Using P/Invoke, you can disable the suspend mode in a Compact Framework smart device application.

Use this native import :

[C#]

[DllImport("coredll.dll")]
internal extern static void SystemIdleTimerReset();

More informations on this method are available here : http://msdn.microsoft.com/library/en-us/wceui40/html/cerefSystemIdleTimerReset.asp?frame=true

This native method reset the internal timer that detect the idle timeout.

You can use the following code the create a Power class that help you to manager the suspend enabling and disabling.

[C#]

using System;
using System.Runtime.InteropServices;
using System.Threading;

/// <summary>
/// Power manage the ability of the device to go into suspend mode
/// </summary>
public sealed class Power
{
 private Power() { }

 private static int _suspendedRequestNumber; // Runtome default = 0;

 /// <summary>
 /// Gets the number of suspended request. If the result is 0, the device can sleep.
 /// </summary>
 /// <value>The suspended request number.</value>
 public static int SuspendedRequestNumber
 {
  get { return Power._suspendedRequestNumber; }
 }

 /// <summary>
 /// DisableSuspend() method set the device not to go into suspend mode. Call
 /// EnableSuspend to reverse
 /// </summary>
 public static void DisableSuspend()
 {
  if (_suspendedRequestNumber++ == 0)
  {

            ThreadStart ts = new ThreadStart(
                Loop
                );

            Thread t = new Thread(ts);
            t.Start();
  }
 }

  
 /// <summary>
 /// EnableSuspend method enable the device to go into suspend mode.
 /// </summary>
 public static void EnableSuspend()
 {
  EnableSuspend(false);
 }

 /// <summary>
 /// EnableSuspend method allow the device to go into suspend mode.
 /// </summary>
 /// <param name="reenableAllSuspendRequests">if set to <c>true</c> reenable all suspend requests.</param>
 public static void EnableSuspend(bool reenableAllSuspendRequests)
 {
  if (reenableAllSuspendRequests)
  {
   _suspendedRequestNumber = 0;
  }
  else if(_suspendedRequestNumber == 0)
  {
   _suspendedRequestNumber--;
  }
 }

 private static void Loop()
 {
  while(_suspendedRequestNumber > 0)
  {
   NativeMethods.SystemIdleTimerReset();
   System.Threading.Thread.Sleep(
    20 * 1000
    );
  }
 }
}

/// <summary>
/// Provides native methods
/// </summary>
internal sealed class NativeMethods
{
 [DllImport("coredll.dll")]
 internal extern static void SystemIdleTimerReset();

}

This class use a second thread to periodically reset the idle timer. the _suspendedRequestNumber hold the number of calls to the DisableSuspend in order to allow multiple threads to query the DisableSuspend and EnableSuspend without conflicting each others.