void rtc_Init(void)
{                          
    //volatile unsigned int temp0, temp1;  
//    for(temp0=0; temp0<0x0040; temp0++)   // Wait for external clock crystal to stabilize
//        for(temp1=0; temp1<0xFFFF; temp1++);
delay_ms(2000);

    DDRF |= (1<<MCLK);
    PORTF |= (1<<MCLK);         // Настроить MCLK на выход
        
    TIMSK2 &=~((1<<TOIE2)|(1<<OCIE2A));     // Disable TC2 interrupt
    ASSR |= (1<<AS2);           // set Timer/Counter2 to be asynchronous from the CPU clock
                                // with a second external clock(32,768kHz)driving it.  
    TCNT2 = 0x00;
    TCCR2B = 0x05;              // prescale the timer to be clock source / 128 to make it
                                // exactly 1 second for every overflow to occur
    while(ASSR&0x11);           // Wait until TCNT2, TCCR2B is updated    // TC2
    
    TIFR2 |= (1 << TOV2);
    TIMSK2 |= (1<<TOIE2);       // set 8-bit Timer/Counter2 Overflow Interrupt Enable                            
    
    __enable_interrupt();       // set the Global Interrupt Enable Bit    
}

#pragma vector=TIMER2_OVF_vect
__interrupt void TIMER2_OVF_ISR()
{  
    PORTD ^= (1 << GREEN);
}

void Initialise()
{
   delay_ms(1000);

    // Timer2 initialisation with a second external clock (32,768kHz) driving it
    // Set Timer/Counter2 to be asynchronous from the CPU clock
    ASSR |= (1 << AS2);          
  
    TCNT2 = 0x00;
    TCCR2 = 0x05;  //(1 << CS22) | (0 << CS21) | (1 << CS20); // prescale the timer to be clock source/128 to make it
                                                     // exactly 1 second for every overflow to occur
    //while(ASSR & ((1 << TCR2UB) | (1 << TCN2UB)));   // Wait until TCNT2, TCCR2B is updated  
      
    TIFR |= (1 << TOV2);      // Clear TC2 interrupt flag
    TIMSK |= (1 << TOIE2);    // set 8-bit Timer/Counter2 Overflow Interrupt Enable  

    MCUCR = (1 << SE);        // Idle по команде __sleep()

__enable_interrupt();   // allow all enabled interrupts
}

void main()
{
    Initialise();           // set up I/O registers, flags & variables

    for(;;)
    {  
        //Idle. Спать до следующего прерывания
        __sleep();
    }
}