lib_twi.c

this document is source code for arm9 of atmel

    return error;
}


/*-----------------------------------------------------------------------------
Function: AT91F_TWI_ReadSingle

Arguments: 
           <SlaveAddr>: Address of the slave device to read from.
           <data>: Pointer to the data to read

Comments : Read single data from a slave device without internal address.

Return Value: <data>: Data read via a pointer.
-----------------------------------------------------------------------------*/
int AT91F_TWI_ReadSingle(int SlaveAddr,
                         char *data)
{
    unsigned int status,error=0, end=0;

    /* Enable Master Mode */
    AT91C_BASE_TWI->TWI_CR = AT91C_TWI_MSEN|AT91C_TWI_SVDIS ;

    /* Set the TWI Master Mode Register */
    AT91C_BASE_TWI->TWI_MMR =  SlaveAddr | AT91C_TWI_MREAD;

    AT91C_BASE_TWI->TWI_CR = AT91C_TWI_START | AT91C_TWI_STOP;

    while (!end)
    {
      status = AT91C_BASE_TWI->TWI_SR;
      if ((status & AT91C_TWI_NACK_MASTER) == AT91C_TWI_NACK_MASTER)
      {
        error = AT91C_TWI_NACK_MASTER;
        end=1;
      }
    /*  Wait for the receive ready is set */
      if ((status & AT91C_TWI_RXRDY) == AT91C_TWI_RXRDY)
        end=1;
    }

    *data = AT91C_BASE_TWI->TWI_RHR;

   /* Wait for the Transmit complete is set */
   status = AT91C_BASE_TWI->TWI_SR;
   while (!(status & AT91C_TWI_TXCOMP_MASTER))
     status = AT91C_BASE_TWI->TWI_SR;

    return (error);
}

/*-----------------------------------------------------------------------------
Function: AT91F_TWI_ReadSingleIadr

Arguments: 
           <SlaveAddr>: Address of the slave device to read from.
           <IntAddr>: Internal slave device address. Set to 0 if no.
           <IntAddrSize>: Size of the internal address.Set to 0 if no.
           <data>: Pointer to the data to read

Comments : Read single data from a slave device with internal address.

Return Value: <data>: Data read via a pointer.
-----------------------------------------------------------------------------*/
int AT91F_TWI_ReadSingleIadr(int SlaveAddr,
                             int IntAddr,
                             int IntAddrSize,
                             char *data)
{
    unsigned int status,error=0, end=0;

    /* Enable Master Mode */
    AT91C_BASE_TWI->TWI_CR = AT91C_TWI_MSEN|AT91C_TWI_SVDIS ;

    /* Set the TWI Master Mode Register */
    AT91C_BASE_TWI->TWI_MMR =  SlaveAddr | IntAddrSize | AT91C_TWI_MREAD;

    /* Set TWI Internal Address Register if needed */
    AT91C_BASE_TWI->TWI_IADR = IntAddr;

    AT91C_BASE_TWI->TWI_CR = AT91C_TWI_START | AT91C_TWI_STOP;

    while (!end)
    {
      status = AT91C_BASE_TWI->TWI_SR;
      if ((status & AT91C_TWI_NACK_MASTER) == AT91C_TWI_NACK_MASTER)
      {
        error = AT91C_TWI_NACK_MASTER;
        end=1;
      }
    /*  Wait for the receive ready is set */
      if ((status & AT91C_TWI_RXRDY) == AT91C_TWI_RXRDY)
        end=1;
    }

    *data = AT91C_BASE_TWI->TWI_RHR;

   /* Wait for the Transmit complete is set */
   status = AT91C_BASE_TWI->TWI_SR;
   while (!(status & AT91C_TWI_TXCOMP_MASTER))
     status = AT91C_BASE_TWI->TWI_SR;

    return (error);
}

/*-----------------------------------------------------------------------------
Function: AT91F_TWI_ReadMultiple

Arguments: 
           <SlaveAddr>: Address of the slave device to read from.
           <NumOfBytes>: Number of data to read
           <data>: Pointer to the data to read

Comments : Read multiple data from a slave device without internal address.

Return Value: <data>: Data read via a pointer.
-----------------------------------------------------------------------------*/
int AT91F_TWI_ReadMultiple(int SlaveAddr,
                           char *data,
                           unsigned int NumOfBytes)
{
    unsigned int status,error=0, ReadCount, end=0;

   /* Enable Master Mode of the TWI */
   AT91C_BASE_TWI->TWI_CR = AT91C_TWI_MSEN|AT91C_TWI_SVDIS ;

   /* Set the TWI Master Mode Register */
   AT91C_BASE_TWI->TWI_MMR =  SlaveAddr | AT91C_TWI_MREAD ;

   /* Send the Start + slave address */
   AT91C_BASE_TWI->TWI_CR = AT91C_TWI_START;

   /* Read and store it into the buffer */
   for ( ReadCount=0; ReadCount <NumOfBytes; ReadCount++ )
   {
     /* if next-lo-last data send the stop */
     if (ReadCount == (NumOfBytes -1) )
       AT91C_BASE_TWI->TWI_CR = AT91C_TWI_STOP;
     
     end=0;
     
     /* Wait until RXRDY is high to read the next data or NACK received */
     while (!end)
     {
       status = AT91C_BASE_TWI->TWI_SR ;
       if ((status & AT91C_TWI_NACK_MASTER) == AT91C_TWI_NACK_MASTER)
       {
         error = AT91C_TWI_NACK_MASTER;
         end=1;
       }
       
       if ((status & AT91C_TWI_RXRDY) == AT91C_TWI_RXRDY)
         end=1;
    }

    /*  Read the char received */
    *data = AT91C_BASE_TWI->TWI_RHR;
    data++;
   }

