INTERFACING OF DS1307 WITH PIC16F877A WITHOUT USING LIBRARY FUNCTIONS

*/use pull up resistors of 330k ,crystal freq:32.768/*

Program:

#include "uartfun.h" //created myown header file for uart functions

void i2c_intialise(int);
void i2c_start();
void i2c_stop();
void i2c_restart();
void i2c_ack();
void i2c_nack();
void WaitSSP();
void i2c_send(unsigned int,unsigned int,unsigned int,unsigned int,unsigned int,unsigned int,unsigned int);
unsigned int i2c_readx(int);
void wait();

void main()
{
  unsigned char time[20]="Time:00:00:00";
  unsigned char dayx[20]="Day:__";
  unsigned char datex[20]="Date:__/__/__";
  short sec;
  short min;
  short hr;
  short days;
  short dates;
  short months;
  short years;
  char seconds[5];
  char minutes[5];
  char hours[5];
  char dayss[5];
  char datess[5];
  char monthss[5];
  char yearss[5];

  uart_intialise(31);
  i2c_intialise(151);
  i2c_send(0X00,0X55,0X09,0X01,0X018,0X10,0X15);// write data  for time,day,calendar

  delay_ms(100);

  while(1)
  {
    sec=i2c_readx(0X00);
    delay_us(100);
    min=i2c_readx(0X01);
    delay_us(100);
    hr=i2c_readx(0X02);
    delay_us(100);
    days=i2c_readx(0X03);
    delay_us(100);
    dates=i2c_readx(0X04);
    delay_us(100);
    months=i2c_readx(0X05);
    delay_us(100);
    years=i2c_readx(0X06);
    delay_us(100);
    
    shorttohex(sec,seconds); //converts short to string
    shorttohex(min,minutes);
    shorttohex(hr,hours);
    shorttohex(days,dayss);
    shorttohex(dates,datess);
    shorttohex(months,monthss);
    shorttohex(years,yearss);
    
    time[5]=hours[0];
    time[6]=hours[1];
    time[8]=minutes[0];
    time[9]=minutes[1];
    time[11]=seconds[0];
    time[12]=seconds[1];
    
    dayx[4]=dayss[0];
    dayx[5]=dayss[1];

    datex[5]=datess[0];
    datex[6]=datess[1];
    datex[8]=monthss[0];
    datex[9]=monthss[1];
    datex[11]=yearss[0];
    datex[12]=yearss[1];

    //below functions own created to display over uart
    uart_ctransmit('\f');
    uart_stransmit(time);
    uart_ctransmit('\r');
    uart_stransmit(dayx);
    uart_ctransmit('\r');
    uart_stransmit(datex);
    delay_ms(100);
  }
}

void i2c_intialise(int n)
{
  TRISC.RC3=1;  // SCL
  TRISC.RC4=1;  // SDA
  SSPSTAT.SMP=1; //slewrate disabled
  SSPCON=0X28; //i2c master mode  SSPEN=1,1000 for master mode baud rate
  SSPADD=n;  //load value to set baudrate ,use formula
}

void i2c_start()
{
  SSPCON2.SEN=1; //enabled start condition
  while(SSPCON2.SEN);//wait for start condition to finish,automatically cleared by hardware
}

void i2c_stop()
{
  SSPCON2.PEN=1;  //enabled stop condition
  while(SSPCON2.PEN);//wait for stop condition to finish,automatically cleared by hardware
}

void i2C_restart()
{
  SSPCON2.RSEN=1;//repeated start enabled
  while(SSPCON2.RSEN);//wait for restart condition to finish,automatically cleared by hardware.
}
void i2c_ack()
{
  SSPCON2.ACKDT=0; //acknowledge data bit as 0,
  SSPCON2.ACKEN=1;//acknowledgement enabled;
  while(SSPCON2.ACKEN);//wait for ack data to send
}

void i2c_nack()
{
  SSPCON2.ACKDT=1;  //acknowledge data bit as 1;
  SSPCON2.ACKEN=1; //acknowledgement enabled
  while(SSPCON2.ACKEN);//wait for nack,data to send on bus
}
/* below function to write/set the time & date*/
void i2c_send(unsigned int second,unsigned int  minute, unsigned int hour,unsigned int day,unsigned int date,unsigned int month,unsigned int year)
{
  i2c_start();   //start
  WaitSSP(); //wait for flag bit to set,cleared manually in software.
  SSPBUF=0XD0;//device address + write command
  WaitSSP();
  SSPBUF=0X00;//write location;
  WaitSSP();
  SSPBUF=second; //move data for second
  WaitSSP();
  SSPBUF=minute; //move data for min
  WaitSSP();
  SSPBUF=hour;//move data for hour
  WaitSSP();
  SSPBUF=day;//move data for day
  WaitSSP();
  SSPBUF=date;//move data for date
  WaitSSP();
  SSPBUF=month;//move data for month
  WaitSSP();
  SSPBUF=year;//move data for year
  WaitSSP();
  i2c_stop();  //stop
  delay_ms(100);
}

/*below function is used to read data*/
unsigned int i2c_readx(int addr)
{
  unsigned int tmp;
  i2c_restart(); //restart
  WaitSSP();
  SSPBUF=0XD0; //slave address + write command
  WaitSSP();
  SSPBUF=addr;
  WaitSSP();
  i2c_restart();
  WaitSSP();
  SSPBUF=0XD1; //slave address command + read command
  WaitSSP();
  SSPCON2.RCEN=1; //enable reception
  WaitSSP();
  i2c_nack();//send acknowledgment as bit 1
  i2c_stop(); //stop
  tmp=SSPBUF;
  return tmp;
}

void WaitSSP() //function to check interrupt flag for i2c
{
  while(PIR1.SSPIF==0);
  PIR1.SSPIF=0;
}