can.c

Luminary cotex-M3 CAN总线 源代码

    {
        //
        // Set the 29 bit version of the Identifier for this message object.
        //
        usArbReg[0] |= pMsgObject->ulMsgID & CAN_IFARB1_ID;
        usArbReg[1] |= (pMsgObject->ulMsgID >> 16) & CAN_IFARB2_ID;

        //
        // Mark the message as valid and set the extended ID bit.
        //
        usArbReg[1] |= CAN_IFARB2_MSGVAL | CAN_IFARB2_XTD;
    }
    else
    {
        //
        // Set the 11 bit version of the Identifier for this message object.
        // The lower 18 bits are set to zero.
        //
        usArbReg[1] |= (pMsgObject->ulMsgID << 2) & CAN_IFARB2_ID;

        //
        // Mark the message as valid.
        //
        usArbReg[1] |= CAN_IFARB2_MSGVAL;
    }

    //
    // Set the data length since this is set for all transfers.
    // This is also a single transfer and not a FIFO transfer so set EOB bit.
    //
    usMsgCtrl |= (pMsgObject->ulMsgLen & CAN_IFMCTL_DLC) | CAN_IFMCTL_EOB;

    //
    // Enable transmit interrupts if they should be enabled.
    //
    if(pMsgObject->ulFlags & MSG_OBJ_TX_INT_ENABLE)
    {
        usMsgCtrl |= CAN_IFMCTL_TXIE;
    }

    //
    // Enable receive interrupts if they should be enabled.
    //
    if(pMsgObject->ulFlags & MSG_OBJ_RX_INT_ENABLE)
    {
        usMsgCtrl |= CAN_IFMCTL_RXIE;
    }

    //
    // Write the data out to the CAN Data registers if needed.
    //
    if(bTransferData)
    {
        CANWriteDataReg(
            pMsgObject->pucMsgData,
            (unsigned long *)(ulBase + CAN_O_IF1DA1), pMsgObject->ulMsgLen);
    }

    //
    // Write out the registers to program the message object.
    //
    CANWriteReg(ulBase + CAN_O_IF1CMSK, usCmdMaskReg);
    CANWriteReg(ulBase + CAN_O_IF1MSK1, usMaskReg[0]);
    CANWriteReg(ulBase + CAN_O_IF1MSK2, usMaskReg[1]);
    CANWriteReg(ulBase + CAN_O_IF1ARB1, usArbReg[0]);
    CANWriteReg(ulBase + CAN_O_IF1ARB2, usArbReg[1]);
    CANWriteReg(ulBase + CAN_O_IF1MCTL, usMsgCtrl);

    //
    // Transfer the message object to the message object specifiec by ulObjID.
    //
    CANWriteReg(ulBase + CAN_O_IF1CRQ, ulObjID & CAN_IFCRQ_MNUM_MSK);

    return;
}

//*****************************************************************************
//
//! Reads a CAN message from one of the message object buffers
//!
//! \param ulBase is the base address of the CAN controller.
//! \param ulObjID is the object number to read (1-32)
//! \param pMsgObject points to a structure containing message object fields
//! \param bClrPendingInt indicates whether an associated interrupt should
//! be cleared
//!
//! This function is used to read the contents of one of the 32 message
//! objects in the CAN controller, and return it to the caller.  The data
//! returned is stored in the fields of the caller supplied structure pointed
//! to by \e pMsgObject.  The data consists of all of the parts of a CAN
//! message, plus some control and status information.
//!
//! Normally this is used to read a message object that has received and
//! stored a CAN message with a certain identifier.  However this could also be
//! used to read the contents of a message object in order to load the fields
//! of the structure in case only part of the structure needs to be changed
//! from a previous setting.
//!
//! When using CANMessageGet, all of the same fields of the structure are
//! populated in the same way as when the CANMessageSet() function is used,
//! with the following exceptions:
//!
//! \e pMsgObject->ulFlags:
//!
//! - MSG_OBJ_NEW_DATA indicates if this is new data since the last
//! time it was read
//! - MSG_OBJ_DATA_LOST indicates that at least one message was received
//! on this message object, and not read by the host before being
//! overwritten.
//!
//! \return None.
//
//*****************************************************************************
void
CANMessageGet(unsigned long ulBase, unsigned long ulObjID,
              tCANMsgObject *pMsgObject, tBoolean bClrPendingInt)
{
    unsigned short usCmdMaskReg;
    unsigned short usMaskReg[2];
    unsigned short usArbReg[2];
    unsigned short usMsgCtrl;

