Category: Microcontroller Objective Questions

8051 Micro-controller Multiple Choice Questions on “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: d
Clarification: 16*2 alphanumeric LCD has 2 rows and 16 columns.

2. How many data lines are there in a 16*2 alphanumeric LCD?
a) 16
b) 8
c) 1
d) 0

Answer: b
Clarification: There are eight data lines from pin no 7 to pin no 14 in an LCD.

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: c
Clarification: Pin no 3 is used for controlling the contrast of the LCD.

4. For writing commands on an LCD, RS bit is
a) set
b) reset
c) set & reset
d) none of the mentioned

Answer: b
Clarification: For writing commands on an LCD, RS pin is 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: a
Clarification: 0x1C is used to shift the entire display to the right.

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: d
Clarification: 0x38 is used to select the 2 lines and 5*7 matrix of an LCD.

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: d
Clarification: To send data to an LCD, RS pin should be set so that LCD will come to know that it will receive data which has to display on the screen. R/W pin should be reset as data has to be displayed (i.e. write to the LCD). High to low pulse must be applied to the E pin when data is supplied to data pins of the LCD.

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: c
Clarification: For reading operations, R/W pin should be made high and added to it, a low to high pulse is also generated at the E pin.

9. Which instruction is used to select the first row first column of an LCD?
a) 0x08
b) 0x0c
c) 0x80
d) 0xc0

Answer: c
Clarification: 0x80 is used to select the first row first column of an LCD.

10. The RS pin is _________ for an LCD.
a) input
b) output
c) input & output
d) none of the mentioned

Answer: a
Clarification: The RS pin is an input pin for an LCD.

AVR Microcontroller Questions and Answers for Freshers on “ADC, DAC Interfacing”.

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/2ⁿ (where n represents the number of bits)
c) it is 0.076mV or 76uV for n=16 and Vref=5V
d) all of the mentioned

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

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

Answer: c
Clarification: 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

Answer: c
Clarification: 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

Answer: a
Clarification: There 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

Answer: c
Clarification: 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

Answer: d
Clarification: A capacitor is connected between the Vref and the Gnd pin in order to stabilize 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

Answer: d
Clarification: For programming the ADC conversion in an AVR, we require the following registers. They are ADCSRA, ADMUX, SPIOR. There are two more registers used for handling the output 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

Answer: c
Clarification: 2.56V is the internal Vref selected for an Atmega32 series based microcontrollers.

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

Answer: b
Clarification: 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

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

MSP430 Microcontroller online test on “TIMER_A”.

1. All channels within Timer_A share the same timer block?
a) yes
b) no
c) cant be said
d) depends on the conditions

Answer: a
Clarification: There is only one TAR in Timer_A so all of its channels share the same timer block.

2. Timer_A has _________
a) RTC module in it
b) Compare/ capture channel
c) Communication channel
d) Converter channel

Answer: b
Clarification: Timer_A has compared/ capture channel inbuilt inside it.

3. TACLK and INCLK are _________
a) internally generated clock pulses
b) externally fed clock pulses
c) of no use in Timer_A
d) very slow

Answer: b
Clarification: TACLK and INCLK clock pulses are the externally fed pulses that are required by the Timer_A.

4. In continuous mode of the counter _________
a) counter moves from 0000-ffff
b) counter moves from ffff-0000-ffff
c) counter moves from 0000-ffff and then again returns to 0
d) all of the mentioned

Answer: c
Clarification: In a continuous mode of the counter, the counter firstly increases from 0000-ffff, then after this value the roll over condition comes and it again gets started from 0000. This particular mode is very useful for capturing inputs.

5. TACLR bit in TACTL _________
a) clear the interrupt flag
b) clear the status flags
c) clear the count in TAR
d) all of the mentioned

Answer: c
Clarification: TACLR bit in TACTL clears the count in the TAR.

