Embedded System Design Questions and answers

 Embedded System Design

Introduction to Microcontrollers & Embedded processors 

Introduction to Microcontrollers

1. In 8086 microprocessor , the address bus is ________ bit wide

  •  10 bit
  •  20 bit
  •  16 bit
  •  12 bit

 Answer 20 bit

2. What is the file extension is used to load in a microcontroller to execute an instruction?

  •  .doc
  •  .c
  •  .txt
  •  .hex

Answer .hex

3. What are the two instruction set architecture (ISA) classifications?

  •  SIDC & BIDC
  •  CISC & RISC
  •  CISC & VISC

Answer CISC & RISC

4. What is internal RAM memory of 8051 microprocessor?

  •  32 bytes
  •  64 bytes
  •  128 bytes
  •  256 bytes

Answer 128 bytes

5. How many timers/counter 8051 16-bit microprocessor have?

  •  1
  •  2
  •  5
  •  8

Answer 2 timers/counter

6. Register that is used to holds the memory address of the next instruction to be executed is

  •  Program Memory
  •  Program Counter
  •  Control Unit
  •  Instruction decoder

Answer Program Counter

7. The 8051 microprocessor has ________ parallel I/O ports.

  •  2
  •  3
  •  4
  •  5

Answer  4 parallel I/O ports.

8. Which instructions affect the program counter?

  •  Call & Return
  •  Call & Jump
  •  Push & Pop
  •  Return & Jump

Answer Call & Jump

9. Which register is used to store the output generated by ALU?

  •  Special Function Register
  •  Timer Register
  •  Accumulator
  •  Stack Pointer

Answer Accumulator

10. ........... signal control the flow of data

  •  DTR
  •  RTS
  •  Both 1 & 2
  •  None of the above

Answer Both 1 & 2

11. Which of the following is the function of the TMOD register?

  •  It is used to interrupt the timer
  •  It is used to load the count of the timer
  •  It is used to set different timer’s or counter’s to their appropriate modes
  •  It Is the destination or the final register where the result is obtained after the operation of the timer

Answer It is used to set different timer’s or counter’s to their appropriate modes

12. Which of the following is the function of the SCON register?

  •  control SMOD registers
  •  control SBUF and SMOD registers
  •  program the start bit, stop bit, and data bits of framing
  •  None of the above

Answer program the start bit, stop bit, and data bits of framing

13. Which of the following is the bit of the IE register is used to enable TxD/RxD interrupt?

  •  IE.D2
  •  IE.D3
  •  IE.D4
  •  IE.D5

Answer IE.D4

14. Which of the following pin of the LCD is used for adjusting its contrast?

  •  pin no 3
  •  pin no 1
  •  pin no 4
  •  pin no 2

Answer pin no 3

15. Point out the correct statement about about DAC0808?

  •  It has current as an output
  •  Parallel digital data to analog data conversion
  •  Both A & B
  •  None of the above

Answer Parallel digital data to analog data conversion

16. Which of the following register usually store the output generated by ALU in several arithmetic and logical operations?

  •  Special Function Register
  •  Timer Register
  •  Accumulator
  •  Stack Pointer

Answer Accumulator

17. Which of the following operations are performed by stack pointer during its incremental phase?

  •  Pop
  •  Push
  •  Return
  •  None of the above

Answer  Push

18. Which of the following is the default value of stack once after the system undergoes the reset condition?

  •  08H
  •  09H
  •  00H
  •  07H

Answer 07H

19. Whichn of the following commands are used for addressing the off-chip data and associated codes respectively by data pointer?

  •  MOVC & MOVY
  •  MOVY & MOVB
  •  MOVZ & MOVA
  •  MOVX & MOVC

Answer MOVX & MOVC

20. Which of the following is the bit addressing range of addressable individual bits over the on-chip RAM?

  •  00H to 7FH
  •  01H to 7FH
  •  00H to FFH
  •  80H to FFH

Answer a 00H to 7FH

21. A microcontroller at-least should consist of:

  • RAM, ROM, I/O ports and timers
  • CPU, RAM, I/O ports and timers
  • CPU, RAM, ROM, I/O ports and timers
  • CPU, ROM, I/O ports and timers

