2.1)

v) MVI A, A7H - Immediate addressing mode (Refer section 2.2.1)

OR

b) Develop an algorithm and 8085 assembly language program to sort 100 byte type data. Explain the instructions used in the program. (Refer Lab experiment 3.1.7)

Ans. : The basic idea underlying the bubble sort is to pass through the array sequentially several times. Each pass consists of comparing each element in the array with its successor (x[i]) with x[i+1] and interchanging the two elements if they are not in proper order. Considering the following array:

25   57  48  37  12  92  86  33

The following comparisons are made to sort the array in the ascending order on the first pass :

x[0] withx[1] i.e.25   with 57   noexchange

x[1] withx[2] i.e.57    with 48   exchange

x[2] withx[3] i.e.57   with 37   exchange

x[3] withx[4] i.e.57   with 12  exchange

x[4] withx[5] i.e.57  with 92 no exchange

x[5] withx[6] i.e.92  with 86 exchange

x[6] withx[7] i.e.92  with 33 exchange

Thus after the first pass, the array is in the order,

25   48   37   12   57   86   33   92

Notice that after this first pass the largest element (in this case 92) is in its proper position within the array. After second pass the array is in the order.

25   37   12   48   57   33   86   92

Notice that 86 has now found its way to the second highest position. Since each iteration places a new element into its proper position an array of n elements requires no more than n-1 iterations. The complete set of iterations are as shown below.

 

Q.13 a) Explain the pinouts of 8051 microcontroller. (Refer section 14.4)

OR

b) Describe the timing diagram of external data memory read cycle of 8051. (Refer section 14.6.2)

Q.14 a) i) Explain the architecture of 8259. (Refer section 9.3) [9]

ii) How 8259 is interfaced with 8085 or 8051 ? (Refer section 9.7) [4]

OR

b) Explain the interfacing of DAC with 8051 or 8085 with neat diagram and write a program for generating any typical waveform. (Refer section 13.3)

Q.15 a) Explain the various bit manipulation instructions in 8051 with examples. (Refer section 15.6)

OR

b) Develop a 8051 ALP to evaluate an arithmetic expression (A - B) x C where A, B, C are 8 bit data in internal memory. Assume A > B and store the result in external memory. Explain the program developed.

Ans.. :

Assume A = 50H, B = 40H and C = 60H

MOV A, #50H ; load A

MOV R0, #40H ; load B

CLR C  ; clear carry flag for subtraction operation

SUBB R0  ; subtract the contents of RO, i.e. B

; from A (A← A - B)

MOV B, #60 H  ;  load C

MUL AB  ; multiply previous result (A - B) with C

MOV DPTR, # Addr16  ; load 16-bit address of external memory in DPTR

MOVX @DPTR, A  ; store lower byte of result in external memory

INC DPTR  ; increment memory pointer

MOV A, B  ; get the higher byte of result

MOVX @DPTR, A  ; store the higher byte of result

; in external memory

 

PART C - (1 × 15 15 Marks)

 

Q.16 a) Design a system using 8085 or 8051 to blink four LEDs. (Refer section 17.2.1)

OR

Design a stepper motor control system using 8051 microcontroller. (Refer section 17.4)