can.c

关于devicenet的源代码。micorchip公司的

 *
 * PreCondition:   	 
 *
 * Input:       	none
 *                  
 * Output:      	none
 *
 * Side Effects:   	
 *
 * Overview:        Indicates to the module that the data has been read.
 *
 * Note:           	This effectively frees the active hardware buffer 
 *					to continue receiving.
 ********************************************************************/
void CANRead(void)
{
	if (_msgRxBuf == 0)
	{
		RXB0CONbits.RXFUL = 0;
	}
	else 
	if (_msgRxBuf == 1)
	{
		RXB1CONbits.RXFUL = 0;
	}	
}

/*********************************************************************
 * Function:        NEAR unsigned char CANIsTxRdy(void)
 *
 * PreCondition:   	 
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char status of the request
 *
 * Side Effects:   	
 *
 * Overview:        Returns TRUE if the transmit engine is ready to 
 *					accept new data to transmit.
 *
 * Note:           	This function is as simple as it gets, i.e. direct
 *					access to only one TX buffer. 
 ********************************************************************/
NEAR unsigned char CANIsTxRdy(void)
{
	return (!(TXB0CONbits.TXREQ));
}

/*********************************************************************
 * Function:        NEAR unsigned char CANIsMsgSent(void)
 *
 * PreCondition:   	 
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char status of the request
 *
 * Side Effects:   	
 *
 * Overview:        Returns the tag of the data that was last transmitted. 
 *					Any additional calls without additional transmissions
 *					will return NULL.
 *
 * Note:           	This is useful to determine when and who's data was 
 *					placed on the bus. This may seem redundent since
 *					only one hardware buffer is used; however, this
 *					architecture allows for expansion to deep software/
 *					hardware buffer designs without major changes to 
 *					the upper level firmware.
 ********************************************************************/
NEAR unsigned char CANIsMsgSent(void)
{
	NEAR unsigned char temp;
	
	if (!(TXB0CONbits.TXREQ))
	{
		temp = _msgTxTag;
		_msgTxTag = 0;
		return (temp);
	}
	else 
		return (0);
}

/*********************************************************************
 * Function:        void CANSend(NEAR unsigned char txTag)
 *
 * PreCondition:   	 
 *
 * Input:       	none
 *                  
 * Output:      	none
 *
 * Side Effects:   	
 *
 * Overview:        Tell the transmit engine that the loaded data is
 *					is ready to send.
 *
 * Note:          	Data may not be sent immediately. The tag is used
 *					to trace the transmission since other data may
 *					also be queued to transmit. 	
 ********************************************************************/
void CANSend(NEAR unsigned char txTag)
{
	// Remember the message that was sent
	_msgTxTag = txTag;

	TXB0CONbits.TXREQ = 1;
}

/*********************************************************************
 * Function:        NEAR unsigned int CANGetRxCID(void)
 *
 * PreCondition:   	 
 *
 * Input:       	none
 *                  
 * Output:      	unsigned int connection ID (11-bit CAN ID)
 *
 * Side Effects:   	
 *
 * Overview:        Get the connection ID from the current receive
 *					message. 
 *
 * Note:          	The CAN ID is assumed to be left justified within
 *					the 16-bit word. 	
 ********************************************************************/
NEAR unsigned int CANGetRxCID(void)
{
	NEAR _INT cid;
	
	// Only return the lower byte
	if (_msgRxBuf == 0)
	{
		cid.bytes.LSB = RXB0SIDL;
		cid.bytes.MSB = RXB0SIDH;
	}
	else //if (_msgRxBuf == 1)
	{
		cid.bytes.LSB = RXB1SIDL;
		cid.bytes.MSB = RXB1SIDH;	
	}
	
	return (cid.word);
}

/*********************************************************************
 * Function:        NEAR unsigned char CANGetRxCnt(void)
 *
 * PreCondition:   	Data should have been received prior to calling 
 *					this function; otherwise, it is likely the returned
 *					count is either not valid or associated to the 
 *					previous message. Use CANIsRxRdy() to determine if 
 *					data is available.
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char count of the data
 *
 * Side Effects:   	
 *
 * Overview:        This function returns the number of bytes waiting
 *					in the receive buffer.
 *
 * Note:          	
 ********************************************************************/
NEAR unsigned char CANGetRxCnt(void)
{
	NEAR unsigned char count;
	
