can.c

CAN_FIFO收发例程

CANMessageSet(unsigned long ulBase, unsigned long ulObjID,
              tCANMsgObject *pMsgObject, tMsgObjType eMsgType)
{
    unsigned short usCmdMaskReg;
    unsigned short usMaskReg0, usMaskReg1;
    unsigned short usArbReg0, usArbReg1;
    unsigned short usMsgCtrl;
    tBoolean bTransferData;
    tBoolean bUseExtendedID;

    bTransferData = 0;

    //
    // Check the arguments.
    //
    ASSERT(CANBaseValid(ulBase));
    ASSERT((ulObjID <= 32) && (ulObjID != 0));
    ASSERT((eMsgType == MSG_OBJ_TYPE_TX) ||
           (eMsgType == MSG_OBJ_TYPE_TX_REMOTE) ||
           (eMsgType == MSG_OBJ_TYPE_RX) ||
           (eMsgType == MSG_OBJ_TYPE_RX_REMOTE) ||
           (eMsgType == MSG_OBJ_TYPE_TX_REMOTE) ||
           (eMsgType == MSG_OBJ_TYPE_RXTX_REMOTE));

    //
    // Wait for busy bit to clear
    //
    while(CANRegRead(ulBase + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
    {
    }

    //
    // See if we need to use an extended identifier or not.
    //
    if((pMsgObject->ulMsgID > CAN_MAX_11BIT_MSG_ID) ||
       (pMsgObject->ulFlags & MSG_OBJ_EXTENDED_ID))
    {
        bUseExtendedID = 1;
    }
    else
    {
        bUseExtendedID = 0;
    }

    //
    // This is always a write to the Message object as this call is setting a
    // message object.  This call will also always set all size bits so it sets
    // both data bits.  The call will use the CONTROL register to set control
    // bits so this bit needs to be set as well.
    //
    usCmdMaskReg = (CAN_IF1CMSK_WRNRD | CAN_IF1CMSK_DATAA | CAN_IF1CMSK_DATAB |
                    CAN_IF1CMSK_CONTROL);

    //
    // Initialize the values to a known state before filling them in based on
    // the type of message object that is being configured.
    //
    usArbReg0 = 0;
    usArbReg1 = 0;
    usMsgCtrl = 0;
    usMaskReg0 = 0;
    usMaskReg1 = 0;

    switch(eMsgType)
    {
        //
        // Transmit message object.
        //
        case MSG_OBJ_TYPE_TX:
        {
            //
            // Set the TXRQST bit and the reset the rest of the register.
            //
            usMsgCtrl |= CAN_IF1MCTL_TXRQST;
            usArbReg1 = CAN_IF1ARB2_DIR;
            bTransferData = 1;
            break;
        }

        //
        // Transmit remote request message object
        //
        case MSG_OBJ_TYPE_TX_REMOTE:
        {
            //
            // Set the TXRQST bit and the reset the rest of the register.
            //
            usMsgCtrl |= CAN_IF1MCTL_TXRQST;
            usArbReg1 = 0;
            break;
        }

        //
        // Receive message object.
        //
        case MSG_OBJ_TYPE_RX:
        {
            //
            // This clears the DIR bit along with everything else.  The TXRQST
            // bit was cleared by defaulting usMsgCtrl to 0.
            //
            usArbReg1 = 0;
            break;
        }

        //
        // Receive remote request message object.
        //
        case MSG_OBJ_TYPE_RX_REMOTE:
        {
            //
            // The DIR bit is set to one for remote receivers.  The TXRQST bit
            // was cleared by defaulting usMsgCtrl to 0.
            //
            usArbReg1 = CAN_IF1ARB2_DIR;

            //
            // Set this object so that it only indicates that a remote frame
            // was received and allow for software to handle it by sending back
            // a data frame.
            //
            usMsgCtrl = CAN_IF1MCTL_UMASK;

            //
            // Use the full Identifier by default.
            //
            usMaskReg0 = 0xffff;
            usMaskReg1 = 0x1fff;

            //
            // Make sure to send the mask to the message object.
            //
            usCmdMaskReg |= CAN_IF1CMSK_MASK;
            break;
        }

        //
        // Remote frame receive remote, with auto-transmit message object.
        //
        case MSG_OBJ_TYPE_RXTX_REMOTE:
        {
            //
            // Oddly the DIR bit is set to one for remote receivers.
            //
            usArbReg1 = CAN_IF1ARB2_DIR;

            //
            // Set this object to auto answer if a matching identifier is seen.
            //
            usMsgCtrl = CAN_IF1MCTL_RMTEN | CAN_IF1MCTL_UMASK;

            //
            // The data to be returned needs to be filled in.
            //
            bTransferData = 1;
            break;
        }

        //
        // This case should never happen due to the ASSERT statement at the
        // beginning of this function.
        //
        default:
        {
            return;
        }
    }

    //
    // Configure the Mask Registers.
    //
    if(pMsgObject->ulFlags & MSG_OBJ_USE_ID_FILTER)
    {
        if(bUseExtendedID)
        {
            //
            // Set the 29 bits of Identifier mask that were requested.
            //
            usMaskReg0 = pMsgObject->ulMsgIDMask & CAN_IF1MSK1_IDMSK_M;
            usMaskReg1 = ((pMsgObject->ulMsgIDMask >> 16) &
                            CAN_IF1MSK2_IDMSK_M);
        }
        else
        {
            //
            // Lower 16 bit are unused so set them to zero.
            //
            usMaskReg0 = 0;

