Category: Microcontroller Objective Questions

8051 Micro-controller Multiple Choice Questions on “Interfacing with RTC”.

1. DS12887 is a ____________
a) Timer IC
b) Serial communication IC
c) RTC IC
d) Motor

Answer: c
Clarification: DS12887 is a real time clock that is widely used to provide accurate time and date for many applications.

2. DS12887 has _____ amount of RAM.
a) 14 bytes
b) 114 bytes
c) 128 bytes
d) 64 bytes

Answer: c
Clarification: DS12887 has 128 bytes of non-volatile RAM.

3. DS12887 has _____ amount of RAM for general purpose applications.
a) 9 bytes
b) 114 bytes
c) 128 bytes
d) 14 bytes

Answer: b
Clarification: DS12887 has 128 bytes of non-volatile RAM. Out of 128 bytes, 14 bytes of RAM for clock/calendar and control registers, and another 114 bytes of RAM for general purpose data storage.

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: d
Clarification: In DS12887, D4-D6 bits of register A are used to turn on the oscillator. A specific value of 010 of D4-D6 is desirable for turning on the oscillator.

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: d
Clarification: In DS12887, SQW pin stands for SQuare Wave. It is an output pin that can provide us with 15 different square waves. The frequency of the square wave is selected by programming register A.

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: a
Clarification: In DS12887, UIP bit of register A stands for Update In Progress. The update-in-progress (UIP) bit is a status flag i.e. 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: b
Clarification: In DS12887, the first ten locations i.e. 00-09H are used to store the values of time, calendar and alarm data.

8. Is DS12887 has non-volatile RAM?
a) Yes
b) No
c) Can’t be determined
d) None of the mentioned

Answer: a
Clarification: Yes, DS12887 has non-volatile RAM.

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: c
Clarification: Register C and D are the read only registers in the DS12887 found at memory locations 0C-0DH.

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: a
Clarification: When Vcc falls below 3V or external voltage source is switched-off, internal lithium battery provides power to DS12887. And this will prevent loss of data.

AVR Micro-controller Multiple Choice Questions on “SPI Protocol”.

1. Why do we make the connection of the SCLK for communicating serially between two devices?
a) to get a clock output from the device
b) to synchronize the two devices
c) to obtain an analog output
d) all of the mentioned

Answer:b
Clarification: We need an SCLK in order for the two devices to communicate with each other properly. It acts as a pulse according to which one device sends a message and the other receives it.

2. What is the function of the CE pin in SPI?
a) it is used for synchronization
b) it is used as a transmitting pin
c) it is used as a receiving pin
d) it is used to initiate and terminate the data transfer

Answer: d
Clarification: CE pin is used to initiate and terminate the data transfer in the controller via SPI interface.

3. Which of the following is correct?
a) MOSI has the same meaning as the SDO
b) SCLK is used to initiate and terminate the data transfer
c) In 3 wire SPI, there is only one pin for transmission and reception
d) In 3 wire SPI, there are three pins MOSI, MISO and SCLK

Answer: c
Clarification: In 3 wire SPI, there is only one pin for transmission and reception and the other two pins SCLK and CE are used for synchronization of data and for initialization and termination of data.

4. If CPHA= 0 and CPOL=1, then which of the following is true?
a) read on rising edge, changed on a falling edge
b) read on falling edge, changed on a rising edge
c) write on rising edge, changed on a falling edge
d) write on rising edge, changed on a falling edge

Answer: b
Clarification: If CPOL= 1 and CPHA= 0, then reading operation is performed on the rising edge and the change occurs at every falling edge.

5. In SPI write, LSB goes first?
a) true
b) false
c) can’t be said
d) depends on the cases

Answer: b
Clarification: In SPI write, MSB goes first.

6. In AVR, which of the following registers are used for SPI?
a) SPSR
b) SPCR
c) SPDR
d) All of the mentioned

Answer: d
Clarification: In AVR, SPSR(SPI Status Register), SPCR(SPI Control Register) and SPDR(SPI Data Register) are used for programming the SPI module.