Answer CPU, RAM, ROM, I/O ports and timers

22. Unlike microprocessors, microcontrollers make use of batteries because they have:

a) high power dissipation

b) low power consumption

c) low voltage consumption

d) low current consumption

Answer low power consumption

23. What is the order decided by a processor or the CPU of a controller to execute an instruction?

a) decode,fetch,execute

b) execute,fetch,decode

c) fetch,execute,decode

d) fetch,decode,execute

Answer fetch,decode,execute

24. If we say microcontroller is 8-bit then here 8-bit denotes size of:

a) Data Bus

b) ALU

c) Control Bus

d) Address Bus

Answer: ALU

25. How are the performance and the computer capability affected by increasing its internal bus width?

a) it increases and turns better

b) it decreases

c) remains the same

d) internal bus width doesn’t affect the performance in any way

Answer: it increases and turns better

26. Abbreviate CISC and RISC.

a) Complete Instruction Set Computer, Reduced Instruction Set Computer

b) Complex Instruction Set Computer, Reduced Instruction Set Computer

c) Complex Instruction Set Computer, Reliable Instruction Set Computer

d) Complete Instruction Set Computer, Reliable Instruction Set Computer

Answer: Complex Instruction Set Computer, Reduced Instruction Set Computer

27. Give the names of the buses present in a controller for transferring data from one place to another?

a) data bus, address bus

b) data bus

c) data bus, address bus, control bus

d) address bus

Answer: data bus, address bus, control bus

28. What is the file extension that is loaded in a microcontroller for executing any instruction?

a) .doc

b) .c

c) .txt

d) .hex

Answer: .hex

29. What is the most appropriate criterion for choosing the right microcontroller of our choice?

a) speed

b) availability

c) ease with the product

d) all of the mentioned

Answer: all of the mentioned

30. Why microcontrollers are not called general purpose computers?

a) because they have built in RAM and ROM

b) because they design to perform dedicated task

c) because they are cheap

d) because they consume low power

Answer: because they design to perform dedicated task

31. How many types of architectures are available, for designing a device that is able to work on its own?

a) 3

b) 2

c) 1

d) 4

Answer: 2

32. Which architecture is followed by general purpose microprocessors?

a) Harvard architecture

b) Von Neumann architecture

c) None of the mentioned

d) All of the mentioned

Answer: Von Neumann architecture

33. Which architecture involves both the volatile and the non volatile memory?

a) Harvard architecture

b) Von Neumann architecture

c) None of the mentioned

d) All of the mentioned

Answer: Harvard architecture

34. Which architecture provides separate buses for program and data memory?

a) Harvard architecture

b) Von Neumann architecture

c) None of the mentioned

d) All of the mentioned

Answer: Harvard architecture

35. Which microcontroller doesn’t match with its architecture below?

a) Microchip PIC- Harvard

b) MSP430- Harvard

c) ARM7- Von Neumann

d) ARM9- Harvard

Answer: MSP430- Harvard

36. Harvard architecture has _____________

a) dedicated buses for data and program memory

b) pipeline technique

c) complex architecture

d) all of the mentioned

Answer: all of the mentioned

37. Which out of the following supports Harvard architecture?

a) ARM7

b) Pentium

c) SHARC

d) All of the mentioned

Answer: SHARC

38. Why most of the DSPs use Harvard architecture?

a) they provide greater bandwidth

b) they provide more predictable bandwidth

c) they provide greater bandwidth & also more predictable bandwidth

d) none of the mentioned

Answer: they provide greater bandwidth & also more predictable bandwidth

39. Which of the following supports CISC as well as Harvard architecture?

a) ARM7

b) ARM9

c) SHARC

d) None of the mentioned

Answer: SHARC

40. Which of the two architecture saves memory?

a) Harvard

b) Von Neumann

c) Harvard & Von Neumann

d) None of the mentioned

Answer: Von Neumann


8051 Microcontrollers

Architecture

1. 8051 microcontrollers are manufactured by which of the following companies?

a) Atmel

b) Philips

c) Intel

d) All of the mentioned

Answer: All of the mentioned

2. AT89C2051 has RAM of:

a) 128 bytes

b) 256 bytes

c) 64 bytes

d) 512 bytes

Answer: 128 bytes

3. 8051 series has how many 16 bit registers?

