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Interview MCQ Set 1

1. What actually are the DB9, DB25 ports available in our computers?
a) they are connectors used to transfer data either serially or parallelly
b) they are the RS232 connectors used to connect two incompatible devices
c) they are the TTL logic connector pins used for communication
d) they are just data transfer pins used to transfer the data

View Answer

Answer: b [Reason:] DB9 and the DB25 ports are the ports that are based on the RS232 logic that are basically used for communicating two incompatible devices.

2. What does RI handshaking signal refer to according to the RS232 logic?
a) if this logic is high then an receive interrupt is generated
b) this pin is high during transmission
c) this pin is high during reception in order to tell that the device is busy at this particular time
d) none of the mentioned

View Answer

Answer: c [Reason:] RI pin of the RS232 logic tells us about the ring indicator i.e it sends a busy signal if the device is currently receiving any data.

3. What is the major difference between a MAX232 and a MAX233 device?
a) one has one serial port other has two
b) one has inbuilt UART other doesn’t have that
c) one needs some additional circuitry to operate while the other doesn’t have that
d) one is used just for transmission while the other is used for both transmission as well as reception

View Answer

Answer: c [Reason:] MAX232 needs some extra capacitors at pins like 1,2 and 3,4 while on the other hand MAX233 has that inbuilt capacitors built inside it only.

4. Which of the following is correct about the baud rate during serial transmission?
a) it tells us about the speed at which the transmission is going to place
b) it tells us about the number of bits transferred during a second
c) none of the mentioned
d) all of the mentioned

View Answer

Answer: d [Reason:] Baud Rate tells us about the speed in which the transmission is being done and this speed is measured in terms of bits per second.

5. With fosc= 8 MHz, what will the count that has to filled in the UBRR register to account for the 9600 baud rate?
a) 67H
b) CEH
c) 33H
d) 34H

View Answer

Answer: c [Reason:] The count that had to be filled in the UBRR register is calculated as (fosc/16(desired baud rate))-1.

6. The USART in AVR based micro controllers operate at which of the following modes?
a) double speed asynchronous mode
b) master synchronous
c) slave synchronous
d) all of the mentioned

View Answer

Answer: d [Reason:] The USART in AVR consists of the following modes. They are the normal asynchronous mode, double speed asynchronous mode, slave synchronous and the master synchronous mode.

7. Which bit of the UCSRA is used for doubling the baud rate of the transmission?
a) DOR
b) PE
c) U2X
d) MPCM

View Answer

Answer: c [Reason:] U2X bit of the UCSRA is used for doubling the baud rate of the transmission.

8. What is the use of the PE and the FE bits of the UCSRA register?
a) they are used for keeping a check at the speed of transmission and reception
b) they are used for keeping a check at the data bits to be transferred
c) they are used to keep the transmission error free
d) they are used as extra redundant bits with no use

View Answer

Answer: c [Reason:] PE and the FE bits of the UCSRA register are used for error checking in the transmission.

9. Which of the following bits are used for setting the data frame size?
a) UCSZ0
b) U2X
c) DOR
d) MPCM

View Answer

Answer: a [Reason:] UCSZ0 and UCSZ1 bits of the UCSRB register and the UCSZ2 bit of the UCSRC register are used for setting the data frame size in AVR based micro controllers.

10. Which of the following parameters should the transmitter and the receiver agree upon before starting a serial transmission?
a) baud rate
b) frame size
c) stop bit
d) all of the mentioned

View Answer

Answer: d [Reason:] Before starting the serial transmission, the following parameters should be taken care of. They are the baud rate, frame size, stop bit and the parity bit.

Interview MCQ Set 2

1. Why are relays used for driving the motors?
a) they act as a switch for driving motors
b) they increase the current capability required by the motors
c) they are used to reduce the back emf from the motors
d) all of the mentioned

View Answer

Answer: a [Reason:] Relays are used as a switch used for driving motors. One such type of relay is the electromagnetic relay, it has three main components the coil, spring and the contacts so when magnetic field is applied to it, then contacts may change from the normal open to the normal close condition or vice-versa.

2. Why are ULN2803 normally used between the micro controllers and the relays?
a) for switching purposes
b) for increasing the current capability required by a relay
c) for increasing the voltage capability required by a relay
d) all of the mentioned

View Answer

Answer: b [Reason:] More current is desired for driving a motor with the help of a relay, so a ULN2803 is used for increasing the current as per the requirement of the relay.

3. Why are opto isolators normally used between the micro controllers and the ULN2803?
a) to optimise the current
b) to reduce the back emf
c) to increase the current
d) to increase the voltage

View Answer

Answer: b [Reason:] Opto isolators are used between the micro controllers and the ULN2803 chips in order to decrease the back emf from the ULN2803 and to save the micro controllers for a long time.

4. Which of the following is a type of a electromagnetic relay?
a) SPST
b) SPDT
c) DPDT
d) All of the mentioned

View Answer

Answer: d [Reason:] Their are normally three kinds of electromagnetic relays. They are SPST(single pole single throw), SPDT(single pole double throw) and the DPDT(double pole double throw) relays.

