#define I2C_SLAVE   0xA0
//#define I2C_SPEED   ( ( CRYSTAL / ( 4 * 50000 ) ) - 1 )   // pull-up = 10k
#define I2C_SPEED   ( ( CRYSTAL / ( 4 * 100000 ) ) - 1 )   // pull-up = 10k
//#define I2C_SPEED   ( ( CRYSTAL / ( 4 * 400000 ) ) - 1 )   // pull-up = 2k
//#define I2C_SPEED   ( ( CRYSTAL / ( 4 * 1000000 ) ) - 1 )   // pull-up = 2k
#define I2C_PAGE_SIZE   64
#define I2C_HALF_PAGE   ( I2C_PAGE_SIZE / 2 )
#define I2C_MEM_SIZE 65536

#define M24515

unsigned int16 i2caddr;
#byte i2caddr_low=i2caddr
#byte i2caddr_high=i2caddr+1
int8 i2cslave,i2cflags,i2cdata,i2ccount,i2ctemp;
#bit i2cerr=i2cflags.0
#bit i2c_page_cross=i2cflags.1
int8   i2cpage[I2C_PAGE_SIZE];
#byte i2cpage=0xA0


// Initialize MSSP for Master I2C mode operation
void I2CInitMaster(void)   {
   i2cslave = I2C_SLAVE;
   SSPCON = 0;
   SSPIE = 0;            // Disable interrupt from I2C module
   TRISC |= 0b00011000;   // Make SCL & SDA to be inputs
   SMP = 1;            //  enable 100KHz & 1MHz !
   CKE = 0;            //   I2C specification !
   GCEN = 0;            //    disable interrupt when detect general call address on the i2c bus .
   SSPADD = I2C_SPEED;
   SSPCON = 0x08;         //   Master mode, 7-bit address, clock=(Fosc/(4*I2CClock))-1;
   SSPIF = 0;
   SSPEN = 1;            //    Enable I2C port
}

// I2CIdle() - from 00735A.PDF
void I2CIdle(void)   {
   while( R_W );   // Check for transmit in progres. If in progress wait.
   while( SSPCON2 & 0x1F );
}

void I2CWait(void)   {
   while( ! SSPIF );
   SSPIF = 0;
}

void I2CWrite(char data)   {
   SSPBUF = data;
   I2CWait();
// In Master Transmit Mode: Check for Acknowledge
   i2cerr = 0;
   if( ACKSTAT )
      i2cerr = 1;
}

void I2CIsFree(void)   {
   i2cerr = 1;
   if( I2C_STOP || ! I2C_START )
      i2cerr = 0;
}

void I2CStart(void) {
   SEN = 1;      // Initiate Start condition
   I2CWait();
}

void I2CSStart(void)   {
   RSEN = 1;                  // Second Start condition
   I2CWait();
   I2CWrite( i2cslave | 0x01 );   // Set Read operation
}

void I2CStop(void)   {
   PEN   = 1;      // Generate STOP condition
   I2CWait();
}

void I2CAck(void)   {
// In Master receive mode: Value that will be transmitted when the user
// initiates an Acknowledge sequence at the end of a receive.
//
   ACKDT = 0;      //   Acknowledge
// In Master receive mode: Initiate Acknowledge sequence on SDA & SCL
// and transmit ACKDT data bit. Automatically cleared by hardware
//
   ACKEN = 1;
   I2CWait();
}

void I2CMasterAck(void)   {
// In Master receive mode: Value that will be transmitted when the user
// initiates an Acknowledge sequence at the end of a receive.
//
   ACKDT = 1;      // Not Acknowledge
// In Master receive mode: Initiate Acknowledge sequence on SDA & SCL
// and transmit ACKDT data bit. Automatically cleared by hardware
//
   ACKEN = 1;
   I2CWait();
}

char I2CRead(void)   {
   while( R_W );         // Wait for transmit to end ...
   RCEN = 1;            // Enter Master mode reception
   I2CWait();            // Wait to receive one byte
   return SSPBUF;
}

void I2CPageCross(void) {
   i2c_page_cross = 0;
   if( ! bit_test(i2caddr,15) && bit_test( i2caddr + (int16)i2ccount, 15 ) )
      i2c_page_cross = 1;
}

