i2c.c

pic18系列单片机与24xxx系列的EEROM用I2C读写的库函数

/********************************************************************
*     Function Name:    HDByteReadI2C                               *
*     Parameters:       EE memory ControlByte, address, pointer and *
*                       length bytes.                               *
*     Description:      Reads data string from I2C EE memory        *
*                       device. This routine can be used for any I2C*
*                       EE memory device, which only uses 1 byte of *
*                       address data as in the 24LC01B/02B/04B/08B. *
*                                                                   *  
********************************************************************/

unsigned char HDByteReadI2C( unsigned char ControlByte, unsigned char HighAdd, unsigned char LowAdd, unsigned char *data, unsigned char length )
{
  IdleI2C();                      // ensure module is idle
  StartI2C();                     // initiate START condition
  while ( SSPCON2bits.SEN );      // wait until start condition is over 
  WriteI2C( ControlByte );        // write 1 byte 
  IdleI2C();                      // ensure module is idle
  WriteI2C( HighAdd );            // WRITE word address to EEPROM
  IdleI2C();                      // ensure module is idle
  while ( SSPCON2bits.RSEN );     // wait until re-start condition is over 
  WriteI2C( LowAdd );             // WRITE word address to EEPROM
  IdleI2C();                      // ensure module is idle
  RestartI2C();                   // generate I2C bus restart condition
  while ( SSPCON2bits.RSEN );     // wait until re-start condition is over 
  WriteI2C( ControlByte | 0x01 ); // WRITE 1 byte - R/W bit should be 1 for read
  IdleI2C();                      // ensure module is idle
  getsI2C( data, length );       // read in multiple bytes
  NotAckI2C();                    // send not ACK condition
  while ( SSPCON2bits.ACKEN );    // wait until ACK sequence is over 
  StopI2C();                      // send STOP condition
  while ( SSPCON2bits.PEN );      // wait until stop condition is over 
  return ( 0 );                   // return with no error
}

/********************************************************************
*     Function Name:    HDPageWriteI2C                              *
*     Parameters:       EE memory ControlByte, address and pointer  *
*     Description:      Writes data string to I2C EE memory         *
*                       device. This routine can be used for any I2C*
*                       EE memory device, which uses 2 bytes of     *
*                       address data as in the 24LC32A/64/128/256.  *
*                                                                   *  
********************************************************************/

unsigned char HDPageWriteI2C( unsigned char ControlByte, unsigned char HighAdd, unsigned char LowAdd, unsigned char *wrptr )
{
  IdleI2C();                      // ensure module is idle
  StartI2C();                     // initiate START condition
  while ( SSPCON2bits.SEN );      // wait until start condition is over 
  WriteI2C( ControlByte );        // write 1 byte - R/W bit should be 0
  IdleI2C();                      // ensure module is idle
  WriteI2C( HighAdd );            // write HighAdd byte to EEPROM 
  IdleI2C();                      // ensure module is idle
  WriteI2C( LowAdd );             // write LowAdd byte to EEPROM
  IdleI2C();                      // ensure module is idle
  putstringI2C ( wrptr );         // pointer to data for page write
  IdleI2C();                      // ensure module is idle
  StopI2C();                      // send STOP condition
  while ( SSPCON2bits.PEN );      // wait until stop condition is over 
  return ( 0 );                   // return with no error
}

/********************************************************************
*     Function Name:    HDSequentialReadI2C                         *
*     Parameters:       EE memory ControlByte, address, pointer and *
*                       length bytes.                               *
*     Description:      Reads data string from I2C EE memory        *
*                       device. This routine can be used for any I2C*
*                       EE memory device, which only uses 2 bytes of*
*                       address data as in the 24xx32 - 24xx512.    *
*                                                                   *  
********************************************************************/

unsigned char HDSequentialReadI2C( unsigned char ControlByte, unsigned char HighAdd, unsigned char LowAdd, unsigned char *rdptr, unsigned char length )
{
  IdleI2C();                      // ensure module is idle
  StartI2C();                     // initiate START condition
  while ( SSPCON2bits.SEN );      // wait until start condition is over 
  WriteI2C( ControlByte );        // write 1 byte 
  IdleI2C();                      // ensure module is idle
  WriteI2C( HighAdd );            // WRITE word address to EEPROM
  IdleI2C();                      // ensure module is idle
  WriteI2C( LowAdd );             // write HighAdd byte to EEPROM
  IdleI2C();                      // ensure module is idle
  RestartI2C();                   // generate I2C bus restart condition
  while ( SSPCON2bits.RSEN );     // wait until re-start condition is over 
  WriteI2C( ControlByte | 0x01 ); // WRITE 1 byte - R/W bit should be 1 for read
  IdleI2C();                      // ensure module is idle
  getsI2C( rdptr, length );       // read in multiple bytes
  NotAckI2C();                    // send not ACK condition
  while ( SSPCON2bits.ACKEN );    // wait until ACK sequence is over 
  StopI2C();                      // send STOP condition
  while ( SSPCON2bits.PEN );      // wait until stop condition is over 
  return ( 0 );                   // return with no error
}

/********************************************************************
*     Function Name:    putstringI2C                                *
*     Return Value:     error condition status                      *
*     Parameters:       address of write string storage location    *
*     Description:      This routine writes a string to the I2C bus,*
*                       until a null character is reached. If Master*
*                       function putcI2C is called. When trans-     *
*                       mission is complete then test for ack-      *
*                       nowledge bit. If Slave transmitter wait for *
*                       null character or not ACK received from bus *
*                       device.                                     *
********************************************************************/

unsigned char putstringI2C( unsigned char *wrptr )
{

unsigned char x;
  for (x = 0; x < PageSize; x++ ) // transmit data until PageSize  
  {
    if ( SSPCON1bits.SSPM3 )      // if Master transmitter then execute the following
    {
      if ( putcI2C ( *wrptr ) )   // write 1 byte
      {
        return ( -3 );            // return with write collision error
      }
      IdleI2C();                  // test for idle condition
      if ( SSPCON2bits.ACKSTAT )  // test received ack bit state
      {
        return ( -2 );            // bus device responded with  NOT ACK
      }                           // terminateputstringI2C() function
    }
    else                          // else Slave transmitter
    {
      PIR1bits.SSPIF = 0;         // reset SSPIF bit
      SSPBUF = *wrptr;            // load SSPBUF with new data
      SSPCON1bits.CKP = 1;        // release clock line 
      while ( !PIR1bits.SSPIF );  // wait until ninth clock pulse received

      if ( ( !SSPSTATbits.R_W ) && ( !SSPSTATbits.BF ) )// if R/W=0 and BF=0, NOT ACK was received
      {
        return ( -2 );            // terminateputstringI2C() function
      }
    }
  wrptr ++;                       // increment pointer
  }                               // continue data writes until null character
  return ( 0 );
}