GTU last year question papers -BE- Sem-Vth -Microcontroller and Interfacing -May/June -2012

GTU last year question papers

GUJARAT TECHNOLOGICAL UNIVERSITY

BE- Vth SEMESTER–EXAMINATION – MAY/JUNE – 2012

Subject code: 151001 

Subject Name: Microcontroller and Interfacing

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.

Q.1 (a) Answer Following Questions

1) What precaution we should take before using SUBB

instruction?

2) What are the conditions for setting the OV flag?

3) Find the system frequency of an 89C51 if the machine

cycle period is 0.546 μs.

4) Under which condition 8051 with internal 4K program

memory would access external program memory?

5) What are the maximum sizes of program memory and

data memory that may be interfaced with MCS-51?

6) What is the difference between a Timer and a Counter?

7) What is the difference between MOVC and MOVX

instructions? 

(b) Draw schematic diagram for 8051 minimum hardware

configuration. Explain function of power – on – reset circuit. 

Q.2 (a) Draw a schematic diagram of 8051 interfaced with 2K

external RAM. With reference to interface diagram drawn,

give the range of memory for which memory can be accessed. 

(b) Write a program to check if the character string of length 7,

stored in RAM location40H onwards is a palindrome. If it

is, output Y to P1. Hint: A palindrome is a string in which

the characters are same whether the string is read in forward or reverse direction. 

OR

(b) Assume that input at port P1 is data for temperature. Two

LEDs are connected at P0.0 (RED) and P0.1 (GREEN)

with their anodes pulled up through 820_ resistor and

cathodes are connected with pins. LEDs Write a program

to acquire temperature data and indicate the status on LED

as below. Note: It is require continuously monitoring the

temperature and indicating status on LEDs.

• If TEMP _ 10° RED LED ON and GREEN LED

OFF

• If 10° < TEMP _ 80° RED LED OFF and GREEN

LED ON

• IF TEMP > °80 RED LED ON and GREEN LED

OFF

Q.3 (a) Sixteen random numbers are stored in an array, starting

from location 40H. Write an assembly program to count

the number of non-zero elements in this array and store it

in location 30H. 

(b) Write an 8051 C program to convert 8-bit binary data to

decimal and display the digits on P0,P1, and P2 

OR

Q.3 (a) Write a program to calculate the average of an array of

unsigned positive integers. The array starts from 41H and

number of terms in the array is available in location 40H.

Store the calculated average in location 3FH. 

(b) Write an 8051 C program to toggle all the bits of P0 and P2

continuously with a 250ms delay. Use the inverting operator 

Q.4 (a) Answer Following:

1) In general, a 12 MHz crystal is used for XX51-based

systems. However, in certain cases, a frequency of

11.0592 is preferred. What is the reason behind it?

2) Why there is no Sign-flag in MCS-51?   

(b) Solve the following:

1) Calculate the reload value for Timer 1 in mode 2 to

generate a baud rate of 2400, if 8051 is interfaced with

a 12 MHz crystal. 

2) Find the time delay generated by the following routine

if the XTAL = 22 MHz.

HERE : MOV R0,#200

AGAIN : DJNZ R0,AGAIN RET

OR

Q.4 (a) Write a program to generate a square wave with frequency

of 10KHz and with 50% duty cycle using Timer 0. Assume

the external crystal frequency of 12 MHz.

 

(b) Timer 0 is used as a counter, and Timer 1 is used as time

base of 1 second. Write an assembly program to find

frequency of signal connected at P3.4 (counter input for

Timer 0). Assume XTAL = 22MHz. 

Q.5 (a) Draw schematic diagram of 8051 interfaced with

ADC08  . Use the 8051 clock to generate necessary clock

signal for ADC08  . Use P1 for Data line connection and P2 for other control signals. 

(b) Write either assembly or C program for above circuit to

convert analog signal into digital and store it in internal RAM. 

OR

Q.5 (a) Draw a schematic diagram of 8051 interfaced with unipolar

stepper motor. Give reason, one need driver IC or circuit

for interfacing stepper motor with 8051. 

(b) Write a program to rotate a stepper motor, as interfaced in

above problem, by 64° in clockwise direction. Assume the

motor has a step angle of 2°. Use the 4 – step sequence.

 

Leave a Comment