a) 2

b) 3

c) 1

d) 0

Answer: 2

4. When 8051 wakes up then 0x00 is loaded to which register?

a) PSW

b) SP

c) PC

d) None of the mentioned

Answer: PC

5. When the microcontroller executes some arithmetic operations, then the flag bits of which register are affected?

a) PSW

b) SP

c) DPTR

d) PC

Answer: PSW

6. How are the status of the carry, auxiliary carry and parity flag affected if the write instruction

MOV A,#9C

ADD A,#64H

a) CY=0,AC=0,P=0

b) CY=1,AC=1,P=0

c) CY=0,AC=1,P=0

d) CY=1,AC=1,P=1

Answer: CY=1,AC=1,P=0

7. How are the bits of the register PSW affected if we select Bank2 of 8051?

a) PSW.5=0 and PSW.4=1

b) PSW.2=0 and PSW.3=1

c) PSW.3=1 and PSW.4=1

d) PSW.3=0 and PSW.4=1

Answer: PSW.3=0 and PSW.4=1

8. If we push data onto the stack then the stack pointer

a) increases with every push

b) decreases with every push

c) increases & decreases with every push

d) none of the mentioned

Answer: increases with every push

9. On power up, the 8051 uses which RAM locations for register R0- R7

a) 00-2F

b) 00-07

c) 00-7F

d) 00-0F

Answer: 00-07

10. How many bytes of bit addressable memory is present in 8051 based microcontrollers?

a) 8 bytes

b) 32 bytes

c) 16 bytes

d) 128 bytes

Answer: 16 bytes


Jump, Loop and Call Instructions

1. “DJNZ R0, label” is ________ byte instruction.

