.......
void Serial_Flash_Write(unsigned char byte,unsigned char card_adr,unsigned char adress_H,unsigned char adress_L)
{
    SF_Start_Soft();
    SF_Tx_Soft(AA1025_ADDR|card_adr|WR);    //adress Memory Card
    SF_Tx_Soft(adress_H);            //adress High
    SF_Tx_Soft(adress_L);            //adress Low  
    SF_Tx_Soft(byte);
    SF_Stop_Soft();
}
.......

.......
#define SERIAL_FLASH_DATA_DIR_SET PORTD.DIRSET|=(1<<SERIAL_FLASH_DATA)
#define SERIAL_FLASH_DATA_DIR_CLR PORTD.DIRCLR&=(1<<SERIAL_FLASH_DATA)
#define SERIAL_FLASH_DATA_SET PORTD.OUTSET|=(1<<SERIAL_FLASH_DATA)
#define SERIAL_FLASH_DATA_CLR PORTD.OUTCLR&=(1<<SERIAL_FLASH_DATA)

#define SERIAL_FLASH_SCL_DIR_SET PORTD.DIRSET|=(1<<SERIAL_FLASH_SCL)
#define SERIAL_FLASH_SCL_UP PORTD.OUTSET|=(1<<SERIAL_FLASH_SCL)
#define SERIAL_FLASH_SCL_DOWN PORTD.OUTCLR&=(1<<SERIAL_FLASH_SCL)

void SF_Init_Soft(void);
void SF_Start_Soft(void);
void SF_Stop_Soft(void);
void SF_Tx_Soft(unsigned char byte);
unsigned char SF_Rx_Soft(unsigned char last_byte);
unsigned char SF_In_Sda(void);

unsigned char SF_error_soft; //error

void SF_Init_Soft(void) //Init Programm I2C
{

SERIAL_FLASH_DATA_DIR_SET;
SERIAL_FLASH_SCL_DIR_SET;
SERIAL_FLASH_SCL_UP; //and SCL in high impedance condition
SF_error_soft=0; //for first no error :-)
}

void SF_Start_Soft(void) //Set Start condition
{
if(SF_error_soft)
return;
SERIAL_FLASH_DATA_DIR_SET;
SERIAL_FLASH_DATA_SET;
delay_us(100);
SERIAL_FLASH_SCL_UP;
delay_us(100);
SERIAL_FLASH_DATA_CLR;
delay_us(100);
SERIAL_FLASH_SCL_DOWN;
}

void SF_Stop_Soft(void) //Set Start condition
{
SERIAL_FLASH_DATA_DIR_SET;
SERIAL_FLASH_DATA_CLR;
delay_us(100);
SERIAL_FLASH_SCL_UP;
delay_us(100);
SERIAL_FLASH_DATA_SET;
delay_us(100);
if(SF_error_soft)
SF_Init_Soft();
}

void SF_Tx_Soft(unsigned char byte) //Send Byte
{
unsigned char count;
if(SF_error_soft)
return;

SERIAL_FLASH_DATA_DIR_SET;
if(SF_error_soft)
return;
for(count=0;count<8;count++)
{
if(byte&0x80)
SERIAL_FLASH_DATA_SET;
else
SERIAL_FLASH_DATA_CLR;
SERIAL_FLASH_SCL_UP;
delay_us(10);
SERIAL_FLASH_SCL_DOWN;
delay_us(10);
byte<<=1;
}
SERIAL_FLASH_DATA_DIR_CLR;
SERIAL_FLASH_SCL_UP;
SF_error_soft=SF_In_Sda();
rtcTime.status=SF_error_soft;
delay_us(10);
SERIAL_FLASH_SCL_DOWN;
delay_us(10);
}

unsigned char SF_Rx_Soft(unsigned char last_byte)
//Recieve byte,if last_byte=0, then bytes? which recieved is last, and no needed request from master
{
unsigned char data=0;
unsigned char mask=0x80;
unsigned char count;

if(SF_error_soft)
return 0;
SERIAL_FLASH_DATA_DIR_CLR;
for(count=0;count<8;count++)
{
SERIAL_FLASH_SCL_UP;
delay_us(10);
if(SF_In_Sda())
data=data+mask;
mask>>=1;
SERIAL_FLASH_SCL_DOWN;
delay_us(10);
}
SERIAL_FLASH_DATA_DIR_SET;
if(last_byte)
SERIAL_FLASH_DATA_CLR;
else
SERIAL_FLASH_DATA_SET;
SERIAL_FLASH_SCL_UP;
delay_us(10);
SERIAL_FLASH_SCL_DOWN;
delay_us(10);
return data;
}

unsigned char SF_In_Sda(void) //Return SDA_line level
{
if(PORTD.IN&(1<<SERIAL_FLASH_DATA))
return 1;
else
return 0;
}
.......

