/*  Name     : main.c
 *  Purpose  : Source code for LDR interface with ATMEGA16.
 *  Author   : Gemicates
 *  Date     : 2017-09-11
 *  Website  : www.gemicates.org
 *  Revision : None
 */
#ifndef F_CPU
#define F_CPU 8000000UL                                        // 8 MHz clock speed
#endif

#include<avr/io.h>
#include<util/delay.h>
 
void LDR_init(void);
unsigned int LDR_read();
 
int main(void)
{
	unsigned int value;
	DDRB=0xFF;
	LDR_init();	                                       // Initialization of ADC

	while(1)
	{
		value=LDR_read();
		PORTB=value;
		_delay_ms(500);
	} 
}
 
void LDR_init(void)		                                // Initialization of ADC
{
	ADMUX=(1<<REFS0);	                                // AVcc with external capacitor at AREF
	ADCSRA=(1<<ADEN)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);	// Enable ADC and set Prescaler division factor as 128
} 
unsigned int LDR_read()
{	
	ADMUX |=0x00;						// selecting channel
 	ADCSRA|=(1<<ADSC);					// start conversion
	while(ADCSRA==0x9f);		                        // waiting for ADIF, conversion complete
	ADCSRA|=(1<<ADIF);					// clearing of ADIF, it is done by writing 1 to it
 	return (ADC);
}