Power States

Describes three power states that are defined by the kernel.

• Off - a state where the device and all peripherals are powered off or inactive, or are characterised by negligible power consumption due to current leakage to the electric and electronic circuits that make up the system. This state is achieved as a result of controlled system shutdown resulting from a user action, an application request, UI inactivity, or as a result of accidental loss of power. This may also be achieved as a result of putting the system into a hibernation state. Note that a reboot is necessary to return the system to the Active state; this could be a cold reboot, or a warm reboot if the system was put into a hibernation state.

• Standby - a low power consuming state that results from turning off most system resources (clocks, voltages), peripherals, memory banks (where possible), cpu and internal logic, while still retaining the state prior to the transition. Typically, the only systems that are active are those that are required to detect the events that force the transition back to the Active state (e.g. RTC, clocks and Peripherals involved in detecting hardware events). Returning to the Active state will normally take a far shorter period of time than that required to reboot the system. This state is achieved as a result of user action or application request.

• Active - the fully active state.

The three power states are defined by the enum values of the TPowerState enum defined in e32power.h.