#define SERIAL_FLASH_DATA_SET       PORTD.OUTSET|=(1<<SERIAL_FLASH_DATA)

#define ADR24AA1025 0xA0 //Адрес карты памяти
#define ADDR_HI 0x08 // Выбор верхней или нижний части памяти
#define ADDR_LOW 0x0
#define CARD_ADDR1 0 //4 карты памяти на шине
#define CARD_ADDR2 2 //
#define CARD_ADDR3 4 //
#define CARD_ADDR4 6

#define READ 0x01 // I2C бит чтения

#define SERIAL_FLASH_DATA 4 // I2C данные: Порт D бит 4
#define SERIAL_FLASH_SCL 5 // I2C строб: Порт D бит 5

#define QDEL delay_us(10) // задержка 10мкс
#define HDEL delay_us(20) // задержка 20мкс

#define I2C_SDL_LO PORTD.OUTCLR&=(1<<SERIAL_FLASH_DATA); // DATA = 0
#define I2C_SDL_HI PORTD.OUTSET|=(1<<SERIAL_FLASH_DATA); // DATA = 1

#define I2C_SCL_LO PORTD.OUTCLR&=(1<<SERIAL_FLASH_SCL); //аналогично
#define I2C_SCL_HI PORTD.OUTSET|=(1<<SERIAL_FLASH_SCL);

#define OUT(BIT) (PORTD.DIRSET|=(1<<BIT))
#define IN(BIT) (PORTD.DIRCLR&=(1<<BIT))

#define I2C_SCL_TOGGLE HDEL; I2C_SCL_HI; HDEL; I2C_SCL_LO;
#define I2C_START I2C_SDL_LO; QDEL; I2C_SCL_LO;
#define I2C_STOP HDEL; I2C_SCL_HI; QDEL; I2C_SDL_HI; HDEL;




// Запись байта на устройство
bool i2cPutbyte(uint8_t
{
int8_t i;
uint8_t j;
rtcTime.status=0;
j=0x80;
for (i=7;i>=0;i--)
{
if ( b & j )
I2C_SDL_HI;
else
I2C_SDL_LO; // address bit
I2C_SCL_TOGGLE; // clock HI, delay, then LO
j >>= 1;
}
IN(SERIAL_FLASH_DATA); // change direction to input on SDA line (may not be needed)
I2C_SDL_HI; // leave SDL HI
// added

HDEL;
I2C_SCL_HI; // clock back up
HDEL;
b = (PORTD.IN&SERIAL_FLASH_DATA); // get the ACK bit
rtcTime.status=b; //отслеживаю АСК и через раз он равен 1.

I2C_SCL_LO; // not really ??
OUT(SERIAL_FLASH_DATA); // change direction back to output
HDEL;
return (b == 0); // return ACK value
}




// чтение байта из устройство
uint8_t i2cGetbyte(uint8_t last)
{
int i;
uint8_t b = 0;

I2C_SDL_HI; // make sure pullups are ativated
IN(SERIAL_FLASH_DATA); // change direction to input on SDA line (may not be needed)

for(i=7;i>=0;i--)
{
HDEL;
I2C_SCL_HI; // clock HI
if((PORTD.IN&(1<<SERIAL_FLASH_DATA))!=0){ b |= 1;} // Может быть что-то здесь?
b <<= 1;
HDEL;
I2C_SCL_LO; // clock LO
}

OUT(SERIAL_FLASH_DATA); // change direction to output on SDA line

if (last)
I2C_SDL_HI; // set NAK
else
I2C_SDL_LO; // set ACK

I2C_SCL_TOGGLE; // clock pulse
I2C_SDL_HI; // leave with SDL HI
return b; // return received byte
}



//! Initialize I2C communication
void i2cInit(void)
{
OUT(SERIAL_FLASH_DATA); // set SDA as output
OUT(SERIAL_FLASH_SCL); // set SCL as output
I2C_SDL_HI; // set I/O state and pull-ups
I2C_SCL_HI; // set I/O state and pull-ups
}




//Чтение одного байта с указанием адреса
uint8_t i2ceepromReadByte(uint16_t memAddr,unsigned char card,bool H_L)
{
uint8_t i2cAddr=0;

I2C_START;
if (H_L) i2cAddr=((ADR24AA1025&0xfe)||ADDR_HI||card);
else i2cAddr=((ADR24AA1025&0xfe)||card);

i2cPutbyte(i2cAddr));
i2cPutbyte((memAddr>>8) & 0xff)
i2cPutbyte(memAddr & 0xff);
HDEL;
I2C_SCL_HI; // do a repeated START
I2C_START; // transition

while(!i2cPutbyte(i2cAddr||READ)); // resend DEVICE, with READ bit set
memAddr = i2cGetbyte(1);
I2C_SDL_LO; // clear data line and
I2C_STOP; // send STOP transition
return ((uint8_t)memAddr);
}




