[nagar]

/*   '_nop_ ()' ( no operation function) is used for delay purpose 

 

'bit'   is a data tye contain only  1 or 0 (any value other then 0 treated as 1)

 

#include<intrins.h>   is used to avoke from nop() function

 

*/

 

 

 

#include<reg51.h>

#include<stdio.h>

#include<string.h>

#include<intrins.h>

sbit rs=P2^4; 

sbit rw=P2^5; 

sbit en=P2^6; 

 

sbit SCL = P2^0;    // connect to SCL pin (Clock)

sbit SDA = P2^1;    // connect to SDA pin (Data)

 

unsigned char i;

unsigned char Data;

 

#define ACK      0

#define NO_ACK   1

void DelayMs(unsigned int count)

{ 

// mSec Delay 11.0592 Mhz

   unsigned int i;                

   while(count)

    {

       i = 115;

         while(i>0) i–;

       count–;

   }

}

 

void cmd(unsigned char x)

{

P1=x;

rs=0;

rw=0;

en=1;

DelayMs(20);

en=0;

}  

 

void dat(unsigned char x)

{

P1=x;

rs=1;

rw=0;

en=1;

DelayMs(20);

en=0;

}

 

void lcd_init()

{

cmd(0x01);

DelayMs(50);

cmd(0x80);

DelayMs(50);

cmd(0x0e);

DelayMs(50);

cmd(0x38);

}

void string(unsigned char *p)

{

while(*p)

{

dat(*p);

p++;

}

}

void start();

void stop();

void WriteI2C(unsigned char);

unsigned char ReadI2C(bit);   // bit is a data type

 

unsigned int s=0,s1=0,s2=0,h=0,h1=0,h2=0,m=0,m1=0,m2=0;

unsigned char z[50];

void main()

{

lcd_init();

while(1)

{

 

  //   seconds    //

  start();

  WriteI2C(0xD0);   // address of RTC

  WriteI2C(0x00);   // address for seconds

  start();

  WriteI2C(0xD1);   // address of RTC to read value

  s=ReadI2C(ACK);  // after read data send acknowledgement

    stop();

 

//  minutes  //

start();

  WriteI2C(0xD0);   // address of RTC

  WriteI2C(0x01);   // address for minutess

  start();

  WriteI2C(0xD1);   

m=ReadI2C(ACK);

stop();

 

//      hour     //

start();

  WriteI2C(0xD0);   // address of RTC

  WriteI2C(0x02);   // address for hourss

  start();

  WriteI2C(0xD1);   

h=ReadI2C(ACK);

   stop();

 

s1=s&0x0f;

s2=(s&0xf0)>>4;

 m1=m&0x0f;

 m2=(m&0xf0)>>4;

h1=h&0x0f;

h2=(h&0xf0)>>4;

cmd(0x80);

dat(h2+48);

dat(h1+48);

dat(':');

dat(m2+48);

dat(m1+48);

dat(':');

dat(s2+48);

dat(s1+48);

cmd(0xc0);

// sprintf(z,"%d%d:%d%d:%d%d",h2,h1,m2,m1,s2,s1);

// string(z);

}

 

}

//

---

// start I2C

//

---

void Start() // SDA pin is high to low _ when clock is high

{

   SDA = 1;

    SCL = 1;

    _nop_();_nop_();  // for delay

    SDA = 0;

    _nop_();_nop_();  // for delay

    SCL = 0;

    _nop_();_nop_();  // for delay

}

 

//

---

// stop I2C

//

---

void Stop()   // SDA pin is low to high _/ when clock is high

{

    SDA = 0;   

    _nop_();_nop_();  // for delay

    SCL = 1;

    _nop_();_nop_();  // for delay

    SDA = 1;

}

 

//

---

// Write I2C

//

---

void WriteI2C(unsigned char Data)   // data bit is change when clock is change 

{  

 

    for (i=0;i<8;i++)

    {

       SDA = (Data & 0x80) ? 1:0;

       SCL=1;

SCL=0;

         Data<<=1;

}

 

 SCL = 1;    // on this extra clock the ACK is receive by the master

    _nop_();_nop_();

    SCL = 0;

 _nop_();_nop_();  // for delay*

}

 

//

---

// Read I2C  when slave sends the complete data it latches the SDA pin high as no ack for wait of another restart bit

//

---

 

unsigned char ReadI2C(bit ACK_Bit)

{

  

    for (i=0;i<8;i++)

    {

         SCL   = 1;      

         Data<<= 1;

         Data = (Data | SDA);    

         SCL   = 0;

         _nop_();

    }

  

   if (ACK_Bit == 1)

    SDA = 0; // Send ACK     

    else    

    SDA = 1; // Send NO ACK               

  

 SCL = 1;    // on this extra clock the ACK is transmitted by the master

    _nop_();_nop_();

    SCL = 0;

 _nop_();_nop_();  // for delay*

 

    return Data;

}

 

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