a) 2

b) 3

c) 1

d) Can’t be determined

Answer: 2

2. JZ, JNZ, instructions checked content of _______ register.

a) DPTR

b) B

c) A

d) PSW

Answer: A

3. Calculate the jump code for again and here if code starts at 0000H

MOV R1,#0

MOV A,#0

MOV R0,#25H

AGAIN:ADD A,#0ECH

JNC HERE

HERE: INC R1 

DJNZ R0,AGAIN

MOV R0,A 

END

a) F3,02

b) F9,01

c) E9,01

d) E3,02

Answer: E9,01

4. When the call instruction is executed the topmost element of stack comes out to be

a) the address where stack pointer starts

b) the address next to the call instruction

c) address of the call instruction

d) next address of the stack pointer

Answer: the address next to the call instruction

5. LCALL instruction takes

a) 2 bytes

b) 4 bytes

c) 3 bytes

d) 1 byte

Answer: 3 bytes

6. Are PUSH and POP instructions are a type of CALL instructions?

a) yes

b) no

c) none of the mentioned

d) cant be determined

Answer: no

7. What is the time taken by one machine cycle if crystal frequency is 20MHz?

a) 1.085 micro seconds

b) 0.60 micro seconds

c) 0.75 micro seconds

d) 1 micro seconds

Answer: 0.60 micro seconds

8. Find the number of times the following loop will be executed

MOV R6,#200

BACK:MOV R5,#100

HERE:DJNZ R5, HERE

DJNZ R6,BACK 

END

a) 100

b) 200

c) 20000

d) 2000

Answer: 20000

9. What is the meaning of the instruction MOV A,05H?

a) data 05H is stored in the accumulator

b) fifth bit of accumulator is set to one

c) address 05H is stored in the accumulator

d) none of the mentioned

Answer: address 05H is stored in the accumulator

10. Do the two instructions mean the same?

1) BACK: DEC R0 

JZ BACK 

2) BACK: DJNZ RO, BACK

a) yes

b) no

c) cant be determined

d) yes and the second one is preferred

Answer: no


I/O Port Programming and Addressing Modes

I/O Port Programming and Addressing Modes

1. To initialize any port as an output port what value is to be given to it?

a) 0xFF

b) 0x00

c) 0x01

d) A port is by default an output port

Answer: A port is by default an output port

2. Which out of the four ports of 8051 needs a pull-up resistor for using it is as an input or an output port?

a) PORT 0

b) PORT 1

c) PORT 2

d) PORT 3

Answer: PORT 0

3. Which of the ports act as the 16 bit address lines for transferring data through it?

a) PORT 0 and PORT 1

b) PORT 1 and PORT 2

c) PORT 0 and PORT 2

d) PORT 1 and PORT 3

Answer: PORT 0 and PORT 2

4. Which of the following registers are not bit addressable?

a) SCON

b) PCON

c) A

d) PSW

Answer: PCON

5. Which instruction is used to check the status of a single bit?

a) MOV A,P0

b) ADD A,#05H

c) JNB PO.0, label

d) CLR P0.05H

Answer: JNB PO.0, label

6. Which addressing mode is used in pushing or popping any element on or from the stack?

a) immediate

b) direct

c) indirect

d) register

Answer: direct

7. Which operator is the most important while assigning any instruction as register indirect instruction?

a) $

b) #

c) @

d) &

Answer: @

8. What is the advantage of register indirect addressing mode?

a) it makes use of registers R0 and R1

b) it uses the data dynamically

c) it makes use of operator @

d) it is easy

Answer: it uses the data dynamically

9. Which of the following comes under the indexed addressing mode?

a) MOVX A, @DPTR

b) MOVC @A+DPTR,A

c) MOV A,R0

d) MOV @R0,A

Answer: MOVC @A+DPTR,A

10. Is this a valid statement?

SETB A

a) yes

b) no

c) cant be determined

d) none of the mentioned

Answer: no


Arithmetic and Logic Instructions

1. When we add two numbers the destination address must always be.

a) some immediate data

b) any register

c) accumulator

d) memory

Answer: accumulator

2. DAA command adds 6 to the nibble if:

a) CY and AC are necessarily 1

b) either CY or AC is 1

c) no relation with CY or AC

d) CY is 1

Answer: either CY or AC is 1

3. If SUBB A,R4 is executed, then actually what operation is being applied?

a) R4+A

b) R4-A

c) A-R4

d) R4+A

Answer: A-R4

4. A valid division instruction always makes:

a) CY=0,AC=1

b) CY=1,AC=1

c) CY=0,AC=0

d) no relation with AC and CY

Answer: CY=0,AC=0

5. In 8 bit signed number operations, OV flag is set to 1 if:

a) a carry is generated from D7 bit

b) a carry is generated from D3 bit

c) a carry is generated from D7 or D3 bit

d) a carry is generated from D7 or D6 bit

Answer: a carry is generated from D7 or D6 bit

6. In unsigned number addition, the status of which bit is important?

a) OV

b) CY

c) AC

d) PSW

Answer: CY

7. Which instructions have no effect on the flags of PSW?

a) ANL

b) ORL

c) XRL

d) All of the mentioned

Answer: All of the mentioned

8. ANL instruction is used _______

a) to AND the contents of the two registers

b) to mask the status of the bits

c) all of the mentioned

d) none of the mentioned

Answer: all of the mentioned

9. CJNE instruction makes _______

a) the pointer to jump if the values of the destination and the source address are equal

b) sets CY=1, if the contents of the destination register are greater then that of the source register

c) sets CY=0, if the contents of the destination register are smaller then that of the source register

d) none of the mentioned

Answer: none of the mentioned

10. XRL, ORL, ANL commands have _______

a) accumulator as the destination address and any register, memory or any immediate data as the source address

b) accumulator as the destination address and any immediate data as the source address

c) any register as the destination address and accumulator, memory or any immediate data as the source address

d) any register as the destination address and any immediate data as the source address

Answer: accumulator as the destination address and any register, memory or any immediate data as the source address