5. Reed switches show connectivity whenever they are in the presence of an electrical field?
a) true
b) false
c) can’t say
d) depends on the conditions

View Answer

Answer: b [Reason:] Reed switches are the devices that show connectivity whenever they are in the presence of some magnetic field.

6. Which of the following is an application of stepper motors?
a) in printers
b) in robots
c) in vehicles
d) all of the mentioned

View Answer

Answer: d [Reason:] Stepper motors are used wherever their is a need of a movement at an angle, may be it in printers, in motors or in vehicles stepper motors are used everywhere.

7. What are normal 4 step sequence of a stepper motor if we start to move in clockwise direction with 0110 value?
a) 1100,1001,0011,0110
b) 0011,1001,1100,0110
c) 1001,1100,0110,0011
d) 0101,1010,0101,1010

View Answer

Answer: b [Reason:] For a normal 4 step sequence of a stepper motor, if we start to move in a clockwise direction then we rotate towards right direction with every rotation.

8. What is the meaning of a step angle?
a) angle which a stepper motor has
b) angle between the two windings of the stator in a stepper motor
c) minimum degree of rotation associated with a step angle
d) angle between the stator and the rotor

View Answer

Answer: c [Reason:] Step angle is the minimum degree of rotation associated with a step angle.

9. For a normal 4 step sequence, what are number of teeth required to accomplish a 2 degree step angle?
a) 180
b) 90
c) 360
d) 45

View Answer

Answer: d [Reason:] For a 2 degree step angle there will be 180 step per rotation, so the total number of rotor teeth are (180/4=45).

10. Ounch-inch is a unit of a torque.
a) true
b) false
c) can’t say
d) depends on the situation

View Answer

Answer: a [Reason:] Torque is a quantity which is obtained by multiplying the amount of force that is applied at a particular angle. It is measured in terms of ounch-inch.

Interview MCQ Set 3

1. What is the function of 8255 chip?
a) the ports of 8255 can act as the input/ output port for the micro controller
b) it is a type of an external memory device that is being interfaced with the micro controller
c) both of the mentioned
d) none of the mentioned

View Answer

Answer: c [Reason:] 8255 is an IC that is used to increase the number of input/output ports of a micro controller. As the chips ports act as the ports for interfacing external devices.

2. Which pins of a micro controller are directly connected with 8255?
a) RD
b) WR
c) D0-D7
d) All of the mentioned

View Answer

Answer: d [Reason:] RD, WR, D0-D7 all are directly connected to the 8051 for telling the chip about the control signals and also for transferring the data.

3. Find the control word for PA= out, PB= in, PCL=out, PCH=out (Mode0)?
a) 0xF0H
b) 0xF2H
c) 0xF4H
d) 0xFFH

View Answer

Answer: b [Reason:] The value that is being loaded in the control word is 10000010b for PB as an input port ans all others as the output ports being operated in mode0.

4. Which pins are used to select the ports and the control register?
a) CS
b) A1
b) A0
d) All of the mentioned

View Answer

Answer: d [Reason:] CS, A0, A1 all are used to select the ports and the control register of 8255.

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 as was before the RESET button was set to zero

View Answer

Answer: d [Reason:] RESET button makes the value of the control register clear if an active high pulse is applied to it. So for clearing the control register RESET button should be set to 1.

6. Why MOVX instruction is being used to access the ports of the 8255?
a) because 8255 is used to access the memory mapped I/O
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.

View Answer

Answer: a [Reason:] MOVX instruction is used to access the external memory, so it is used to access the memory mapped I/O.

7. What is correct about the BSR mode from below?
a) it is active low input used to select the individual bits of the PORTA
b) it is active low input used to select the individual bits of the PORTB
c) it is active low input used to select the individual bits of the PORTC
d) none of the mentioned

View Answer

Answer: c [Reason:] BSR is used to select the individual bits of the PORTC. It is the D7 bit of the control register.

8. How many pins of the 8255 can be used as the I/O ports?
a) 8
b) 16
c) 24
d) 32

View Answer

Answer: c [Reason:] Their are 3 ports available in the 8255 so 24 pins are available for the I/O ports pins.

9. 8255 is a ____ pin IC.
a) 16
b) 8
c) 40
d) 60

View Answer

Answer: c [Reason:] 8255 is a 4 pin IC.

10. 8255 has handshaking capability?
a) yes
b) no
c) cant be said
d) depends on the conditions

View Answer

Answer: a [Reason:] 8255 is a device that with the help of its handshaking property gets interfaced with any micrcontroller.

11. The 8255 can be programmed in any of the
a) 2 modes
b) 3 modes
c) 4 modes
d) 5 modes

View Answer

Answer: c [Reason:] 8255 can be programmed in any of the 4 modes.

Interview MCQ Set 4

1. RTC is used for
a) conversion
b) communication
c) real time and clock measurement
d) memory management

View Answer

Answer: c [Reason:] RTC is a device that is basically used for all the real time clock related issues.