   /* Wait for the Transmit complete is set */
   status = AT91C_BASE_TWI->TWI_SR;
   while (!(status & AT91C_TWI_TXCOMP_MASTER))
     status = AT91C_BASE_TWI->TWI_SR;
   
   return (error);
}

/*-----------------------------------------------------------------------------
Function: AT91F_TWI_ReadMultipleIadr

Arguments: 
           <SlaveAddr>: Address of the slave device to read from.
           <IntAddr>: Internal slave device address. Set to 0 if no.
           <IntAddrSize>: Size of the internal address.Set to 0 if no.
           <data>: Pointer to the data to read
           <NumOfBytes>: Number of data to read

Comments : Read multiple data from a slave device with internal address.

Return Value: <data>: Data read via a pointer.
-----------------------------------------------------------------------------*/
int AT91F_TWI_ReadMultipleIadr(int SlaveAddr,
                               int IntAddr,
                               int IntAddrSize,
                               char *data,
                               unsigned int NumOfBytes)
{
    unsigned int status,error=0,ReadCount,end=0 ;

   /* Enable Master Mode of the TWI */
   AT91C_BASE_TWI->TWI_CR = AT91C_TWI_MSEN|AT91C_TWI_SVDIS ;

   /* Set the TWI Master Mode Register */
   AT91C_BASE_TWI->TWI_MMR =  SlaveAddr | IntAddrSize | AT91C_TWI_MREAD;

   /* Set TWI Internal Address Register if needed */
   AT91C_BASE_TWI->TWI_IADR = IntAddr;

   /* Send the Start + slave address */
   AT91C_BASE_TWI->TWI_CR = AT91C_TWI_START;

   /* Read and store it into the buffer */
   for ( ReadCount=0; ReadCount <NumOfBytes; ReadCount++ )
   {
     /* if next-lo-last data send the stop */
     if (ReadCount == (NumOfBytes -1) )
       AT91C_BASE_TWI->TWI_CR = AT91C_TWI_STOP;
     
     end=0;
     
     /* Wait until RXRDY is high to read the next data or NACK received */
     while (!end)
     {
       status = AT91C_BASE_TWI->TWI_SR ;
       if ((status & AT91C_TWI_NACK_MASTER) == AT91C_TWI_NACK_MASTER)
       {
         error = AT91C_TWI_NACK_MASTER;
         end=1;
       }
       
       if ((status & AT91C_TWI_RXRDY) == AT91C_TWI_RXRDY)
         end=1;
    }

    /*  Read the char received */
    *data = AT91C_BASE_TWI->TWI_RHR;
    data++;
   }

   /* Wait for the Transmit complete is set */
   status = AT91C_BASE_TWI->TWI_SR;
   while (!(status & AT91C_TWI_TXCOMP_MASTER))
     status = AT91C_BASE_TWI->TWI_SR;
   
   return (error);
}

/*----------------------------------------------------------------------------
Function : AT91F_TWI_ProbeDevices
Arguments: 
           <SlaveAddr>: Address of the slave device to probe.

Comments : Write a single data into a slave device to see if it is connected on
           the bus.

Return Value: AT91C_TWI_NACK_MASTER if so, SlaveAddress otherwise.
-----------------------------------------------------------------------------*/
int AT91F_TWI_ProbeDevices(int SlaveAddr)
{
    unsigned int end = 0, status, Return;

    /* Enable Master Mode */
    AT91C_BASE_TWI->TWI_CR = AT91C_TWI_MSEN|AT91C_TWI_SVDIS ;

    /* Set the TWI Master Mode Register */
    AT91C_BASE_TWI->TWI_MMR =  SlaveAddr & ~AT91C_TWI_MREAD;

    /* Write the data to send into THR. Start conditionn DADDR and R/W bit
       are sent automatically */
    AT91C_BASE_TWI->TWI_THR = 0x55;

    while (!end)
    {
      status = AT91C_BASE_TWI->TWI_SR;
      if ((status & AT91C_TWI_NACK_MASTER) == AT91C_TWI_NACK_MASTER)
      {
        Return = AT91C_TWI_NACK_MASTER ;
        end=1;
      }
      /*  Wait for the Transmit ready is set */
      else if ((status & AT91C_TWI_TXRDY_MASTER) == AT91C_TWI_TXRDY_MASTER)
      {
        end=1;
        Return = SlaveAddr>>16;
      }
    }

    /* Wait for the Transmit complete is set */
    status = AT91C_BASE_TWI->TWI_SR;
    while (!(status & AT91C_TWI_TXCOMP_MASTER))
      status = AT91C_BASE_TWI->TWI_SR;

    return (Return);
}

/*-----------------------------------------------------------------------------
* \fn    AT91F_TWI_Open
* \brief Initializes TWI device
-----------------------------------------------------------------------------*/
void AT91F_TWI_Open(int TwiClock)
{
    /* Configure the PIO pins corresponding to the TWI pins */
    AT91F_TWI_CfgPIO ();

    /* Configure PMC by enabling TWI clock */
    AT91F_TWI_CfgPMC ();

    /* Reset the TWI */
    AT91C_BASE_TWI->TWI_CR = AT91C_TWI_SWRST;

    /* Configure TWI in master mode */
    AT91F_TWI_Configure (AT91C_BASE_TWI);

    /* Set TWI Clock Waveform Generator Register */
    AT91F_SetTwiClock(TwiClock);
}