6. TAxCCTLn is a _________
a) set of 2 bits used for selecting the mode of operation of the timer
b) a register of 8 bits used for giving the count to the timer
c) a register of 16 bits used to select the compare/capture channel of the Timer_Ax
d) a register of 16 bits used to cause the timer interrupt

Answer: c
Clarification: TAxCCTLn is a register of 16 bits used to select the compare/capture channel of the Timer_Ax.

7. CCI1B comes from _________
a) ACLK
b) CAOUT
c) SCLK
d) TACLK

Answer: b
Clarification: CCI1B comes from CAOUT.

8. Which of the following parameters are given by the TAxCCRn?
a) Capture/compare input. The selected input signal can be read by this bit
b) Synchronized capture/compare input. The selected CCI input signal is latched with the EQUx signal and can be read from this bit
c) Holds the data for the comparison to the timer value in the Timer_A Register, TAR
d) None of the mentioned

Answer: c
Clarification: Compare mode: TAxCCRn holds the data for the comparison to the timer value in the Timer_A Register, TAR.
Capture mode: The Timer_A Register, TAR, is copied into the TAxCCRn register when capture is performed.

8051 Micro-controller Multiple Choice Questions on “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: d
Clarification: For detecting that whether the key is actually pressed or not, firstly this must be ensured that initially all the keys are closed. Then we need to mask the bits individually to detect that which key is pressed. Then we need to check that is the key actually pressed or not, by checking that whether the key pressed for a time more than 20 micro seconds.

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: d
Clarification: This particular command CJNE A,#00001111b, ROW1 compares the value of the accumulator with OFH and jumps to ROW1 address 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: d
Clarification: We can mask or we can even rotate the bits to check that particularly in which column is the key placed.

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: b
Clarification: If no key is pressed, then all the keys show 1 as they are all connected to power supply.

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: b
Clarification: If a key is to operate in an interrupt mode then it will generate an external hardware interrupt.

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: b
Clarification: To detect that which key is being pressed, we need to ground the pins one by one.

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: b
Clarification: They are two different works that are involved in Keyboard Interfacing. One is used for checking that which key is being actually pressed and the other is used to check that is the key actually pressed or not.

AVR Micro-controller Multiple Choice Questions on “Sensor Interfacing”.

1. Which of the following is correct about the word sensors?
a) that senses something
b) it is a type of a transducer that converts one form of energy to another
c) it can produce output in the form of electrical pulses, current or voltage
d) all of the mentioned

Answer: d
Clarification: Sensors are the devices that are used to sense a particular thing by converting one form of energy into another, this converted form can be in the form of some analog output, or in the form of current or the voltage as the case may be.

2. Why do we need to apply the concept of signal conditioning to a sensor?
a) in order to convert it into a desirable form of energy
b) for testing
c) for sensing something
d) all of the mentioned

Answer: a
Clarification: Signal Conditioning is the concept that is used for data acquisition of the signal. For measuring and analyzing this value at a practical stage, by converting it into a desirable form of energy.

3. Which of the following is correct about LM35 based sensors?
a) its output voltage is directly proportional to the Celsius scale
b) its output voltage is directly proportional to the Fahrenheit scale
c) none of the mentioned
d) all of the mentioned

Answer: a
Clarification: LM35 based sensors are those sensors whose output voltage is directly proportional to the Celsius scale.

4. What is the difference between the LM34 and the LM35 based sensors?
a) one requires external calibration while other does not
b) one has output voltage proportional to the Celsius scale while others have to the Fahrenheit scale
c) one is fast other is slow
d) all of the mentioned

Answer: b
Clarification: LM35 has the output voltage proportional to the Celsius scale while the LM35 based sensors have output voltage proportional to the Fahrenheit scale.

5. Every transducer must be connected with the signal conditioning circuit?
a) true
b) false
c) can’t say
d) depends on the conditions

Answer: a
Clarification: For analyzing purposes, every transducer must be connected to a signal conditioning circuit in order to measure its value as a practical platform.

