Default Registry Settings for System Power States (Compact 2013)
3/26/2014
The registry keys for the default system power states are defined in the following location:
%_WINCEROOT%\Public\Common\Oak\Files\Common.reg
For example, the SystemIdle system power state is defined with the following registry key:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\SystemIdle]
"Default"=dword:2 ; D2
"Flags"=dword:0
In the SystemIdle state, the user is not using the system, but system programs may still be running on the user's behalf. Therefore, Power Manager places devices in device power state D2 (Standby) when it transitions the system to SystemIdle, as shown in the preceding example. However, some devices that aren't actively in use can be powered on. For this reason, the next registry entry explicitly turns the display off during SystemIdle:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\SystemIdle\{EB91C7C9-8BF6-4a2d-9AB8-69724EED97D1}]
"Default"=dword:4 ; D4
The GUID {EB91C7C9-8BF6-4a2d-9AB8-69724EED97D1} represents the class of all power-manageable display devices. Because of this setting in Common.reg, the display device enters the device power state D4 (Off) when Power Manager transitions the system to SystemIdle state. All other devices in the system remain in the device power state D2 (Standby).
You can override the settings in Common.reg by redefining them in your Platform.reg file. For example, you can include the following registry setting in your Platform.reg file:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\SystemIdle\{EB91C7C9-8BF6-4a2d-9AB8-69724EED97D1}]
"Default"=dword:2 ; D2
This setting overrides the default setting for SystemIdle state so that Power Manager leaves the display in device power state D2 (Standby) rather than transitioning it to D4 (Off).