Timer Programming

1. What is the clock source for the timers?

a) some external crystal applied to the micro-controller for executing the timer

b) from the crystal applied to the micro-controller

c) through the software

d) through programming

Answer: from the crystal applied to the micro-controller

2. What is the frequency of the clock that is being used as the clock source for the timer?

a) some externally applied frequency f’

b) controller’s crystal frequency f

c) controller’s crystal frequency /12

d) externally applied frequency/12

Answer: controller’s crystal frequency /12

3. What is the function of the TMOD register?

a) TMOD register is used to set various operation modes of timer/counter

b) TMOD register is used to load the count of the timer

c) Is the destination or the final register where the result is obtained after the operation of the timer

d) Is used to interrupt the timer

Answer: TMOD register is used to set various operation modes of timer/counter

4. What is the maximum delay that can be generated with the crystal frequency of 22MHz?

a) 2978.9 sec

b) 0.011 msec

c) 11.63 sec

d) 2.97 msec

Answer: 2.97 msec

5. Auto reload mode is allowed in which mode of the timer?

a) Mode 0

b) Mode 1

c) Mode 2

d) Mode 3

Answer: Mode 2

6. Find out the roll over value for the timer in Mode 0, Mode 1 and Mode 2?

a) 00FFH,0FFFH,FFFFH

b) 1FFFH,0FFFH,FFFFH

c) 1FFFH,FFFFH,00FFH

d) 1FFFH,00FFH,FFFFH

Answer: 1FFFH,FFFFH,00FFH

7. What steps are followed when we need to turn on any timer?

a) load the count, start the timer, keep monitoring it, stop the timer

b) load the TMOD register, load the count, start the timer, keep monitoring it, stop the timer

c) load the TMOD register, start the timer, load the count, keep monitoring it, stop the timer

d) none of the mentioned

Answer: load the TMOD register, load the count, start the timer, keep monitoring it, stop the timer

8. If Timer 0 is to be used as a counter, then at what particular pin clock pulse need to be applied?

a) P3.3

b) P3.4

c) P3.5

d) P3.6

Answer: P3.4

9. In the instruction “MOV TH1,#-3”, what is the value that is being loaded in the TH1 register?

a) 0xFCH

b) 0xFBH

c) 0xFDH

d) 0xFEH

Answer: 0xFDH

10. TF1, TR1, TF0, TR0 bits are of which register?

a) TMOD

b) SCON

c) TCON

d) SMOD

Answer: TCON


Serial Port Communication

1. Which devices are specifically being used for converting serial to parallel and from parallel to serial respectively?

a) timers

b) counters

c) registers

d) serial communication

Answer: registers

2. What is the difference between UART and USART communication?

a) they are the names of the same particular thing, just the difference of A and S is there in it

b) one uses asynchronous means of communication and the other uses synchronous means of communication

c) one uses asynchronous means of communication and the other uses asynchronous and synchronous means of communication

d) one uses angular means of the communication and the other uses linear means of communication

Answer: one uses asynchronous means of communication and the other uses asynchronous and synchronous means of communication

3. Which of the following best describes the use of framing in asynchronous means of communication?

a) it binds the data properly

b) it tells us about the start and stops of the data to be transmitted or received

c) it is used for error checking

d) it is used for flow control

Answer: it tells us about the start and stops of the data to be transmitted or received

4. Which of the following signal control the flow of data?

a) RTS

b) DTR

c) RTS & DTR

d) None of the mentioned

Answer: RTS

5. Which of the following is the logic level understood by the micro-controller/micro-processor?

a) TTL logic level

b) RS232 logic level

c) None of the mentioned

d) TTL & RS232 logic level

Answer: TTL logic level

6. What is a null modem connection?

a) no data transmission

b) no MAX232

c) the RxD of one is the TxD for the other

d) no serial communication

Answer: the RxD of one is the TxD for the other

7. Which of the following best states the reason that why baud rate is mentioned in serial communication?

a) to know about the no of bits being transmitted per second

b) to make the two devices compatible with each other, so that the transmission becomes easy and error free

c) to use Timer 1

d) for wasting memory

Answer: to make the two devices compatible with each other, so that the transmission becomes easy and error free