6. LM35 provides _______ V for each degree count?
a) 1
b) 0.1
c) 0.001
d) 10

Answer: c
Clarification: LM35 provides 10mV for every degree change of the Celsius scale.

7. Why for the 8 bit analog input we select Vref as the 2.56V?
a) to obtain each degree count as the 2.56V
b) to get 2.56V at the output
c) to obtain each degree count as the 10mV
d) to get 10mV as the output

Answer: c
Clarification: For an 8 bit analog input, each degree count is calculated as the Vref/256, so if Vref is selected as 2.56V then we can obtain 10mV for each degree count of the scale.

8. What is the temperature for LM35 sensor if the analog output is 0011 1001?
a) 3
b) 9
c) 57
d) 41

Answer: c
Clarification: The binary for the above output is 57, so in case of LM35 sensors we obtain the output as 57 C.

9. In an external hardware, there are how many pins available for the LM35 and the LM34 based sensors?
a) 2
b) 3
c) 10
d) 1

Answer: b
Clarification: LM35 consists of mainly 3 pins, they are Vcc, Gnd, analog output.

10. Do LM34 and LM35 based sensors have linear output?
a) yes
b) no
c) depends on the conditions
d) can’t say

Answer: a
Clarification: LM34 and the LM35 based sensors are linearly proportional to their corresponding Fahrenheit and the Celsius scale, so they are linear by nature.

MSP430 Microcontroller online quiz on “TIMER_B”.

1. Why Timer_B is not considered as most suitable one for receiving asynchronous signals?
a) because of the absence of the TBOUTH input pin
b) because of the presence of the TBOUTH input pin
c) because of the absence of the SCCI bit
d) because of the presence of the SCCI bit

Answer: c
Clarification: The SCCI bit is absent in the Timer_B which means that the sampling mode is absent in it that’s why it is considered as unsuitable for receiving asynchronous signals.

2. There is double buffering in the immediate mode?
a) true
b) false
c) cant be said
d) depends on the conditions

Answer: b
Clarification: Immediate mode offers no double buffering condition. As here, values are copied to TBCLn as soon as they are written to TBCCRn.

3. Double buffering protects channel 0.
a) as it acts as the limit in the Up and up/down modes
b) it doesn’t actually protect it
c) as it does not accept the inputs
d) none of the mentioned

Answer: a
Clarification: Double buffering protects channel 0 as it acts as the limit in the Up and Up/Down modes.

4. Timer_B has _________
a) three serial communication ports
b) seven LCD driver
c) seven compare/capture channels
d) three LED driver ports

Answer: c
Clarification: Timer_B has seven compare/capture channels.

5. The capture/compare registers TBCCRn are double-buffered when used for compare events?
a) true
b) false
c) cant be said
d) depends on the conditions

Answer: a
Clarification: The capture/compare registers TBCCRn are double-buffered when used for compare events.

6. The length of TBR can be programmed to be _________
a) 8 bits
b) 12 bits
c) 16 bits
d) all of the mentioned

Answer: d
Clarification: The length of TBR can be programmed to be 8, 12, 16 or 10 bits long.

7. TBOUTH can pin can be used to _________
a) values are moved from one place to another
b) the length of the number of bits is selected by this register
c) it can be used to put all the outputs of the Timer_B register in the high impedance state
d) it can be used for outputting the input values of the timers

Answer: c
Clarification: TBOUTH pin is used to put all the outputs of the Timer_B register in the high impedance state by a high external signal applied to this pin.

8. TBCLn provided in each channel is actually _________
a) a comparator
b) compare latch
c) controller
d) control logic

Answer: b
Clarification: TBCLn is actually a compare latch that is provided in its every channel.

9. When TBR counts to zero?
a) TBCLn is updated from TBCCRn
b) CLLDx is updated to TBCCTLn
c) CLLDx is updated to TBCCRn
d) TBCLn is updated to CLLDx

Answer: a
Clarification: When TBR counts to zero, TBCLn is updated from TBCCRn.