MICROPROCESSORS AND MICROCONTROLLERS-OCTOBER-2009

FOURTH  SEMESTER DIPLOMA EXAMINATION IN ENGINEERING/TECHNOLOGY-OCTOBER, 2009

MICROPROCESSORS AND MICROCONTROLLERS

PART-A

(Maximum marks:15)

v  Answer the following questions in one or two sentences:

1.Write the function of ALE pin of 8085.

2.What is the function of stack pointer of 8085?

3.Which is the bit addressable memory area of 8051?

4.What is the internal ROM size of 8051?

5.Write an 8051 assembly instruction to jump to label if zero flag is set.

6.What happens whenMOVC A,@A+DPTR is executed?

7.State the port status of 8255 in mode 1 operation.

8.State the function of 8251.

9.What is common cathode 7 segment display?

10.Why is keyboard debounced in matrix keyboard?

PART-B

(Maximum marks:60)

(Answer one full question from each unit)

Unit-1

v  (a)Draw the functional block diagram of 8085 and explain the blocks.(6)

          (b)Brief the functions of the following pins of 8085.

                (i)HOLD             (ii)HLDA(4)

OR

v  (a)Explain the interrupts of 8085.(6)

(b)Draw the timing diagram of memory write cycle of 8085.(6)

Unit-2

v  (a)Draw the pin diagram of 8051.(6)

(b)Explain the flags of the following registers:

(i)TMOD         (ii)TCON (6)

         

OR

v  (a)Find the TH1 value in both decimal and hex toset the baud rate to each of the following:Assume SMOD=1 and crystal=11.0592 MHz.

(i)9600           (ii)4800(6)

          (b)Describe the following modes of 8091:

(i)Idle mode            (ii)Power down mode(6)

UNIT-3

v  (a)Write an assembly program for 8051 togenerate a square wave of 100 Hzfrequency on pin P1.2.Assume crystal at 12 MHz.Use Timer 0 and timer interrupt.(8)

          (b)Write a program for 8051 to copy a block of 10 bytes of data from RAM locations starting at 20H to RAM locations starting at 30H.(4)

OR

v  (a)Write a program for 8051 to transfer message”YES”serially at 9600 baud rate,8 bit,1 stop bit continuously.Assume crystal=11.0592 MHZ.(8)

          (b)Write a program for 8051 to OR the contents of ports 1 and 2 and put the result in external RAM location 2400h.(4)

UNIT-4

v  (a)Draw the block diagram of 8255 and explain the blocks.(10)

(b)State the function of 8253.(2)

OR

v  (a)Explain the block diagram of 8257.(10)

          (b)State the use of 8279.(2)

UNIT-5

v  (a)Draw the circuit diagram for interfacing an 8 bit ADC to 8051.(6)

          (b)Write an assembly code for reading the ADC values to register R6.(6)

OR

v  (a)Draw the circuit diagram for interfacing a stepper motor to PORT 2 of 8051.(6)

(b)Write an assembly code for the stepper motor interface.(6)

        

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