Engineering Questions with Answers - Multiple Choice Questions

MCQs on Power Control Register

1 - Question

The power control register is
a) used for power saving during idle state
b) used for eventual power off to 8051 chip
c) non-bit addressable register
d) all of the mentioned

View Answer

Answer: d
Explanation: The power control register is used for power saving during idle state of the microcontroller and eventual power off to the microcontroller chip. It has SMOD bit which is used to double the baud rate.




2 - Question

The state of signals in idle mode is
a) ALE is high
b) PSEN is high
c) PSEN(active low) is high
d) ALE and PSEN(active low) are high

View Answer

Answer: d
Explanation: ALE and PSEN(active low) remain high in Idle mode.




3 - Question

To come out of idle mode, the external interrupt that is enabled is
a) SI(serial)
b) INT0
c) INT1
d) All of the mentioned

View Answer

Answer: d
Explanation: To come out of idle mode, any external interrupt that is enabled like SI(Serial), INT0 and INT1.




4 - Question

The microcontroller enters into power down mode when
a) SMOD bit of PCON is set
b) GF1 bit of PCON is set
c) PD bit of PCON is set
d) GF2 bit of PCON is set

View Answer

Answer: c
Explanation: If the PD bit of PCON register is set, it enters power down mode.




5 - Question

The clock signal is disabled to all parts of 8051 in
a) normal mode
b) idle mode
c) power down mode
d) addressing mode

View Answer

Answer: c
Explanation: In power down mode, the clock signal to all parts of 8051 chip is disabled.




6 - Question

During power down to save battery, the supply voltage can be reduced to a value of
a) 4 volts
b) 2 volts
c) 8 volts
d) 1 volt

View Answer

Answer: b
Explanation: The supply voltage can be reduced to a value of around 2 volts, during power down to save battery.




7 - Question

The signal that only pulls the microcontroller(8051) out of the power down mode is
a) CLEAR
b) LEAVE
c) RESET
d) EXIT

View Answer

Answer: c
Explanation: Only Reset signal can pull 8051 out of the power down mode.




8 - Question

The state of signals in power down mode is
a) ALE is high
b) PSEN is low
c) ALE and PSEN(active low) are high
d) ALE and PSEN(active low) are low

View Answer

Answer: d
Explanation: ALE and PSEN(active low) remain low in power down mode of 8051.




9 - Question

In power down mode,
a) Port pins maintain their logic levels
b) SFRs maintain their logic levels
c) Clock signal is disabled
d) All of the mentioned

View Answer

Answer: d
Explanation: In power down mode, the clock signal is disabled and all the port pins and respective SFRs maintain their logic levels.




10 - Question

The SMOD bit is used to
a) decrease the baud rate by 2
b) increase the baud rate by 4
c) increase the baud rate by 2
d) triple the baud rate

View Answer

Answer: c
Explanation: The SMOD bit is used to double the baud rate.

Get weekly updates about new MCQs and other posts by joining 18000+ community of active learners