8. With what frequency UART operates( where f denoted the crystal frequency )?

a) f/12

b) f/32

c) f/144

d) f/384

Answer: f/384

9. What is the function of the SCON register?

a) to control SBUF and SMOD registers

b) to program the start bit, stop bit, and data bits of framing

c) to control SMOD registers

d) none of the mentioned

Answer: to program the start bit, stop bit, and data bits of framing

10. What should be done if we want to double the baud rate?

a) change a bit of the TMOD register

b) change a bit of the PCON register

c) change a bit of the SCON register

d) change a bit of the SBUF register

Answer: change a bit of the PCON register


Interrupt Programming

1. When an interrupt is enabled, then where does the pointer moves immediately after this interrupt has occurred?

a) to the next instruction which is to be executed

b) to the first instruction of ISR

c) to a fixed location in memory called interrupt vector table

d) to the end of the program

Answer: to a fixed location in memory called interrupt vector table

2. What are the contents of the IE register, when the interrupt of the memory location 0x00 is caused?

a) 0xFFH

b) 0x00H

c) 0x10H

d) 0xF0H

Answer: 0x00H

3. After RETI instruction is executed then the pointer will move to which location in the program?

a) next interrupt of the interrupt vector table

b) immediate next instruction where interrupt is occurred

c) next instruction after the RETI in the memory

d) none of the mentioned

Answer: immediate next instruction where interrupt is occurred

4. Which pin of the external hardware is said to exhibit INT0 interrupt?

a) pin no 10

b) pin no 11

c) pin no 12

d) pin no 13

Answer: pin no 12

5. Which bit of the IE register is used to enable TxD/RxD interrupt?

a) IE.D5

b) IE.D2

c) IE.D3

d) IE.D4

Answer: IE.D4

6. Which of the following combination is the best to enable the external hardware interrupt 0 of the IE register (assuming initially all bits of the IE register are zero)?

a) EX0=1

b) EA=1

c) any of the mentioned

d) EX0=1 & EA=1

Answer: EX0=1 & EA=1

7. Why normally LJMP instructions are the topmost lines of the ISR?

a) so as to jump to some other location where there is a wider space of memory available to write the codes

b) so as to avoid overwriting of other interrupt instructions

c) all of the mentioned

d) none of the mentioned

Answer: all of the mentioned

8. Which register is used to make the interrupt level or an edge triggered pulse?

a) TCON

b) IE

c) IPR

d) SCON

Answer: TCON

9. What is the disadvantage of a level triggered pulse?

a) a constant pulse is to be maintained for a greater span of time

b) another interrupt may be generated if the low-level signal is not removed before the ISR is finished

c) it is difficult to produce

d) another interrupt may be caused if the signal is still low before the completion of the last instruction

Answer: another interrupt may be caused if the signal is still low before the completion of the last instruction

