File content as of revision 0:d8f50b1e384f:

/******************************************************************************
 * 
 * Controller Area Network (CAN) Demo-Application
 * Atmel AVR with Microchip MCP2515 
 * 
 * Copyright (C) 2005 Martin THOMAS, Kaiserslautern, Germany
 * <eversmith@heizung-thomas.de>
 * http://www.siwawi.arubi.uni-kl.de/avr_projects
 *
 *****************************************************************************
 *
 * File    : mcp2515.c
 * Version : 0.9
 * 
 * Summary : MCP2515 "low-level" driver
 *
 * Parts of this code are adapted from a MCP2510 sample-application 
 * by KVASER AB, http://www.kvaser.com (KVASER-code is marked as free)
 *
 * This code-module is free to use but you have to keep the copyright
 * notice.
 *
 *
 *****************************************************************************
 *
 * File    : mcp2515.cpp (mbed LPC1768 version)
 * Version : 0.1
 *
 * All credits to the nerds above, this source has been adapted for the 
 * LPC1768 platform by J.Engelman. And does'nt require and of the copyrighted
 * SPI or AVR controller code that Martin or co have excluded copyright.
 * This module remains free.
 *
 *
 *****************************************************************************/

#include "mcp2515.h"

#include <mbed.h>
#include "mcp2515_can.h"
#include "mcp2515_defs.h"
#include "mcp2515_bittime.h"

#define SPI_NULL (0x00)



mcp2515::mcp2515(PinName mosi, PinName miso, PinName clk, PinName ncs)
        : _spi(mosi, miso, clk), _ncs(ncs) {

     // _spi.format(8,0);
     // _spi.frequency(10000000);
    //_spi.frequency(5000000);

}


void mcp2515::_reset() {

    _select();
    _spi_readwrite(MCP_RESET);
    _deselect();
    wait(0.001);
}

void mcp2515::setRegister(const uint8_t address, const uint8_t value)
{
    _select();
    _spi_readwrite(MCP_WRITE);
    _spi_readwrite(address);
    _spi_readwrite(value);
    _deselect();
}

uint8_t mcp2515::configRate(const uint8_t canSpeed)
{
    uint8_t set, cfg1, cfg2, cfg3;
    
    set = 0;
    
    switch (canSpeed) {
        case (CAN_125KBPS) :
            cfg1 = MCP_4MHz_125kBPS_CFG1 ;
            cfg2 = MCP_4MHz_125kBPS_CFG2 ;
            cfg3 = MCP_4MHz_125kBPS_CFG3 ;
            set = 1;
            break;
        case (CAN_20KBPS) :
            cfg1 = MCP_4MHz_20kBPS_CFG1 ;
            cfg2 = MCP_4MHz_20kBPS_CFG2 ;
            cfg3 = MCP_4MHz_20kBPS_CFG3 ;
            set = 1;
            break;
        default:
            set = 0;
            break;
    }
    
    if (set) {
        setRegister(MCP_CNF1, cfg1);
        setRegister(MCP_CNF2, cfg2);
        setRegister(MCP_CNF3, cfg3);
        return MCP2515_OK;
    }
    else {
        return MCP2515_FAIL;
    }
} 

uint8_t mcp2515::readRegister(const uint8_t address)
{
    uint8_t ret;
    
    _select();
    _spi_readwrite(MCP_READ);
    _spi_readwrite(address);
    ret = _spi_read();
    _deselect();
    
    return ret;
}

void mcp2515::readRegisterS(const uint8_t address, 
    uint8_t values[], const uint8_t n)
{
    uint8_t i;
    
    _select();
    _spi_readwrite(MCP_READ);
    _spi_readwrite(address);
    // mcp2515 has auto-increment of address-pointer
    for (i=0; i<n; i++) {
        values[i] = _spi_read();
    }
    _deselect();
}

void mcp2515::modifyRegister(const uint8_t address, 
    const uint8_t mask, const uint8_t data)
{
    _select();
    _spi_readwrite(MCP_BITMOD);
    _spi_readwrite(address);
    _spi_readwrite(mask);
    _spi_readwrite(data);
    _deselect();
}


uint8_t mcp2515::readXXStatus_helper(const uint8_t cmd)
{
    uint8_t i;
    
    _select();
    _spi_readwrite(cmd);
    i = _spi_read();
    _deselect();
    
    return i;
}
    
uint8_t mcp2515::readStatus(void)
{
    return readXXStatus_helper(MCP_READ_STATUS);
}

uint8_t mcp2515::RXStatus(void)
{
    return readXXStatus_helper(MCP_RX_STATUS);
}

