ADC.c

//Includes the public interface file and the private register definitions for the ADC driver.
#include "ADC_Interface.h"  
#include "ADC_Private.h"

void ADC_Init(adc_reference_t reference, adc_prescaler_t prescaler){//Function to initialize the ADC with:voltage reference,clock prescaler
    switch (reference)//Checks which voltage reference source will be used.
    {
        case AVCC://Selects AVCC as reference voltage.
            clearBit(ADMUX, 7); //Clear REFS1 bit
            setBit(ADMUX, 6); //Set REFS0 bit
            break;
        case AREF:
            clearBit(ADMUX, 7); //Clear REFS1 bit
            clearBit(ADMUX, 6); //Clear REFS0 bit
            break;
        case INTERNAL:
            setBit(ADMUX, 7); //Set REFS1 bit
            setBit(ADMUX, 6); //Set REFS0 bit
            break;
    }
    switch (prescaler)//Selects ADC clock division factor.
    {
        case DIV_2:
            clearBit(ADCSRA, 2); //Clear ADPS2 bit
            clearBit(ADCSRA, 1); //Clear ADPS1 bit
            clearBit(ADCSRA, 0); //Clear ADPS0 bit
            break;
        case DIV_4:
            clearBit(ADCSRA, 2); //Clear ADPS2 bit
            setBit(ADCSRA, 1); //Set ADPS1 bit
            clearBit(ADCSRA, 0); //Clear ADPS0 bit
            break;
        case DIV_8:
            clearBit(ADCSRA, 2); //Clear ADPS2 bit
            setBit(ADCSRA, 1); //Set ADPS1 bit
            setBit(ADCSRA, 0); //Set ADPS0 bit
            break;
        case DIV_16:
            setBit(ADCSRA, 2); //Set ADPS2 bit
            clearBit(ADCSRA, 1); //Clear ADPS1 bit
            clearBit(ADCSRA, 0); //Clear ADPS0 bit
            break;
        case DIV_32:
            setBit(ADCSRA, 2); //Set ADPS2 bit
            clearBit(ADCSRA, 1); //Clear ADPS1 bit
            setBit(ADCSRA, 0); //Set ADPS0 bit
            break;
        case DIV_64:
            setBit(ADCSRA, 2); //Set ADPS2 bit
            setBit(ADCSRA, 1); //Set ADPS1 bit
            clearBit(ADCSRA, 0); //Clear ADPS0 bit
            break;
        case DIV_128:
            setBit(ADCSRA, 2); //Set ADPS2 bit
            setBit(ADCSRA, 1); //Set ADPS1 bit
            setBit(ADCSRA, 0); //Set ADPS0 bit
            break;
    }
    setBit(ADCSRA, 7); //Enable ADC (ADEN bit)
}
u16 ADC_Read(adc_channel_t channel){//Reads analog signal from selected channel and returns digital value.
    //Select the ADC channel by setting the MUX bits in ADMUX register
    ADMUX &= 0xE0; //Clear MUX bits (keep REFS bits)
    ADMUX |= channel; //Set the desired channel
    setBit(ADCSRA, 6); //Start conversion (ADSC bit)
    while(readBit(ADCSRA, 6)); //Wait for conversion to complete
    u8 low = ADCL; //Read low byte first (triggers latch)
    u8 high = ADCH; //Read high byte
    return (high << 8) | low; //Return ADC result
}
f32 ADC_read_v(adc_channel_t channel, f32 vref)//Reads ADC value and converts it into voltage.
{
    u16 adc_value = ADC_Read(channel);//Gets raw digital ADC value.
    f32 voltage = (adc_value / 1023.0) * vref; //Calculate voltage in volts
    return voltage;
}
void ADC_FreeRunningMode(adc_channel_t channel){//Enables continuous ADC conversion mode.
     ADMUX &= 0xE0;//Selects ADC channel.
    ADMUX |= channel;
    setBit(ADCSRA, 5);      // ADATE - enable auto trigger
    clearBit(ADCSRB, 2);    // Clear ADTS2 (was SFIOR bit 7)
    clearBit(ADCSRB, 1);    // Clear ADTS1 (was SFIOR bit 6)
    clearBit(ADCSRB, 0);    // Clear ADTS0 (was SFIOR bit 5)
    setBit(ADCSRA, 6);      // ADSC - start conversion
}