10. What is the correct order of priority that is set after a controller gets reset?

a) RI/TI > TF1 > TF0 > INT1 > INT0

b) RI/TI < TF1 < TF0 < INT1 < INT0

c) INT0 > TF0 > INT1 > TF1 > RI/TI

d) INT0 < TF0 < INT1 < TF1 < RI/TI

Answer: INT0 > TF0 > INT1 > TF1 > RI/TI


LCD Interfacing

1. How many rows and columns are present in a 16*2 alphanumeric LCD?

a) rows=2, columns=32

b) rows=16, columns=2

c) rows=16, columns=16

d) rows=2, columns=16

Answer: rows=2, columns=16

2. How many data lines are there in a 16*2 alphanumeric LCD?

a) 16

b) 8

c) 1

d) 0

Answer: 8

3. Which pin of the LCD is used for adjusting its contrast?

a) pin no 1

b) pin no 2

c) pin no 3

d) pin no 4

Answer: pin no 3

4. For writing commands on an LCD, RS bit is

a) set

b) reset

c) set & reset

d) none of the mentioned

Answer: reset

5. Which command of an LCD is used to shift the entire display to the right?

a) 0x1C

b) 0x18

c) 0x05

d) 0x07

Answer: 0x1C

6. Which command is used to select the 2 lines and 5*7 matrix of an LCD?

a) 0x01

b) 0x06

c) 0x0e

d) 0x38

Answer: 0x38

7. Which of the following step/s is/are correct for sending data to an LCD?

a) set the R/W bit

b) set the E bit

c) set the RS bit

d) all of the mentioned

Answer: all of the mentioned

8. Which of the following step/s is/are correct to perform reading operation from an LCD?

a) low to high pulse at E pin

b) R/W pin is set high

c) low to high pulse at E pin & R/W pin is set high

d) none of the mentioned

Answer: low to high pulse at E pin & R/W pin is set high

9. Which instruction is used to select the first row first column of an LCD?

a) 0x08

b) 0x0c

c) 0x80

d) 0xc0

Answer: 0x80

10. The RS pin is _________ for an LCD.

a) input

b) output

c) input & output

d) none of the mentioned

Answer: input


Keyboard Interfacing

1. Which of the following steps detects the key in a 4*4 keyboard matrix about the key that is being pressed?

a) masking of bits

b) ensuring that initially, all keys are open

c) checking that whether the key is actually pressed or not

d) all of the mentioned

Answer: all of the mentioned

2. What is described by this command: CJNE A,#00001111b, ROW1

a) it masks the bit and then jumps to the label where ROW1 is written

b) it makes the value of the accumulator 0FH and then jumps at the address where ROW1 label is written

c) it compares the value of the accumulator with 0FH and jumps to the location where ROW1 label is there if the value becomes equal

d) it compares the value of the accumulator with 0FH and jumps to the location where ROW1 label is there if the value is not equal

Answer: it compares the value of the accumulator with 0FH and jumps to the location where ROW1 label is there if the value is not equal

3. To detect that in which column, the key is placed?

a) we can mask the bits and then check it

b) we can rotate the bits and then check that particular bit which is set or reset(according to the particular condition)

c) none of the mentioned

d) all of the mentioned

Answer: all of the mentioned

4. In reading the columns of a matrix, if no key is pressed we should get all in binary notation

a) 0

b) 1

c) F

d) 7

Answer: 1

5. If we need to operate a key of a keyboard in an interrupt mode, then it will generate what kind of interrupt?

a) ES

b) EX0/EX1

c) T0/T1

d) RESET

Answer: EX0/EX1

6. To identify that which key is being pressed, we need to:

a) ground all the pins of the port at a time

b) ground pins of the port one at a time

c) connect all the pins of the port to the main supply at a time

d) none of the mentioned

Answer: ground pins of the port one at a time

7. Key press detection and Key identification are:

a) the same processes

b) two different works are done in Keyboard Interfacing

c) none of the mentioned

d) any of the mentioned

Answer: two different works are done in Keyboard Interfacing


ADC, DAC Interfacing

1. Why two pins for ground are available in ADC0804?

a) for controlling the ADCON0 and ADCON1 register of the controller

b) for controlling the analog and the digital pins of the controller

c) for both parts of the chip respectively

d) for isolate analog and digital signal

Answer: for isolate analog and digital signal

2. What is the function of the WR pin?

a) its active high input used to inform ADC0804 to the end of conversion

b) its active low input used to inform ADC0804 to the end of conversion

c) its active low input used to inform ADC0804 to the start of conversion

d) its active high input used to inform ADC0804 to the start of conversion

Answer: its active low input used to inform ADC0804 to the start of conversion

3. State which of the following statements are false?

a) CLK IN pin used for External Clock Input or Internal Clock with external RC element

b) INTR pin tells about the end of the conversion

c) ADC0804 IC is an 8 bit parallel ADC in the family of the ADC0800 series

d) None of the mentioned

Answer: None of the mentioned

4. While programming the ADC0808/0809 IC what steps are followed?

a) select the analog channel, start the conversion, monitor the conversion, display the digital results

b) select the analog channel, activate the ALE signal (L to H pulse), start the conversion, monitor the conversion, read the digital results

c) select the analog channel, activate the ALE signal (H to L pulse), start the conversion, monitor the conversion, read the digital results

d) select the channel, start the conversion, end the conversion

Answer: select the analog channel, activate the ALE signal (L to H pulse), start the conversion, monitor the conversion, read the digital results

5. In ADC0808/0809 IC which pin is used to select Step Size?

a) Vref

b) Vin

c) Vref/2 & Vin

d) None of the mentioned

Answer: Vref

6. What is the difference between ADC0804 and MAX1112?

a) ADC0804 has 8 bits and MAX1112 has 1 bit for data output

b) ADC0804 is used for adc and dac conversions whereas MAX1112 is used for serial data transmissions