            //
            // Put the 11 bit Mask Identifier into the upper bits of the field
            // in the register.
            //
            usMaskReg1 = ((pMsgObject->ulMsgIDMask << 2) &
                            CAN_IF1MSK2_IDMSK_M);
        }
    }

    //
    // If the caller wants to filter on the extended ID bit then set it.
    //
    if((pMsgObject->ulFlags & MSG_OBJ_USE_EXT_FILTER) ==
       MSG_OBJ_USE_EXT_FILTER)
    {
        usMaskReg1 |= CAN_IF1MSK2_MXTD;
    }

    //
    // The caller wants to filter on the message direction field.
    //
    if((pMsgObject->ulFlags & MSG_OBJ_USE_DIR_FILTER) ==
       MSG_OBJ_USE_DIR_FILTER)
    {
        usMaskReg1 |= CAN_IF1MSK2_MDIR;
    }

    if(pMsgObject->ulFlags & (MSG_OBJ_USE_ID_FILTER | MSG_OBJ_USE_DIR_FILTER |
                              MSG_OBJ_USE_EXT_FILTER))
    {
        //
        // Set the UMASK bit to enable using the mask register.
        //
        usMsgCtrl |= CAN_IF1MCTL_UMASK;

        //
        // Set the MASK bit so that this gets transferred to the Message Object.
        //
        usCmdMaskReg |= CAN_IF1CMSK_MASK;
    }

    //
    // Set the Arb bit so that this gets transferred to the Message object.
    //
    usCmdMaskReg |= CAN_IF1CMSK_ARB;

    //
    // Configure the Arbitration registers.
    //
    if(bUseExtendedID)
    {
        //
        // Set the 29 bit version of the Identifier for this message object.
        //
        usArbReg0 |= pMsgObject->ulMsgID & CAN_IF1ARB1_ID_M;
        usArbReg1 |= (pMsgObject->ulMsgID >> 16) & CAN_IF1ARB2_ID_M;

        //
        // Mark the message as valid and set the extended ID bit.
        //
        usArbReg1 |= CAN_IF1ARB2_MSGVAL | CAN_IF1ARB2_XTD;
    }
    else
    {
        //
        // Set the 11 bit version of the Identifier for this message object.
        // The lower 18 bits are set to zero.
        //
        usArbReg1 |= (pMsgObject->ulMsgID << 2) & CAN_IF1ARB2_ID_M;

        //
        // Mark the message as valid.
        //
        usArbReg1 |= CAN_IF1ARB2_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_IF1MCTL_DLC_M);

    //
    // Mark this as the last entry if this is not the last entry in a FIFO.
    //
    if((pMsgObject->ulFlags & MSG_OBJ_FIFO) == 0)
    {
        usMsgCtrl |= CAN_IF1MCTL_EOB;
    }

    //
    // Enable transmit interrupts if they should be enabled.
    //
    if(pMsgObject->ulFlags & MSG_OBJ_TX_INT_ENABLE)
    {
        usMsgCtrl |= CAN_IF1MCTL_TXIE;
    }

    //
    // Enable receive interrupts if they should be enabled.
    //
    if(pMsgObject->ulFlags & MSG_OBJ_RX_INT_ENABLE)
    {
        usMsgCtrl |= CAN_IF1MCTL_RXIE;
    }

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

    //
    // Write out the registers to program the message object.
    //
    CANRegWrite(ulBase + CAN_O_IF1CMSK, usCmdMaskReg);
    CANRegWrite(ulBase + CAN_O_IF1MSK1, usMaskReg0);
    CANRegWrite(ulBase + CAN_O_IF1MSK2, usMaskReg1);
    CANRegWrite(ulBase + CAN_O_IF1ARB1, usArbReg0);
    CANRegWrite(ulBase + CAN_O_IF1ARB2, usArbReg1);
    CANRegWrite(ulBase + CAN_O_IF1MCTL, usMsgCtrl);

    //
    // Transfer the message object to the message object specifiec by ulObjID.
    //
    CANRegWrite(ulBase + CAN_O_IF1CRQ, ulObjID & CAN_IF1CRQ_MNUM_M);

    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:
//!
//! - \b MSG_OBJ_NEW_DATA indicates if this is new data since the last time it
//! was read
//! - \b 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 usMaskReg0, usMaskReg1;
    unsigned short usArbReg0, usArbReg1;
    unsigned short usMsgCtrl;

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

    //
    // This is always a read to the Message object as this call is setting a
    // message object.
    //
    usCmdMaskReg = (CAN_IF1CMSK_DATAA | CAN_IF1CMSK_DATAB |
                    CAN_IF1CMSK_CONTROL | CAN_IF1CMSK_MASK | CAN_IF1CMSK_ARB);

    //
    // Clear a pending interrupt and new data in a message object.
    //
    if(bClrPendingInt)
    {
        usCmdMaskReg |= CAN_IF1CMSK_CLRINTPND;
    }

    //
    // Set up the