Interface of Pic18f8722 with RTC DS1307

//************************************************************************************//
//************************************************************************************//
// Project: //
// Header: 8722 Project //
// PIC used: PIC18F8722 //
// Start Date: 1st Dec 2009 //
// Function for I2C2 //
// the interface of DS1307 with Pic18f8722 //
// Backup power by lithium battery(3.3v) //
// Microcontroller is in master mode, I2c has been designed for 100Khz, //
// I have connected pullup resistors(2.2 Kohm Each) with the SDA and SCl lines, //
// 32Khz Crystal oscillator for DS1307 //
//************************************************************************************//
//************************************************************************************//
//** HEADER FILES ********************************************************************/
#include <p18F8722.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <usart.h>
#include <timers.h>
#include <delays.h>
#include <i2c.h>
//** CONFIGURATION BITS **************************************************************/
#pragma config OSC = HSPLL
#pragma config WDT = OFF
#pragma config LVP = OFF
#pragma config DEBUG = ON
//** FUNCTION PROTOTYPES *************************************************************/
void Init_Ports(void);
void Configure_I2C2(void);
void Day_Decision (void);
//** DEFINITIONS *********************************************************************/
#define ControlByte 0xD0 //Control is always D0 for reads (& D1 for writes)
#define CLEAR 0
#define SET 1
#define BRGValue 0x63
//** GLOBALS *************************************************************************/
unsigned char Second =0x00, Minutes=0x59, Hours=0x23, Days=0x7, Date=0x31, Month=0x12, Year=0x09;
unsigned char Day,Sec,Min,Hr,Dy,Dat,Mon,Ye;
unsigned char Monday,Tuesday,Wenesday,Thursday,Friday,Saturday,Sunday;
//** MAIN CODE ***********************************************************************/
void main(void)
{
Init_Ports();
Configure_I2C2 ();
EEByteWrite2( ControlByte, 0x07 , 0x00); // control byte 0x00;
EEByteWrite2( ControlByte, 0x00 , Second);
EEByteWrite2( ControlByte, 0x01 , Minutes);
EEByteWrite2( ControlByte, 0x02 , Hours);
EEByteWrite2( ControlByte, 0x03 , Days);
EEByteWrite2( ControlByte, 0x04 , Date);
EEByteWrite2( ControlByte, 0x05 , Month);
EEByteWrite2( ControlByte, 0x06 , Year);

while(SET)
{
Sec = EERandomRead2( 0xD0, 0x00 );
Min = EERandomRead2( 0xD0, 0x01 );
Hr = EERandomRead2( 0xD0, 0x02 );
Days= EERandomRead2( 0xD0, 0x03 );
Dat= EERandomRead2( 0xD0, 0x04 );
Mon = EERandomRead2( 0xD0, 0x05 );
Ye= EERandomRead2( 0xD0, 0x06 );
Day_Decision ();
}
}
//*************************************************************************************
void Init_Ports(void)
{
PORTD = CLEAR;
LATD = 0b01100001;
TRISD = 0b01100001; // intialized RD6(SCL2) AND RD5(SDA2).
}
//*************************************************************************************
void Configure_I2C2 (void)
{
SSP2STAT = 0x80; //Disable SMBus &
SSP2CON1 = 0x28; //Enable MSSP Master
SSP2CON2 = 0x00; //Clear MSSP Conrol Bits
SSP2ADD = 0x63;
}
///********************************************************************
* Function Name: WriteI2C2 *
* Return Value: Status byte for WCOL detection. *
* Parameters: Single data byte for I2C2 bus. *
* Description: This routine writes a single byte to the *
* I2C2 bus. *
********************************************************************/
unsigned char WriteI2C2( unsigned char data_out )
{
SSP2BUF = data_out; // write single byte to SSP2BUF
if ( SSP2CON1bits.WCOL ) // test if write collision occurred
return ( -1 ); // if WCOL bit is set return negative #
else
{
while( SSP2STATbits.BF ); // wait until write cycle is complete
return ( 0 ); // if WCOL bit is not set return non-negative #
}
}
///*********************************************************************
* Function Name: EERandomRead2 *
* Return Value: error condition status and/or data byte *
* Parameters: EE memory control byte with R/W set to 1 *
* Description: Reads 1 byte from passed address to EE memory*
* device. This routine can be used for any I2C *
* EE memory device, which only uses 1 byte of *
* address data as in the 24LC01B/02B/04B/08B. *
* *
*********************************************************************/
unsigned int EERandomRead2( unsigned char control, unsigned char address )
{
IdleI2C2(); // ensure module is idle
StartI2C2(); // initiate START condition
while ( SSP2CON2bits.SEN ); // wait until start condition is over
if ( PIR3bits.BCL2IF ) // test for bus collision
{
return ( -1 ); // return with Bus Collision error
}
else
{
if ( WriteI2C2( control ) ) // write 1 byte
{
return ( -3 ); // return with write collision error
}

IdleI2C2(); // ensure module is idle
if ( !SSP2CON2bits.ACKSTAT ) // test for ACK condition, if received
{
if ( WriteI2C2( address ) ) // WRITE word address for EEPROM
{
return ( -3 ); // return with write collision error
}

IdleI2C2(); // ensure module is idle
if ( !SSP2CON2bits.ACKSTAT ) // test for ACK condition, if received
{
RestartI2C2(); // generate I2C bus restart condition
while ( SSP2CON2bits.RSEN );// wait until re-start condition is over
if ( PIR3bits.BCL2IF ) // test for bus collision
{
return ( -1 ); // return with Bus Collision error
}

if ( WriteI2C2( control+1 ))// write 1 byte - R/W bit should be 1
{
return ( -3 ); // return with write collision error
}

IdleI2C2(); // ensure module is idle
if ( !SSP2CON2bits.ACKSTAT )// test for ACK condition, if received
{
SSP2CON2bits.RCEN = 1; // enable master for 1 byte reception
while ( SSP2CON2bits.RCEN ); // check that receive sequence is over
NotAckI2C2(); // send ACK condition
while ( SSP2CON2bits.ACKEN ); // wait until ACK sequence is over
StopI2C2(); // send STOP condition
while ( SSP2CON2bits.PEN ); // wait until stop condition is over
if ( PIR3bits.BCL2IF ) // test for bus collision
{
return ( -1 ); // return with Bus Collision error
}
}
else
{
return ( -2 ); // return with Not Ack error
}

}
else
{
return ( -2 ); // return with Not Ack error
}
}
else
{
return ( -2 ); // return with Not Ack error
}
}
return ( (unsigned int) SSP2BUF ); // return with data
}
//************************************************************************************
void Day_Decision (void)
{
if (Days ==1) {Dy = Monday;}
if (Days ==2) {Dy = Tuesday;}
if (Days ==3) {Dy = Wenesday;}
if (Days ==4) {Dy = Thursday;}
if (Days ==5) {Dy = Friday;}
if (Days ==6) {Dy = Saturday;}
if (Days ==7) {Dy = Sunday;}
}