c) ADC0804 has 32 bits and MAX1112 has 3 bit for data output

d) None of the mentioned

Answer: ADC0804 has 8 bits and MAX1112 has 1 bit for data output

7. Which of the following statements are true about DAC0808?

a) parallel digital data to analog data conversion

b) it has current as an output

c) all of the mentioned

d) none of the mentioned

Answer: parallel digital data to analog data conversion

8. 8 input DAC has ________

a) 8 discrete voltage levels

b) 64 discrete voltage levels

c) 124 discrete voltage levels

d) 256 discrete voltage levels

Answer: 256 discrete voltage levels

9. INTR, WR signal is an input/output signal pin?

a) both are output

b) both are input

c) one is input and the other is output

d) none of the mentioned

Answer: one is input and the other is output

10. What is the function of the SCLK pin in MAX1112?

a) It is used to bring data in

b) It is used to bring data out and send in the control byte, one at a time

c) It is used to get output clock

d) It is used to get serial output

Answer: It is used to bring data out and send in the control byte, one at a time


Sensor Interfacing

1. A thermistor is a __________

a) sensor

b) adc

c) transducer

d) micro controller

Answer: transducer

2. 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 corresponds to the Celsius temperature

3. 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

4. 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

5. 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

6. LM35 has how many pins?

a) 2

b) 1

c) 3

d) 4

Answer: 3

7. 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


Interfacing with 8255

1. The 8255 is a ______ chip.

a) Input/Output

b) Analog to Digital

c) Digital to analog

d) None of the mentioned

Answer: Input/Output

2. 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

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

a) 0x02H

b) 0x82H

c) 0x83H

d) 0x03H

Answer: 0x82H

4. 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

5. 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

6. 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

7. 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

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

a) 8

b) 16

c) 24

d) 32

Answer: 24


Interfacing with RTC

1. DS12887 is a ____________

a) Timer IC

b) Serial communication IC

c) RTC IC

d) Motor

Answer: RTC IC

2. DS12887 has _____ amount of RAM.

a) 14 bytes

b) 114 bytes

c) 128 bytes

d) 64 bytes

Answer: 128 bytes

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

a) 9 bytes

b) 114 bytes

c) 128 bytes

d) 14 bytes

Answer: 114 bytes

4. 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

5. 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

6. 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

7. 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

8. Is DS12887 has non-volatile RAM?

a) Yes

b) No

c) Can’t be determined

d) None of the mentioned

Answer: Yes

9. 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

10. 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


Interfacing with Motors

1. What is the principle on which electromagnetic relays operate?

a) electromagnetic induction

b) motor control

c) switching

d) none of the mentioned

Answer: electromagnetic induction

2. What are DPDT relays?

a) Single pole, single throw

b) Single pole, double throw

c) Double pole, double throw

d) None of the mentioned

Answer: Double pole, double throw

3. Why do we need a ULN2803 in driving a relay?

a) for switching a motor

b) for increasing the current

c) for increasing the power

d) for switching the voltage

Answer: for increasing the current

4. Why are solid-state relays advantageous over electromechanical relays?

a) they need zero voltage circuit

b) they need less current to be energised

c) they need less voltage to be energised

d) none of the mentioned

Answer: they need less current to be energised

5. What are optoisolators?

a) it is a driver

b) it is a thing isolated from the entire world

c) it is a device that can be used as an electromagnetic relay without a driver

d) none of the mentioned

Answer: it is a device that can be used as an electromagnetic relay without a driver

6. How can we control the speed of a stepper motor?

a) by controlling its switching rate

b) by controlling its torque

c) by controlling its wave drive 4 step sequence

d) cant be controlled

Answer: by controlling its switching rate

7. Which of the following can be a unit for torque?

a) kg/m2

b) ounce-inch

c) kg-m3

d) g/m

Answer: ounce-inch

8. The RPM rating given for the DC motor is for?

a) no-loaded

b) loaded

c) none of the mentioned

d) all of the mentioned

Answer: no-loaded

9. How can we change the speed of a DC motor using PWM?

a) By changing amplitude of PWM

b) By keeping fixed duty cycle

c) By changing duty cycle of PWM

d) By increasing power of PWM

Answer: By changing duty cycle of PWM

10. How can the direction of the DC motor be changed?

a) by changing the torque

b) by changing the switching speed

c) by changing the polarity of voltages connected to the leads

d) by changing the RPM rating

Answer: by changing the polarity of voltages connected to the leads

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