The example shows the initialization, writing, and reading data from the transmit and receive buffer register ofan I2C module, respectively. The example shows the connection of an I2C module to the serial EEPROM memory 24C02. The realization is carried out by using the mikroC compiler for dsPIC30F microcontrollers. Fig. 13-11 shows the electrical connection of an I2C module to the EEPROM memory 24C02. The example covers writing to the EEPROM memory, reading data, and data transfer to the PORTF.

void main() {
 ADPCFG = 0xFFFF;
 PORTB = 0;
 TRISB = 0;
 
 dAddr = 0x02;

 I2c_Init(100000);
 I2c_Start(); // issue I2C start signal
 I2c_Write(0xA2); // send byte via I2C (command to 24cO2)
 I2c_Write(dAddr); // send byte (address of EEPROM location)
 I2c_Write(0xF4); // send data (data to be written)
 I2c_Stop();

 Delay_100ms();

 I2c_Start(); // issue I2C start signal
 I2c_Write(0xA2); // send byte via I2C (device address + W)
 I2c_Write(0x02); // send byte (data address)
 I2c_Restart(); // issue I2C signal repeated start
 I2c_Write(0xA3); // send byte (device address + R)
 PORTB = I2c_Read(1); // Read the data (NO acknowledge)
 I2c_Stop();

}//~!

Also, an example is presented showing the connection of a device from the dsPIC30F family to the RTC (Real-Time Clock) generator Philips PCF8583P. The example covers writing to and reading from the RTC generator by using an I2C standard interface. Date and time are printed at LCD.

//RTCWrite

void main() {
 ADPCFG = 0xFFFF;
 I2C_Init(10000); // initialize full master mode
 I2C_Start(); // issue start signal
 I2C_Write(0xA0); // address PCF8583
 I2C_Write(0); // start from word at address 0 (configuration word)
 I2C_Write(0x80); // write 0x80 to config. (pause counter...)
 I2C_Write(0); // write 0 to cents word
 I2C_Write(0); // write 0 to seconds word
 I2C_Write(0x30); // write 0x30 to minutes word
 I2C_Write(0x11); // write 0x11 to hours word
 I2C_Write(0x24); // write 0x24 to year/date word
 I2C_Write(0x08); // write 0x08 to weekday/month
 I2C_Stop(); // issue stop signal

 I2C_Start(); // issue start signal
 I2C_Write(0xA0); // address PCF8530
 I2C_Write(0); // start from word at address 0
 I2C_Write(0); // write 0 to config word (enable counting)
 I2C_Stop(); // issue stop signal
}//~!

//RTCRead
 
unsigned char sec, min1, hr, day, mn, year;
char *txt, tnum[4];

void Zero_Fill(char *value) { // fill text repesentation
 if (value[1] == 0) { // with leading zero
 value[1] = value[0];
 value[0] = 48;
 value[2] = 0;
 }
}//~

//--------------------- Reads time and date information from RTC (PCF8583)
void Read_Time(char *sec, char *min, char *hr, char *day, char *mn, char *year) {
 I2C_Start();
 I2C_Write(0xA0);
 I2C_Write(2);
 I2c_Restart();
 I2C_Write(0xA1);
 *sec =I2c_Read(0);
 *min =I2c_Read(0);
 *hr =I2c_Read(0);
 *day =I2c_Read(0);
 *mn =I2c_Read(1);
 I2C_Stop();
}//~

//-------------------- Formats date and time
void Transform_Time(char *sec, char *min, char *hr, char *day, char *mn, char *year) {
 *sec = ((*sec & 0xF0) >> 4)*10 + (*sec & 0x0F);
 *min = ((*min & 0xF0) >> 4)*10 + (*min & 0x0F);
 *hr = ((*hr & 0xF0) >> 4)*10 + (*hr & 0x0F);
 *year = (*day & 0xC0) >> 6;
 *day = ((*day & 0x30) >> 4)*10 + (*day & 0x0F);
 *mn = ((*mn & 0x10) >> 4)*10 + (*mn & 0x0F);
}//~

//-------------------- Output values to LCD
void Display_Time(char sec, char min, char hr, char day, char mn, char year) {
 ByteToStr(day,tnum);
 txt = rtrim(tnum);
 Zero_Fill(txt);
 Lcd_Custom_Out(1,6,txt);
 ByteToStr(mn,tnum);
 txt = rtrim(tnum);
 Zero_Fill(txt);
 Lcd_Custom_Out(1,9,txt);
 Lcd_Custom_Chr(1,15,52+year);
 ByteToStr(hr,tnum);
 txt = rtrim(tnum);
 Zero_Fill(txt);
 Lcd_Custom_Out(2,6,txt);
 ByteToStr(min,tnum);
 txt = rtrim(tnum);
 Zero_Fill(txt);
 Lcd_Custom_Out(2,9,txt);
 ByteToStr(sec,tnum);
 txt = rtrim(tnum);
 Zero_Fill(txt);
 Lcd_Custom_Out(2,12,txt);
}//~

//------------------ Performs project-wide init
void Init_Main() {
 ADPCFG = 0xFFFF;
 Lcd_Custom_Init_EasyDsPIC4();
 I2C_Init(100000); // initialize I2C
 txt = "Date:"; // prepare and output static text on LCD
 Lcd_Custom_Out(1,1,txt);
 Lcd_Custom_Chr(1,8,':');
 Lcd_Custom_Chr(1,11,':');
 txt = "Time:";
 Lcd_Custom_Out(2,1,txt);
 Lcd_Custom_Chr(2,8,':');
 Lcd_Custom_Chr(2,11,':');
 txt = "200";
 Lcd_Custom_Out(1,12,txt);
 Lcd_Custom_Cmd(LCD_CURSOR_OFF); // cursor off
}//~

//----------------- Main function
void main() {
 Init_Main(); // perform initialization
 while (1) {
 Read_Time(&sec,&min1,&hr,&day,&mn,&year); // read time from RTC(PCF8583)
 Transform_Time(&sec,&min1,&hr,&day,&mn,&year); // format date and time
 Display_Time(sec, min1, hr, day, mn, year); // prepare and display on LCD
 Delay_ms(1000); // wait 1s
 }
}