/*
  Project: Multiple I2C devices on a common bus
  MCU: PIC18F2550 * 48.0 MHz (StartUSB for PIC board)
  Copyright * Rajendra Bhatt
  May 6, 2011
*/
// Define LCD module connections.
 sbit LCD_RS at RC6_bit;
 sbit LCD_EN at RC7_bit;
 sbit LCD_D4 at RB4_bit;
 sbit LCD_D5 at RB5_bit;
 sbit LCD_D6 at RB6_bit;
 sbit LCD_D7 at RB7_bit;
 sbit LCD_RS_Direction at TRISC6_bit;
 sbit LCD_EN_Direction at TRISC7_bit;
 sbit LCD_D4_Direction at TRISB4_bit;
 sbit LCD_D5_Direction at TRISB5_bit;
 sbit LCD_D6_Direction at TRISB6_bit;
 sbit LCD_D7_Direction at TRISB7_bit;
// End LCD module connection definition

void Delay2s(){
 Delay_ms(2000);
}
void check_device(unsigned short dev_address){
 I2C1_Start();
 if (I2C1_Wr(dev_address)){
  Lcd_Out(2,1,"Device not found");
 }
 else Lcd_Out(2,1,"Device is OK");
 I2C1_Stop();
}
//--------------- Writes data to 24LC512 EEPROM - single location
void EEPROM_WriteByte(unsigned DeviceSelect, unsigned short wAddress, unsigned short wData) {
    unsigned short wAddrH, wAddrL;
    wAddrH = 0;
    wAddrL = wAddress;
    I2C1_Start();        // issue I2C1 start signal
    I2C1_Wr(DeviceSelect);   // send control byte
    I2C1_Wr(wAddrH);     // send higher address byte
    I2C1_Wr(wAddrL);     // send lower address byte
    I2C1_Wr(wData);      // send data (data to be written)
    I2C1_Stop();
}
//--------------- Reads data from 24LC512 EEPROM - single location
unsigned short EEPROM_ReadByte(unsigned short EEPROM_Select, unsigned short rAddress) {
    unsigned short rAddrH, rAddrL, result;
    rAddrH = 0;
    rAddrL = rAddress;
    I2C1_Start();             // issue I2C1 start signal
    I2C1_Wr(EEPROM_Select);   // send byte via I2C1  (device address + W)
    I2C1_Wr(rAddrH);          // send Higher address byte
    I2C1_Wr(rAddrL);          // send Lower address byte
    I2C1_Repeated_Start();    // issue I2C1 signal repeated start
    I2C1_Wr(EEPROM_Select+1);            // send byte (device address + R)
    result = I2C1_Rd(0u);     // Read the data (NO acknowledge)
    while (!I2C1_Is_Idle())
      asm nop;                // Wait for the read cycle to finish
    I2C1_Stop();
    return result;
}
char message1[] = "I2C Devices ";
char message2[] = "with PIC18F2550" ;
char Sample[] = "Sample 0";
char temp[] = "00.0000 C";
unsigned int address, Fraction_Temp;
unsigned short i,MS_Byte, LS_Byte, Whole_Temp;
const int EEPROM1 = 0xA0, EEPROM2 = 0xA2, DS1631 = 0x90;
void main() {
  CMCON = 0x07;   // Disable comparators
  ADCON1 = 0x0F;  // Disable Analog functions
  TRISC = 0x00;
  TRISB = 0x00;
  Lcd_Init();        // Initialize LCD
  Lcd_Cmd(_LCD_CLEAR);             // CLEAR display
  Lcd_Cmd(_LCD_CURSOR_OFF);        // Cursor off
  Lcd_Out(1,1,message1);   // Write message1 in 1st row
  Lcd_Out(2,1,message2);   // Write message1 in 1st row
  Delay2s();
  I2C1_Init(100000);   // Initiate I2C
  // Check EEPROM1
  Lcd_Cmd(_LCD_CLEAR);
  Lcd_Out(1,1,"EEPROM1");
  check_device(EEPROM1);
  Delay2s();
  
  // Check EEPROM2
  Lcd_Cmd(_LCD_CLEAR);
  Lcd_Out(1,1,"EEPROM2");
  check_device(EEPROM2);
  Delay2s();
  
  // Check Sensor
  Lcd_Cmd(_LCD_CLEAR);
  Lcd_Out(1,1,"DS1631");
  check_device(DS1631);
  Delay2s();
  for (i=0; i<5; i++) {
    Lcd_Cmd(_LCD_CLEAR);
    Lcd_Out(1,1,"Reading Temp.");
    // Read temperature
    I2C1_Start();
    I2C1_Wr(DS1631);               // Send device address
    I2C1_Wr(0x51);                 // Start Convert Temp command
    I2C1_Stop();
    Delay_ms(750);
    I2C1_Start();
    I2C1_Wr(DS1631);               // DS1631 Address again
    I2C1_Wr(0xAA);                 // Read Temperature command
    I2C1_Repeated_Start();
    I2C1_Wr(DS1631+1);              // Address with Read
    MS_Byte = I2C1_Rd(1);           // Read MSB and send ACK
    LS_Byte = I2C1_Rd(0);            // Read LSB and send NAK
    I2C1_Stop();
    Delay2s();
    // Write the MS Byte to EEPROM1
    
    Lcd_Cmd(_LCD_CLEAR);
    Lcd_Out(1,1,"Writing MS Byte");
    EEPROM_WriteByte(EEPROM1, i, MS_Byte);
    Delay2s();
    // Write the LS Byte to EEPROM2
    Lcd_Cmd(_LCD_CLEAR);
    Lcd_Out(1,1,"Writing LS Byte");
    EEPROM_WriteByte(EEPROM2, i, MS_Byte);
    Delay2s();
  }
    // Reading stored temperature samples
    Lcd_Cmd(_LCD_CLEAR);
    Lcd_Out(1,1,"Reading EEPROMs");
    Delay2s();
    for (i=0; i<5; i++){
     Lcd_Cmd(_LCD_CLEAR);
     Sample[7] = i+49;
     Lcd_Out(1,1,Sample);
     Whole_Temp = EEPROM_ReadByte(EEPROM1, i);
     Fraction_Temp = EEPROM_ReadByte(EEPROM2, i);
     Fraction_Temp = Fraction_Temp >>4;
     Fraction_Temp = 625*Fraction_Temp; // 12 bit resolution is 0.0625C
     temp[0] = Whole_Temp/10+48;
     temp[1] = Whole_Temp%10+48;
     temp[3] = Fraction_Temp/1000+48;
     temp[4] = (Fraction_Temp/100)%10+48;
     temp[5] = (Fraction_Temp/10)%10+48;
     temp[6] = Fraction_Temp%10+48;
     Lcd_Out(2,5,temp);
     Delay2s();
    }
  }