// read-modify-write - better: Bit Modify Instruction
uint8_t mcp2515::setCANCTRL_Mode(uint8_t newmode)
{
    uint8_t i;
    
    i = readRegister(MCP_CANCTRL);
    i &= ~(MODE_MASK);
    i |= newmode;
    setRegister(MCP_CANCTRL, i);
    
    // verify as advised in datasheet
    i = readRegister(MCP_CANCTRL);
    i &= MODE_MASK;
    if ( i == newmode ) {
        return MCP2515_OK; 
    }
    else {
        return MCP2515_FAIL;
    }
}


void mcp2515::setRegisterS(const uint8_t address, 
    const uint8_t values[], const uint8_t n)
{
    uint8_t i;
    
    _select();
    _spi_readwrite(MCP_WRITE);
    _spi_readwrite(address);
    // mcp2515 has auto-increment of address-pointer
    for (i=0; i<n; i++) {
        _spi_readwrite(values[i]);
    }
    _deselect();
}

void mcp2515::read_can_id( const uint8_t mcp_addr, 
    uint8_t* ext, uint32_t* can_id )
{
    uint8_t tbufdata[4];
    
    *ext = 0;
    *can_id = 0;
    
    readRegisterS( mcp_addr, tbufdata, 4 );
    
    *can_id = (tbufdata[MCP_SIDH]<<3) + (tbufdata[MCP_SIDL]>>5);
    
    if ( (tbufdata[MCP_SIDL] & MCP_TXB_EXIDE_M) ==  MCP_TXB_EXIDE_M ) {
        // extended id
        *can_id = (*can_id<<2) + (tbufdata[MCP_SIDL] & 0x03);
        *can_id <<= 16;
        *can_id = *can_id +(tbufdata[MCP_EID8]<<8) + tbufdata[MCP_EID0];
        *ext = 1;
    }
}


// Buffer can be MCP_RXBUF_0 or MCP_RXBUF_1
void mcp2515::read_canMsg( const uint8_t buffer_sidh_addr,
    CANMessage* msg)
{
/*
    uint8_t mcp_addr, ctrl;

    mcp_addr = buffer_sidh_addr;
    
    read_can_id( mcp_addr, &(msg->extended_identifier), 
        &(msg->identifier) );
    
    ctrl = readRegister( mcp_addr-1 );
    msg->dlc = readRegister( mcp_addr+4 );
    
    //if ((*dlc & RTR_MASK) || (ctrl & 0x08)) {
    if ((ctrl & 0x08)) {
        msg->rtr = 1;
    } else {
        msg->rtr = 0;
    }
    
    msg->dlc &= MCP_DLC_MASK;
    readRegisterS( mcp_addr+5, &(msg->dta[0]), msg->dlc );
    */
}


void mcp2515::write_can_id( const uint8_t mcp_addr, 
    const uint8_t ext, const uint32_t can_id )
{
    uint16_t canid;
    uint8_t tbufdata[4];
    
    canid = (uint16_t)(can_id & 0x0FFFF);
    
    if ( ext == 1) {
        tbufdata[MCP_EID0] = (uint8_t) (canid & 0xFF);
        tbufdata[MCP_EID8] = (uint8_t) (canid / 256);
        canid = (uint16_t)( can_id / 0x10000L );
        tbufdata[MCP_SIDL] = (uint8_t) (canid & 0x03);
        tbufdata[MCP_SIDL] += (uint8_t) ((canid & 0x1C )*8);
        tbufdata[MCP_SIDL] |= MCP_TXB_EXIDE_M;
        tbufdata[MCP_SIDH] = (uint8_t) (canid / 32 );
    }
    else {
        tbufdata[MCP_SIDH] = (uint8_t) (canid / 8 );
        tbufdata[MCP_SIDL] = (uint8_t) ((canid & 0x07 )*32);
        tbufdata[MCP_EID0] = 0;
        tbufdata[MCP_EID8] = 0;
    }
    setRegisterS( mcp_addr, tbufdata, 4 );
}

// Buffer can be MCP_TXBUF_0 MCP_TXBUF_1 or MCP_TXBUF_2
void mcp2515::write_canMsg( const uint8_t buffer_sidh_addr, 
     CANMessage* msg)
{
    uint8_t mcp_addr, dlc;

    mcp_addr = buffer_sidh_addr;
    dlc = msg->len;
    
    setRegisterS(mcp_addr+5, &(msg->data[0]), dlc );  // write data bytes
    write_can_id( mcp_addr, msg->format,
        msg->id );  // write CAN id
    if ( msg->type == 1)  dlc |= MCP_RTR_MASK;  // if RTR set bit in byte
    setRegister( (mcp_addr+4), dlc );  // write the RTR and DLC
}

void mcp2515::start_transmit(const uint8_t buffer_sidh_addr)
{
	// TXBnCTRL_addr = TXBnSIDH_addr - 1
   modifyRegister( buffer_sidh_addr-1 , MCP_TXB_TXREQ_M, 
		MCP_TXB_TXREQ_M );
}

uint8_t mcp2515::getNextFreeTXBuf(uint8_t *txbuf_n)
{
	uint8_t res, i, ctrlval;
	uint8_t ctrlregs[MCP_N_TXBUFFERS] = { MCP_TXB0CTRL, MCP_TXB1CTRL, MCP_TXB2CTRL };
	
	res = MCP_ALLTXBUSY;
	*txbuf_n = 0x00;
	