    //
    // Check the arguments.
    //
    ASSERT((ulBase == CAN0_BASE) ||
           (ulBase == CAN1_BASE));
    ASSERT((ulObjID <= 32) && (ulObjID != 0));

    //
    // This is always a read to the Message object as this call is setting
    // a message object.
    //
    usCmdMaskReg = CAN_IFCMSK_DATAA | CAN_IFCMSK_DATAB | CAN_IFCMSK_CONTROL |
                   CAN_IFCMSK_MASK | CAN_IFCMSK_ARB;

    //
    // Clear a pending interrupt and new data in a message object.
    //
    if(bClrPendingInt)
    {
        usCmdMaskReg |= CAN_IFCMSK_CLRINTPND;
    }

    //
    // Set up the request for data from the message object.
    //
    CANWriteReg(ulBase + CAN_O_IF2CMSK, usCmdMaskReg);

    //
    // Transfer the message object to the message object specifiec by ulObjID.
    //
    CANWriteReg(ulBase + CAN_O_IF2CRQ, ulObjID & CAN_IFCRQ_MNUM_MSK);

    //
    // Wait for busy bit to clear
    //
    while(CANReadReg(ulBase + CAN_O_IF2CRQ) & CAN_IFCRQ_BUSY)
    {
    }

    //
    // Read out the IF Registers.
    //
    usMaskReg[0] = CANReadReg(ulBase + CAN_O_IF2MSK1);
    usMaskReg[1] = CANReadReg(ulBase + CAN_O_IF2MSK2);
    usArbReg[0] = CANReadReg(ulBase + CAN_O_IF2ARB1);
    usArbReg[1] = CANReadReg(ulBase + CAN_O_IF2ARB2);
    usMsgCtrl = CANReadReg(ulBase + CAN_O_IF2MCTL);

    pMsgObject->ulFlags = MSG_OBJ_NO_FLAGS;

    //
    // Determine if this is a remote frame by checking the TXRQST and DIR bits.
    //
    if((!(usMsgCtrl & CAN_IFMCTL_TXRQST) && (usArbReg[1] & CAN_IFARB2_DIR)) ||
       ((usMsgCtrl & CAN_IFMCTL_TXRQST) && (!(usArbReg[1] & CAN_IFARB2_DIR))))
    {
        pMsgObject->ulFlags |= MSG_OBJ_REMOTE_FRAME;
    }

    //
    // Get the Identifier out of the register, the format depends on size of
    // the Mask.
    //
    if(usArbReg[1] & CAN_IFARB2_XTD)
    {
        //
        // Set the 29 bit version of the Identifier for this message object.
        //
        pMsgObject->ulMsgID = ((usArbReg[1] & CAN_IFARB2_ID) << 16) |
            usArbReg[0];

        pMsgObject->ulFlags |= MSG_OBJ_EXTENDED_ID;
    }
    else
    {
        //
        // The Identifier is an 11 bit value.
        //
        pMsgObject->ulMsgID = (usArbReg[1] & CAN_IFARB2_ID) >> 2;
    }

    //
    // Indicate that we lost some data.
    //
    if(usMsgCtrl & CAN_IFMCTL_MSGLST)
    {
        pMsgObject->ulFlags |= MSG_OBJ_DATA_LOST;
    }

    //
    // Set the flag to indicate if ID masking was used.
    //
    if(usMsgCtrl & CAN_IFMCTL_UMASK)
    {
        if(usArbReg[1] & CAN_IFARB2_XTD)
        {
            //
            // The Identifier Mask is assumed to also be a 29 bit value.
            //
            pMsgObject->ulMsgIDMask =
                ((usMaskReg[1] & CAN_IFMSK2_MSK) << 16) | usMaskReg[0];
            //
            // If this is a fully specified Mask and a remote frame then don't
            // set the MSG_OBJ_USE_ID_FILTER because the ID was not really
            // filtered.
            //
            if((pMsgObject->ulMsgIDMask != 0x1fffffff) ||
               ((pMsgObject->ulFlags & MSG_OBJ_REMOTE_FRAME) == 0))
            {
                pMsgObject->ulFlags |= MSG_OBJ_USE_ID_FILTER;
            }
        }
        else
        {
            //
            // The Identifier Mask is assumed to also be an 11 bit value.
            //
            pMsgObject->ulMsgIDMask = (usMaskReg[1] & CAN_IFMSK2_MSK) >> 2;

