Multiple Choice Questions & Answers on 8051 Interfacing

1. An electronic device which converts physical quantity or energy from one form to another is called ______

a) Sensor

b) Transistor

c) Transducer

d) Thyristor

Answer: Transducer

2. A thermistor is a __________

a) sensor

b) adc

c) transducer

d) micro controller

Answer: transducer

3. DS12887 is a ____________

a) Timer IC

b) Serial communication IC

c) RTC IC

d) Motor

Answer: RTC IC

4. DS12887 has _____ amount of RAM.

a) 14 bytes

b) 114 bytes

c) 128 bytes

d) 64 bytes

Answer: 128 bytes

5. The 8255 is a ______ chip.

a) Input/Output

b) Analog to Digital

c) Digital to analog

d) None of the mentioned

Answer: Input/Output

6. DS12887 has _____ amount of RAM for general purpose applications.

a) 9 bytes

b) 114 bytes

c) 128 bytes

d) 14 bytes

Answer: 114 bytes

7. How many pins of the 8255 can be used as the I/O ports?

a) 8

b) 16

c) 24

d) 32

Answer: 24

8. LM35 has how many pins?

a) 2

b) 1

c) 3

d) 4

Answer: 3

9. Find the control word for PA = out, PB = in, PCL = out, PCH = out (Mode0)?

a) 0x02H

b) 0x82H

c) 0x83H

d) 0x03H

Answer: 0x82H

10. In DS12887, what is the range of RAM addresses which are used to store the values of time, calendar and alarm data?

a) 00-7FH

b) 00-09H

c) 0EH-7FH

d) 0A-0DH

Answer: 00-09H

11. What is the difference between LM 34 and LM 35 sensors?

a) one is a sensor and the other is a transducer

b) one’s output voltage corresponds to the Fahrenheit temperature and the other corresponds to the Celsius temperature

c) one is of low precision and the other is of higher precision

d) one requires external calibration and the other doesn’t require it

Answer: one’s output voltage corresponds to the Fahrenheit temperature and the other

12. What is signal conditioning?

a) to analyse any signal

b) conversion or modification is referred to as conditioning

c) conversion from analog to digital is signal conditioning

d) conversion from digital to analog is signal conditioning

Answer: conversion or modification is referred to as conditioning

13. What steps have to be followed for interfacing a sensor to a microcontroller 8051?

a) make the appropriate connections with the controller, ADC conversion, analyse the results

b) interface sensor with ADC and ADC with 8051

c) interface sensor with the MAX232, send now to microcontroller, analyse the results

d) none of the mentioned

Answer: interface sensor with ADC and ADC with 8051

14. Why Vref is set of ADC0848 to 2.56 V if analog input is connected to the LM35?

a) to set the step size of the sampled input

b) to set the ground for the chip

c) to provide supply to the chip

d) all of the mentioned

Answer: to set the step size of the sampled input

15. In DS12887, which bits of the Register A are used to turn on the oscillator?

a) D4

b) D5

c) D6

d) All of the mentioned

Answer: All of the mentioned

16. In DS12887, which out of the following is correct about the SQW pin?

a) it is an output pin

b) it can provide up to 15 different square waves

c) the frequency of the square wave is set by the register A

d) all of the mentioned are correct

Answer: all of the mentioned are correct

17. In DS12887, what is correct about the UIP bit of the register A?

a) it is a read only bit

b) it is used to know about the result

c) it is used to select the DS12887 datasheet

d) all of the mentioned

Answer: it is a read only bit

18. Is DS12887 has non-volatile RAM?

a) Yes

b) No

c) Can’t be determined

d) None of the mentioned

Answer: Yes

19. Name the read only registers are present in the DS12887?

a) register A, register B

b) register B, register C

c) register C, register D

d) register D, register A

Answer: register C, register D

20. In DS12887, when the external source is turned-off, how does DS12887 get power to retain its data?

a) Internal Lithium Battery

b) Internal Lead Battery

c) Additional external Alkaline Battery

d) Additional external Lithium Battery

Answer: Internal Lithium Battery

21. Which pins of a microcontroller are directly connected with 8255?

a) RD

b) WR

c) D0-D7

d) All of the mentioned

Answer: All of the mentioned

22. Which pins are used to select the ports and the control register?

a) CS

b) A1

c) A0

d) All of the mentioned

Answer: All of the mentioned

23. What is the value of the control register when RESET button is set to zero?

a) 0x00H

b) 0xFFH

c) 0x11H

d) value remains the same

Answer: value remains the same

24. Why MOVX instruction is being used to access the ports of the 8255?

a) because 8255 is connecting a microcontroller in memory mapped I/O configuration

b) because 8255 is used to access the external communication

c) because 8255 is used to access the data transfer

d) because 8255 is used to access the interfacing of LCD, motor etc

Answer: because 8255 is connecting a microcontroller in memory mapped I/O configuration

25. What is correct about the BSR mode from below?

a) In BSR mode, only the individual bits of PORT A can be programmed

b) In BSR mode, only the individual bits of PORT B can be programmed

c) In BSR mode, only the individual bits of PORT C can be programmed

d) none of the mentioned

Answer: In BSR mode, only the individual bits of PORT C can be programmed