Module for communicating with C_CAN device on C8051F500 and other

C_CAN.c

/*
	Module for communicating with C_CAN device on C8051F500 and F580.
*/

#include "myPlatform.h"
#define __C_CAN_H 1
#	include "C_CAN.h"
#undef __C_CAN_H

// CAN0STAT masks
#define BOff	0x80		// Busoff Status
#define EWarn	0x40		// Warning Status
#define EPass	0x20		// Error Passive
#define RxOk	0x10		// Receive Message Successfully
#define TxOk	0x08		// Transmitted Message Successfully
#define LEC		0x07		// Last Error Code

// breaks between write-read pairs
#define CAN_nop()	NOP();NOP();NOP();NOP()

#ifdef CAN0_PAGE
void CAN0_init(void)
{
unsigned char SFRPAGE_save = SFRPAGE;
	SFRPAGE = CAN0_PAGE;
	CAN0CN = 1;						// start Intialization mode
	CAN_nop();						// wait
	// initialize general CAN peripheral settings
	CAN0CN |= 0x4E;					// enable Error, Module and access to bit timing register
	CAN_nop();						// wait
	CAN0BT = 0x1402;				// based on 24 Mhz CAN clock, set the CAN bit rate to 1 Mbps
	CAN0CN |= 0x80;					// enable test mode
	CAN_nop();						// wait
	CAN0TST = 0x04;					// enalbe basic mode
	// CAN initalization is complete
	CAN0CN &= ~0x41;				// return to Normal Mode and disable access to bit timing register
	
	SFRPAGE = SFRPAGE_save;
}

void CAN0_send(CAN_message_t *m)
{
unsigned char SFRPAGE_save = SFRPAGE;
unsigned short _A2, _A1;			// temporary arbitration regs
	SFRPAGE = CAN0_PAGE;

	// message control register
	CAN0IF1MC = 0x1480 | m->Length;

	// command request and mask registers
	CAN0IF1CR = 0x0000;
	CAN0IF1CM = 0x00F3;

	// arbitration registers
	if (m->Extended)
	{	// extended frame
		m->ID &= 0x1FFFFFFF;
		_A1 = m->ID;			// lower half of id
		_A2 = (m->ID >> 16);	// upper half of id
		_A2 |= 0x4000;		// set extended flag
	}
	else
	{	// standard frame
		m->ID &= 0x000007FF;
		_A1 = 0;
		_A2 = (m->ID << 2);	// id fits in bits 28-18
	}

	if (m->Remote)
		_A2 &= ~0x2000;		// a remote frame
	else
		_A2 |= 0x2000;		// not a remote frame
	
	CAN0IF1A1 = _A1;
	CAN0IF1A2 = _A2;

	// data registers 
	CAN0IF1DA1H = m->Data[0];	CAN0IF1DA1L = m->Data[1];
	CAN0IF1DA2H = m->Data[2];	CAN0IF1DA2L = m->Data[3];
	CAN0IF1DB1H = m->Data[4];	CAN0IF1DB1L = m->Data[5];
	CAN0IF1DB2H = m->Data[6];	CAN0IF1DB2L = m->Data[7];

	// send message
	CAN0IF1CM = 0x0087;				// set Direction to Write TxRqst
	CAN0IF1CR = 0x8000;				// start command request
	CAN_nop();
	while (CAN0IF1CRH & 0x80) {}	// poll on Busy bit
	
	SFRPAGE = SFRPAGE_save;
}

#ifdef CAN0_RAW
void CAN0_send_raw(long id, unsigned char *msg, unsigned char len)
{
unsigned char SFRPAGE_save = SFRPAGE;
short	idN = id & 0x07FF;
long	idX = id & 0x1FFFFFFF;
unsigned short _A2, _A1;			// temporary arbitration regs
	SFRPAGE = CAN0_PAGE;

	// message control register
	CAN0IF1MC = 0x1480 | (len & 0x0F);

	// command request and mask registers
	CAN0IF1CR = 0x0000;
	CAN0IF1CM = 0x00F3;

	// arbitration registers
	if (idN != id)
	{	// extended frame
		_A1 = idX;					// lower half of id
		_A2 = (idX >> 16);			// upper half of id
		_A2|= 0x4000;				// set extended flag
	}
	else
	{	// standard frame
		_A1 = 0;
		_A2 = (idN << 2);			// id fits in bits 28-18
	}
	_A2 |= 0x2000;					// not a remote frame

	CAN0IF1A1 = _A1;
	CAN0IF1A2 = _A2;

	// data registers 
	CAN0IF1DA1H = msg[0];	CAN0IF1DA1L = msg[1];
	CAN0IF1DA2H = msg[2];	CAN0IF1DA2L = msg[3];
	CAN0IF1DB1H = msg[4];	CAN0IF1DB1L = msg[5];
	CAN0IF1DB2H = msg[6];	CAN0IF1DB2L = msg[7];