	// Read out of the selected message buffer
	if (_msgRxBuf == 0)
	{
		count = RXB0DLC;
	}
	else //if (_msgRxBuf == 1)
	{
		count = RXB1DLC;	
	}
	
	return (count);
}



/*********************************************************************
 * Function:        unsigned char * NEAR CANGetRxDataPtr(void)
 *
 * PreCondition:   	Data should have been received prior to calling 
 *					this function; otherwise, it is likely the returned
 *					pointer is either not valid or associated to the 
 *					previous message. Use CANIsRxRdy() to determine if 
 *					data is available. 
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char * 
 *
 * Side Effects:   	
 *
 * Overview:        This function returns the pointer to the RX buffer.
 *					
 * Note:          	Use the direct block copy methods for faster data
 *					movement. 	
 ********************************************************************/
unsigned char * NEAR CANGetRxDataPtr(void)
{	
	// Read out of the selected message buffer
	if (_msgRxBuf == 0)
	{
		return(&RXB0D0);
	}
	else //if (_msgRxBuf == 1)
	{
		return(&RXB1D0);	
	}
}



/*********************************************************************
 * Function:        void CANGetRxDataTyp0(unsigned char * NEAR usrBuf)
 *					void CANGetRxDataTyp1(unsigned char * NEAR usrBuf)
 *					void CANGetRxDataTyp2(unsigned char * NEAR usrBuf)
 *
 * PreCondition:   	Data should have been received prior to calling 
 *					this function; otherwise, it is likely the returned
 *					count is either not valid or associated to the 
 *					previous message. Use CANIsRxRdy() to determine if 
 *					data is available. 
 *
 * Input:       	pointer to user supplied buffer
 *                  
 * Output:      	void
 *
 * Side Effects:   	
 *
 * Overview:        Get block data from the buffer. 
 *					
 * Note:          	These functions copy blocks of data rather than 
 *					single bytes. This method is very fast; however,
 *					data limits are not checked. It is up to the 
 *					caller to verify the count to toss data that is  
 *					not valid.
 ********************************************************************/
void CANGetRxDataTyp0(unsigned char * NEAR usrBuf)
{	
	// Read out of the selected message buffer
	if (_msgRxBuf == 0)
	{
		*((_CAN_DATA_TYP0 *)usrBuf) = *((_CAN_DATA_TYP0 *)(&RXB0D0));
	}
	else //if (_msgRxBuf == 1)
	{
		*((_CAN_DATA_TYP0 *)usrBuf) = *((_CAN_DATA_TYP0 *)(&RXB1D0));	
	}
}

void CANGetRxDataTyp1(unsigned char * NEAR usrBuf)
{	
	// Read out of the selected message buffer
	if (_msgRxBuf == 0)
	{
		*((_CAN_DATA_TYP1 *)usrBuf) = *((_CAN_DATA_TYP1 *)((&RXB0D0)+1));
	}
	else //if (_msgRxBuf == 1)
	{
		*((_CAN_DATA_TYP1 *)usrBuf) = *((_CAN_DATA_TYP1 *)((&RXB1D0)+1));	
	}
}

void CANGetRxDataTyp2(unsigned char * NEAR usrBuf)
{	
	// Read out of the selected message buffer
	if (_msgRxBuf == 0)
	{
		*((_CAN_DATA_TYP2 *)usrBuf) = *((_CAN_DATA_TYP2 *)((&RXB0D0)+2));
	}
	else //if (_msgRxBuf == 1)
	{
		*((_CAN_DATA_TYP2 *)usrBuf) = *((_CAN_DATA_TYP2 *)((&RXB1D0)+2));	
	}
}



/*********************************************************************
 * Function:        void CANPutTxCID(NEAR unsigned int txCID)
 *
 * PreCondition:   	The function CANIsTxRdy() must be called prior
 *					to using this function; otherwise, the previous
 *					transmission request may be corrupted. 
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char * 
 *
 * Side Effects:   	
 *
 * Overview:        Write the CID to the TX buffer.
 *					
 * Note:          	 	
 ********************************************************************/
void CANPutTxCID(NEAR unsigned int txCID)
{
	NEAR _INT temp;

	temp.word = txCID;

