Power Saving Mode in 8051

There are two types of power saving modes in 8051 which are Idle mode Power down mode.

There is a SFR ( Click here to read what is SFR and types of SFRs present in 8051 ) for power control mode in 8051. Only two bits in the register are related to power saving mode in 8051 ( PD, IDL )

PD	IDL	Status
0	0	Normal Power mode
0	1	Idle mode
1	0	Power down mode
1	1	Power down mode

Whenever the processor restarts by default it is in normal mode. The figure below depicts the PCON ( power control ) register. 

IDLE MODE:

In this mode the clock is cut from the processor only, other parts of the microcontroller such as timers…. . In this mode 80% of power is saved. The 20% power is used to get the microcontroller from idle mode to normal mode. 

To Get out from idle mode:

1. By interrupt
   This is similar to sleep mode in computers , when the keyboard key is pressed or the mouse is moved. In this way recent data is restored.
2. Restart
   In this method, the system is restarted, and the previous data is lost.

POWER DOWN MODE:

In this mode, clock supply is cut from the whole system. In this power saving mode maximum amount of power is saved. 

To Get out from idle mode:

1. Restart
   In this method, the system is restarted, and the previous data is lost. 

Idle mode is equivalent to sleep mode and power down mode is equivalent to hibernate in this generation of computers.

This is all about the power saving mode of 8051. For more information about 8051 visit the section of 8051.

To access complete series of articles about 8051 microcontroller , click here.