	// send message
	CAN0IF1CM = 0x0087;				// set Direction to Write TxRqst
	CAN0IF1CR = 0x8000;				// start command request
	CAN_nop();
	while (CAN0IF1CRH & 0x80) {}	// poll on Busy bit

	SFRPAGE = SFRPAGE_save;
}
#endif

void CAN0_ISR(void) interrupt INTERRUPT_CAN0
{	// SFRPAGE is set to CAN0_Page automatically when ISR starts
unsigned char status;
long _arb;
CAN_message_t *m = &CAN0_receive;
//unsigned char Interrupt_ID;
	
	status = CAN0STAT;				// read status, which clears the Status Interrupt bit pending in CAN0IID
	
	CAN0IF2CM = 0x007F;				// read all of message object to IF2 Clear IntPnd and newData
	CAN_nop();
	while (CAN0IF2CRH & 0x80) {}	// poll on Busy bit

	if (status & RxOk)
	{	// receive completed successfully
		_arb = ((long)CAN0IF2A2 << 16) | CAN0IF2A1;

		m->Extended = (_arb >> 30) & 1;
		
		m->Remote = (_arb >> 29) & 1;

		if(m->Extended)
			m->ID = (_arb & 0x1FFFFFFF);
		else
			m->ID = ((_arb >> 18) & 0x07FF);

		// retreive the number of bytes in the packet (upto 8)
		m->Length = (CAN0IF2MCL & 0x0F);
		
		// copy message into CAN0rx;
		m->Data[0] = CAN0IF2DA1L;	m->Data[1] = CAN0IF2DA1H;
		m->Data[2] = CAN0IF2DA2L;	m->Data[3] = CAN0IF2DA2H;
		m->Data[4] = CAN0IF2DB1L;	m->Data[5] = CAN0IF2DB1H;
		m->Data[6] = CAN0IF2DB2L;	m->Data[7] = CAN0IF2DB2H;

		CAN0_received = 1;			// indicate recieved
	}

	// if an error occured, simply update the global variable and continue
	if (status & LEC)
	{	// the LEC bits identify the type of error, but those are grouped here
		if ((status & LEC) != 0x07)
		{
			CAN0_error = 1;
		}
	}
	if (status & BOff)
	{
		CAN0_error = 1;
	}
	if (status & EWarn)
	{
		CAN0_error = 1;
	}
}
#else	// CAN0_PAGE
#error	CAN0 not defined (check myPlatform includes the correct target definitions)
#endif	// CAN0_PAGE

C_CAN.h

/*
	Module for communicating with C_CAN device on C8051F500 and F580.
	
	NB: make sure init.c:CAN_Init() sets the clock to below 25Mhz (and enable CAN0_interrupt)
	USAGE:
		to send a CAN packet, fill in CAN0_transmit with the desired state and call 
			CAN0_send(&CAN0_transmit);
		on the arrival of a message, the interrupt will fill CAN0_receive and set CAN0_received 
			to a truthy value, which can be checked in your main loop. Example loop:
	while(1)
	{
		if(CAN0_received == 1)
		{
			CAN_message_t *m = &CAN0_receive;
			if(m->Remote == 1)
			{
				m->Remote = 0;
				CAN0_send(m);
			}
			CAN0_received = 0;
		}
	}
			will reply to remote frames with random data.
*/

// magic externs
#ifdef __C_CAN_H
#	define EXTERN /**/
#else
#ifdef __cplusplus
#	define EXTERN extern "C"
#else
#	define EXTERN extern
#endif	// C++
#endif	// __C_CAN_H

typedef struct CAN_MSG{
	long ID;
	unsigned char Data[8];
	char Length : 4;
	char Extended : 1;
	char Remote : 1;
} CAN_message_t;

// only define thins if there exists a C_CAN device on the processor
#ifdef CAN0_PAGE

//#define CAN0_RAW

// holds error state for CAN0
EXTERN unsigned char CAN0_error;

// true if a message has been received
EXTERN unsigned char CAN0_received;

// a received message
EXTERN CAN_message_t xdata CAN0_receive;
// a message to use for sending data
EXTERN CAN_message_t xdata CAN0_transmit;

// initialise CAN0
EXTERN void CAN0_init(void);
// send a message object
EXTERN void CAN0_send(CAN_message_t *message);
// send the `len` bytes in `*msg` with `id` as the identifier
EXTERN void CAN0_send_raw(long id, unsigned char *msg, unsigned char len);

#endif	// CAN0_PAGE

#undef EXTERN

This code is out of date, you should look at FallingBullets/C8051_lib for a more up-to-date version of this code