            //
            // If this is a fully specified Mask and a remote frame then don't
            // set the MSG_OBJ_USE_ID_FILTER because the ID was not really
            // filtered.
            //
            if((pMsgObject->ulMsgIDMask != 0x7ff) ||
               ((pMsgObject->ulFlags & MSG_OBJ_REMOTE_FRAME) == 0))
            {
                pMsgObject->ulFlags |= MSG_OBJ_USE_ID_FILTER;
            }
        }

        //
        // Indicate if the extended bit was used in filtering.
        //
        if(usMaskReg[1] & CAN_IFMSK2_MXTD)
        {
            pMsgObject->ulFlags |= MSG_OBJ_USE_EXT_FILTER;
        }

        //
        // Indicate if direction filtering was enabled.
        //
        if(usMaskReg[1] & CAN_IFMSK2_MDIR)
        {
            pMsgObject->ulFlags |= MSG_OBJ_USE_DIR_FILTER;
        }
    }

    //
    // Set the interupt flags.
    //
    if(usMsgCtrl & CAN_IFMCTL_TXIE)
    {
        pMsgObject->ulFlags |= MSG_OBJ_TX_INT_ENABLE;
    }
    if(usMsgCtrl & CAN_IFMCTL_RXIE)
    {
        pMsgObject->ulFlags |= MSG_OBJ_RX_INT_ENABLE;
    }

    //
    // See if there is new data available.
    //
    if(usMsgCtrl & CAN_IFMCTL_NEWDAT)
    {
        //
        // Get the amount of data needed to be read.
        //
        pMsgObject->ulMsgLen = (usMsgCtrl & CAN_IFMCTL_DLC);

        //
        // Don't read any data for a remote frame, there is nothing valid
        // in that buffer anyway.
        //
        if((pMsgObject->ulFlags & MSG_OBJ_REMOTE_FRAME) == 0)
        {
            //
            // Read out the data from the CAN registers.
            //
            CANReadDataReg(pMsgObject->pucMsgData,
                           (unsigned long *)(ulBase + CAN_O_IF2DA1),
                           pMsgObject->ulMsgLen);
        }

        //
        // Now clear out the new data flag.
        //
        CANWriteReg(ulBase + CAN_O_IF2CMSK, CAN_IFCMSK_NEWDAT);

        //
        // Transfer the message object to the message object specifiec by
        // ulObjID.
        //
        CANWriteReg(ulBase + CAN_O_IF2CRQ, ulObjID & CAN_IFCRQ_MNUM_MSK);

        //
        // Wait for busy bit to clear
        //
        while(CANReadReg(ulBase + CAN_O_IF2CRQ) & CAN_IFCRQ_BUSY)
        {
        }

        //
        // Indicate that there is new data in this message.
        //
        pMsgObject->ulFlags |= MSG_OBJ_NEW_DATA;
    }
    else
    {
        //
        // Along with the MSG_OBJ_NEW_DATA not being set the amount of data
        // needs to be set to zero if none was available.
        //
        pMsgObject->ulMsgLen = 0;
    }
}

//*****************************************************************************
//
//! Clears a message object so that it is no longer used
//!
//! \param ulBase is the base address of the CAN controller.
//! \param ulObjID is the message object number to disable (1-32)
//!
//! This function frees the specified message object from use.  Once a
//! message object has been "cleared" it will no longer automatically
//! send or receive messages, or generate interrupts.
//!
//! \return None.
//
//*****************************************************************************
void
CANMessageClear(unsigned long ulBase, unsigned long ulObjID)
{
    //
    // Check the arguments.
    //
    ASSERT((ulBase == CAN0_BASE) ||
           (ulBase == CAN1_BASE));
    ASSERT((ulObjID >= 1) && (ulObjID <= 32));

    //
    // Wait for busy bit to clear
    //
    while(CANReadReg(ulBase + CAN_O_IF1CRQ) & CAN_IFCRQ_BUSY)
    {
    }

    //
    // Clear the message value bit in the arbitration register.
    // This indicates the message is not valid.
    //
    CANWriteReg(ulBase + CAN_O_IF1CMSK, CAN_IFCMSK_WRNRD | CAN_IFCMSK_ARB);
    CANWriteReg(ulBase + CAN_O_IF1ARB1, 0);
    CANWriteReg(ulBase + CAN_O_IF1ARB2, 0);

    //
    // Initiate programming the message object
    //
    CANWriteReg(ulBase + CAN_O_IF1CRQ, ulObjID & CAN_IFCRQ_MNUM_MSK);
}

//*****************************************************************************
//
// Close the Doxygen group.
//! @}
//
//*****************************************************************************