AVR Freaks

__flash int TEMP_Farenheit_pos[] =  // Positive Farenheit temperatures (ADC-value)
        {                           // from 0 to 140 degrees
		    938, 935, 932, 929, 926, 923, 920, 916, 913, 909, 906, 902, 898, 
    		894, 891, 887, 882, 878, 874, 870, 865, 861, 856, 851, 847, 842, 
    		837, 832, 827, 822, 816, 811, 806, 800, 795, 789, 783, 778, 772, 
    		766, 760, 754, 748, 742, 735, 729, 723, 716, 710, 703, 697, 690, 
    		684, 677, 670, 663, 657, 650, 643, 636, 629, 622, 616, 609, 602, 
    		595, 588, 581, 574, 567, 560, 553, 546, 539, 533, 526, 519, 512, 
    		505, 498, 492, 485, 478, 472, 465, 459, 452, 446, 439, 433, 426, 
    		420, 414, 408, 402, 396, 390, 384, 378, 372, 366, 360, 355, 349, 
    		344, 338, 333, 327, 322, 317, 312, 307, 302, 297, 292, 287, 282, 
    		277, 273, 268, 264, 259, 255, 251, 246, 242, 238, 234, 230, 226, 
    		222, 219, 215, 211, 207, 204, 200, 197, 194, 190, 187, 
        };

int ADC_read(void)
{
    char i;
    int ADC_temp;
    int ADC = 0;
    
    // To save power, the voltage over the LDR and the NTC is turned off when not used
    // This is done by controlling the voltage from a I/O-pin (PORTF3)
    
    sbi(PORTF, PORTF3);     // Enable the VCP (VC-peripheral)
    sbi(DDRF, PORTF3);        

    sbi(ADCSRA, ADEN);     // Enable the ADC

    //do a dummy readout first
    ADCSRA |= (1<<ADSC);        // do single conversion
    while(!(ADCSRA & 0x10));    // wait for conversion done, ADIF flag active
        
    for(i=0;i<8;i++)            // do the ADC conversion 8 times for better accuracy 
    {
        ADCSRA |= (1<<ADSC);        // do single conversion
        while(!(ADCSRA & 0x10));    // wait for conversion done, ADIF flag active
        
        ADC_temp = ADCL;            // read out ADCL register
        ADC_temp += (ADCH << 8);    // read out ADCH register        

        ADC += ADC_temp;      // accumulate result (8 samples) for later averaging
    }

    ADC = ADC >> 3;     // average the 8 samples
        
    cbi(PORTF, PORTF3);     // disable the VCP
    cbi(DDRF, PORTF3);  
    
    cbi(ADCSRA, ADEN);      // disable the ADC

    return ADC;
}