twi_lib.c

基于UCOS-II制作的MP3

    //STATE 78h:   Arbitration lost in SLA+R/W as MASTER. General call
    //             has arrived ack returned
    //ACTION:      Receive DATA. return ACK. Restart master
    case 0x78 :
      I2C_SET_START;
      b_I2C_busy = TRUE;
    break;

    //STATE 80h:   Previously addressed with own SLA. Data received 
    //             and ACK returned 
    //ACTION:      Read DATA. 
    case 0x80 :
      I2C_slave_data[I2C_RecPtr] = SSDAT;
      I2C_RecPtr ++;
      if ( I2C_RecPtr < I2C_NB_SLAVE_DATA )
      {
        I2C_SET_AA;  // ACK will be returned
      }
      else
      {
        I2C_CLEAR_AA; // it was last data not ACK will be returned ( buffer full )
      }
    break;

    //STATE 88h:   Previously addressed with own SLA. Data received     
    //             and NOT ACK returned                                 
    //ACTION:      Dont' Read DATA. Enter NOT addressed SLV mode        
    case 0x88 :
      I2C_SET_AA;  // ready to send another ACK if addresed as slave
    break;

    //STATE 90h:   Previously addressed with general call. Data received
    //             and ACK returned                                     
    //ACTION:      Read DATA.                                           
    case 0x90 :
      I2C_slave_data[I2C_RecPtr] = SSDAT;
      I2C_RecPtr = I2C_RecPtr + 1;
      SSCON  = 0xC1;
    break;

    //STATE 98h:   Previously addressed with general call. Data arrved
    //             and NOT ACK returned 
    //ACTION:      Dont Read DATA. Enter NOT addressed SLV mode
    case 0x98 :
      I2C_SET_AA;
    break;

    //STATE A0h:   A stop or repeated start has arrived, whilst still
    //             addressed as SLV/REC or SLV/TRX
    //ACTION:      Dont Read DATA. Enter NOT addressed SLV mode
    case 0xA0 :
      I2C_SET_AA;
      b_I2C_busy = FALSE;
      I2C_Err = Tranfer_OK;
    break;

    //STATE A8h:   addressed with own SLA+R
    //ACTION:      Prepare first data to be transmited
    case 0xA8 :
      I2C_SET_AA;
      b_I2C_busy = TRUE;
      I2C_RecPtr=0;
      SSDAT = I2C_slave_data[0];  //Prepare next data
    break;


    //STATE B8h:   Previously addressed with own SLA. Data sent 
    //             and ACK returned 
    //ACTION:      Write DATA. 
    case 0xB8 :
      I2C_RecPtr ++;
      if ( I2C_RecPtr < I2C_NB_SLAVE_DATA )
      {
        SSDAT = I2C_slave_data[I2C_RecPtr];
      }
      else
      {
      ///////// FIX ME : adressed with as slave + R : but not enought data"
        I2C_CLEAR_AA; // it was last data not ACK will be returned ( buffer full )
      }
    break;


    //STATE C0h:   Previously addressed with own SLA. Data sent 
    //             and NACK returned 
    //ACTION:      It was last data to be sent 
    case 0xC0 :
      b_I2C_busy=FALSE;
      I2C_Err  = Tranfer_OK;
    break;

     //if we arrived here, unknown state has occurred..... 
    default :
      I2C_SET_STOP;
      b_I2C_busy = FALSE;
      I2C_Err  = UnknownError;
    break;
  }
}


/*F**************************************************************************
* NAME: I2C_Send_Message_polling 
*----------------------------------------------------------------------------
* PARAMS:
* *slave_adr:  The slave component address
* rw: Read or write operation flag ( read = 1 )
* nbbytes: number of bytes to be read or write 
* *info: pointer to the data to be processed
* return:  I2C error code state
*----------------------------------------------------------------------------
* PURPOSE: 
* This function can be used to send an I2C message to a slave 
* in polling mode.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
unsigned char I2C_Send_Message_polling (unsigned char slave_adr,bit rw, unsigned char nbbytes, unsigned char *info )
{
  I2C_message.address = slave_adr;
  I2C_message.rw = rw;
  I2C_message.nbbytes = nbbytes;
  I2C_message.buf = info;
  I2C_CLEAR_STOP;
  DISABLE_I2C_IT;
  I2C_nb_transmited=0;

  if ( ~b_I2C_busy )
  {
    b_I2C_busy =1;
    I2C_Err = Tranfer_OK;
    I2C_SET_START;
    while( b_I2C_busy  )
    {
      I2C_WAIT_EVENT;
      I2C_decode_status();
      I2C_CLEAR_SI;
    }
    I2C_SET_STOP;
    return I2C_Err;
  }
  else
  {
    I2C_SET_STOP;
    return I2C_NOT_FREE;
  }
}



/*F**************************************************************************
* NAME: I2C_Send_Message_interrupt 
*----------------------------------------------------------------------------
* PARAMS:
* *slave_adr:  The slave component address
* rw: Read or write operation flag ( read = 1 )
* nbbytes: number of bytes to be read or write 
* *info: pointer to the data to be processed
* return:  I2C error code state
*----------------------------------------------------------------------------
* PURPOSE: 
* This function can be used to send an I2C message to a slave 
* in interrupt mode.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
unsigned char I2C_Send_Message_interrupt (unsigned char slave_adr,bit rw, unsigned char nbytes, unsigned char *info)
{
  I2C_message.address = slave_adr;
  I2C_message.rw = rw;
  I2C_message.nbbytes = nbytes;
  I2C_message.buf = info;
  I2C_CLEAR_STOP;
  I2C_nb_transmited=0;
  if ( ~b_I2C_busy )
  {
    I2C_Err = Tranfer_OK;
    b_I2C_busy =1;
    ENABLE_I2C_IT;
    I2C_SET_START; 
  }
  else
  {
    I2C_SET_STOP;
    return I2C_NOT_FREE;
  }
}


/*F**************************************************************************
* NAME: I2C_slave_polling 
*----------------------------------------------------------------------------
* PARAMS:
* return:  I2C error code state
*----------------------------------------------------------------------------
* PURPOSE: 
* This function can be called to be able to answer another master request
* in polling mode.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
unsigned char I2C_slave_polling (void)
{
  I2C_WAIT_EVENT;
  I2C_decode_status();
  I2C_CLEAR_SI;
  while( b_I2C_busy  )
  {
    I2C_WAIT_EVENT;
    I2C_decode_status();
    I2C_CLEAR_SI;
  }
  return I2C_Err;
}


/*F**************************************************************************
* NAME: I2C_slave_interrupt 
*----------------------------------------------------------------------------
* PARAMS:
* return:  none
*----------------------------------------------------------------------------
* PURPOSE: 
* This function can be called to be able to answer another master request
* in interrupt mode (stand alone mode).
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
void I2C_slave_interrupt (void)
{
  ENABLE_IT;
  ENABLE_I2C_IT;
}



/*F**************************************************************************
* NAME: I2C_interrupt 
*----------------------------------------------------------------------------
* PARAMS:
* return:  none
*----------------------------------------------------------------------------
* PURPOSE: 
* I2C interrupt routine service
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE: 
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
void I2C_interrupt() interrupt IRQ_I2C using 1
{
  I2C_decode_status();
  I2C_CLEAR_SI;
}