configuring-and-reading-real-time-clock-and-calendar-pic16f877a.c

#define _7SEG_DATA PORTB
#define _7SEG1_LE  RD0_bit
#define _7SEG2_LE  RD1_bit
#define _7SEG3_LE  RD2_bit
#define _7SEG4_LE  RD3_bit

#define HEXNUM_0   0b00111111
#define HEXNUM_1   0b00000110
#define HEXNUM_2   0b01011011
#define HEXNUM_3   0b01001111
#define HEXNUM_4   0b01100110
#define HEXNUM_5   0b01101101
#define HEXNUM_6   0b01111101
#define HEXNUM_7   0b00000111
#define HEXNUM_8   0b01111111
#define HEXNUM_9   0b01101111
#define HEXNUM_A   0b01110111
#define HEXNUM_B   0b01111100
#define HEXNUM_C   0b00111001
#define HEXNUM_D   0b01011110
#define HEXNUM_E   0b01111001
#define HEXNUM_F   0b01110001

void RTC_Write(unsigned char ADD, unsigned char DATA);
unsigned char RTC_Read(unsigned char ADD);
void _7SEG1(unsigned char DATA);
void _7SEG2(unsigned char DATA);
void _7SEG3(unsigned char DATA);
void _7SEG4(unsigned char DATA);

unsigned char HEXNUM[16]=
         {HEXNUM_0,HEXNUM_1,HEXNUM_2,HEXNUM_3,
         HEXNUM_4,HEXNUM_5,HEXNUM_6,HEXNUM_7,
         HEXNUM_8,HEXNUM_9,HEXNUM_A,HEXNUM_B,
         HEXNUM_C,HEXNUM_D,HEXNUM_E,HEXNUM_F};
         
void main()
{
    unsigned char seconds=0;

    TRISB=0x00;        //set whole PORTB as output

    TRISD0_bit=0;      //set RD0-RD3 as output
    TRISD1_bit=0;
    TRISD2_bit=0;
    TRISD3_bit=0;

    TRISC3_bit=0;      //set I2C Pins as output
    TRISC4_bit=0;
    RC3_bit=0;         //clear both I2C Pins output
    RC4_bit=0;
    Delay_Us(1);
    RC3_bit=1;         //set both I2C Pins output
    RC4_bit=1;
    Delay_Us(1);
    TRISC3_bit=1;      //set I2C pins as input
    TRISC4_bit=1;
    
    I2C1_Init(100000);  //initiate I2C at 100kbps

    _7SEG1(0x00);      //clear 7 Segment 1
    _7SEG2(0x00);      //clear 7 Segment 2
    _7SEG3(0x00);      //clear 7 Segment 3
    _7SEG4(0x00);      //clear 7 Segment 4

    RTC_Write(0x00,0b00000000);    //enable osc and set seconds to 0

    while(1)
    {
        seconds=RTC_Read(0x00);
        
        _7SEG3(HEXNUM[seconds>>4]);
        
        _7SEG4(HEXNUM[seconds&0x0f]);
    }
}

void RTC_Write(unsigned char ADD, unsigned char DATA)
{
    I2C1_Start();              //I2C Start
    I2C1_Wr(0b11010000);       //device address + write bit
    I2C1_Wr(ADD);              //Address
    I2C1_Wr(DATA);             //Data
    I2C1_Stop();
}

unsigned char RTC_Read(unsigned char ADD)
{
    unsigned char DATA=0;

    I2C1_Start();              //I2C Start
    I2C1_Wr(0b11010000);       //device address + write bit
    I2C1_Wr(ADD);              //Address
    I2C1_Repeated_Start();
    I2C1_Wr(0b11010001);       //device address + read bit
    DATA=I2C1_Rd(0);
    I2C1_Stop();
    
    return DATA;
}

void _7SEG1(unsigned char DATA)
{
    _7SEG_DATA=DATA; //put the DATA to the 8 I/O PORT
    _7SEG1_LE=1;     //Latch 1 LE to 1 to latch out the output to 7 Segment 1
    _7SEG1_LE=0;     //Latch 1 LE to 0
}

void _7SEG2(unsigned char DATA)
{
    _7SEG_DATA=DATA; //put the DATA to the 8 I/O PORT
    _7SEG2_LE=1;     //Latch 2 LE to 1 to latch out the output to 7 Segment 2
    _7SEG2_LE=0;     //Latch 2 LE to 0
}

void _7SEG3(unsigned char DATA)
{
    _7SEG_DATA=DATA; //put the DATA to the 8 I/O PORT
    _7SEG3_LE=1;     //Latch 3 LE to 1 to latch out the output to 7 Segment 3
    _7SEG3_LE=0;     //Latch 3 LE to 0
}

void _7SEG4(unsigned char DATA)
{
    _7SEG_DATA=DATA; //put the DATA to the 8 I/O PORT
    _7SEG4_LE=1;     //Latch 4 LE to 1 to latch out the output to 7 Segment 4
    _7SEG4_LE=0;     //Latch 4 LE to 0
}