gistfile1.cpp

// -------------------------------------------------------------------------
// Schreibt/liest ein Byte ueber den Hardware SPI Bus

uint8_t spi_putc( uint8_t data )
{
  // put byte in send-buffer
  SPDR = reverse_byte(data); // Reverse byte flips the bits in the byte to simulate a MSB SPI_mode 
  
	// wait until byte was send
	while( !( SPSR & (1<<SPIF) ) )
		;
	
  /*return SPDR;*/
  return reverse_byte(SPDR);
}
// -------------------------------------------------------------------------
void mcp2515_write_register( uint8_t adress, uint8_t data )
{
	RESET(MCP2515_CS);
	
	spi_putc(SPI_WRITE);
	spi_putc(adress);
	spi_putc(data);
	
	SET(MCP2515_CS);
}

// -------------------------------------------------------------------------
uint8_t mcp2515_read_register(uint8_t adress)
{
	uint8_t data;
	
	RESET(MCP2515_CS);
	
	spi_putc(SPI_READ);
	spi_putc(adress);
	
	data = spi_putc(0xff);	
	
	SET(MCP2515_CS);
	
	return data;
}

// -------------------------------------------------------------------------
void mcp2515_bit_modify(uint8_t adress, uint8_t mask, uint8_t data)
{
	RESET(MCP2515_CS);
	
	spi_putc(SPI_BIT_MODIFY);
	spi_putc(adress);
	spi_putc(mask);
	spi_putc(data);
	
	SET(MCP2515_CS);
}

// ----------------------------------------------------------------------------
uint8_t mcp2515_read_status(uint8_t type)
{
	uint8_t data;
	
	RESET(MCP2515_CS);
	
	spi_putc(type);
	data = spi_putc(0xff);
	
	SET(MCP2515_CS);
	
	return data;
}

// -------------------------------------------------------------------------
uint8_t mcp2515_init(uint8_t speed)
{
		
	
	SET(MCP2515_CS); // Digital pin 10
	SET_OUTPUT(MCP2515_CS); // Digital pin 10
	
  /*RESET(P_SCK);*/
  /*RESET(P_MOSI);*/
  /*RESET(P_MISO);*/
	
  /*SET_OUTPUT(P_SCK);*/
  /*SET_OUTPUT(P_MOSI);*/
	/*SET_INPUT(P_MISO);*/
	
	SET_INPUT(MCP2515_INT); // Digital pin 2
	SET(MCP2515_INT); // Digital pin 2
	
	// active SPI master interface
	/*SPCR = (1<<SPE)|(1<<MSTR) | (0<<SPR1)|(1<<SPR0);*/
	/*SPSR = 0;*/
	
	// reset MCP2515 by software reset.
	// After this he is in configuration mode.
	RESET(MCP2515_CS);
	spi_putc(SPI_RESET);
	SET(MCP2515_CS);
	
	// wait a little bit until the MCP2515 has restarted
	_delay_us(10);
	
	// load CNF1..3 Register
	RESET(MCP2515_CS);
	spi_putc(SPI_WRITE);
	spi_putc(CNF3);
	
/*	spi_putc((1<<PHSEG21));		// Bitrate 125 kbps at 16 MHz
	spi_putc((1<<BTLMODE)|(1<<PHSEG11));
	spi_putc((1<<BRP2)|(1<<BRP1)|(1<<BRP0));
*/
/*	
	spi_putc((1<<PHSEG21));		// Bitrate 250 kbps at 16 MHz
	spi_putc((1<<BTLMODE)|(1<<PHSEG11));
	spi_putc((1<<BRP1)|(1<<BRP0));
*/	
	spi_putc((1<<PHSEG21));		// Bitrate 250 kbps at 16 MHz
	spi_putc((1<<BTLMODE)|(1<<PHSEG11));
	//spi_putc(1<<BRP0);
    spi_putc(speed);

	// activate interrupts
	spi_putc((1<<RX1IE)|(1<<RX0IE));
	SET(MCP2515_CS);
	
	// test if we could read back the value => is the chip accessible?
	if (mcp2515_read_register(CNF1) != speed) {
		/*SET(LED2_HIGH);*/

		return false;
	}
	
	// deaktivate the RXnBF Pins (High Impedance State)
	mcp2515_write_register(BFPCTRL, 0);
	
	// set TXnRTS as inputs
	mcp2515_write_register(TXRTSCTRL, 0);
	
	// turn off filters => receive any message
	mcp2515_write_register(RXB0CTRL, (1<<RXM1)|(1<<RXM0));
	mcp2515_write_register(RXB1CTRL, (1<<RXM1)|(1<<RXM0));
	
	// reset device to normal mode
	mcp2515_write_register(CANCTRL, 0);
//	SET(LED2_HIGH);
	return true;
}