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5.4 Power management
Power management refers to controlling the use of power stored in the device’s battery. The aim is to extend
the runtime of the battery. This is done in numerous ways:
•
Monitoring the battery status (see previous chapter)
•
Using power in energy-saving mode when possible
•
Activating the suspend mode when the device is not used for longer periods
The power-saving mode includes dimming or switching off the backlight display (see Chapter 5.5).
The suspend mode freezes the operating status of the processor and memory. This means that the device
only requires a fraction of energy when it is not being used. Online connections etc. are disconnected when
the suspend mode is triggered. The acddev power management sends messages to all applications notifying
them that the device will soon enter suspend mode (see also acddev header file power.h).
Suspend can be either time-controlled to switch on after a defined number of seconds has elapsed or can be
triggered manually. The suspend behaviour can be set separately for battery operation and for the external
power supply.
Set the time to elapse before suspend is entered in the Registry at
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Power\Timeouts]
in the ACSuspend or BattSuspend parameters. This differentiates between the suspend behaviour in AC
power supply and battery operation. The [AC|Batt]SystemIdle and [AC|Batt]UserIdle parameters are
added to the suspend parameters, they may not be 0.
5.5 Display and backlight
The display backlight consumes a lot of power. One significant way of reducing power consumption is
therefore to switch off or dim the backlight when not in use. These parameters can be set in the dev.ini file.
Section [display]
Definition
BacklightNormal
Intensity of backlight in normal operation
(0 – 10)
BacklightReduced
Intensity of backlight in reduced power-saving operation
(0 – 10)
BattBacklightReducedTime
Time (s) from the last touch/keyboard action until the power-
saving mode is activated in battery operation (0 disabled)
BattBacklightOffTime
Time (s) from the activation of power-saving mode until the
backlight is switched off in battery operation
ACBacklightReducedTime
As above, but for operation with AC supply
ACBacklightOffTime
As above, but for operation with AC supply
Table 5 – dev.ini backlight
These parameters can be modified with API (acddev header file display.h). The parameters persist and are
entered into the dev.ini file when the
ACD_SetAsDefaultBacklightParams()
function is called.