18
Power
User may check the power status of the main battery by clicking on the power icon. In the
power properties menu, for the
Battery
tab, user may check on the option to
Always show
icon on the taskbar
. Another option that user may check on is to
Show critical battery
Warning
, which means a window will be popped out when the device is low battery.
System Power States
The OS have
4 different power states
that will be the four states of the internal power
manager state machine. The state transition will be linked to system conditions:
a)
User activities
b)
System activities
c)
Application requests
d)
Timers
The four states are:
On
- In this state the device is full active and user can use all the different peripherals,
and by consequence the current consumption is maximum
User Idle
- This state is reach when user is not using the device after a time out, the
power consumption can be reduced by, for example, decreasing the display backlight
intensity and disabling peripherals.
System Idle
- after application inactivity, the power manager switch to this state.
Suspend
- in this state the device is consuming the less power as possible, but the
device cannot be used, the processor clock is decreased (or turned in a suspend state
if supported), the peripherals are usually turned off and the SDRAM is still refreshed.
The transition from On to User Idle and User Idle to Suspend is done after timer’s expiration,
those timers value can be setup through the control panel’s Power applet to customize your
device.