	// Write the CID to the buffer
	TXB0SIDL = temp.bytes.LSB;
	TXB0SIDH = temp.bytes.MSB;
}



/*********************************************************************
 * Function:        void CANPutTxCnt(NEAR unsigned char txCount)
 *
 * PreCondition:   	The function CANIsTxRdy() must be called prior
 *					to using this function; otherwise, the previous
 *					transmission request may be corrupted.  
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char * 
 *
 * Side Effects:   	
 *
 * Overview:        Write the count to the TX buffer.
 *					
 *
 * Note:          	 	
 ********************************************************************/
void CANPutTxCnt(NEAR unsigned char txCount)
{
	TXB0DLC = txCount & 0x0F;
}


/*********************************************************************
 * Function:        unsigned char * NEAR CANGetTxDataPtr(void)
 *
 * PreCondition:   	The function CANIsTxRdy() must be called prior
 *					to using this function; otherwise, the pointer
 *					may be invalid.
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char * 
 *
 * Side Effects:   	
 *
 * Overview:        Return a pointer to the buffer.
 *					
 *
 * Note:          	 	
 ********************************************************************/
unsigned char * NEAR CANGetTxDataPtr(void)
{
	return (&TXB0D0);
}


/*********************************************************************
 * Function:        void CANPutTxDataTyp0(unsigned char * NEAR usrBuf)
 *					void CANPutTxDataTyp1(unsigned char * NEAR usrBuf)
 *					void CANPutTxDataTyp2(unsigned char * NEAR usrBuf)
 *
 * PreCondition:   	The function CANIsTxRdy() must be called prior
 *					to using this function; otherwise, the previous
 *					transmission request may be corrupted.  
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char * 
 *
 * Side Effects:   	
 *
 * Overview:        Put a block of data in the TX buffer.
 *					
 * Note:          	Copying a block into the buffer does not imply
 *					that the entire block must be transmitted. This
 *					function mearly loads the data into the buffer
 *					following the specified format TYP0, TYP1, or TYP2. 	
 ********************************************************************/
void CANPutTxDataTyp0(unsigned char * NEAR usrBuf)
{
	*((_CAN_DATA_TYP0 *)((&TXB0D0))) = *((_CAN_DATA_TYP0 *)usrBuf);
}

void CANPutTxDataTyp1(unsigned char * NEAR usrBuf)
{
	*((_CAN_DATA_TYP1 *)((&TXB0D0)+1)) = *((_CAN_DATA_TYP1 *)usrBuf);
}

void CANPutTxDataTyp2(unsigned char * NEAR usrBuf)
{
	*((_CAN_DATA_TYP2 *)((&TXB0D0)+2)) = *((_CAN_DATA_TYP2 *)usrBuf);
}



/*********************************************************************
 * Function:        void CANInit(void)
 *
 * PreCondition:   	 
 *
 * Input:       	none
 *                  
 * Output:      	unsigned char * 
 *
 * Side Effects:  	Filters are removed. 	
 *
 * Overview:        Initialize the module.
 *					
 * Note:          	
 ********************************************************************/
void CANInit(void)
{
	CANClose();
	
	// Init some internal control registers
	_msgTxTag = 0;
	_msgRxBuf = 0;

	// Init device specific hardware for CAN
	CIOCON = 0x20;		
	LATBbits.LATB2 = 1;
	TRISBbits.TRISB2 = 0;
	TRISBbits.TRISB3 = 1;
	
	RXM0SIDH = 0xFF;
	RXM0SIDL = 0xFF;
	RXM1SIDH = 0xFF;
	RXM1SIDL = 0xFF;
	RXF0SIDL = 0xFF;
	RXF1SIDL = 0xFF;
	RXF2SIDL = 0xFF;
	RXF3SIDL = 0xFF;
	RXF4SIDL = 0xFF;
	RXF5SIDL = 0xFF;
	
	RXB0CON = 0x20;
	RXB1CON = 0x20;
}