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Example System Power States

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The following registry settings show a sample system power state to device power state mapping.

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\On]
    "Default"=dword:0           ; D0
    "Flags"=dword:10000         ; POWER_STATE_ON
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\UserIdle]
    "Default"=dword:1           ; D1
    "Flags"=dword:0
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\SystemIdle]
    "Default"=dword:2           ; D2
    "Flags"=dword:0
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\Suspend]
    "Default"=dword:3           ; D3
    "Flags"=dword:200000        ; POWER_STATE_SUSPEND
; @CESYSGEN IF CE_MODULES_NDIS
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\Suspend\{98C5250D-C29A-4985-AE5F-AFE5367E5006}]
    "Default"=dword:4           ; D4
; @CESYSGEN ENDIF CE_MODULES_NDIS

This following table shows the system power state and the device power state mapping according to the previous registry example.

System power state Device power state
On D0
UserIdle D1
SystemIdle D2
Suspend D3, except for NDIS miniports, which are set to D4

When the system enters the Suspend state using this sample configuration, all possible wake sources are enabled with the exception of NDIS miniports. If a device does not support D3, it should automatically enter D4 instead.

Applications can create device power requirements by using SetPowerRequirement. You can create additional device power requirements by using Power Manager Control Panel application.

See Also

System Power States

 Last updated on Tuesday, May 18, 2004

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