Interfacing AT89S52 with AT24C64 EEPROM using I2C

Other Hardware Storage
1

Hi All,
I am interfacing AT89S52 with AT24C64 EEPROM using I2C protocol. My purpose is to send a value, say "1" to a memory location and readback the same value.
But the problem I am facing is that : whatever value I am sending to the memory location, while reading, I am always getting 0.
Can some one please help me to sort out this problem?
I know I am doing some mistakes in my code, but not able to solve it.
Also, I written two different Read and Write function, but I am not sure which one will work.

Following is my code:

#include <AT89X52.H>  // Header file for IO operations
#include "intrins.h"

/* AT24C64 Memory*/
#define SDA P3_7
#define SCL P3_5
#define WP  P3_4

bit ack_bit;
unsigned char output;

void I2CInit(){
        SDA = 1;
        SCL = 1;
}

void I2CStart(){
        SDA = 1;
		SCL = 1;
		_nop_();         //No operation
		_nop_();
		_nop_();
        SDA = 0;
		_nop_();         //No operation
		_nop_();
		_nop_();
        //SCL = 0;
}

void I2CRestart(){
        SCL = 0;
        SDA = 1;
        SCL = 1;
        SDA = 0;
}

void I2CStop(){
        SDA = 0;
		SCL = 1;
		_nop_();         //No operation
		_nop_();
		_nop_();
        SDA = 1;
		_nop_();         //No operation
		_nop_();
		_nop_();
		//SCL = 0;
}

void I2CAck(){
        SDA = 0;
        SCL = 1;
		_nop_();         //No operation
		_nop_();
		_nop_();
        SCL = 0;
        //SDA = 1;
}

void I2CNak(){
        SCL = 0;
		SDA = 1;
        SCL = 1;
        SCL = 0;
		SDA = 0;
}

unsigned char I2CSend1(unsigned char Data)
{
         unsigned char i;
         for(i=0;i<8;i++){
                SCL = 0;
                if((Data&0x80)==0)
                        SDA = 0;
                else
                        SDA = 1;
                SCL = 1;
                Data<<=1;
         }
         SCL = 0;
	     ack_bit = SDA;
		 SCL = 1;
		 SCL = 0;
         //SDA = 1;
	
		 return !ack_bit;
}

void I2CSend(unsigned char value)	//send byte serially
{ 
	unsigned int i;
	unsigned char send;
	send=value;
	for(i=0;i<8;i++)
	{
		SDA=send/128;			//extracting MSB
		send=send<<1;			//shiftng left
		SCL=1;
		_nop_();
		_nop_();
		SCL=0;
	}
   ack_bit=SDA;					//reading acknowledge
   SDA=0;
}

unsigned char I2CRead1()			//reading from EEPROM serially
{
	unsigned int i,reead;

	SDA=1;
	reead=0;
	for(i=0;i<8;i++)
	{
		reead=reead<<1;
		SCL=1;
		_nop_();
		_nop_();
		if(SDA==1)
			reead++;
		SCL=0;
	}
	SDA=0;
	return reead;				//Returns 8 bit data here
}	

unsigned char I2CRead(){
        unsigned char i, Data=0;
        for(i=0;i<8;i++){
                SCL = 0;
                SCL = 1;
                if(SDA)
                        Data |=1;
                if(i<7)
						Data<<=1;
        }
        SCL = 0;
        SDA = 1;
        return Data;
}

void Save()					//save in EEPROM
{
	I2CStart();
	I2CSend(0xA0);						//device address
	I2CAck();
	I2CSend(0x11);						//word address
	I2CAck();
	I2CSend("1");							//send data
	I2CAck();
	I2CStop();							   
	if(ack_bit==0)
	{
		//
	}
	else
		//
}

void Read()
{
	I2CStart();
	I2CSend(0xA0);
	I2CAck();
	I2CSend(0x11);
	I2CAck();
	I2CStart();
	I2CSend(0xA1);					 //device address
	I2CAck();
	output=I2CRead(); //read the value
	I2CAck();
	I2CStop();
}


int main(void)
{

Save(); //first save the values in EEPROM

Read(); //Then read the values from EEPROM


}
2

http://www.hobbytronics.co.uk/arduino-external-eeprom

The above link is an excellent tutorial of how to use the 24LC256, you should be able to use it with the LC64.

It uses the Wire Library which prevents you from re-inventing the wheel. Only down side with the library is the 16 byte input buffer, useless for a C256, but may be enough for a C64.