2. RTC chips use______to compute time, date when the power is off.
a) ac supply
b) generators
c) rectifiers
d) battery

View Answer

Answer: d [Reason:] RTC chips require batteries in order to calculate the time and date when the power of the device is off.

3. DS12887 is known for as a
a) Communication device
b) Good battery device
c) RTC chip
d) All of the mentioned

View Answer

Answer: c [Reason:] DS12887 is known as an RTC chip.

4. DS1307 is a parallel RTC with I2C bus.
a) true
b) false
c) cant be said
d) depends on the conditions

View Answer

Answer: b [Reason:] DS1307 is a serial RTC with I2C bus.

5. DS1307 is a _______ pin IC and operates on_______ clock frequency.
a) 16, 8Mhz
b) 8, 16Mhz
c) 16, 32Mhz
d) 8, 32Mhz

View Answer

Answer: d [Reason:] DS1307 is a 8 pin IC and operates on a 32KHz clock frequency.

6. Vbat requires a positive signal of
a) 3V
b) 5V
c) 9V
d) 12V

View Answer

Answer: a [Reason:] Vbat requires a positive signal of 3V which can be obtained through a battery.

7. SQW(pin no 7) is an
a) input pin
b) output pin
c) i/o pin
d) none of the mentioned

View Answer

Answer:b [Reason:] SQW(pin no 7) is an output pin.It provides a clock of frequency 1khz, 4khz, 8khz, 32khz if the pin is enabled.

8. DS1307 has a total of _______ bytes of RAM space?
a) 32
b) 64
c) 128
d) 256

View Answer

Answer: b [Reason:] DS1307 has a total of 64 bytes(00-3F) of RAM space.

9. DS1307 control register has an address of
a) 00H
b) 03H
c) 07H
d) 10H

View Answer

Answer: c [Reason:] DS1307 control register has an address of 07H.

10. What does the CH bit of the DS1307 demonstrate?
a) clock high
b) clock halt
c) clear high
d) clear halt

View Answer

Answer: b [Reason:] CH bit means clock halt bit. If it is set to 1, then the oscillator gets disabled and vice versa.

Interview MCQ Set 5

1. Which of the following is correct about the word resolution in ADC DAC converters in AVR’s?
a) it is the smallest change that can be described by an ADC
b) it is equal to Vref/2^n (where n represents the number of bits)
c) it is 0.076 for n=16 and Vref=5V
d) all of the mentioned

View Answer

Answer: d [Reason:] Resolution is defined as the smallest change in the step size that be described by an ADC, it is equal to Vref/2^n.

2. In an ADC, we can calculate the output voltage from the formula
a) Step size / Vin
b) Step size * Vin
c) Vin / step size
d) Vref / step size

View Answer

Answer: c [Reason:] The output voltage can be calculated by using the formula Vin / step size.

3. ADC0848 is a ____________ bit converter?
a) 16
b) 4
c) 8
d) 48

View Answer

Answer: c [Reason:] ADC0848 is a 8 bit converter.

4. Which of the following factors can affect the step size calculation?
a) number of bits
b) input current
c) output current
d) all of the mentioned

View Answer

Answer: Their are mainly two factors that can affect the step size calculation of an ADC converter, they are the number of bits and the Vref voltage.

5. MAX1112 is a _________ type of ADC converter?
a) parallel
b) 12 bit
c) serial
d) all of the mentioned

View Answer

Answer: c [Reason:] MAX1112 is a serial ADC converter, as it has only one pin for the data output.

6. Why do we connect a capacitor between the Vref and the Gnd pin?
a) to remove the leakage
b) to ensure more current at that place
c) to make more Vref
d) to make Vref stable and also to increase the precision of the ADC

View Answer

Answer: d [Reason:] A capacitor is connected between the Vref and the Gnd pin in order to stabalize the Vref value and also to increase the precision of the ADc converter.

7. Which of the following are the registers that are used for controlling the ADC conversion in the AVR?
a) ADCSRA
b) ADMUX
c) SPIOR
d) All of the mentioned

View Answer

Answer: d [Reason:] For programming the ADC conversion in an AVR, we require the following registers. They are ADCSRA, ADMUX, SPIOR. Their are two more registers used for handling the oytput data, they are ADCH and ADCL registers.

8. What is the internal Vref of an Atmega32 series?
a) 5V
b) 3.3V
c) 2.56V
d) all of the mentioned

View Answer

Answer: c [Reason:] 2.56V is the internal Vref selected for an Atmega32 series based micro controllers.

9. The output of a DAC0808 is in form of
a) electrical pulse
b) current
c) voltage
d) all of the mentioned

View Answer

Answer: b [Reason:] The output of a DAC0808 is in the form of a current.

10. In a DAC the input is ______ and the output is ______
a) analog, digital
b) current, voltage
c) digital, analog
d) analog, current

View Answer

Answer: c [Reason:] In a DAC, the input is digital and the output is analog in nature.