owirepdd.c

Microsoft WinCE 6.0 BSP FINAL release source code for use with the i.MX27ADS TO2 WCE600_FINAL_MX27_S

        }
    }

    LeaveCriticalSection(&g_hOwireLock);

    OWIRE_FUNCTION_EXIT();

    return TRUE;
}


//------------------------------------------------------------------------------
//
// Function: OwireReadData
//
// Read count number of bytes from DS2502.
// This function calls OwireReadByte to read one byte at
// a time into readBuf.
//
// Parameters:
//      readBuf
//          [out] Buffer for bytes read from DS2502
//      count
//          [in] Number of bytes to read into readBuf
//
// Returns:
//      TRUE if read sequence successful
//      FALSE if read sequence failed
//
//------------------------------------------------------------------------------
BOOL OwireReadData(BYTE* readBuf, DWORD count)
{
    UINT32 i;

    OWIRE_FUNCTION_ENTRY();

    EnterCriticalSection(&g_hOwireLock);

    // Read one byte at a time from the DS2502
    for (i = 0; i < count; i++) 
    {
        if (!OwireReadByte(&readBuf[i]))
        {
            return FALSE;
        }
        DEBUGMSG(ZONE_READWRITE, (TEXT("Read byte[%d] = %x\r\n"), i, readBuf[i]));
    }

    LeaveCriticalSection(&g_hOwireLock);

    OWIRE_FUNCTION_EXIT();

    return TRUE;
}


//------------------------------------------------------------------------------
//
// Function: OwireWriteByte
//
// Sends 8 bits of data to DS2502.
// This function calls WriteBit to send the 8-bit data one bit at a time.
//
// Parameters:
//      UINT8 byte - 8-bit data to be sent to DS2502
//
// Returns:
//      FALSE if writing sequence failed
//      TRUE if writing sequence successful
//
//------------------------------------------------------------------------------
BOOL OwireWriteByte(UINT8 byte)
{
    UINT8 byte_bit;
    UINT8 count;

    OWIRE_FUNCTION_ENTRY();

    DEBUGMSG(ZONE_READWRITE, (TEXT("Writing byte %x\r\n"), byte));

    byte_bit = byte;
    for (count = 0; count < 8; count++)
    {
        if (!OwireWriteBit(byte_bit & 0x1))
        {
            DEBUGMSG(ZONE_ERROR, (TEXT("Writing bit[%d] = %d failed!\r\n"), count, byte_bit & 0x1));
            return FALSE;
        }
        byte_bit >>= 1;
    }

    OWIRE_FUNCTION_EXIT();

    return TRUE;
}


//------------------------------------------------------------------------------
//
// Function: OwireReadByte
//
// Read 8 bits of data from DS2502.
// This function calls ReadBit to read one bit at
// a time and reconstruct the byte of information.
//
// Parameters:
//      by
//          [out] Pointer to byte where 8-bit data
//          from the DS2502 is stored
//
// Returns:
//      TRUE if read sequence successful
//      FALSE if read sequence failed
//
//------------------------------------------------------------------------------
BOOL OwireReadByte(BYTE *byte)
{
    BYTE result;
    UINT8 count;

    OWIRE_FUNCTION_ENTRY();

    // Clear byte.  We will build this byte from
    // the eight bits we read.
    *byte = 0;

    for (count = 0; count < 8; count++)
    {
        result = OwireReadBit();
        if (result == ERROR_READ_FAULT)
        {
            DEBUGMSG(ZONE_ERROR, (TEXT("Reading byte[%d] failed!  Data invalid.\r\n"), count));
            return FALSE;
        }
        DEBUGMSG(ZONE_READWRITE, (TEXT("Read bit %x\r\n"), result));
		
        *byte |= ((result & 0x1) << count);
    }

    DEBUGMSG(ZONE_READWRITE, (TEXT("Read byte %x\r\n"), *byte));