7. How do we set the SPI, to operate in the master mode 1?
a) We set the MSTR bit, and make the CPOL= 1 and CPHA=0
b) We set the MSTR bit, and make the CPOL= 0 and CPHA=1
c) We reset the MSTR bit, and make the CPOL= 1 and CPHA=0
d) We reset the MSTR bit, and make the CPOL= 0 and CPHA=1

Answer: b
Clarification: In SPI, to make it work in the master mode, we make the MSTR bit is equal to 1 and for operating it in the mode 1 we make the CPOL=0 and CPHA=1.

8. SPI can act as a half duplex transmission?
a) true
b) false
c) depends on the conditions
d) can’t be said

Answer: b
Clarification: No, SPI can’t work in the half duplex transmission mode.

9. Which frequency is not recommended for SPI clock?
a) fosc/4
b) fosc/64
c) fosc/16
d) fosc/2

Answer: d
Clarification: fosc/2 is not recommended frequency for SPI transfer in AVR.

10. To select the value of the clock to be fosc/16, what are the appropriate values?
a) SPI2X= 0, SPR1= 0, SPR0=1
b) SPI2X= 0, SPR1= 1, SPR0=0
c) SPI2X= 1, SPR1= 1, SPR0=0
d) SPI2X= 0, SPR1= 1, SPR0=1

Answer: a
Clarification: For obtaining this very clock frequency of fosc/16, we set the values of SPI2X= 0, SPR1=0 and SPR0=1.

MSP430 Microcontroller Questions and Answers for Campus interviews on “Sigma Delta ADC”.

1. The basic idea behind the sigma delta converter is that
a) to carry out the conversion
b) to carry out communication
c) to reduce the circuit to its simplest way possible and then carry out the conversion
d) all of the mentioned

Answer: c
Clarification: The main idea behind the sigma delta converter is that to reduce the circuit to its simplest way possible and then carry out the conversion.

2. Sigma delta converter is a __________
a) 1 bit converter
b) 2 bit converter
c) 3 bit converter
d) 4 bit converter

Answer: a
Clarification: Sigma delta converter is a 1 bit converter.

3. Sigma delta converter is having good resolution.
a) yes
b) no
c) cant be said
d) depends on the conditions

Answer: b
Clarification: Sigma delta converter is having poor resolution quality.

3. Oversampling ratio is defined as the _________
a) final frequency
b) oversampling frequency
c) oversampling frequency/final frequency
d) final frequency/oversampling frequency

Answer: c
Clarification: Oversampling ratio is defined as the ration of the oversampling frequency fm to the final frequency fs.

4. Here the word sigma represents _________
a) subtraction
b) differentiation
c) integration
d) none of the mentioned

Answer: c
Clarification: In a sigma delta converter, sigma word represents that the output obtained from the delta function is getting integrated.

5. SD16_A features are controlled by _________
a) memory mapped registers
b) register mapped registers
c) data mapped registers
d) none of the mentioned

Answer: a
Clarification: SD16_A features are controlled by the memory mapped registers.

6. The second part of the ADC handles purely digital signals.
a) true
b) false
c) cant be said
d) depends on the conditions

Answer: a
Clarification: The second part of the ADC handles purely digital signals.

7. The second part of the ADC’s output is in the form of _________
a) the fast stream of single bits
b) the fast stream of multiple bits
c) the slow stream of single bits
d) the slow stream of multiple bits

Answer: d
Clarification: The second part of the ADC take in fast stream of single bit and give out a slow stream of multiple bit values.

8. The filtered digital signal is then decimated to
a) reduce the rate of samples from fm to fs
b) reduce the rate of samples from fs to fm
c) increase the rate of samples from fm to fs
d) increase the rate of samples from fs to fm

Answer: a
Clarification: The filtered digital output is then decimated in order to reduce the rate of samples from fm to fs.

9. Decimated means _________
a) multipled by 10
b) multiplied by 100
c) divided by 10
d) divided by 100

Answer: c
Clarification: Decimated means to divide the result by 10.

10. The SD16 has a second-order modulator with a _________
a) sinc filter
b) sinc² filter
c) sinc³ fiter
d) rect filter

Answer: c
Clarification: The SD16 has a second-order modulator with a sinc³ filter.