/*  Name     : main.c
 *  Purpose  : Source code for EEPROM interface with ATMEGA16.
 *  Author   : Gemicates
 *  Date     : 2017-09-12
 *  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 init_i2c()
{
TWSR = 0X00;
TWBR = 0X47;
TWCR = (1<<TWEN);
}

unsigned char read_i2c()
{
TWCR = (1<<TWINT)|(1<<TWEN);
while(!(TWCR & (1<<TWINT)));
return TWDR;
}

void write_i2c(unsigned char ch)
{
TWDR = ch;
TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWEA);
while(!(TWCR&(1<<TWINT)));
}

void start()
{
TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
while((TWCR &(1<<TWINT))==0);
}

void stop()
{
TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO);
_delay_ms(1);
}

void eeprom_write(char dev_addr,char dev_loc,char dev_data)
{
start();
write_i2c(dev_addr);
write_i2c(dev_loc);
write_i2c(dev_data);
stop();
_delay_ms(10);
}

unsigned char eeprom_read(char dev_addr,char dev_loc)
{
char ch;

start();

write_i2c(dev_addr);
write_i2c(dev_loc);

start();
write_i2c(dev_addr|0x01);
ch = read_i2c();

stop();
return ch;
}

int main()
{
char ch,i;

DDRC =0XFF;
init_i2c();

for(i = 0;i<26;i++)
eeprom_write(0xa0,i,'A'+i);

for(i = 0;i<26;i++)
{
ch = eeprom_read( 0xa0 , i);
eeprom_write(0xa0,i+40,ch);
}
}