Test: Power Control Register - Computer Science Engineering (CSE) MCQ

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.

ALE and PSEN(active low) remain high in Idle mode.

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

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

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

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

Only Reset signal can pull 8051 out of the power down mode.

ALE and PSEN(active low) remain low in power down mode of 8051.

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

The SMOD bit is used to double the baud rate.