// Запись одного байта с указанием адреса
void i2ceepromWriteByte(uint16_t memAddr,unsigned char card, bool H_L, uint8_t data)
{
uint8_t i2cAddr=0;

I2C_START;
if (H_L) i2cAddr=((ADR24AA1025&0xfe)||ADDR_HI||card);
else i2cAddr=((ADR24AA1025&0xfe)||card);

i2cPutbyte(i2cAddr);
i2cPutbyte((memAddr>>8) & 0xff)
i2cPutbyte(memAddr & 0xff);
i2cPutbyte(data);

I2C_SDL_LO; // clear data line and
I2C_STOP; // send STOP transition
}

i2ceepromWriteByte(0,CARD_ADDR1, 0, 15); //Пишу значение 15 на младшую часть памяти 1, с адресом 0.
Digit(rtcTime.status); // отслеживаю АСК

i2ceepromWriteByte(0,CARD_ADDR1, 0, 15);
Digit(rtcTime.status);

i2ceepromWriteByte(0,CARD_ADDR1, 0, 15);
Digit(rtcTime.status);

i2ceepromWriteByte(1,CARD_ADDR2, 0, 15);
Digit(rtcTime.status);

i2ceepromWriteByte(1,CARD_ADDR2, 0, 15);
Digit(rtcTime.status);

i2ceepromWriteByte(1,CARD_ADDR2, 0, 15);
Digit(rtcTime.status);

Digit(i2ceepromReadByte(0,CARD_ADDR1,0)); // читаю и вывожу на экран
Digit(rtcTime.status); // слежу за АСК

Digit(i2ceepromReadByte(0,CARD_ADDR1,0));
Digit(rtcTime.status);

Digit(i2ceepromReadByte(0,CARD_ADDR1,0));
Digit(rtcTime.status);

Digit(i2ceepromReadByte(1,CARD_ADDR2,0));
Digit(rtcTime.status);

Digit(i2ceepromReadByte(1,CARD_ADDR2,0));
Digit(rtcTime.status);

Digit(i2ceepromReadByte(1,CARD_ADDR2,0));
Digit(rtcTime.status);

Digit(i2ceepromReadByte(1,CARD_ADDR3,0));
Digit(rtcTime.status);

Digit(i2ceepromReadByte(1,CARD_ADDR3,0));
Digit(rtcTime.status);

Digit(i2ceepromReadByte(1,CARD_ADDR3,0));
Digit(rtcTime.status);

#define I2C_SDL_LO      PORTD.OUTCLR&=(1<<SERIAL_FLASH_DATA);       // DATA = 0
#define I2C_SDL_HI      PORTD.OUTSET|=(1<<SERIAL_FLASH_DATA);        // DATA = 1

#define I2C_SCL_LO      PORTD.OUTCLR&=(1<<SERIAL_FLASH_SCL);         //аналогично
#define I2C_SCL_HI      PORTD.OUTSET|=(1<<SERIAL_FLASH_SCL);

#define I2C_SDL_LO      PORTD.DIRSET=(1<<SERIAL_FLASH_DATA);       // OUTPUT!!!!, DATA = 0
#define I2C_SDL_HI      PORTD.DIRCLR=(1<<SERIAL_FLASH_DATA);       // INPUT!!!      DATA = 1

#define I2C_SCL_LO      PORTD.DIRSET=(1<<SERIAL_FLASH_SCL);         //аналогично
#define I2C_SCL_HI      PORTD.DIRCLR=(1<<SERIAL_FLASH_SCL);

#define I2C_SDL_LO      PORTD.OUTCLR&=(1<<SERIAL_FLASH_DATA); PORTD.DIRSET|=(1<<SERIAL_FLASH_DATA);       // OUTPUT, DATA = 0
#define I2C_SDL_HI      PORTD.DIRSET|=(1<<SERIAL_FLASH_DATA);    PORTD.DIRCLR&=(1<<SERIAL_FLASH_DATA);       // INPUT, DATA = 1

#define     SERIAL_FLASH_DATA  4           // I2C данные: Порт D бит 4
#define     SERIAL_FLASH_SCL    5           // I2C строб:  Порт D бит 5
......
if((PORTD.IN&(SERIAL_FLASH_DATA))!=0){ b |= 1;} // При чтении            
..........                                                                   //                           PORTD&0b00000100 ?
b = (PORTD.IN&(SERIAL_FLASH_DATA));                 // При записи