DS1307 + PIC16F877A

DS1307 is a popular Real Time Clock (RTC) chip from MAXIM . Now, PIC16F877A is my favorite microcontroller. So, I was looking for information about interfacing DS1307 with PIC16F877A but I found only information in assembly language (assembly is not my cup of tea) and other C compilers. I use only mikroC. I adapted what I have found from the Internet. The source code is listed below:

//Sample code for
//DS1307 RTC Ineterfacing with PIC16F877A
//Coded by Pynn Pynn
//Compiler: mikroC 8.0.0
//Use with your own risk

unsigned short read_ds1307(unsigned short address );
unsigned short sec;
unsigned short minute;
unsigned short hour;
unsigned short day;
unsigned short date;
unsigned short month;
unsigned short year;
unsigned short data;
char time[9];
char ddate[11];

unsigned char BCD2UpperCh(unsigned char bcd);
unsigned char BCD2LowerCh(unsigned char bcd);

void main(){

I2C_Init(100000); //DS1307 I2C is running at 100KHzPORTB = 0;
TRISB = 0; // Configure PORTB as output
Lcd_Init(&PORTB); // Initialize LCD connected to PORTBLcd_Cmd(Lcd_CLEAR); // Clear displayLcd_Cmd(Lcd_CURSOR_OFF); // Turn cursor offLcd_Out(1, 1, "TIME:");
Lcd_Out(2, 1, "DATE:");

sec=read_ds1307(0); // read secondminute=read_ds1307(1); // read minutehour=read_ds1307(2); // read hourday=read_ds1307(3); // read daydate=read_ds1307(4); // read datemonth=read_ds1307(5); // read monthyear=read_ds1307(6); // read year

time[0] = BCD2UpperCh(hour);
time[1] = BCD2LowerCh(hour);
time[2] = ':';
time[3] = BCD2UpperCh(minute);
time[4] = BCD2LowerCh(minute);
time[5] = ':';
time[6] = BCD2UpperCh(sec);
time[7] = BCD2LowerCh(sec);
time[8] = '\0';

ddate[0] = BCD2UpperCh(date);
ddate[1] = BCD2LowerCh(date);
ddate[2] ='/';
ddate[3] = BCD2UpperCh(month);
ddate[4] = BCD2LowerCh(month);
ddate[5] ='/';
ddate[6] = '2';
ddate[7] = '0';
ddate[8] = BCD2UpperCh(year);
ddate[9] = BCD2LowerCh(year);
ddate[10] = '\0';


unsigned short read_ds1307(unsigned short address)
I2C_Wr(0xd0); //address 0x68 followed by direction bit (0 for write, 1 for read) 0x68 followed by 0 --> 0xD0I2C_Wr(address);
I2C_Wr(0xd1); //0x68 followed by 1 --> 0xD1

unsigned char BCD2UpperCh(unsigned char bcd)
return ((bcd >> 4) + '0');

unsigned char BCD2LowerCh(unsigned char bcd)
return ((bcd & 0x0F) + '0');

As I don't have DS1307 in hand, so I test my code with Proteus ISIS simulator. The image shows the working clock. Click on the image for big image.

Schematic of DS1307 and PIC16F877a or PIC16F887

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