@msdn=http://search.microsoft.com/search/results.aspx?qu=$$$ @pinvoke=http://pinvoke.net/$$$.htm Summary: This function resets a system timer that controls whether or not the device will automatically go into a suspended state. !!!!C# Signature: [DllImport("coredll.dll")] static extern void SystemIdleTimerReset(); !!!!VB Signature: Declare Sub SystemTimerReset Lib "coredll.dll" Alias "SystemIdleTimerReset" () !!!!User-Defined Types: None. !!!!Alternative Managed API: None. !!!!Notes: To keep a device awake indefinitely, you can use SystemParametersInfo() (also in CoreDll) to query the three idle timeouts SPI_GETBATTERYIDLETIMEOUT, SPI_GETEXTERNALIDLETIMEOUT, and SPI_GETWAKEUPIDLETIMEOUT. Ignoring any values that are zero, use the minimum of these three values as your N, set a recurring timer to fire *more* often than every N seconds, and call SystemIdleTimerReset() every time it fires. When you're done with your critical operation, kill the timer, and the device will be able to sleep again. I tried this from C# and each idle-timeout value was 0, so I just called SystemIdleTimerReset() every 30 seconds during the critical operation. You can also look at the configured timeouts at the registry key "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power". !!!!Tips & Tricks: Please add some! !!!!Sample Code: /// <summary> /// This function resets a system timer that controls whether or not the /// device will automatically go into a suspended state. /// </summary> [DllImport("CoreDll.dll")] public static extern void SystemIdleTimerReset(); private static int nDisableSleepCalls = 0; private static System.Threading.Timer preventSleepTimer = null; public static void DisableDeviceSleep() { nDisableSleepCalls++; if (nDisableSleepCalls == 1) { Debug.Assert(preventSleepTimer == null); // start a 30-second periodic timer preventSleepTimer = new System.Threading.Timer(new TimerCallback(PokeDeviceToKeepAwake), null, 0, 30 * 1000); } } public static void EnableDeviceSleep() { nDisableSleepCalls--; if (nDisableSleepCalls == 0) { Debug.Assert(preventSleepTimer != null); if (preventSleepTimer != null) { preventSleepTimer.Dispose(); preventSleepTimer = null; } } } private static void PokeDeviceToKeepAwake(object extra) { try { SystemIdleTimerReset(); } catch (Exception e) { // TODO } } Documentation: SystemIdleTimerReset@msdn on MSDN
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