	// check all 3 TX-Buffers
	for (i=0; i<MCP_N_TXBUFFERS; i++) {
		ctrlval = readRegister( ctrlregs[i] );
		if ( (ctrlval & MCP_TXB_TXREQ_M) == 0 ) {

			*txbuf_n = ctrlregs[i]+1; // return SIDH-address of Buffer
			res = MCP2515_OK;
			return res; /* ! function exit */
		}
	}
	
	return res;
}

void mcp2515::initCANBuffers(void)
{
    uint8_t i, a1, a2, a3;
    
    // TODO: check why this is needed to receive extended 
    //   and standard frames
    // Mark all filter bits as don't care:
    write_can_id(MCP_RXM0SIDH, 0, 0);
    write_can_id(MCP_RXM1SIDH, 0, 0);
    // Anyway, set all filters to 0:
    write_can_id(MCP_RXF0SIDH, 1, 0); // RXB0: extended 
    write_can_id(MCP_RXF1SIDH, 0, 0); //       AND standard
    write_can_id(MCP_RXF2SIDH, 1, 0); // RXB1: extended 
    write_can_id(MCP_RXF3SIDH, 0, 0); //       AND standard
    write_can_id(MCP_RXF4SIDH, 0, 0);
    write_can_id(MCP_RXF5SIDH, 0, 0);
    
    // Clear, deactivate the three transmit buffers
    // TXBnCTRL -> TXBnD7
    a1 = MCP_TXB0CTRL;
    a2 = MCP_TXB1CTRL;
    a3 = MCP_TXB2CTRL;
    for (i = 0; i < 14; i++) { // in-buffer loop
        setRegister(a1, 0);
        setRegister(a2, 0);
        setRegister(a3, 0);
        a1++;
        a2++;
        a3++;
    }
    
    // and clear, deactivate the two receive buffers.
    setRegister(MCP_RXB0CTRL, 0);
    setRegister(MCP_RXB1CTRL, 0);
}

uint8_t mcp2515::init(const uint8_t canSpeed)
{
    uint8_t res;
    
    _deselect();
    //MCP_CS_DDR |= ( 1 << MCP_CS_BIT );
    
    _reset();
    
    res = setCANCTRL_Mode(MODE_CONFIG);
    
    if ( res == MCP2515_FAIL ){
     printf("FAIL here");
     return res;  /* function exit on error */
    }
    res = configRate(canSpeed);
    
    if ( res == MCP2515_OK ) {
        initCANBuffers();
        

        // enable both receive-buffers to receive messages
        // with std. and ext. identifiers
        // and enable rollover
        modifyRegister(MCP_RXB0CTRL, 
            MCP_RXB_RX_MASK | MCP_RXB_BUKT_MASK, 
            MCP_RXB_RX_STDEXT | MCP_RXB_BUKT_MASK );
        modifyRegister(MCP_RXB1CTRL, MCP_RXB_RX_MASK, 
            MCP_RXB_RX_STDEXT);

    }
    
    return res;
}

/*
 * Select function
 */
 
void mcp2515::_select() {
//printf("{");
    _ncs = 0;
}


/*
 * Deselect function
 */

void mcp2515::_deselect() {
    _ncs = 1;
//printf("}");
}

int mcp2515::status() {
    int status = 0;
    _select();
    _spi.write(0xd7);
    status = (_spi.write(0x00) << 8 );
    status |= _spi.write(0x00);
    _deselect();
    return status;
}

void mcp2515::_pollbusy() {
    volatile int busy = 1;
    while (busy) {
        // if bit 7 is set, we can proceed
        if ( status() & 0x80 ) {
            busy = 0;
        }
    }
}


uint8_t mcp2515::_spi_readwrite(uint8_t data)
{
     //printf("W0x%x ", data);
      uint8_t ret = _spi.write(data);
       //     printf("R0x%x,", ret);
    return ret;
}

uint8_t mcp2515::_spi_read(void)
{
    return _spi_readwrite(SPI_NULL);
}