//-------------------------------------------------------------------
//
// This routine checks the main power once per second and puts 
// system to sleep if main power has been removed.
//
// "Critical systems" are application-specific hardware or data that 
// must be prepared for turning off external power.  These functions 
// are optional.
//
// Note that serial and Ethernet port drivers will re-initialize 
// themselves upon wakeup, so you don't need to do anything special 
// with them.  However, if you have to reinitialize (or de-initialize) 
// the devices on the other end of the serial port, the 
// "CriticalSystems" functions are the place to do it (if the hardware 
// been powered off, it may have have forgotten how you configured it).
//
// As long as backup power is not interrupted while the system is
// asleep, data will be intact and the application will resume 
// running where it left off when the system reawakens.
//
//-------------------------------------------------------------------
void PowerManagementThread()
{
  while (TRUE)
  {
    if (MainPowerOk())
      Sleep (1000);  // check main power once every second
    else
    {
      ShutDownCriticalSystems();  
      Sleep(250);  // make sure everything has settled (optional)

//      PutSystemToSleepForTime(60);  // sleep for sixty seconds, then check power again
      PutSystemToSleep();  // sleep until awakened with the RqOnOff signal
      Sleep(250);  // system goes to sleep somewhere during this time

      // system is awake now; check main power immediatly
      if (MainPowerOk())
        RestartCriticalSystems();
    }
  }
}

//-------------------------------------------------------------------
// This routine reads an A/D input connected to the power input and
// determines if the main power is still valid.  Assumes that the 
// power input is connected to the A/D input through a 1/11 voltage 
// divider (e.g. 100k and 10k resistors).
//-------------------------------------------------------------------
BOOl MainPowerOk()
{
  UINT reading;
  float voltage, minVoltage=8.0, vRef=2.5, multiplier=11.0;

  reading = SIOAnalogConversion(1);  // assumes channel 0 (PA0) connected to DCIN_Pos
  voltage = reading/1023 * Vref * multiplier;

  if (voltage > minVoltage)
    return TRUE
  else
    return FALSE;

}


//-------------------------------------------------------------------
// Puts system to sleep.  System must be awakened manually (RqOnOff)
//-------------------------------------------------------------------
void PutSystemToSleep()
{
  keybd_event(VK_OFF,0,0,0);  // simulate pressing the "power off" key
}


//-------------------------------------------------------------------
// Puts system to sleep.  Wakes after sleepDur seconds (minimum 
// is 15 seconds)
//-------------------------------------------------------------------
void PutSystemToSleepForTime(int sleepDur);
{
  // see topic.asp?TOPIC_ID=649 for
  // an example of how to wake at regular intervals
}