//******************************************************************************
//
// File Name		: 'spi.c'
// Author		: Skytrack ltd - Copyright (C) 2008
// Created		: 12/07/2008
// Version		: 1.0
//
// This code is property of Skytrack company
//
//******************************************************************************

#include <iom48.h>
#include "spi.h"

void SPI_MasterInit(void)
{
	DDR_SPI |= (1 << DD_MOSI)|(1 << DD_SCK)|(1 << DD_SS);
	DDR_SPI &= ~(1 << DD_MISO);
	SPCR = (1 << SPE)|(1 << MSTR);
	//SPSR |= (1 << SPI2X);
}

char SPI_MasterTransmit(char cData)
{
	SPDR = cData;
	while(!(SPSR & (1<<SPIF)));
	return SPDR;
}

//end

//******************************************************************************
//
// File Name		: 'spi.h'
// Author		: Skytrack ltd - Copyright (C) 2008
// Created		: 12/07/2008
// Version		: 1.0
//
// This code is property of Skytrack company
//
//******************************************************************************

#ifndef SPI_H

#define SPI_H

#define DDR_SPI	DDRB
#define DD_SS	PB2
#define DD_MOSI	PB3
#define DD_MISO	PB4
#define DD_SCK	PB5

void SPI_MasterInit(void);
char SPI_MasterTransmit(char cData);

#endif

//end


//******************************************************************************
//
// File Name		: 'mcp2515.c'
// Author		: Skytrack ltd - Copyright (C) 2008
// Created		: 12/07/2008
// Version		: 1.0
//
// This code is property of Skytrack company
//
//******************************************************************************

#include <iom48.h>
#include <intrinsics.h>
#include "mcp2515.h"
#include "spi.h"

#define CS_LOW	PORTB &= ~(1 << PB2);
#define CS_HIGH	PORTB |= (1 << PB2);

void MCP2515_Init()
{
 	DDRD |= (1 << PD7);
	PORTD |= (1 << PD7);
	DDRB |= (1 << PB2);	
	CS_HIGH;
}

void MCP2515_SoftReset()
{
	CS_LOW;
	SPI_MasterTransmit(MCP2515_RESET);		
	CS_HIGH;
}

void MCP2515_HardReset()
{
	PORTD |= (1 << PD7);
	__delay_cycles(1600000);
	PORTD &= ~(1 << PD7);
	__delay_cycles(1600000);
	PORTD |= (1 << PD7);
	__delay_cycles(1600000);
}

unsigned char MCP2515_Read(unsigned char address)
{
	unsigned char nResult;
	CS_LOW;
	SPI_MasterTransmit(MCP2515_READ);		
	SPI_MasterTransmit(address);		
	nResult = SPI_MasterTransmit(0);
	CS_HIGH;
	return nResult;
}

void MCP2515_Write(unsigned char address, unsigned char data)
{	
	CS_LOW;
	SPI_MasterTransmit(MCP2515_WRITE);		
	SPI_MasterTransmit(address);		
	SPI_MasterTransmit(data);		
	CS_HIGH;
}

unsigned char MCP2515_ReadStatus()
{	
	unsigned char nResult;
	CS_LOW;
	SPI_MasterTransmit(MCP2515_STATUS);		
	nResult = SPI_MasterTransmit(0);		
	CS_HIGH;
	return nResult;
}

void MCP2515_BitMod(unsigned char address, unsigned char mask, unsigned char data)
{
	CS_LOW;
	SPI_MasterTransmit(MCP2515_BITMOD);		
	SPI_MasterTransmit(address);		
	SPI_MasterTransmit(mask);		
	SPI_MasterTransmit(data);		
	CS_HIGH;
}

void MCP2515_Rts(unsigned char TXBn)
{
	unsigned char RTS_Value = MCP2515_RTS | TXBn;
	CS_LOW;
	SPI_MasterTransmit(RTS_Value);		
	CS_HIGH;
}

void MCP2515_Set_Config_Mode()
{
	do {
		MCP2515_BitMod(0x0F, 0xE0, 0x80);
	} while ((MCP2515_Read(0x0E) & 0xE0) != 0x80);
}

void MCP2515_Set_Listen_Mode()
{
	MCP2515_BitMod(0x0F, 0xE0, 0x60);
}

void MCP2515_Set_Normal_Mode()
{
	do {
		MCP2515_BitMod(0x0F, 0xE0, 0x80);
		MCP2515_BitMod(0x0F, 0xE0, 0x00);
	} while(MCP2515_Read(0x0E) & 0xE0);
}

void MCP2515_Set_Sleep_Mode()
{
	do {
		MCP2515_BitMod(0x0F, 0xE0, 0x80);
		MCP2515_BitMod(0x0F, 0xE0, 0x00);
	} while(MCP2515_Read(0x0E) & 0xE0);
}

// end

Ну и открывок кода

		__watchdog_reset();	
		MCP2515_HardReset();
		__watchdog_reset();	
		MCP2515_Set_Config_Mode();

		TRACE("MCP2515 IS IN CONFIG MODE\r\n");
	
		// Disable ClkOut
		MCP2515_BitMod(CANCTRL, 0x07, 0x00);   
		
		// Configure input buffers
		MCP2515_Write(RXB0CTRL, 0x00);        
		MCP2515_Write(RXB1CTRL, 0x00);        

		// Receive buffer 1 will no be used during this lab
		MCP2515_Write(RXM1SIDH, 0xFF);        
		MCP2515_Write(RXM1SIDL, 0xE0);     
		MCP2515_Write(RXF2SIDH, 0x00);
		MCP2515_Write(RXF2SIDL, 0x00);
		MCP2515_Write(RXF3SIDH, 0x00);
		MCP2515_Write(RXF3SIDL, 0x00);
		MCP2515_Write(RXF4SIDH, 0x00);
		MCP2515_Write(RXF4SIDL, 0x00);
		MCP2515_Write(RXF5SIDH, 0x00);
		MCP2515_Write(RXF5SIDL, 0x00);
		
		if (nVehicle == VEHICLE_MERCEDES) 
		{
			// Set speed
			MCP2515_Write(CNF1, 0x4B);
			MCP2515_Write(CNF2, 0x8A);
			MCP2515_Write(CNF3, 0x01);
	
			MCP2515_Write(RXM0SIDH, 0xFF);        
			MCP2515_Write(RXM0SIDL, 0xE0);        
			MCP2515_Write(RXF0SIDH, 0x39);
			MCP2515_Write(RXF0SIDL, 0x40);
			MCP2515_Write(RXF1SIDH, 0xFF);
			MCP2515_Write(RXF1SIDL, 0xE0);
		}
   
		// Disable all MCP2515 interrupts
		MCP2515_Write(CANINTE, 0x00);					

		__watchdog_reset();
		// Put MCP2515 into Normal Mode
		TRACE("MCP2515 TRY NORMAL MODE\r\n");
		MCP2515_Set_Normal_Mode();
		TRACE("MCP2515 IS IN NORMAL MODE\r\n");

чтение - в цикле

			if (MCP2515_ReadStatus() & 0x01) {
				unsigned char sidh = MCP2515_Read(RXB0SIDH);
				unsigned char sidl = MCP2515_Read(RXB0SIDL);
				unsigned char d0   = MCP2515_Read(RXB0D0);
				unsigned char d1   = MCP2515_Read(RXB0D1);