void I2CRestoreAddress(void) {
   i2caddr -= (i2ctemp-1);
}

// I2CWriteAddr()
void I2CWriteAddr(void)   {
   WCOL = 0;
   I2CIsFree();         // If I2C is free ?
   if(   i2cerr )
      return;            // bus is busy !
   I2CStart();            // Send Start signal
#ifdef M24515
   if( bit_test(i2caddr,15) )
      i2cslave |= 0x08;
   else
      i2cslave &= ~0x08;
#endif
   I2CWrite( i2cslave );   // Set Write operation
   if( i2cerr )
      return;
   I2CWrite( i2caddr_high );   // Send high byte of address
   if( i2cerr )
      return;
   I2CWrite( i2caddr_low );         //   Send low byte of address
}

char I2CReadByte(void)   {
   I2CWriteAddr();         // Write address in address registers
   if( i2cerr )
      return;            // bus is busy !
   I2CSStart();         // Second Start ...
   if( i2cerr )
      return;            // bus is busy !
   i2cdata = I2CRead();
   I2CMasterAck();         // Send Not Acknowledge signal
   I2CStop();            // Generate Stop condition
}

void I2CReadSeq(void)   {
   I2CWriteAddr();         // Write address in address registers
   if( i2cerr )
      return;            // bus is busy !
   I2CSStart();         // Second Start ...
   if( i2cerr )
      return;            // bus is busy !
   i2ctemp = i2ccount;
#ifdef M24515
   I2CPageCross();
#endif
   do {
      INDF = I2CRead();
      FSR++;
      if( --i2ccount == 0 )
         break;
#ifdef M24515
      if( ++i2caddr == 0x8000 ) {
         I2CStop();
         I2CWriteAddr();
         if( i2cerr )
            break;
         I2CSStart();
         if( i2cerr )
            break;
      } else
         I2CAck();
#else
      I2CAck();
#endif
   } while( 1 );
   I2CRestoreAddress();
   I2CMasterAck();         // Send Not Acknowledge signal
   I2CStop();            // Generate STOP condition
}

void I2CWriteByte(void)   {

   I2CWriteAddr();         // Write address in address registers
   if( i2cerr )
      return;            // bus is busy !
   I2CWrite( i2cdata );
   I2CStop();
// Verifiy record ...
   do {
      I2CWriteAddr();
   } while( i2cerr );
   I2CSStart();         // Send Start signal
   if( i2cerr )
      return;
   if( i2cdata != I2CRead() )
      i2cerr = 1;
   else
      I2CMasterAck();      // Send Not Acknowledge signal
   I2CStop();            // Generate STOP condition
}

void I2CWriteSeq(void)   {
   I2CWriteAddr();
   if( i2cerr )
      return;
   i2ctemp = i2ccount;
#ifdef M24515
   I2CPageCross();
#endif
   do {
      I2CWrite( INDF );
      if( i2cerr )
         return;
      FSR++;
      if( --i2ccount == 0 )
         break;
#ifdef M24515
      if( ++i2caddr == 0x8000 ) {
         I2CStop();
         I2CWriteAddr();
         if( i2cerr )
            break;
      }
#endif
   } while( 1 );
   I2CStop();
   I2CRestoreAddress();
        // Verify record ...
   do {
      I2CWriteAddr();
   } while( i2cerr );
   I2CSStart();         // Send Start signal
   if( i2cerr )
      return;
   FSR -= i2ctemp;
   i2ccount = i2ctemp;
#ifdef M24515
   I2CPageCross();
#endif
   do {
      if( INDF != I2CRead() ) {
         i2cerr = 1;
         break;
      }
      FSR++;
      if( --i2ccount == 0 )
         break;
#ifdef M24515
      if( ++i2caddr == 0x8000 ) {
         I2CStop();
         I2CWriteAddr();
         if( i2cerr )
            break;
         I2CSStart();
         if( i2cerr )
            break;
      } else
         I2CAck();
#else
      I2CAck();
#endif
   } while( 1 );
   I2CRestoreAddress();
   I2CMasterAck();      // Send Not Acknowledge signal
   I2CStop();         // Generate STOP condition
}

   do {
      I2CWriteAddr();
   } while( i2cerr );

   do {
      I2CWriteAddr();
      if( i2cerr )
         I2CInitMaster();
      else
         break;
   } while( 1 );