    OWIRE_FUNCTION_EXIT();

    return TRUE;
}


//------------------------------------------------------------------------------
//
// Function: OwireWriteBit
//
// This is a function to write a bit, 0 or 1, to DS2502.
//
// Parameters:
//      UINT8 bit
//          bit is 0 : Write 0 (set 1 to WR0 bit of OWIRE_CR)
//                 1 : Write 1 (set 1 to WR1 bit of OWIRE_CR)
//
// Returns:
//      TRUE if writing sequence successful
//      FALSE if writing sequence failed
//
//     WR0
//      ____a                _____b__________
//          |               /     :
//          |       A       |  B  :
//          |_______________|     :
//          *****************
//     ----------------------------------------------------
//        a: Set WR0 b:WR0 auto cleared
//        A: 100us    B:17us
//
//     WR1
//      ____a    _________________b__________
//          |   /                 :
//          | A |        B        :
//          |___|                 :
//          *****
//     ----------------------------------------------------
//        a: Set WR1 b:WR1 auto cleared
//        A: 5us        B:112us
//
//     *: Master Transmits
//
//------------------------------------------------------------------------------
BOOL OwireWriteBit(UINT8 bit)
{
    OWIRE_FUNCTION_ENTRY();

    switch(bit)
    {
        case 0:
            INSREG16(&g_pOWIRE->CR, CSP_BITFMASK(OWIRE_CR_WR0), 
                CSP_BITFVAL(OWIRE_CR_WR0, OWIRE_CR_WR0_WRITE));

            // Need to delay here for 117uSec while
            // the write 0 operation is acknowledged.
            // Try to give remaining timeslice to another 
            // thread while waiting.
            while (EXTREG16(&g_pOWIRE->CR, CSP_BITFMASK(OWIRE_CR_WR0), OWIRE_CR_WR0_LSH))
                Sleep(0);

            break;
        case 1:
            INSREG16(&g_pOWIRE->CR, CSP_BITFMASK(OWIRE_CR_WR1RD), 
                CSP_BITFVAL(OWIRE_CR_WR1RD, OWIRE_CR_WR1RD_WRITE));

            // Need to delay here for 117uSec while
            // the write 1 operation is acknowledged.
            // Try to give remaining timeslice to another 
            // thread while waiting.
            while (EXTREG16(&g_pOWIRE->CR, CSP_BITFMASK(OWIRE_CR_WR1RD), OWIRE_CR_WR1RD_LSH))
                Sleep(0);

            break;
        default:
            return FALSE;
    }
    OWIRE_FUNCTION_EXIT();
    return TRUE;
}


//------------------------------------------------------------------------------
//
// Function: OwireReadBit
//
// This is a function to read a bit, 0 or 1, from DS2502.
//
// Parameters:
//      None.
//
// Returns:
//      0  - Read 0 bit (RDST bit is 0).
//      1  - Read 1 bit (RDST bit is 1).
//      ERROR_READ_FAULT - Failed (WR1/RD bit wasn't cleared)
//
//    Read 0
//      ____a                _____b__________
//          |               /     :
//          |       A       |  B  :
//          |_______________|     :
//          *****
//     ----------------------------------------------------
//        a: Set WR1/RD     b:WR1/RD auto cleared
//        A: 45us           A+B:117us
//
//  Read 1
//      ____a    _________________b__________
//          |   /                 :
//          | A |        B        :
//          |___|                 :
//          *****
//     ----------------------------------------------------
//        a: Set WR1/RD     b:WR1/RD auto cleared
//        A: 5us            A+B:117us
//
//     *: Master Transmits
//
//------------------------------------------------------------------------------
BYTE OwireReadBit(void)
{
    BYTE bit = 0;

    OWIRE_FUNCTION_ENTRY();

    // Write to WR1RD bit in order to perform a read
    INSREG16(&g_pOWIRE->CR, CSP_BITFMASK(OWIRE_CR_WR1RD), 
        CSP_BITFVAL(OWIRE_CR_WR1RD, OWIRE_CR_WR1RD_WRITE));

    // Need to delay here for 117uSec before
    // reading bit from RDST field.
    // Try to give remaining timeslice to another 
    // thread while waiting.
    while (EXTREG16(&g_pOWIRE->CR, CSP_BITFMASK(OWIRE_CR_WR1RD), OWIRE_CR_WR1RD_LSH))
        Sleep(0);

    if (EXTREG16(&g_pOWIRE->CR, CSP_BITFMASK(OWIRE_CR_WR1RD), OWIRE_CR_WR1RD_LSH))
    {
        DEBUGMSG(ZONE_ERROR, (TEXT("Reading failed!\r\n")));
        return ERROR_READ_FAULT;
    }

    // Read bit from RDST and return
    bit = EXTREG16(&g_pOWIRE->CR, CSP_BITFMASK(OWIRE_CR_RDST), OWIRE_CR_RDST_LSH);

    OWIRE_FUNCTION_EXIT();

    return bit;
}