wakeup function

[SRAM.11]

Please some one help me to how to get controller from sleep the configuration I made is not working.The below given code working fine and putting the controller in sleep but controller not waking up.The condition depends on mains (ADC Input channel 5)when it detects a value other than zero in mains voltage my controller should wake-up

while(MV<100)
	{
		ADC_Read1(&MV);
	 delay_ms(100);
		Set_LED(0);
		idle_counter++;
		
		if (idle_counter>=300)
		{
		
		 EnterSleepMode();
		}
    
	}



// rest of the code//


void TIM2_Config(void)
{
    TIM2_TimeBaseInit(TIM2_PRESCALER_32768, 244);
    TIM2_ClearFlag(TIM2_FLAG_UPDATE);
    TIM2_ITConfig(TIM2_IT_UPDATE, ENABLE);
    TIM2_Cmd(ENABLE);
		AWU_DeInit();
		
		/* auto wake up at 32ms */
		AWU_Init(AWU_TIMEBASE_32MS);
		
		/* enable auto wake up*/
		AWU_Cmd(ENABLE);
		
		enableInterrupts();
}


  
INTERRUPT_HANDLER(TIM2_UPD_OVF_BRK_IRQHandler, 13)
{
    if (TIM2_GetITStatus(TIM2_IT_UPDATE) != RESET)
    {
			
        // Increment the idle_counter every 500ms
        idle_counter++;

        // Enter sleep mode if idle for approximately 30 seconds (60 * 500ms)
        if (idle_counter >= 300)
        {
            EnterSleepMode();
        }
				TIM2_ClearITPendingBit(TIM2_IT_UPDATE);
    }
}

void EnterSleepMode(void)
{
    // Disable TIM2 interrupt
    TIM2_ITConfig(TIM2_IT_UPDATE, DISABLE);

    // Disable ADC peripheral
    ADC1_Cmd(DISABLE);

    // Disable GPIO inputs
    GPIO_Init(GPIOD, GPIO_PIN_3, GPIO_MODE_IN_PU_NO_IT);
    GPIO_Init(GPIOD, GPIO_PIN_5, GPIO_MODE_IN_FL_IT);
    GPIO_Init(GPIOC, GPIO_PIN_4, GPIO_MODE_IN_PU_NO_IT);

   halt();

    // Re-enable ADC peripheral
    
}

void Inc500mSCounter(void)
{
    if (_500ms_tick < 500)
    {
        _500ms_tick++;
    }
    else
    {
        _500ms_tick = 0;
        idle_counter++;
    }
}